Maxillo, Pain EYE & ENT DNB Q & A

Dr. Azam’s

Notes in Anesthesiology

Postgraduates appearing 3rd Edition for MD, DNB & DA Exams

Maxfax, Pain, Eye, ENT & Orthopedic

Edited by: Dr. Azam Consultant Anesthesiologist & Critical Care Specialist

www.drazam.com 2 Dr Azam’s Notes in Anesthesiology 2013

Dedication

To Mohammed Shafiulla, my father, my oxygen, companion, and best friend; for being my major pillar of support and making this vision a reality. Thank you for your continual sacrifices with boundless love and limitless gratitude, for the sake of your children. I owe you a debt I can never repay.

I also would like to thank my mom (Naaz Shafi), my wife (Roohi Azam), my two lovely kids (Falaq Zohaa & Mohammed Izaan), for their support, ideas, patience, and encouragement during the many hours of writing this book.

Finally, I would like to thank my teachers (Dr.Manjunath Jajoor & team) & Dr T. A. Patil . The dream begins with a teacher who believes in you, who tugs and pushes and leads you to the next plateau, sometimes poking you with a sharp stick called "truth."

Dr Azam’s Notes in Anesthesiology 2013 Dr Azam’s Notes in Anesthesiology 2013

A NOTE TO THE READER

Anesthesiology is an ever-changing ﬁeld. Standard safety precautions must be followed, but as new research and clinical experience broaden our knowledge, changes in treatment and drug therapy may become necessary or appropriate. Readers are advised to check the most current product information provided by the manufacturer of each drug to be administered to verify the recommended dose, the method and duration of administration, and contraindications.

However, in view of the possibility of human error or changes in medical sciences, neither the author nor the publisher nor any other party who has been involved in the preparation or publication of this work warrants that the information contained herein is in every respect accurate or complete, and they disclaim all responsibility for any errors or omissions or for the results obtained from use of the information contained in this work. Readers are encouraged to conﬁrm the information contained herein with other sources. It is the responsibility of the licensed prescriber, relying on experience and knowledge of the patient, to determine dosages and the best treatment for each individual patient. Neither the publisher nor the editor assumes any liability for any injury and/or damage to persons or property arising from this publication.

Dr. Azam

Dr Azam’s Notes in Anesthesiology 2013 Contents Dr Azam’s Notes in Anesthesiology 2013

1. Maxillo-Facial Trauma & Anesthesia - 6 32.Anesthetic Management of Cleft Lip & Cleft Palate - 90 2. Anatomy of Nociception - 8 33.Polytrauma - 103 3. Pain Theories - 13 34.Tourniquet & Anesthesia - 122 4. Pain Clinic - 15 35.Tourniquet - 126 5. Patient controlled analgesia - 16 36.Grading of Nerve Injury - 128 6. Secondary Analgesia (Co-Analgesia) - 18 37.Spinal Surgery - 129 7. Adjuvant Analgesic Methods - 20 38.Total Hip Replacement - 130 8. Electrical Stimulation - 21 39.Total Knee Replacement. - 143 9. Cancer & Anesthesia - 22 40.Speciﬁc problems of Orthopedics - 145 10.Cancer Pain Management - 23 11.Neurolept Analgesia - 27 12.Post operative Management - 29 13.Complex Regional Pain Syndrome.(CPRS) - 42 14.Trigeminal Neuralgia - 45 15.Bromage Scale. (L1 - S2) - 47 16.Nitrous Oxide in Middle ear surgery - 48 17.Bleeding Tonsil - 49 18.Post tonsillectomy management - 51 19.Endoscopy & Anesthesia - 52 20.Bronchoscopy - 54 21.Fiber Optic Bronchoscopy - 55 22.Bronchography - 56 23.Foreign Body aspiration & Anesthesia - 57 24.Post extubation Stridor - 59 25.Anesthesia for Micro-laryngeal Surgery - 60 26.NO & ARDS - 66 27.Dental Anesthesia. - 67 28.Intraocular Pressure - 69 29.Keratoplasty - 71 30.Open Eye Surgery & Full Stomach - 72 31.Anesthetic for Opthalmic Surgeries - 74

Dr Azam’s Notes in Anesthesiology 2013 1. Maxillo-Facial Trauma & Anesthesia. Dr Azam’s Notes in Anesthesiology 2013

• Maxillofacial injuries are commonly seen in accident and Le Fort I: emergency department. • A horizontal fracture of the maxilla passing above the floor of the • These injuries can disturb patient ability to nose, involving the lower third of the septum. • Breath /See/Hear/Talk/Eat/Walk Anesthetic implication – • The major cause of death in facial trauma may be related to • Affords little difficulty to an anaesthesiologist. The patient may be airway obstruction. intubated orally or nasally and the airway usually is secured without • To attain patent and clear airway, the anaesthesiologists need to problem. recognize damages of soft tissue cartilaginous and bony Le Fort II: compartments in the face & skull area. • Fracture is pyramidal shaped. Facial skeleton can be divided into 3 broad compartments: • It begins at the junction of upper thick nasal bones with lower thinner 1. Lower third portion which form the upper margin of anterior nasal aperture. The • Mandible fracture crosses the medial wall of the orbit with lacrymal bone 2. Middle third passes beneath the zygomaticomaxillary suture. Crosses the lateral • Maxilla wall of antrum and traverses posteriorly through the pterygoid plates. • Zygomatic bone Anaesthetic implication: • Zygomatic process of temporal bones • Because this type of fracture involves nose, nasal intubation is • Frontal processes relatively contraindicated. One must always consider the possibility • Nasal bones and eye orbits of concomitant fracture of the base of the skull. 3. Upper third Le Fort III: • Frontal bone • The mid face is separated from the cranium. The fracture line • Fronto-zygomatic processes extends through the base of the nose and the ethmoid in its depth and through the orbital plates in proximity to cribriform plate which Mandibular fracture: may also be fractured. It crosses the lesser wing of sphenoid then Can be unilateral or bilateral seen following passes downwards to the pterigomaxillary fissure and • Road traffic accident sphenopalatine fossa. • Assassination attempt • Bimandibular “Andy Gump” fracture may cause life threatening airway occlusion or airway closure.

Facial fracture: Rene Le Fort classiﬁed facial fracture into three categories: I. Le Fort I – Maxilla (low level) II. Le Fort II – Mid face (sub zygomatic) III. Le Fort III – Separation of mid face structure from cranium.

Dr Azam’s Notes in Anesthesiology 2013 Maxillo-Facial Trauma & Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

! !"#$%&'(' !"#$%&'((' !"#$%&'(((' Rules for airway management: • Determine the absolute urgency of the situation • Consider the possibility of concurrent head injury • Consider the possibility of concurrent cervical injury • Consider the possibility of concurrent ocular injury • Remember full stomach consideration • Suspect airway obstruction by Foreign Body. Airway assessment and management: • Oxygenation by nasal prongs and face mask From the base of the inferior orbital ﬁssure, it extends laterally and • Nasal and or oropharyngeal airway upwards towards frontozygomatic suture. • LMA • Awake intubation Anaesthetic implication: • Orotracheal • Base of the skull and cribriform plate are fractured. The • Blind nasotracheal intracranial subarachnoid space may be open and • Fiber optic oro / naso tracheal intubation communicating with nasal cavity. • Cricothyroid puncture • Attempted nasotracheal intubation – serious risk of tube entering • Minitracheostomy the skull and may damage brain and other intracranial structure • Tracheostomy and also pushing contaminated foreign bodies into the skull Post operative extubation: which may cause meningitis. • Depends upon development of airway edema Common concurrent surgical problems in facial injury patients: • Post operative mechanically ventilated patient should be sedated 1. Pelvic bone fracture and opioids should be given. 2. Ruptured intra abdominal viscera. Thoracic injury - a. Pneumothorax b. - Flail chest c. - Cardiac tamponade d. - Cardiac hematoma 3. Cervical spine fracture 4. Ocular trauma Intra cranial injury - a. Extradural hematoma b. Subdural hematoma c. Intracranial hemorrhage 5. Bleeding – may be life threatening

Dr Azam’s Notes in Anesthesiology 2013 2. Anatomy of Nociception. Dr Azam’s Notes in Anesthesiology 2013

Pain pathways: - First order Neuron: • Pain is conducted along three neuron pathways that transmit • Majority of 1st order neurons send proximal end of their axons into noxious stimuli from the periphery to cerebral cortex. the spinal cord via dorsal (sensory) spinal root at each cervical, • Primary afferent neurons are located in dorsal root ganglia lie in thoracic, lumbar and sacral level. vertebral foramina at each spinal cord level. • Some unmyelinated afferent (c) fibers → enter spinal cord →via • Each neuron has a single axon that bifurcates, sending one end ventral nerve (motor) root – accounting for observations that some to the peripheral tissues it innervates and other into the dorsal patients continue to feel pain even after transaction of the dorsal horn of the spinal cord. nerve root (rhizotomy) and report pain following ventral root • In the dorsal horn, primary afferent neurons synapses with a stimulation. second order neuron – axons cross the midline and ascend in • In dorsal horn, in addition to synapsing with 2nd order neurons the 1st contralateral spinothalamic tract to reach thalamus. order neurons may synapse with interneurons, sympathetic neurons • Second order neuron synapse in thalamic nuclei with third order and ventral horn motor neurons. neurons – which in turn sends projections through the internal • Pain fibers originating from head → carried by trigeminal (v) facial capsule and corona radiate to the post central gyrus of the (VII), glossopharyngeal (IX) and vagal (x) nerves cerebral cortex. • Sensory fibres: (All the three fibres are Divisions of trigeminal neurons are in gasserian ganglion) • Ophthalmic • Maxillary • Mandibular • Sensory afferent neurons of facial are located in geniculate ganglion • Sensory afferent neurons of glossopharyngeal nerve lie in superior and petrosal ganglia • Sensory afferent of vagal nerve are located in jugular (somatic) ganglion and ganglion nodosum (visceral) • Proximal axonal processes of 1st order neurons in these ganglia reach the brain Stem via tissue respective cranial nerves, where they synapse with 2nd order neurons in brain stem nuclei.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of Nociception.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Second order Neurons: • Nociceptive specific neurons • As afferent fibers enter spinal cord →they segregate according • Serve only noxious stimuli → • Neurons are arranged somatotopically in lamina I, have • To size ,with large, myelinated fibers become medial and discrete, somatic receptive fields, normally silent, responds only • Small, unmyelinated fibers become lateral to high threshold noxious stimulation, poorly encoded stimulus • Pain fibers may ascend or descend one to three spinal cords intensity. nd segments in Lissaverʼs tract before synapses with 2 order • WDR neurons: neurons in the gray matter of ipsilateral dorsal horn. • Serve both noxious and non noxious afferent input from AB, A∂ • Spinal cord gray matter was divided by Rexed into 10 lamina and C fibres. • First 6 lamina →make Dorsal horn • Most prevalent cell type in the dorsal horn, found throughout • Receive all afferent neural activity dorsal horn • Principle site of modulation of pain by ascending & • During repeated stimulation, WDR neurons characteristically descending neural pathway . decrease in firing rate exponentially in a graded fashion (“Wind • Second order neurons are either up”) even with the same stimulus intensity. • Nociceptive specific (or) • Have large receptive fields compared with Nociceptive specific • Wide dynamic range (WDR) neurons. neurons • Most nociceptive “C” fibers send collaterals to or terminate on, second order neurons in lamina I, II and to a lesser extent on lamina V. • Nociceptive A∂ fibres synapse mainly in lamina I, V and to lesser degree lamina X • Lamina I →responds primarily to noxious stimuli from cutaneous and deep somatic tissues. • Lamina II →also called substantia gelatinosa • Contains many interneurons • Play major role in processing and modulating nociceptive input from cutaneous nociceptors. • Major site of action for opioids.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of Nociception.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Lamina III and IV – Receive primarily non-nociceptive sensory • Medial spinothalamic tract (Paleospinothalamic) input • Projects to medial thalamus • Lamina VIII and IX – Make anterior horn • Mediates the autonomic and unpleasant emotional perception of • Lamina VII → Called intermediolateral column and contains the pain. cell bodies of preganglionic sympathetic neurons. • Some spinothalamic fibers also project to the periaqueductal gray • Visceral afferents terminate primarily in lamina V and to a lesser mater and important link between the ascending and descending extent lamina I. These two lamina represents points of central pathways. convergence between somatic and visceral inputs. • Collateral fibers project into RAS and hypothalamus → responsible • Lamina V responds to both noxious and non noxious sensory for the arousal response to pain. input and receives both visceral and somatic pain afferents. Alternative pain pathway: - • This phenomenon of convergence between visceral and somatic • As with Epicratic sensation, pain fibers ascend diffusely ipsilaterally sensory input is manifested clinically as referred pain and contralaterally, hence some patients continue to perceive pain • Compared with somatic fibers, visceral nociceptive fibers are following ablation of contralateral spinothalamic tract. fewer in number, more widely distributed, proportionately activate • Other ascending pain pathways important are a large number of spinal neurons, and are not organized • Spinoreticular tract→Mediate arousal and autonomic responses to somatotopically. pain. The Spinothalamic tract: - • Spinomesencephalic tract →Important in activating anti-nociceptive, • Axons of most 2nd order neurons cross the midline close to their descending pathways, because it has some projections to level of origin (at Anterior commisure) to contralateral side of the periaqueductal graymater . spinal cord before they form spinothalamic tract and send their • Spinohypothalamic and Spinotelencephalic tracts →Activate the fibers to the hypothalamus evoked emotional behavior. • Thalamus • Spinocervical tract → Ascends uncrossed to lateral cervical nucleus, • Reticular formation which relays the fibers to contralateral thalamus. This tract is major • Nuclear raphe magnus alternative pain pathway. • Periaqueductal gray. • Dorsal column →Carry light touch and proprioception, are responsive • Spinothalamic tract - major pain pathway to pain, they ascend medially and ipsilaterally. • Lies anterolaterally in white matter of spinal cord. Integration with the Sympathetic and motor systems: - • Ascending tract divided as lateral & medial • Somatic and visceral afferents are fully integrated with the skeletal • Lateral spinothalamic tract (Neospinothalamic ) motor and sympathetic systems in the spinal cord, brainstem and • Projects to ventral posterolateral nucleus of thalamus higher centers. • Carries discriminative aspects of pain, such as location, • Afferent dorsal horn neurons synapse both directly and indirectly with intensity and duration. anterior horn motor neurons. • These synapses are responsible for reflex muscle activity → whether normal and abnormal – that is associated with pain.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of Nociception.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Simple, efficient, minimally instrument method Synapses between afferent nociceptive neurons and • • Unidimensional, describes intensity but not quality. sympathetic neurons in the intermediolateral column result in • → reflex sympathetically mediated vasoconstriction, smooth muscle • MPQ checklist of words describing symptoms spasm, and the release of catecholamines, both locally and from the adrenal medulla. 3 dimensions: Sensory discriminative (nociceptive pathway) Third order Neurons: - • Motivational affective (reticular and limbic structures) • Located in thalamus and send fibers to somatosensory areas I • and II in the post central gyrus of the parietal cortex and superior • Cognitive evaluation (cerebral cortex) wall of sylvian fissure. Perception and discrete localization of pain take place in these 20sets of descriptive words divided in four major groups • • 10 sensory cortical areas. • 5 affective Lateral thalamic nuclei project to primary somatosensory cortex. • • 1 evaluative Intralaminar and medial nuclei project to anterior cingulated gyrus • 4 miscellaneous and mediate suffering and emotional component of pain. EVALUATING THE PATIENT WITH PAIN: - • Patient selects the sets that apply to his pain and circles the word. • Distinguish between acute and chronic pain • Pain rating index is derived from words encircled. Reliable and can be completed in 5-15 minutes • Management of Acute pain →primarily therapeutic • • High levels of anxiety and psychological disturbance can observe → • Chronic pain Investigative measures and careful history, MPQʼs discriminative capacity. review of previous medical evaluations and treatment, through Psychological evaluation: psychological and sociological evaluations. • Most useful when medical evaluation fails • First evaluation – Benefits both patient and physician. • Commonly used tests are • Written questionnaire – Nature, onset, duration of pain . • Minnesota Multiphase Personality Inventory (MMPI) • Physical examination- Muscular skeletal and serologic systems • Beck Depression Inventory (BDI) Imaging studies – X-rays, CT, MRI and bone scans. • MMPI → 566 items, true-false questionnaire that define patients Pain Measurement: • personality on 10 clinical scales. • Helps in therapeutic intervention and evaluate the efficacy of Rx. • - Cultural difference can affect • Pain is a subjective experience. • - Test is lengthy and some patient feel insulting • Pain can be due to tissue distruction (or) bodily (or) emotional • reaction. - Difficult to differentiate between organic and functional pain • Visual Analog Scale (VAS) • Mc gill pain questionnaire (MPQ) • VAS → 10 cm horizontal line o “No pain” at one end o Worst pain imaginable at other end

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of Nociception.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Electromyography and Nerve conduction studies: - • Diagnoses of entrapment syndromes, radicular syndromes, neural trauma and polyneuropathies • Can differentiate between neurogenic and myogenic disorder • Useful in differentiating between organic or functional syndrome • Electromyography • Peripheral nerve conduction • Nerve conduction studies. • Thermography

Dr Azam’s Notes in Anesthesiology 2013 3. Pain Theories. Dr Azam’s Notes in Anesthesiology 2013

Peripheral pattern theory: The theory proposes following Mechanisms: • States that all fiber endings are alike, so that the pattern of pain 1. The transmission of impulses from afferent fibres to the spinal cord is produced by intense stimulation of nonspecific receptors. T cells is modulated by a spinal gating mechanism in the dorsal Central summation theory: horn. • Suggested that intensive stimulation resulting from nerve and 2. Relative activity of large fibres which tend to close the gate and tissue damage activates fibres that project to pools of neurons in small fibres which tend to open the gate and perceive pain the spinal cord creating abnormal activity in closed self exciting 3. Nerve impulse from brain descend down to modulate pain neuron loops. This activity bombards the spinal cord • Medial raphe nucleus transmission (T) cells which project to brain. • Thalamus Fourth theory of pain: - Has two components • Periaqueductal nucleus. 1)Reception of pain • Specialized system by large diameter rapidly conducting fibres 2)Reaction to pain labeled as “central control trigger” activates selective cognitive 1. Sensory interaction theory: Small fibre, slow conducting processes that then influence by way of descending fibres the impulse produce pain where as large fibre, fast conducting modulating properties of the spinal gating mechanisms. impulses inhibit pain. 2. Gate control Theory: By Melzack and wall in 1950 3. This theory took into account the evidence of physiologic specialization, central summation, patterning, modulation of input, and the influence of psychologic factors. Impulses evoked by peripheral stimulation are transmitted to three system: a. The cells in the substantial gelatinosa (SG) b. Dorsal column fibres that project toward the brain and c. And the spinal cord transmission (T) cells that mediates information to brain.

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Dr Azam’s Notes in Anesthesiology 2013 Pain Theories.Continuation: Dr Azam’s Notes in Anesthesiology 2013

1. Peripheral pattern theory (PPT) 2. Central summation theory (CST) 3. Fourth theory of pain( FTOP) 4. Sensory interaction theory( SIT) 5. Gate control theory (GCT)

Dr Azam’s Notes in Anesthesiology 2013 4. Pain Clinic. Dr Azam’s Notes in Anesthesiology 2013

Organization and Designing • A pain clinic must have a place for evaluation, treatment, recovery Introduction: room additional facilities for office and clerical function, conference • There is growing emphasis on need for multidisciplinary, room and patients changing room and waiting room should be interdisciplinary team approach to study pain mechanism & its available management. • Examination room – should include standard equipment such as • Pain unit was established for the first time at the Beth Israel sphygmomonometer / examination lights, instruments for Hospital in Boston in 1979 neurological examinations, temperature probes, drug cup board, data • ASA committee on pain treatment suggested in 1977 that storage etc. • Pain clinic – consists of out patient facilities • Treatment room – requires approx 180 sq meters area • Pain center – consists of both inpatient and outpatient facilities • Basic treatment equipments – and educational programs. • Overhead lightings • In recent years Anaesthesiologists have been taking an active • Multiple O2 and vacuum sources role in the establishment and management of clinics for the relief • Multiple electrical sources of chronic pain. • Fully tilting O.T table Staffing: Monitoring – ECG, pulse oximetry, BP temperature • Anaesthesiologist will be director of the pain clinic • Emergency resuscitation equipment. • Attending physicians. • Intravenous therapy • Professional staff nurses • Portable image intensifier for phonoscope monitoring • Secretary • Recovery room – properly equipped staff, O2 and vacuum ports • Trainees • Standard monitoring facilities. Specialists from following departments usually participate in Multi disciplinary Pain clinic: multidisciplinary pain units: Receives patient by referral from family doctors • General surgery/ Orthopedic surgery/ General Medicine/ On arrival patient → Neurology/ Oncology/ Psychiatry /Rehabilitation medicine/ Detailed History – cause, duration location, aggravation factors Physical medicine /Radio therapy / Clinical pharmacology. Treatment History:To rule out any treatable cause for symptoms. Requirements for ideal pain clinic: • Complete medical and psychological Exam 1. Waiting room • Investigations 2. Office rooms • Record keeping case sheet. 3. Examination rooms • Facilities for TENS –Transcutaneous Electrical Nerve stimulation. 4. Block room / large room 5. Semi private room 6. Recovery room to monitor patients 7. Conference room

Dr Azam’s Notes in Anesthesiology 2013 5. Patient controlled analgesia. Dr Azam’s Notes in Anesthesiology 2013

Most patient with moderate to severe post operative pain require • Lock out interval: Minimum interval between doses. Aim is to provide parenteral analgesics (or) neural blockade during 1-6 days sufficient time for administered drug to act & prevent administration following the surgery. of analgesic before onset of action of previous dose. • Parenteral analgesics include, NSAIDS, opiods and ketamine. • Most opiods – 8-10 min • Opiod analgesia can be given SC /IM and IV injections. • Maximum dose: Many devices can be programmed to limit • Advances in computer technology have allowed the development maximum amount of drug that can be delivered over period of time. of PCA • General guide lines for PCA in Average Adults Definition: Lockout Interval Opioid Bolus close Demand dose • Self administration of small doses of opiods by patients when (min) they experience pain. Principle: Morphine 1-3 mg 10-20 min 0-2 μg/kg • A negative feed back loop exists. When pain is experienced Fentanyl 15-25 mg 10-20 min analgesic medication is demanded. When pain is reduced there Meperidine 10-15 mg 5-15 min is no further demand. By pushing a button, the patient are able to self administer precise doses of opiods intravenously on an as PCA as controlled infusion needed basis. • Patient who benefit most from a continuous basal infusion are those PCA devices: requiring large amounts of opiods. • Most IV PCA devices consists of microprocessor controlled • 30-50% of the 24 hr consumption can be given as basal infusion e.g pump triggered by pushing a button. When pump is triggered a patient requiring 60 mg / day of morphine – basal infusion 1-1.5 mg / preset amount (set by physician) of opiod is delivered into IV hr line. A timer in pump prevents administration of additional doses • Advantage – prevents the analgesic level from appreciably until a specific period is elapsed --Lockout period (minimal decreasing when patient sleeps – less likely to awaken in severe interval between doses) pain Important parameters in PCA devices: • Disadvantage – highly variable pharmacokinetics and sometimes • Loading dose: Initial dose that is infused gradually over period of decrease analgesic requirements – more likely to produce respiratory time in order to attain serum level of analgesic equal to minimum depression effective analgesic concentration (MEAC) [Analgesic blood levels at which patient with severe pain reporting of pain ,experience Advantages: analgesia and the severity of pain rapidly diminishes. Small a)Cost effective technique b)Superior analgesia c)High patient increase above this point produce a large increase in Analgesia.] satisfaction d)Autonomy to patient e)Inherent safety if patient too • Demand dose: Dose administered every time the patient pushes sleepy - patient will not be able to push button. button (or) makes demand (Too small dose →patient do not appreciate improvement in analgesia. Too large dose →makes system dangerous)

Dr Azam’s Notes in Anesthesiology 2013 Patient controlled analgesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Disadvantages: a) Side effects of opiods b)Incorrect programming →over dosage c) Siphoning of large amounts of opiods into patients IV infusion due to crack in the delivery system →latest devices have changes in mounting devices and anti siphoning valves d)Mechanical malfunctioning of PCA PCA in Children: • As young as 6 yrs depending maturity and pre op preparation Fentanyl 1-2 mg/kg, Meperidine 1.5 mg/kg. PCA Epidural Analgesia: • Loading dose to establish comfort – setting of PCA pump to deﬁne amount of patient activated bolus and lockout period and usually continuous back ground infusion. Morphine Demand dose Lockout period Loading dose 0-2 µg/kg 10 min 2-3 mg

Dr Azam’s Notes in Anesthesiology 2013 6. Secondary Analgesia (Co-Analgesia). Dr Azam’s Notes in Anesthesiology 2013

Definition: Co-analgesic, or adjuvant drugs, are medications Anti Convulsants: whose primary indication is for a purpose other than pain relief, but Suppress the spontaneous neuronal firing. They include. that demonstrate some analgesic effects. Examples • Phenytoin: 100mg., three times daily, for refractory pain. • Antidepressant • Carbamazepine: 200mg., to start and 200mg increments, upto • Anticonvulsant 1500mg, daily. • Anxiolytics. • Sodium valproate: 500mg., HS., upto 1500mg. • Corticosteroids. Corticosteroids: Most of the pure neural injury pain are best treated with secondary • There is often an area of inflammation around a tumour and pressure analgesics. on neighboring veins and lymphatics, leads to further local or Antidepressants: regional swelling. Corticosteroids reduce the inflammation and MAOI: reduce the total mass of the tumour and associated pain. Steroids • They inhibit Mono Amino Oxidase enzyme, which leads onto the also elevate the mood and stimulate appetite. accumulation of 5HT and Noradrenaline, thereby enhancing the Indications of Corticosteriod Therapy: activity of descending inhibitory pathway. In brain it causes • Bone pain (Metastatic Arthralgia) excitement and mood elevation. • Nerve compression pain Adverse Effects: • Raised intracranial pressure Include Head Ache, Disturbed sleep, Psychosis and Convulsions. • Dyspnoea with bronchospasm or partial obstruction. Hypotensive crisis with some food stuffs such a Cheese, Yeast • Anorexia extract, Buttermilk, Meat etc., is reversed by pentolamine 5 mg. • Dysphagia caused by tumour mass. Dose: Iproniazid Prednisolone is the commonly used drug which can be given orally. Isocarboazid – 10-30 mg/day., upto 50mg. Usually used parenteral preparations are betamethazone and Phenelzine - - 45-60mg dexamethazone. Tranylcipramine Triamcilone and methyl prednisolone are also injected epidurally to Tricyclic Antidepressants: relieve chronic low back pain and advanced cancer pain. • They block the presynaptic reuptake of Serotonin and Noradrenaline. Amitryptyline is the commonly used Interruption of pain pathways: antidepressant. Nerve Blocks: • Fluoxetine, a selective serotonin reuptake inhibitor, enhances the They have greatest value in the management of cancer pain. analgesic effect of morphine, methadone and pethidine Nerve Blocks are usually used either for • Imipramine: is given in a dose of 50-100 mg daily. • Diagnostic purpose and / or Sedative Anxiolytics: • Therapeutic purpose. Include benzodiazepines such as • Alprazolam: 0.25-0.50mg., HS (0.005-0.01mg/kg) • Diazepam: 10mg., HS (0.1-0. 2mg/kg) • Midazolam: 0.07-0.08 mg/kg. 18

Dr Azam’s Notes in Anesthesiology 2013 Secondary Analgesia (Co-Analgesia).Continuation: Dr Azam’s Notes in Anesthesiology 2013

Diagnostic Purpose: To determine whether an afferent nociceptive stimulus exists and which neural pathway is affected, and also to know the type of pain. Pain in the lower half of the body is treated by subarchnoid or epidural block. Upper extremity pain are treated by other regional blocks. • If pain is relieved by placebo, then probably the pain is of psychogenic origin. • If pain is relieved by sympathetic blockade, the source may be reﬂex sympathetic dystrophy. • If pain is relieved by sensory blockade, then the pain is a true somatic pain.

Dr Azam’s Notes in Anesthesiology 2013 7. Adjuvant Analgesic Methods. Dr Azam’s Notes in Anesthesiology 2013

Transcutaneous Electrical Nerve Stimulation (TENS): • TENS is a technique whereby nerves in the skin and subcutaneous tissue are stimulated by surface electrodes connected to a small portable battery powered device. Because TENS has no side effects it is a highly recommended and much used treatment for patients with chronic pain. It has to be used atleast 3 times daily and duration of relief lasts for minutes to hours. It is especially useful in neuropathic, myofacial and musculoskeletal pains. • TENS is produced by placing two conductive rubber electrodes on the skin overlying the nerve bundles from painful areas and attaching the electrodes to a signal generator. • High Frequency TENS requires the AC Current at a rate of 40-400 cycles per second. Pulse width should be 20-250 microseconds and the amplitude should be set at a level which will produce parasthesia without producing muscular contraction. Onset of analgesia is within 20 minutes and effect last to less than 1 hour. • Low Frequency TENS stimulate at a lower current frequency of 1-5 cycles per second with a pulse width of 250-500 micro seconds, and an amplitude of sufﬁcient intensity to cause strong rhythemic muscular contractions. It stimulates A∂ and C ﬁbres an increase the release of endorphins and serotonins.

Acupuncture: • It may be performed in several ways. Manual rotation of pairs of needle or low and high frequency electrical stimulation through them. It is particularly useful in painful muscle spasm.

Dr Azam’s Notes in Anesthesiology 2013 8. Electrical Stimulation. Dr Azam’s Notes in Anesthesiology 2013

Electrical stimulation of nervous system can produce analgesia in Spinal cord stimulation / Dorsal column stimulation patient with acute and chronic pain. • Thought to produce analgesia by directly stimulating large AB fibers Current may be applied in the dorsal columns of spinal cord. • Transcutaneously • Proposed mechanisms – activation of descending modulating • Epidurally (or) systems and inhibition of sympathetic out flow most effective for • By electrodes implanted into CNS neuropathic pain Accepted Indications: Transcutaneous stimulation • Sympathetically mediated pain Trancutaneous Electrical Nerve stimulation (TENS) is through to • Spinal cord lesions with localized segmental pain produce analgesia by stimulating large afferent fibres. • Phantom Limb • The gate theory of pain processing suggests that afferent input • Ischemic lower extremity pain from large epicratic fibers competes with that from the smaller • Adhesive arachnoiditis pain fibers. • Temporary electrodes are initially placed epidurally connected to an • Another theory proposes that at high rates of stimulation, TENS external generator to evaluate efficacy → causes conduction block in small afferent pain fibers. • If a favourable response obtained →permanent electrodes are • It may have a role in patient with mild to moderate acute pain usually placed percutaneously, tunneled and connected to a and those with chronic low back pain, arthritis and neuropathic subcutaneous generator. Efficacy decrease with time in some pain. patients. Conventional TENS: Intra cerebral stimulation • Electrodes are applied to the same dermatome as pain and are Indications: stimulated by direct current from a generator usually for 30min • Intractable cancer pain for several times a day. A current of 10-30 ma is applied with a • Intractable neuropathic pain of Non-malignant origin pulse width of 50-80ms at a frequency of 80-100Hz. Electrodes are implants stereotactically into Low frequency TENS: • Periaqueductal & peri ventricular gray areas – Nociceptive pain • Some patients refractory to conventional TENS respond to this. It (cancer and LBP) employs stimuli at with a pulse width of >200ms at a frequency • Specific sensor thalamic Nucleus – Neuropathic pain. <10Hz for 5-15min unlike conventional TENS, it is atleast partly Complications reversed by Naloxone, suggesting a note of endogenous opioids. • Most serious are intracranial hemorrhage and infection.

Dr Azam’s Notes in Anesthesiology 2013 9. Cancer & Anesthetic Consideration. Dr Azam’s Notes in Anesthesiology 2013

Anesthetic Consideration in patients with Cancer: • Consider pathophysiology & manifestations of particular cancer and the adverse effects of chemotherapeutic drugs used. • Nausea, vomiting common. • Metoclopramide ,ondansetron ,Droperidol useful • Tricyclic Antidepressants useful to potentiate analgesic effects of opioids which are commonly used for cancer pain • Do pre-op lab tests • Consider cardiac toxicity: Hence avoid volatile anesthetics & ﬂuid over load etc • Consider pulmonary ﬁbrosis: especially with Bleomycin , hence • do / CXR, CT, ABG, PFT, Sao2 etc.Also consider IPPV during and after surgery. • Hydrate well with colloids, transfuse blood if anemic. • Consider CNS depression, peripheral neuropathy, ANS dysfunction. • Consider renal and hepatic dysfunction: decrease dose of NDMR etc. • Expect prolong action with scoline when patient are Rx with Alkylating agents • Consider Anemia, malnutrition, coagulopathies, Electrolyte imbalance • Observe strict asepsis technique. • Supplement intraoperative steroids. . • More prone for DVT and pulmonary embolism, hence consider early ambulation and prophylactic anticoagulants.

Dr Azam’s Notes in Anesthesiology 2013 10. Cancer Pain Management. Dr Azam’s Notes in Anesthesiology 2013

• Pain is the most common and most feared symptom of cancer, post surgical syndromes feared more sometimes than death itself. Pain is experienced by • post thoracotomy atleast 75% those with advanced disease and 20% to 25% at the • post mastectomy time of diagnosis .In India more than 1 million people suffer from • phantom limb and stump pain cancer pain and majority of these individuals do not get • phantom rectum pain adequate pain relief. • post radical neck dissection • Pain is precisely what the patient says “hurts” and the Post radiation syndromes international association for study of pain defines pains as “a • Radiation fibrosis of brachial plexus sensory and emotional experience associated with actual or • Radiation fibrosis of lumbosacral plexus potential tissue damage or described in terms of such damage”. • Radiation myelopathy Pain is a subjective experience where sensory component of PAIN UNRELATED TO CANCER pain to a great extent depends on the emotional status of the • Acute and post herpetic neuralgia individual and also influenced by factors other than tissue • Osteoarthritis damage. • Osteoporosis COMMON PAIN SYNDROMES: Management: • Pain may be due to cancer itself, its treatment or totally • Pain management should be available to all cancer patients at all unrelated, severe pains may simultaneously and each requires stages of their disease. Judicial use of analgesics, co-analgesics and diagnosis before treatment in advanced cancer, many of these non-drug methods can substantially reduces pain in 90% of patients. pains co-exist. Effective treatment of pain starts with a detailed history, diagnosis PAIN ASSOCIATED WITH TUMOR INFILTRATION and assessment of pain. • Soft tissue infiltration The world health Organization (WHO) has developed a three step • Infiltration of plexus or nerve roots or peripheral nerves analgesic ladder for effective pain management in cancer. The five • Infiltration of bone essential components in the WHO approach to drug therapy are: • Infiltration of epidural space _+ spinal cord compression a. By the mouth: the oral route is the most preferred routes • Infiltration to base of skull or cranial nerves advisable, unless for some reason patient cannot take orally. • Increased intracranial tension b. By the mouth: drug should be taken at regular time interval and PAIN ASSOCIATED WITH THERAPY not as needed Post chemotherapy c. By the ladder: unless the patient is in severe pain, begin by • peripheral neuropathy prescribing a non opioid drug and go up the ladder to week • steroid pseudorheumatism opioid and a strong opioid for moderate severe pain. • headache d. For the individual: for eg: strong opioid morphine. The right dose of oral morphine is the dose that relieves the pain. The dose of morphine is tailored to the needs of the patient. It may range as little as 5mg to more than 1000 mg. e. With attention to detail: 23

Dr Azam’s Notes in Anesthesiology 2013 !"#$%&'()#*+,-)#./#$/-),0-)1+2+34######!"#"$ 56-7+/8#981,1+/# # Cancer Pain Management.Continuation: # Dr Azam’s Notes in Anesthesiology 2013

THE%&'$()&$)*$+,+-.'/01$-+22'3 W.H.O ANALGESIC LADDER $ Type to enter text # # R=#6GIM*P#MS.M.!## # T#*M*5#MS.MS!## # T#$!UVW$*G## # J=#Q9$Y#MS.MS!# # T#*M*#Z#MS.MS!# $ TX5# $!UVW$*G## $ # $ ;=#*M*#MS.M.!# TX#$!UVW$*G## # $ # # # # STEP$ I- NON – OPIOIDST# Includes# acetaminophen and non- steroidal anti- inflammatory # drugs/%'4$$$0# to treat5$,*,$ mill moderate6$*40*02/ cancer$ pain. Action:# # ./72>8-)# &7-,&'1/+?0-/# &/8# /+/5#),-"+18&2#&/,15# 1/@2&''&,+"4# 8">3)# ,+# ,"-&,# It produces analgesia by decreasing the levels of inflammatory •'122#'+8-"&,-#7&/7-"#?&1/=# # !"#$%&mediates# '( # 1,# generated ?"+8>7-)# &/&23-)1&#at the site A4#of tissue 8-7"-&)1/3# injury ,0-# by inhibiting 2-B-2)# +@# 1/@2&''&,+"4#the '-81&,-)# 3-/-"&,-8#enzyme# cyclooxygenase &,# ,0-# )1,-# +@# ,1))>-# when 1/C>"4# catalyzes A4# 1/01A1,1/3# the conversion ,0-# -/%4'-# of 7472++D43-/&)-# <0-/# arachidonic acid to prostaglandinʼs and leukotrienes which 7&,&24%-)#,0-#7+/B-")1+/#+@#&"&7018+/17#&718#,+#?"+),&32&/81/E)#&/8#2->F+,"1-/-)#<0170## sensitize nerves to painful stimuli. They do not active opioid )-/)1,1%-#/-# "B-)#,+#?&1/@>2#),1'>21=#G0-4#8+#/+,#&7,1B-#+?1+18#"-7-?,+")=#G0-#7+/7>""-/,# receptors. The concurrent use if the opioid and NSAIDs provide >)-#1@#,0-#+?1+18#&/8#*6$.!)#?"+B18-#'+"-#&/&23-)1&#,0&/#-1,0-"#8">3#&2+/-=#.,#8+-)#/+,## 8-B-2+?#,+2-"&/7-#+"#?04)17&2#8-?-/8-/7-=#.,#0&)#7-121/3#-@@-7,#)>70#,0&,#1/7"-&)1/3#,0-#more analgesia than either drug alone. It does not develop # 8+tolerance)-#A-4+/8#-",&1/#2-B-2#8+-)#/+,#?"+8>7-#&881,1B-#-@@-7,)= or physical dependence. It has ceiling effect such# that increasing# the dose beyond a certain level does not produce +789:;9$9<<9=>;additive# effects. ?$$ Adverse)$&%*# '(#!4)?-?)1&H#0-&",#A>"/H#/&>)-&H#B+'1,1/3H#81&""0+-&H#7+/),1?&,1+/H#-?13&),"17#?&1/# effects: •&/8#&A8+'1/&2#?&1/=Minor: # Dyspepsia,# heart burn, nausea, vomiting, diarrhea, )+,%*constipation,# ?$#I-/&2#@&12>"-#0-?&,17#@&12>"-H#A2--81/3#&/8#3&),"17#>27-"&, epigastric pain and abdominal pain. 1+/=# • Major: Renal failure hepatic failure, bleeding and gastric *-<#3-/-"&,1+/#+@#*6$.!#1)#&"-#7472++D43-/&)-#J#KLMNTT## 5JO#)-2-7,1B-#1/01A1,+")#&/8#&"-# F/+"4=ulceration. # • New generation of NSAID is are cyclooxygenase 2 (COX-2) /%'4$00$('+@$*40*02/selective inhibitors and are known$ to have less adverse effect # profileQ-&F#+?1+18)#&"-#<-&F#'> and decrease G.I. injury.5#&3+/1),)## 24 -+./(+&0(+"#$%&$ 1%2/$ 13*+#$%&(%4(+"#$%&$ !"#$%&$' ()*+),-' .*+'/01' Dr Azam’s Notes in Anesthesiology 2013 2$340"50"365/$&$' +7',-'8%4/' +*='/01'$;"&",%;:<':&#' 9:0:;$4:,"<' ;",,"&<6'>1$#' ?0:,:#"<'/6#0";/<"0%#$'8%4/',>'@' 7)*A)),-' ./01'$35$&1%B$' :;# # <<<=!"$%&'=7+'# # Cancer Pain Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

STEP II WEAK OPIOIDS ADVERSE EFFECTS Weak opioids are weak mu- agonists • Day time drowsiness, dizziness, which resolve within a few days of Name and action Dose Duration of action initiation of therapy Codeine 30-60mg 4-6 hrs • Nausea and vomiting occur in one third or half of the patients in the ﬁrst few days, can be controlled by antiemetics Dextroproxyphene 65 mg with 6-8 hrs economical • Constipation is almost invariable and it should be anticipated and Paracetamol and commonly used treated with peristaltic stimulants and stool softeners. Tramadol hydrochloride 50-100mg 4hrs expensive • Pruritis-A few require antihistamines with mu – agonist With • Urinary retention is relatively rare. amine uptake inhibitory action BUPRENORPHINE • The most commonly used sublingual opiod. It is mu- opioid receptor Pentazocine: agonist. Dose: 0.2 to 0.4 mg 8 hourly. It has a ceiling to its to its Not recommended for long- term usage as it has psychomimetic analgesic effects at a of 3.5 mg / day which limits its use in cancer side effect. pain. Weak opioids are extensively used in our country for the following TRANSDERMAL FENTANYL PATCHES reasons • It is now available in our country for the past 2 years. It consists of a • Non- availability of strong opioids on all places reservoir / drug sealed in a chamber with a rate controlling • Due to stringent narcotic regulations of our government membrane, whose area determine the rate at which the drug is • “Misconceptions” about oral morphine amongst public and also delivered. Currently available patches deliver 25/50/100 micrograms medical professionals that it causes ADDICTION, per hour for 72 hours. The patch has to be changed every 72 hours RESPIRATORY DEPRESSION AND HASTENS DEATH. and is expensive. Adverse effects are the same as other opioids but less severe intensity. STEP II – STRONG OPIOIDS ORAL MORPHINE: Is the preferred strong opioid of choice for cancer ADJUVANT DRUGS pain management the world over. • Adjuvant drugs: are used at each step of the ladder, a non – opioid Dose: Is that which relives pain. It has no ceiling dose and /or an adjuvant drug can be added depending on the cause of Dose titration: pain, combination of these analgesics and analgesics can provide • Dosage should be titrated to the individual patientʼs pain it is excellent relief in the majority of cases usually done with immediate releases oral morphine sulphate tablets/ solution. OMS 5 to 10 mg 4 hourly and the same dose for breakthrough pain. Total daily dose of morphine should be reviewed after 24 hrs intervals and regular 4 hourly dose can then be adjusted. The four hourly dose of immediate release morphine can be readily converted to the twice daily controlled release formulations. 25

Dr Azam’s Notes in Anesthesiology 2013 Cancer Pain Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

ANALGESIC TECHNIQUES Other Routes of administration TREATMENT EXAMPLES INDICATIONS • If the patients cannot swallow or absorb drugs via the upper G.I tract NSAIDs Paracetamol mild pain, bone pain liver or suffering from severe side effects, It may be necessary to use the Diclofenac capsule pain Ibuprofen other routes like: Nimesulide • Rectal Naproxen ,pyroxicam • Continuous subcutaneous infusion through syringe driver Celocoxib, Refocoxib • Intravenous WEAK OPIOIDS Dextroproxyphen Moderate pain Tramadolhydrochlorie • Transdermal Codeine • Epidural / spinal STRONG OPIOID Morphine: immediate release Severe pain • Nasal Or controlled release Nerve block: Transdermal fentanyl patches • Have a limited role in cancer pain management. It is only perform when the oral pharmacologic approach fails. Commonly used nerve block are: STEROIDS Dexamethasone Raised intracranial pressure • Neurolytic celiac plexes block for upper abdominal / Prednisolone Liver capsule pain pancreaticmalignancy Nerve compression Lumber sympathetic block for neuropathic pain of lower extremity ANTIDEPRESSANTS Amitripyline Nerve pain • Dothiepin Deafferenation pain • Superior hypogastric plexes block for pelvic visceral pain ANTICONVULSANTS Carbamazepine Never pain • Continuous epidural analgesia Sodium valproate Psychological approaches: ANTI- ARRHYTHMICS Flecainide Resistant nerve pain • Relaxation, stress management and cognitive approaches plus Mexiletine sensitive psycho social counseling are necessary with medical MUSCLE RELAXANTS Baclofen Muscle never pain management to minimize the pain and improve quality of life. Dizepam CONCLUSION: CYTOREDUCTIVE Chemotherapy/ radiation Palliation of bone pain • Much suffering would be prevented by application of simple, WHO 3 THERAPY Superior vena caval step ladder analgesic therapy.” Quality of life and comfort death” Obstruction could considerable improved and certainly be achieved if one has the PSYCHOLOGICAL Cognitive Decrease “the will to do so. Coping strategies Perception Hypnosis STIMULATION- INDUCED Transcutaneous electrical Somatic and nerve pain Nerve stimulation Acupuncture NERVE BLOCKS Bupivacaine plus morphine severe pain Via epidural route

Dr Azam’s Notes in Anesthesiology 2013 11. Neurolept Analgesia. Dr Azam’s Notes in Anesthesiology 2013

Definition: Neurolept analgesia: • Neurolept analgesia is a term used to describe the state of a Is the term used to describe the State of a patient following the patient following the administration of a combination of a major administration of a combination of a major tranquilly (Butyrophenones, tranquilizer (butyrophenones – droperidol or haloperidol) and a droperidol, haloperidol) and opioid analgesia. potent opioid analgesic (fentanyl or phenoperidine). This was 1. In diagnostic procedures like aortography, angiocardiography, introduced by J.A. De Castro and Mundeleer in 1959 and is bronchoscopy, oesophagoscopy, fibreoptic gastroscopy etc. characterized by analgesia, absence of clinically apparent motor 2. As a supplement to thiopentone, relaxant and gas-oxygen activity, suppression of autonomic reflexes, maintenance of anaesthesia. cardiovascular stability and amnesia. The addition of an inhaled 3. As an alternative to conventional anaesthesia. anaesthetic, usually nitrous oxide, improves amnesia and 4. To provide sedation during regional analgesia. analgesia and has been called neuroleptanaesthesia. 5. During bypass in cardiovascular surgery in order to avoid the • The commercial preparation of droperidol& fentanyl (Innovar) is cardiac depressant and dysrrhythmic effects of volatile agents. the combination used to produce neuroleptanalgesia although 6. In ophthalmology to provide sedation in patients undergoing many other combinations are possible. It contains droperidol 2.5 intraocular operation under LA. mg/ml and fentanyl 50 mg/ml (50: 1). Lactic acid is added for 7. For ICU to facilitate intubation and IPPV. adjustment of pH to 3.5. The pharmacological effects are additive 8. To increase afferent block during halothane anaesthesia. effect of the two component drugs. Droperidol produces • Dosage: Induction of GA: If the components are given separately, hypnosis, sedation and antiemetic effects by occupying GABA droperidol should be administered first in a dose of about 5-10 mg receptors on the post synaptic membrane thereby reducing (5-15 mcg/kg) and followed by incremental doses of fentanyl in 50 to synaptic transmission and resulting in a buildup of dopamine in 100 mcg increments. The usual induction dose of Innovar is 0.1-0.15 the intersynaptic cleft which alters the balances of dopamine and ml/kg administered with nitrous oxide and a muscle relaxant. A test acetylcholine in certain brain sites. Fentanyl acts through opioid does of 1-2 ml may be administered prior to induction because of receptors and produces analgesia. possible vasodilatation and hypotension. 200-300 ml of balanced salt solution may also be administered prior to induction. Uses of Neurolept analgesia: • Maintenance of GA: Supplementation of anaesthesia during NLAN 1. As premedication -0.5 to 2 ml of innovar. should be with fentanyl and not Innovar (prolonged duration of action 2. In certain neurosurgical operations when the patients of droperidol will produce post-operative somnolence if it is conscious co-operations is required during surgery. Eg. repeated). Stereotactic surgery and anterolateral tractotomy. • Sedation and analgesia: 0.5-1.0 ml of Innovar I.V. repeated and titrated to desired effect. IM dose is 1-2 ml.

Dr Azam’s Notes in Anesthesiology 2013 Neurolept Analgesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Side Effects: 1. Muscle rigidity due to large doses of fentanyl managed with muscle relaxants. 2. Respiratory depression – due to fentanyl – can be reversed with naloxone. 3. Prolonged somnolence – due to droperidol. 4. Hypotension due to alpha blockade of droperidol can be treated with blood volume expansion and alpha agonist (phenylephrine). 5. Extrapyramidal complications – may be treated with diphenhydramine or benztropine. 6. Unusual psychological reaction. 7. Hallucinations, sensation of weightlessness – can be treated with benzodiazepine. 8. Malignant neuroleptic syndrome (hyperthermia, muscular rigidity, autonomic instability). Can be treated with dantrolene and bromocriptine.

Contraindications: a. First trimester of pregnancy b. Patients receiving MAO inhibitors c. Parkinsonʼs disease.

Dr Azam’s Notes in Anesthesiology 2013 12. Post operative Management. Dr Azam’s Notes in Anesthesiology 2013

PAIN Fibre Conduction Innervation Diameter Definition: group Velocity • The International association for the study of pain IASP has Aα Primary muscle spindle motor 12-20 70-120m/sec defined pain as to skeletal muscle • “An unpleasant sensory and emotional experience associated β Cutaneous touch and 5-15 0-70 m/sec with actual or potential tissue damage or described in terms of pressure afferents such damage”. γ Motor to muscle spindle 6-8 15-30 m/sec Terminologies related to pain: δ Mechanoreceptors, 1-4 12-30 m/sec • Allodynia →Pain resulting from a non noxious stimulus to normal Nociceptors, thermoreceptors skin B Sympathetic Preganglionic 1-3 3-15 m/sec • Analgesia → Absence of pain on noxious stimulation • Anesthesia Dolarosa → pain in an area that is anaesthetized. C Mechanoreceptors, 0.5 – 1.5 0.5 – 2 m/sec nociceptors, thermoreceptors • Dysesthesia → An unpleasant abnormal sensation. Sympathetic post ganglionic • Hyperalgesia → Decreased sensitivity to noxious stimulation. • Hyperesthesia → Increased sensitivity to stimulation. • One can predict the conduction velocity of the large myelinated fibres • Hypoalgesia → Decreased sensitivity to noxious stimulation by multiplying the axonal diameter by a factor of 6; for the small • Hypoesthesia → Decreased sensitivity to stimulation myelinated fibres by a factor of 4.5 and for the unmyelinated fibres by • Nociceptor → A receptor preferentially sensitive to a noxious or a factor 1.7. potentially noxious stimuli. • Lloyd, proposed a different terminology for afferent fibres that supply • Pain threshold → The least stimulus intensity at which a subject muscles. perceive pain. • Large myelinated fibres were grouped as Ia, Ib, II, the thinly • Pain tolerance level → The greatest stimulus intensity causing myelinated fibres under III and the unmyelinated fibres in group IV. pain that a subject is prepared to tolerate.

Pain fibres: • The pain receptors are free nerve endings in the skin and other organs and are activated by various stimuli such as thermal, mechanical electrical or chemical. The nerve fibres which are primary afferents are classified as follows 1. Gasses classification 2. Lloyd classification • Gasses classified according to size of the axon, degree of myelination and conduction velocity. 29

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Conduction Fibres Innervations Diameter (um) REXED divided the spinal gray into ten principal laminae Velocity • Lamina I – VI make up the dorsal horn Ia Annuls spiral ending of 11-20 um 70-120 m/sec • Lamina VII – IX the ventral horn and lamina X composed of a column muscle spindle of cells clustered around the central canal of the cord. Ib Neurotendinous spindle • These laminae run the entire length of the cord and fuse with a II Flower spray ending of 4-12 um 25-70 m/sec similar structure in the medulla called the modularly dorsal horn. neuro muscular spindle • Lamina I → Receives nociceptive impulses from small diameter III Pressure sensor in 1-4 um 10-25 m/sec afferent fibres muscle nociceptors • Also called as marginal or cap layer IV Unmyelinated ʻCʼ fibres 0.5 – 1.5 um 0.5 – 2 m/sec • Contains cells that respond only to noxious stimuli, nociceptive mechanical nociceptors specific neurons and cells which responds both to innocuous thermal stimuli and to noxious stimuli and can differentiate between • Large fibres → these two by discharging at higher frequency to noxious stimuli. • Composed of Aα and Aβ fibres. These are called wide dynamic range neurons [WDR]. • Rapidly conducting fibres; subserve the perception of non • Most of the cells are projection cells having long axons that make up noxious stimulus long ascending pathways, projecting to thalamus, brain stem and to • Have low threshold stimulation. cerebellum. • Other interconnect with near and distant spinal segments and are involved in segmental organization of sensory transmission. • Small fibres → Comprises of Aδ and C fibres • Lamina II and III → Together form Substantia Gelatinosa. • A-delta fibres → Finely myelinated; relatively rapidly conducting; Two types of cells: pain carried is well localized. • → Limiting or stalked cells excitatory in nature • C fibres → Very fine, non myelinated; conduct at slow rate → Central or islet cells inhibitory in function. stimulation threshold is higher. Pain carried is poorly localized. • These cells are principally involved in local circuits and are • The small fibres form the first order neurons in nociception • pathways. They have their cell bodies in dorsal root ganglia, internunucial in type. enter the dorsal horn and end by synapsing with dorsal horn • This layer represent a unique intermediary system for modulating the cells of spinal cord. input of sensory nerves to cells in lamia V T-cells which transmit inform to brain. • This system is a type of brake on T cells and acts as an inhibitory mechanism.

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Lamina IV: • Excitation of Aα - Aβfibres stimulates SG cells, enhances the SG • Receive large cutaneous afferent fibres carrying non noxious output and increases the brake action on T cells [closed gate] sensory impulses and output into the ipsilateral dorsolateral • Lamina V cells play a key role in transmissions of information and pathways and to lamina V cells. hence T cells system. Lamina V • Activity of large fibres of touch or temperature excites not only these • Receives input from A delta and ʻCʼ nociceptors cells but also the cells of SG whose function is to inhibit T cells. • Commonest cells are WDR neurons These excitation of T cells is brief. Activity in small diameter fibres • The neurons of this and those of lamina I constitute one half of excites the lamina V T cells and also inhibits SG cells so that the long projection ascending systems. discharge of T cells is unimpeded. • Also show responses to tactile and nociceptive specific responses. • The output from here is a type of afferent final common impulse and cells are designated as transmission cells. Lamina VI • Related to responses to non-noxious stimuli • Large A- beta and gamma fibres terminate here Drug action on lamina: • Ketamine suppresses lamina I and V activity. • N2o suppresses lamina V activity and increases the activity of lamina VI • Morphine has lamina specific action; suppresses lamina I and V activity GATE CONTROL THEORY: • Proposed by Melzack and wall in 1965. At the level of spinal cord, • Descending influences are essentially identical in the influences of • The input of impulses from afferent fibres to lamina V T-cells is central activity on the anterior motor horn cells that eventuate in the modulated and regulated by the activity of cells in the SG output of the motor neurons to muscle cells known as the final [laminae II and III] common path of Sherrington. The gating mechanism is controlled principally by the relative • • A combination of peripheral afferent input with SG modulation and of activity of Aα - Aβ fibres compared to Aδ and ʻCʼ fibres thus. central biasing by descending impulses results in the net output of • Excitation of small diameter fibres inhibits SG cells, decrease SG the transmission cells. When this output exceeds a critical level and output, brake action on T cells – decreased; this permits lamina bombards the action system is elicited. A sequential pattern of V cells to be more active and uninhibited [open gate] reflexes, behaviors and voluntary activity characteristic of pain is elicited.

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

PATHWAYS: • Reticular nuclei of medulla, pons and mesencephalon The following system play role in transmission of nociceptive • Tetcal area of mesencephalon deep to superior and inferior colliculi information. • Periaqueductal gray region • Lateral and ventral spino thalamic tract • From the brain stem areas, multiple short fibre neurons relay the pain • Spino reticular tracts. signals upward into the intra laminar and ventrolateral nuclei of the • Dorsal column post synaptic spinomedullary systems. thalamus and into certain portions of the hypothalamus. The third • Propriospinal multisynaptic ascending systems. order neuron from the thalamus then project to the cortex. On entering the spinal cord, the pain signals take two pathways to • There is evidence that dorsal column tract, the dorsal column post the centre through synaptic system, the spinocervical tract and the multisynaptic • Neo spinothalamic tract ascending systems may also have a role in nociception. On the • Paleo spinothalamic tract. whole, all ascending tracts are considered parts of two major Neo spinothalamic tract for fast pain: - systems – the lateral or leminiscal system – the medial or non • Fibres carrying mechanical and acute thermal pain terminate in leminiscal system. lamina I and excite second order neuron of the tract. These give • The lateral system includes the neospino thalamic tract, DCT, DCPS, rise to long fibres that cross immediately to the opposite side of SCT. These are composed of long relatively thick fibres that conduct the cord through the ant commissure and then pass upwards to rapidly, have a discrete somato tropic organization and make the brain stem in the Ventrolateral columns connection with ventrobasal thalamus and then to the somato • Few fibres terminate in reticular areas of the brain stem, but sensory cortex. most pass all the way to the thalamus, terminating in the • The medial system is composed of order pathways – Paleo ventrobasal complex along with the dorsal column – medial spinothalamic tract, SRT, SMT, MAS. Because of the thinness of leminiscal tract for tactile sensation. A few fibres also terminate in these fibres their multisynaptic nature and the lack of somatotropic the post nuclear group of the thalamus. From here, the signals to organization, impulses passing through this system are much slower the somato sensory cortex. in reaching the centre than those in the lateral system.

Paleospinothalamic tract: Central Neuro physiologic Mechanisms of Pain: - • Transmits mainly of slow chronic type ʻCʼ fibres and also of few Sensory Discriminative Dimensions: Aδ fibres. Fibres terminate in lamina II and III, then pass through • Achieved at the nuclei of ventrobasal thalamus. From here one or more additional short fibre neurons within the dorsal processed information is supplied to the somatosensory cortex horns before entering lamina V. Here long axon neurons arises posterior to the central sulcus. This information impinges on the and mostly join fibres from the fast pain pathway, crosses to the engrained body images in two cortical areas (S I. II) and evokes opposite side of the cord, then upward to the brain in the discrete appreciation and response. ventrolateral pathway. These fibres terminate principally in one of three areas

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Motivation – Affective Component: Modulation of Nociception: • The quality of unpleasantness is imparted to a sensory • It can occur either in the periphery or at any point where synaptic component from noxious stimuli that usually disrupts ordinary transmission occurs. behavior and thought, alters the individualʼs normal Peripheral modulation: responsiveness and demands attention. The individual is • Tissue injury activates nociceptors in the periphery by causing the motivated into activity aimed at stopping the pain and avoiding release of neurotransmitters such as substance P and Glutamate the cause. which activate nociceptors. Others allogenic mediators such as K+, • This aspect is related to impulses from spinal ʻTʼ cells carried by H, lactic acid, serotonin, bradykinin, histamine and PGs further paleospinothalamic tract and their projection into medial intra- sensitive and exite nociceptors and act as mediators of inflammation. laminar nuclei of thalamus and limbic system. Information here • Aspirin, NSAID, and specific COX2 inhibitors exert an analgesic deals with affective qualities of pleasantness or unpleasantness effects by inhibiting PGs synthesis and reducing PG E1and E2 of a sensation and the process of reward and punishment. mediated sensitization of peripheral nociceptors. Cognitive Dimensions: Spinal Modulation: • The sensory input is selected and a specific attention span is • It results from the action of neurotransmitter substances in the dorsal devoted to processing the information. Possible diversionary or horn or from spinal reflexes which convey efferent impulses back to protective strategies are identified and the consequents are the peripheral nociceptive field. The excitatory AA transmitters, α- recognized, especially in terms of past experience. All these glutamate and aspartate and several neuro – peptides including VIP, modify pain experience and judgment is made to best strategy. CGRP and neuropeptide - γ are found in central terminals of the first • The frontal cortex and the association areas provide a central order neurons – substance P found in synaptic vesicle of role in this cognitive process. unmyelinated ʻCʼ fibres aggravates pain PGs produced in response Motor mechanisms: to inflammation play a role in inflammation – evoked central • Various motor responses are evoked as pain is experienced. The sensitization of spinal cord neurons. pain reaction is divided into the operant and respondent. • Inhibitory substances include enkephalins, β endorphins, nor • Operant or voluntary behavior includes Verbalization, facial epinephrine, dopamine and adenosine, somatostatin. Pain fibres grimacing, withdrawal activities. enter the spinal cord through dorsal horn and synapse at lamina I II. • Respondent reactions are autonomic and include vascular, At this time, substance P contained in the terminals of the primary visceral and endocrine responses. afferent pain neurons, is released simultaneously by a negative feed • At spinal level, segmental reflexes are elicited to produce flexion back loop, the interneurons release enkephalin which has a or withdrawal; in the medulla cardio respiratory changes are presynaptic inhibitory effect to reduce or modulate pain transmission evoked. In the hypothalamus, the secretions of pituitary to higher neuron system. This initial modulation at the segmental hormones are affected. The hypothalamus also elicits level is designated as the endogenous opioid link. sympathetic nervous system phenomena and expression of anger and fear. In RAS, arousal ensure the midbrain – thalamus imparts a feature of suffering. The limbic system deals with many features of behaviors. 33

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• This neurotransmitters system is congruent with the gate control Therapeutic Correlates of Spinal Afferent System and Supraspinal mechanism of melzack and wall. Sensory input from the modulation: stimulation of large, low threshold mechano receptors carried by • According to Gate control theory, intense sensory input from A fibres inhibits the nociception by closing the transmission gate. stimulation of low threshold sensory mechano receptors is capable of inhibiting the nociceptors. Descending Supraspinal Modulation: • Modalities producing such ʻAʼ fibre sensory input include TENS, • This involves activation of enkephalins containing cells in the acupuncture, acupressure, sedative and deep massage technique. periaqueductal gray of mid brain as well as serotonin • Electrical stimulation of peri ventricular nuclei is effective against • Containing cells in medullary nucleus raphe magnus. These intractable somatic and visceral pain. The degree of relief is about inhibitory neuro transmitter are carried by fibres of descending equal to a moderate dose of morphine. Dorsal column electrical dorsolateral funiculus which communicates with the enkephalin stimulation also suppresses pain. TENS has been effective in the containing inter neurons in the SG. This reinforces the spinal management of acute pain of trauma or post operative pain. endogenous opioid link. Other tracts involved are corticospinal, • Electro – accupuncture and needling accupuncture have been shown tectospinal, medullary nuclei with their descending tracts passing to decrease levels of β endorphin in CSF. in the dorso lateral funiculus to the spinal segments they provide Post Operative Pain and Its Management: an integrated inhibitory activity. Definition: Modulation at cortical level: “Pain that is present in a surgical patient because of pre existing • This includes behavior modification hypnosis, bio feedback and disease, surgical procedure or a combination of disease related and psychotherapy. procedure related sources. • Perception is the phenomenon by which noxious stimuli reach Understanding of effective central of post operative pain is important consciousness. This is subdivided into cognition and attention. because Cognitive modulation of pain involves the patients ability to relate • It is an essential step in surgical and anaesthetic management of the a painful experience to another event. For eg: pain experienced patient. in a pleasant environment elicits, a less intense response than • Associated with various systemic adverse pathophysiological experienced in a setting of depression. changes when pain is poorly controlled. • Attention operates on the premise that only a fixed number of • Significant reduction in morbidity and needless suffering can be afferent stimuli can reach cortical centers. If the patient in pain achieved. concentrates on a separate and unrelated image, it is possible to • Brings emotional satisfaction. reduce the effect of a painful sensation. The positive impact on • Hospital stay is shortened and economically beneficial. pain from bio feedback or hypnosis operates on this principle.

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Factors affecting magnitude of pain: 3. Education and participation of patients and families in peri operative 1. Site of operation: Intra thoracic, abdominal, renal, spinal pain control. surgeries are associated with severe pain. Major joint surgeries 4. Assessment and documentation of a peri operative pain produce reflex muscular spasm and severe pain. management. 2. Type and Extent of surgical incision: Thoracic and upper 5. 24 hrs availability of anaesthetic personnel abdominal / renal surgical incisions are under tension. Deep 6. Use of standardized institutional policies and procedures for breathing, cough, movements increase tension and pain. ordering, administering or discontinuing pain management. 3. Pre operative preparation of the patient 7. Use of 3 specific techniques 4. Patient with pre operative anxiety and neurosis experience - Patient controlled analgesia with systemic opioids. more pain in post operative period. - Neuroaxial opioids or with local anaesthetic mixture 5. Well pre-medicated, psychologically counseled patients require - Regional anaesthetic technique. less post operative analgesia. 8. Multimodality approach 6. Surgical complications produce more pain 9. Use of two or more analgesic or techniques involving different sites 7. Anaesthetic Management or mechanisms or synergy of the effects. a. Preoperative – poor premedication / psychological 10.Organized inter disciplinary approach preparation 11.Recognition and management of specific features of paediatric pain b. Intra operative – Traumatic intubation, inadequate management relaxation etc have high incidence of post operative pain. 12.Recognition and management of geriatric pain 8. Age: Children have extreme expression of pain. Some have 13.Recognition of special features of pain management in ambulatory less expression of pain for the fear of painful injections. Elderly surgical patients. experience less pain. Modes of Treatment: 9. Pre emptive analgesia and intraoperative analgesia reduces Time of administration severity of post operative pain. a. Pre emptive analgesia ASA Guidelines for Peri operative Pain Management: b. Pre operative Purpose: c. Intra operative To prevent d. Post operative • Adverse outcomes of under treatment of post operative pain • Adverse outcomes of pain management. 1. Proactive planning: Predetermining the strategy for post operative analgesia based on type of surgery. Underlying medical distress, intra operative or post incisional preparation of patients for pain management. 2. Education and training of hospital personnel.

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Methods → Common Oral Recommendation: Pharmacological Drug Dose Interval(hrs) Onset of action (hrs) a. Oral – NSAIDS, OPIOIDS Aspirin 50-75 mg/kg/d 4 0.5 -1 b. Parenteral a. m/ I. V. – NSAIDS, OPIOIDS Ibuprofen 10-20 mg/kg 4-6 0.5 b. Neuroxial - Intrathecal /Epidural Naproxen 275 – 550 mg 6-8 1-2 hrs c. Patient controlled analgesia Indomethacin 25-50 mg 8-12 0.5 d. IV/ Subcutaneous/ Neuraxial/ Transdermal / Sublingual / Transmucosal/ Rectal / Infiltrations/ Ketorolac 10 mg 4-6 0.5-1 Intra articular Diclofenae 50-100 mg (2mg/ 8-12 0.5-1 e. Electrical –TENS sodium kg/day) c. Thermal – cryoanalgesia Celecoxib 100 -200 mg 12 3 d. Psychological – relaxation, hypnosis etc Rofecoxib 12.5-50 mg 24 2-3 Pre-emptive Analgesia: PCT 10-15 mg/kg 4 0.5 • Antinociceptive treatment that prevents establishment of altered central processing which amplifies post operative pain. • CNS sensitization can be prevented by blocking pain pathways Parenteral route: before incision. • Ketorolac 0.5 mg/kg upto 30 mg Iv/Im 28 H • It can be achieved by pre operative administration of opioids, • Diclofenac 75-100 mg Im Q8H NMDA receptor antagonists, NSAIDS, peripheral neural • Indo methaein 25 mg Iv and 5 mg/hr infusion. blockade or local infiltrations before surgery. • Rectal suppositories of diclofenac sodium are also available. Non opioid Analgesics: Adverse effects: • Aspirin, Acetaminophen, NSAIDs, selective COX2 inhibitors are • G.I discomfort – nausea, vomiting, dyspepsia, heart burn and used. Their common mechanism of action is inhibition of epigastric discomfort prostaglandin mediated amplification of chemical and • Contraindicated in hepatic and renal insufficiency mechanical irritation on the sensory pathways. • Exacerbation of bronchospasm in asthmatics and rhinitis in nasal poly patients. Opioid Analgesia: • Morphine and related compounds, endogenous neuromodulating peptides of enkephalin and β endorphins bind to opioid receptors. Currently 5 classes of opioid receptors identified.

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Mu Delta Kappa Sigma Sub lingual: Effect µ1 µ2 δ k σ • Avoidance of ﬁrst pass metabolism • No injection discomfort Analgesia Supraspinal Spinal Spinal - • Less side effects of nausea, vomiting and respiratory depression Affect Euphoria Sedation - Sedation Dysphoria • Buprenorphine is commonly employed Pupil Miosis - - Miosis Mydriasis Intranasal: Side effects are less compared to other routes R.S. - Depression Depression - Tachypnoea • • Effect achieved faster G.I.T Nausea / Constipation Nausea / • Ideal for immediate relief of moderate to severe post operative pain Vomiting Vomiting • Butorphanol is commonly employed in metered doses. Genitor Urinary - Urinary Transepithelial: urinary retention retention • Rapid onset of action system • Avoidance of ﬁrst pass metabolism Physical Yes Yes Little Titratability is problematic dependence • • Fentanyl has been used transdermally and transmucosaly Subcutaneous: Moderate to severe pain is best treated with opioids alone or • Earlier, commonly used route along with NSAIDs. Analgesia is achieved by blunting the central • Now primarily for expected long term administration response to noxious stimuli without loss of consciousness or • Mainly for cancer patients. affecting tactile, visual or auditory sensation. • Intra muscular: Dose limiting side effects such as nausea, vomiting, constipation, • • Produces a rapid onset and time to peak effect compared to oral urinary retention and ventilation. Depression can be overcome route. by proper selection of the agent and route of administration. • Pain at the injection site, patients apprehensiveness of needle prick • Sedation and euphoria may be desired in the immediate post the potential for delayed ventilator depression and wide variability in operative period. drug serum concentration limit the viability of this route. Agonist – antagonist, can be effective in post-op period because • • Most opioids can be administered by this route. they have a ceiling effect for ventilator depression Intravenous: Routes of Opiate administration: • Rapid onset of pain relief Oral Delivers a more predictable max concentration by eliminating the Generally slower onset of action • • absorption process compared to other routes. • Delayed peak time • Longer duration of effect • Disadvantage is pre systemic elimination • Oral sustained release preparation are also available. May be best suited for providing analgesia for cancer pain.

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Disadvantages: • Lock out interval: Time interval between 2 triggers during which no • Analgesic effect is short drug is administered even after pressing the trigger. • A larger dose may be required to deliver analgesia for a longer • Back up infusion: Basal infusion which to delivered by the machine time. whether or not the button is triggered. • Continuous I.V Infusions in surgical ICU requires close patient • Morphine is the commonest drug used. Others one Fentanyl. observation for early detection of accumulating plasma Pethidine, Tramadol, hydromorphone concentration that are in a toxic range. Daily care of PCA: • I.V infusions coupled with demand bolus analgesia are used in • Total dose in past 24 hrs; PCA setting readjustments should be seen PCA • Side effects of drugs used should be checked Rectal route: • Evaluation of pain, if out of proportion careful observation of the • Not dependent on gastric emptying as seen with oral route cause. • Bypasses ﬁrst pass effect. • Change of doses based on patients response • Has got bio availability twice that of oral route Advantages: • This is also suitable for sustained release preparation of opioids. • Superior quality of analgesia Patient Controlled Analgesia: [PCA] • Patient satisfaction • It has been a major development in post operative pain • Lesser requirements of analgesics management and now is considered the therapeutic standard for • Less chance of respiratory depression the management of acute post operative pain. • Freedom from painful injection • PCA is self administration of Intravenous, neuraxial / • Analgesia during sleep subcutaneous analgesics on demand through a computerized Disadvantages: device. • Human error in setting • PCA is delivered using micro processors controlled by syringe • Device malfunctioning pumps which delivers the preset amount of opioid whenever the Dosing guidelines for I.V. PCA.: patient presses the button. The trigger button to be activated on Loading Lockout Drug Connecting Bolus dose Infusion rate demand by the patient for demand dose. dose internal • The principle behind the working of PCA is the minimum effective Morphine 1mg/ml 3-10mg 0.5-1.5mg 6-8 min 0.5-1.5 mg/ analgesic concentration (MEAC). It is the minimum plasma level hr of a speciﬁc analgesic which will control pain. Fentanyl 20µg/ml 30-100µg 10-20µg 5-6min 10-20µg/hr • In IM administration MEAC is exceeded only for brief periods, Meperidine 10mg/ml 26-50mg 5-15mg 6-8min whereas in PCA, the patient doses himself to retain the plasma levels of opioid close to the MEAC. Bolus dose or demand dose: The drug dose the machine will deliver with each triggering of the pump on demand. Loading dose is 1st dose administered decreased supervision before getting demand dose 38

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Central Neuraxial Analgesia: Intermittent Epidural bolus: • The use intrathecal or epidural narcotics and LA for post op Advantages: analgesia is becoming popular. Both bolus and infusion • Simple [providing resident accepts the responsibility of catheter technique can be used Epidural rather than intrathecal injections] techniques are needed to provide analgesia consistently for • No need of infusion devices more than 24 hrs. Disadvantages: • Intrathecal administration is done • Limited number of suitable opioids a. Along with LAs for surgical anaesthesia • Higher incidence of side effects b. As a separate technique during or at the end of general • More difﬁcult to titrate the dose anaesthesia • Extra effort to inject catheter every 8-12hrs. Two major factors determine the use of intrathecal analgesia Continuous epidural infusion: • Risk of spinal headache with multiple dural punctures Advantages: • Risk of infection or nerve damage with intrathecal catheters • Less rostral spread, so side effects are minimized • These factors limit intrathecal analgesia to single shot • Provides continuous analgesia avoiding variations seen with administration in most practices. intermittent bolus • A long acting analgesic is therefore most appropriate and • Allows for concomitant use of dilute local anaesthetic solutions Morphine has been the drug of choice. • Allows the use of shorter acting opiates such as fentanyl or Intrathecal opioid dosages: sufentanyl Drug Single dose Onset Duration of action • Less potential risk of contamination for injection because the catheter system has fewer breaks in sterile technique Morphine 0.1 – 0.3 mg 15 min 8-24 hrs • Simple and easy maintenance Fentanyl 0.005 – 0.25 5 min 3-6 hrs Disadvantage: mg • Need for sophisticated infusion device. Meperidine 10-30 mg ? 10-24 hrs Epidural drug dosages: Epidural opioid Analgesia: • Morphine: 1-6 mg as single dose. DOA– 6-24 hrs. OOA-30 min . This is the most frequent method of spinal analgesia today. It • Infusion rate 0.1-1mg/hr allows the safe placement of a catheter for multiple or continuous • Fentanyl: 0.025 mg – 0.1 mg as single dose. DOA 2-4 hrs. OOA-6 dosing. min. Infusion rate 0.075 mg /hr Epidural access can be obtained • LA: Bupivacaine, a long acting LA is preferred 0.0625 – 0.125% • During preemptive analgesia alone or in combination with opioids can be used • As a separate technique following GA • As combined spinal – Epidural technique

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Patient controlled Epidural Analgesia: (PCEA): Features of post op analgesia in paediatric age group: • Here the patient takes control of his pain like with a PCA. The • Lack of safe method of analgesia main indication is to treat the break through pain caused by a • Difficulty in assessing pain severity fixed dose regimen or to facilitate physiotherapy and • Expression of pain in post op period is less because of fear of painful mobilization. The usual practice is to fix a continuous infusion of injections any of the regimens mentioned and set a bolus dose with each • NSAID are considered adjuncts to but not primary in moderate to trigger. severe pain Epidural-PCA Dosing guidelines: • Opioid induced respiratory depression is more common Lockout Continuous Epi PCA LD Conc. • Caudal epidural analgesia is effective in selected cases. interval rate line Features of Geriatric post op analgesia: Morphine 2-4 mg 10-15 min 6-12 ml/hr 2-4 ml 50 μg/ml • Presence of systemic diseases Fentanyl 75-100 µg 6min 6-12ml/hr 2-4 ml 5μg/ml • Pain is reported less in elderly • Reluctant to play active role in PCA Peripheral Nerve Blocks and Other Regional Techniques: • Opioid related respiratory depression is common • Provide excellent pain relief with little adverse effect • NSAIDs are more beneficial • Single shot of Bupivacaine 0.25 – 0.375% provides upto 8 hrs of • Careful titration of drug doses analgesia • Regional analgesia is more advantageous. • Use of catheter can result in a continuous nerve plexus block Pathophysiology of acute pain: • Nerve blocks that can be performed are Brachial plexus block 1. Following injury a local reflex established and releases bradykinin, intercostal, femoro sciatic, triple block for ankle, penile block, PGs, substance P sensitize nociceptors immediately adjacent to hernia field block, supra/infra orbital block the site of injury, resulting in heightened inflammatory response, • Caudal block a simple and efficient way of managing post op neurogenic edema and hyperalgesia. pain for lower abdominal and perineal surgeries in children 2. Centered facilitation is initiated by the action of neuropeptides and [1-1.25ml/kg of 0.25% Bupivacaine]. excitatory AA such as aspartate and glutamate upon Neurokinin • Continuous technique also practiced with 19 G catheters placed and NMDA. Substance P promotes the release of EAAs and caudally. increase the responsiveness of dorsal horn WDR neurons to • This analgesic technique ideally must be instituted before NMDA resulting in two phases of hyperalgesic responses initial emergence from GA to allow the patient to wakeup pain free. fast, Secondary slow long term. Other methods: TENS Cryo analgesia • Use of ketamine 1mg/kg followed by 3-4 mg/kg /hr infusion • Nitrous oxide: for acute painful periods of short duration example Dressing of wounds • Psychological methods: Relaxation, hypnosis etc 40

Dr Azam’s Notes in Anesthesiology 2013 Post operative Management.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Sympathoadrenal activation Neurotransmitters: • Perioperative ischemia, provoked by hypothermia, anxiety and • Pro-nociceptives → Neurokinin A & B, substance P, VIP, CGRP tracheal intubation • Excitatory Amino acid like glutamate and aspartate. • Tachycardia and other responses to poorly controlled pain • Anti-nociceptives → Opioid peptides, β endorphins, Enkephelins (µ • HTN →risk of MI and stroke and ∂ receptor agonists ). • Altered perfusion à as blood flow is directed to high priority • Substance P: A neuropeptide widely distributed in CNS organs, perfusion in injured tissue and adjacent musculature • Found in terminals of primary afferent neurons diminished poor wound healing. • Substance p rich areas are amygdale, periaqueductal gray, raphe Neuroendocrine responses: nuclei • The stress response to injury is characterized by elevations in • Also regulates axon reflexes causing vaso dilatation in injured area. plasma levels of cortisol, glucagon and epinephrine resulting in • The release of it from dorsal horns are blocked by opiates. hyperglycemia, negative nitrogen balance, prolonged tissue catabolism many adversely affect post surgical outcome. Alterations in pulmonary function: • Increased RR, Decreased TV, VC and FEV1, are seen. The reduction in VC, FEV1 is highest in patient with upper abdominal and thoracic surgery and lowest in patient recovering from pelvic and extremity surgeries • Reduction in pulmonary function are due to poorly controlled pain, reflex spasm of chest wall and pleuritic irritation. These are associated with atelectasis and a reduced ability to cough and to clear secretions. Following these, significant hypoxia, pneumonia occurs particularly in patients with underlying pulmonary disease. D.V.T: • Poorly controlled pain limits patient ambulation ending in decreased venous return. Catecholamines, angiotension and factors associated with surgical stress, increased platelet adhesiveness and lead to a hypercoagulable state. This venous stasis and hypercoagulable state increases the risks of clot formation and D.V.T.

Dr Azam’s Notes in Anesthesiology 2013 13. Complex Regional Pain Syndrome.(CPRS). Dr Azam’s Notes in Anesthesiology 2013

• CRPS is a new name for an old disease • A third classification “CRPS type III” has been used. Classify • It is most commonly misdiagnosed and under treated. sympathetic pain “Not otherwise specified”- pain that does not fit into • It has minimal or no preceding signs and symptoms and the pain the other two categories, including pain of central origin. is disproportionate to the events causing it & the distribution by • Pain is the cardinal symptom of CRPS pain is non dermatomal. • Pain is a burning, lancinating pain which is more severe than could Other names of CRPS: - be expected from the initiating event. 1. Causalgia minor, major • Pain must be present for diagnosis and must be allodynic or 2. Pain dysfunction hyperpathic in nature. 3. Traumatic angiospasm • Allodynia →Perception of pain to normally non painful stimuli. 4. Post traumatic oedema • Causalgia → Burning pain after a nerve injury 5. Variable pain syndrome • Dystrophy→ Defective changes that result from defective tissue 6. Sympathetically mediated pain nutrition. 7. Chronic traumatic oedema • Hyperalgesia →Increased perception of painful stimuli. 8. Acute atrophy of bone → 9. Spreading neuralgia • Hyperpathic Increased response and increased threshold to stimuli 10.Neuro vascular dystrophy • Neuralgia → Pain in the distribution by nerves 11.Reflex dystrophy • Neuropathic pain → Pain caused by nerve damage 12.Reflex sympathetic dystrophy (RSD) • Paresthesia → Abnormal sensation to stimuli 13.Thermolgia • Tremor, dystonia or weakness may be present; but motor weakness 14.Shoulder-hand syndrome is not important for diagnosis. 15.Hyperpathic pain • Autonomic impairment like temperature, vascularity, hair growth, skin changes and nail growth may be present but not important for Classified into: diagnosis. CRPS I CRPS II Clinical stages: - Stage I: (Acute) 1-3 months 1.Former name: RSD Causalgia • Edema 2.Cause: Noxious event (micro injury) Nerve injury (macro • Hyperthermia or hypothermia injury) • Increased hair and nail growth 3.Symptons: Allodynia • Disuse – immobilization Hyperalgesia Same • Burning pain beyond dermatomes 4.Ditribution: Non dermatomal Same 5.Signs: Edema, pseudomotor, autonomic Same 6. Rx: Does not respond to sympathetic blockade Responds

Dr Azam’s Notes in Anesthesiology 2013 Complex Regional Pain Syndrome.(CPRS).Continuation: Dr Azam’s Notes in Anesthesiology 2013

Theories on CRPS: Stage II: (Dystrophic), 3-7 months 1. Artificial synapses that cause “Electrical short circuits are formed • Progressive oedema where efferent fibres are diverted towards centre and percieved as • Hypothermia pain • Hair loss 2. Wind up phenomenon: Due to wide – dynamic range (WDR) • Nail breakage neurons in the cords causes pain multiplication or intensification • Cyanosis thereby perceiving non painful stimuli as severe pain • Weakness, tremors, spasticity Stage III: (Atrophic) >7 months 3. Turbulence theory. • Skin dehydration 4. Neural sprout out growth theory: Is an aberrant growth of neural • Smooth, glossy skin tissue resulting from a nerve injury. • Cyanotic or pale skin Clinical findings: • Lymphedema Pain Oedema • Muscle wasting • Hyperhydrosis Atrophy • Flexion contracture • Hair loss Skin changes • Ankylosing joints • Changes in temperature Tremor, dystonia, weakness • Spasm, dystonia tremor • Stage IV: (End stage) • Nail changes Motor weakness • Frozen • Cyanosis Flexion contractures Laboratory tests: • Useless extremity Scoring criteria for diagnosis of CRPS: • Severe depression Burning pain • Suicidal • Incidence: 3 times more common is women • Hyperpathia / allodynia • -3-4 decades • Color changes • Associated with psychological disorders • Hair growth changes • May follow after knee arthroscopy • Sweating changes Pathophysiology: -triad of disturbances in CRPS • Temperature changes ! • Edema "#$#%!! • Sudomotor changes measurements • Osteoporosis • Response to sympathetic blockade &'$#(#)*+!!! ,%#-.*+!/.0*%1!(0*21!34*(!$56$'%5! #3$5#-#%#3*37!

Dr Azam’s Notes in Anesthesiology 2013 Complex Regional Pain Syndrome.(CPRS).Continuation: Dr Azam’s Notes in Anesthesiology 2013

Points 23. Chemical and surgical sympatholysis. • < 3--- No RSD 24. Spinal cord stimulation. • 3-4.5-- Possible RSD 25. Intrathecal opioids. • > 5-- Probable RSD

EMG . • SSEP . 3) Thermography. 4) Sweat test and cold stress test • Digital plethysmography.6) Trans cutaneous O2 Monitoring • X-ray: Osteoporotic changes. 8) Bone scan. 9) MRI and CT scan. • Response to sympathetic blockade . Treatment: 1. Physical therapy. 2. TENS. 3. Heat application. 4. Hypnosis. 5. Bio feedback. 6. Psychologic counseling. 7. Immobilization. 8. Acupuncture. 9. Steroids. 10.Calcitonin. 11.β-blockers. 12. Bretylium. 13. α - blockers. 14. α2 agonists. 15. Opioids. 16.NSAIDs. 17. Anti depressants. 18.Anti convulsants . 19.Ca blockers. 20.Bier blocks. 21.IV L.A. 22.Sympathetic block (stellate block).

Dr Azam’s Notes in Anesthesiology 2013 14. Trigeminal Neuralgia. Dr Azam’s Notes in Anesthesiology 2013

• Trigeminal neuralgia is characterized by sudden attacks of brief Thermocoagulation: but intense unilateral facial pain triggered by local sensory stimuli • Thermocoagulation of neural elements has been most effective in to the affected side of the face. The pain is precipitated by patients with trigeminal neuralgia who do not respond to medical touching the “trigger zones” of the affected side of the face. The therapy. various stimuli which may be sufficient to bring an attack are a • Thermocoagulation of gasserian ganglion is accomplished by cold wind blowing across the face, washing the face, chewing or percutaneous passage of a probe through the infra temporal fossa even talking. 2nd and 3rd divisions of the trigeminal nerve are and foramen ovale, using the standard clinical approach for injection usually involved. of the gasserian ganglion. Light intravenous analgesia and sedation • Trigeminal neuralgia most often manifests after 50 years of age. are usually necessary (Eg fentanyl 50mcg and droperidol 2.5mg). By Appearance before 50 should arouse the suspicion of multiple means of a stimulating current, the electrode is localized on the part sclerosis. This is consistent with histological evidence of of the ganglion corresponding to the tic pain, patient confirming the degeneration or absence of myelin changes is unknown, but location. The patient is then given a short acting general anaesthetic proposed mechanisms include viral infection and vascular (usually with inhalation of nitrous oxide) to relieve pain from creation compression of the nerve. of the thermal lesion. Because of its effectiveness and low incidence Treatment: of side effects, this technique is now preferable to alcohol block of I. Medical: gasserian ganglion. The patient is spared hemi facial numbness with • Trigeminal neuralgia is an example of the central pain state and its conjunctival inflammatory problems. stimuli producing pain is believed to arise from within the CNS. • A new device cryoprobe uses expansion of nitrous oxide to produce Pain is probably caused by some defect in the transmission an ice ball at the tip of the probe. These instruments disrupt sensory system whereby intermediate cells generate aversive afferent nerve function for several weeks and do not seem to be associated stimuli. This condition resembles abnormal epileptic activity on with the denervation neuralgia that often follows destruction of nerve the sensory input side of the nervous system and requires with neurolytic agents. specific drug therapy. Conventional analgesics and sedatives Trigeminal nerve block: provide little relief for the condition. • Trigeminal nerve divides into 3 main branches in the middle cranial • The most appropriate medications are phenytoin and fossa. These divisions, the ophthalmic, maxillary and mandibular Carbamazepine (Drug of choice). nerves, provide sensation to the eye and forehead, midface and Phenytoin: 100 mg tid. Most patients respond favourably to this upper jaw and lower jaw respectively. With the exception of motor treatment alone fibers to the muscles of mastication carried by mandibular nerve Carbamazepine: Refractory cases respond to Carbamazepine these nerves are wholly sensory. starting with 200 mg a day, increasing by 200 mg increments to a a) Gasserian ganglion block: approached classically through the maximum of 1500 mg a day. foramen ovale. In the past, was primarily applied to the diagnosis and • Medical Therapy is usually effective for 85% of patients with treatment of trigeminal neuralgia. However the increasing popularity trigeminal neuralgia. and safety of thermocoagulation have rendered neurolytic block obsolete.

Dr Azam’s Notes in Anesthesiology 2013 Trigeminal Neuralgia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Advantages: Other surgical approaches: • Blockade of 2nd and 3rd divisions of trigeminal nerve or its • Selective radio frequency destruction of trigeminal nerve ﬁbres. peripheral branches are still used in management or diagnosis of • Microsurgical decompression of the trigeminal nerve. trigeminal neuralgia. Neurolytic blockade – considerations: Disadvantages: • Because peripheral nerve destruction with alcohol or phenol is • Protective corneal sensation may be lost. frequently followed by denervation dysaesthetic pain that is often as • Block of maxillary nerve can be associated with haematoma bad, if not worse than the original pain, this type of therapy has now formation as well as spread of local anaesthetic solution to been almost abandoned. Incidence of post neurolytic neuralgia is involve gasserian ganglion. least after the neurolytic therapy of branches of trigeminal nerve. • Spread of local anaesthetic solution to the optic nerve can cause • Alcohol and phenol are the most widely used agents. Injection of temporary blindness. alcohol is very painful, lasting for a few seconds until neurolysis • In mandibular nerve block pharynx may be entered, increasing occurs. Injection of phenol which is usually mixed with saline or the risk of contamination of the infra temporal fossa. glycerin is painless. Neurolytic effect of alcohol is more intensive than • Rarely subarchnoid spread of local anesthetic producing brain phenol which has both local anaesthetic and neurolytic action. No stem anaesthesia. permanent neurolytic block is truly permanent and sensation and • Technique: Mandibular and maxillary nerves are blocked pain returns within weeks or months. Diagnostic nerve blocks should through the same needle site entry. always precede the use of neurolytic agents for the patient to • Maxillary nerve: The coronoid notch of the mandible is located evaluate the ﬁnal outcome of therapy. and with the mouth closed, a 22G-8cm needle is inserted at the inferior edge of the coronoid notch perpendicular to the skin. The needle will contact the lateral pterygoid plate at a depth of about 5cm. It is then withdrawn and redirected anteriorly and superiorly to ʻwalk offʼ the plate and is advanced 0.5cm into the pterygopalatine fossa. 3-5ml of local anaesthetic solution is injected. • Mandibular nerve: Blocked via the same entry site. Bone of lateral pterygoid plate is contacted. The needle is withdrawn and redirected along the posterior border of the pterygoid plate. The needle should not be inserted more than 0.5cm past the plate. 3-5ml of solution is injected.

Dr Azam’s Notes in Anesthesiology 2013 15. Bromage Scale. (L1 - S2) Dr Azam’s Notes in Anesthesiology 2013

• No block (0%) - Full Flexion of knees & feet possible. • Partial (33%) - Just Able to flex knees, still full flexion of feet possible • Almost complete (66%) - Unable to flex knees. Still flexion of feet • Complete (100%) - Unable to move legs or feet. Right Left Hip flexion (L2) 1 1 Knee extension (L3) 1 1 Ankle Dorsiflexion (L4) 1 1 Great toe Dorsiflexion (L5) 1 1 Ankle plantar flexion (S2) 1 1 5 + 5 =10 Complete Motor Block

• Abdominal Muscle power may be assessed by the Rectus abdomenus Muscle (RAM) test. This is useful in Abdominal surgery when Abdominal Muscle blockade is required rather than lower limb muscle blockade. On the other hand Bromage scale is useful for lower limb surgery. Both scales may be used when a comprehensive picture is required. RAM test (T5 – T12) of Bromage scale (L1 – S2) RAM Test: 100 % power Able to rise from supine to sitting position with hands behind head. 80% power Can sit only with Arms extended 60% power Can lift only Head and scapulae off the bed 40% power Can lift only shoulders off the Bed 20% power An increase in Abdominal Muscle tension can be felt during effort, No other response.

Dr Azam’s Notes in Anesthesiology 2013 16. Nitrous Oxide in Middle ear surgery. Dr Azam’s Notes in Anesthesiology 2013

• The middle ear and paranasal sinuses are normal body air Prevention: cavities that consist of open non-ventilated spaces. The middle • N2O should be discontinued 15 min before closure of middle ear. ear is ventilated intermittently when Eustachian tube is opened. • Subsequent decrease in sub-atmospheric pressure can be avoided • N2O is about 34 times more soluble in blood when compared to by flushing the middle ear with air prior to closure of tympanic nitrogen and because of this disparity N2O will diffuse into any membrane. air containing cavity more rapidly before the nitrogen can leave. In a fixed cavity such as middle ear, this result in an increase in pressure. • Normally, passive venting by the Eustachian tube occurs at a pressure of approximately 200-300 mm/H2O. If the Eustachian tube function decreases because of surgical trauma, disease or acute inflammation and edema, middle ear pressure can reach 375-400 mm/H2O, within 30min start on N2O. • In addition after discontinuation of N2O the gas is rapidly reabsorbed and marked negative middle ear pressure may develop. When Eustachian tube function is abnormal, negative pressure may reach285-300 mm/H2O. N2O produce two type of pressure effect on middle ear I) Due to rapid increase in middle ear pressure during anesthesia: a. Usually proportional to the inhaled concentration of N2O. b. Nausea and vomiting c. Rupture of tympanic membrane specially if Eustachian tube is blocked d. A bulging eardrum and lifting of tympanic membrane graft displacement can occur during tympanoplasty surgery.

II) Due to negative pressure within middle ear cavity (After discontinuation of N2O) a. Serious otitis media b. Disarticulation of stapes. c. Impaired hearing secondary to hemotympanic

Dr Azam’s Notes in Anesthesiology 2013 17. Bleeding Tonsil. Dr Azam’s Notes in Anesthesiology 2013

Causes: Anaesthetic Management: a. Primary – at the time of surgery. Premedication b. Secondary – usually 4to 6 day onwards. • If the condition permits, agitated or frightened children may be c. Reactionary – 8 to 48 hr. sedated with Midazolam (50 to 100 μg/kg) or IV Fentanyl (1 g /kg) IV, • Posting tonsillectomy bleeding is one of the most dangerous and to relieve anxiety and make them more co-operative. challenging situations in pediatric anaesthesia practice. Failure • Atropine (0.02mg/kg) IV to initiate prompt action has been one of the main causes of Preparation: death associated with tonsillectomy. • At least one, preferably two well-functioning suction apparatus with • The child with tonsillar bleeding may be brought back to the large bore suction tubes. operating room several hours post-operatively or even days or • Extra Laryngoscope blades and handles. weeks following surgery. The child needs to be anaesthetized to • Several ETT with lubricated stylets. suture or pack the bleeding area. • An experience assistant to apply cricoid pressure and help the Clinical picture: anaesthesiologist during the rapid-sequence induction. The child is hypovolemic, anemic, agitated or in shock, with a • Induced with Thiopental sodium (3-4mg/kg) with stable stomach full of blood clots. cardiovascular status Clinical assessment: • Ketamine (2mg/kg) may be used if the child is still anaemic and Volume status: dehydrated. • Maybe tachycardiac + increase B.P. due to release of • Intubated with rapid sequence technique endogenous catecholamines or may be hypotensive. • Relaxed with succinylcholine (2mg/kg) and intubated orally with Hypovolemia (mild to moderate): cuffed ETT to prevent blood from entering the trachea around • Child able to sit up without feeling dizzy. Estimate Haemoglobin the uncuffed tube. and hematocrit, urine speciﬁc gravity and other additional a. 75% of bleeding occurs within 6th of surgery. information b. 25% of cases within 24 hr of surgery. • Hypovolemia (severe): Child may be lying down, diminished c. Bleeding tonsillar fossa (67%) and adenoidectomy site 27%. consciousness, pale conjunctiva, hypotension Bleeding may be • Maintenance and emergence in these patients is focused on massive hypovolemia and a full stomach. • Volume Resuscitation must be started without delay. • Maintenance with N2O +O2 + Halothane + Inj Vecuronium • I.V. Access must be established (unless already present) to • Fluid and blood transfused as per the volume status. rehydrate or transfuse without delay. • A large bore gastric tube is introduced through the mouth carefully to • I.V. access may be difﬁcult due to extreme vasoconstriction – If decompress the stomach, although it is not possible to evacuate all so a surgical cutdown may be indicated. blood clot and solid food. • Rapid hydration and transfusion should be started in patients in hypovolemic shock.

Dr Azam’s Notes in Anesthesiology 2013 Bleeding Tonsil.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Both sides of chest are carefully auscultated and the Problems during anaesthesia: endotracheal tube is suctioned to rule out aspiration of blood or • Unsuspected hypovolemia, full stomach / Airway obstruction. gastric content. When in doubt a portable chest x-ray is taken Replace fluid with crystalloid /blood. • Reversed with Neostigmine (0.50 mg/kg) + Atropine (0.02 mg/kg) • Induction: Depending on hemodynamic stability • Extubated when the patient is fully awake and normal gag and • Thiopentone + Glyco (sleep dose) cough reflexes have returned. • Ketamine • Patient is put in lateral position and monitored in the recovery • Rapid sequence induction with head down to protect against room. aspiration of blood into trachea and glottis. Additional person to Classification: provide suctioning of blood. 1. Primary hemorrhage at the time of surgery • Nasogastric tube after induction. 2. Reactionary hemorrhage: from 8to 48hr, due to effect of • Maintain with gas O2 volatile anaesthetics, opioids. adrenaline weaning off, post op increase in BP. Slipping of • Extubation after patient is awake as in tonsillectomy ligature. Prophylactic measure: 3. Secondary hemorrhage: usually 4th and 6th day onwards due to • After tonsillectomy, do laryngoscopy; see for clots keep patient in sloughing of arteries due the infection. trendelenburg, head low lateral. Post tonsillectomy management: • post-op trickles of blood→ laryngospasm. • Incidence 0.3 – 0.6%. occurs with in 6hrs of surgery • (Have assistant for throat suctioning.) Anaesthetic consideration: • Extent of blood loss not obvious, often underestimated • Coagulation profile should be checked (check BT/CT.) • No premedication should be given / no sedations/ IV Ranatidine + metoclopramide. • Secure good IV line with available of cross matched blood. • Achieve adequate hydration of patient • N-G tube to aspirate ingested blood à to prevent post-operative nausea and vomiting

Dr Azam’s Notes in Anesthesiology 2013 18. Post tonsillectomy management Dr Azam’s Notes in Anesthesiology 2013

• Incidence 0.3-0.6% occurs within 6hrs of surgery Anaesthetic consideration: • Extent of blood loss not obvious, often underestimated • Coagulation proﬁle should be checked. • No premedication should be given / no sedation. • IV Ranitidine + metoclopramide • Secure good IV line with availability of cross matched blood. • Achieve adequate hydration of patients.

Problems during anesthesia: • Unsuspected hypovolemia, full stomach, airway obstruction • Replace ﬂuid with crystalloid / blood. • Induction: depending on hemodynamic stability • Thio + glyco (sleep dose) • Ketamine • Rapid sequence induction with head down to protect against aspiration of blood into trachea and glottis (additional person to provide suctioning of blood). • Nasogastric tube after induction. • Maintain with gas, O2 volatile anesthetics, opioids. • Extubation – after patient is awake as in tonsillectomy. Prophylactic measures: • After tonsillectomy, do laryngoscopy, see for clots, keep patient in head low lateral. • Post op – trickle of blood, laryngospasm

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Dr Azam’s Notes in Anesthesiology 2013 :;# # <<<=!"$%&'=7+'# # Endoscopy & Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

CVS stability: CVS instability is due to a) Vagal stimulation → bradycardia b) Inadequate depth (Awareness) c) ANS stimulation d) Pre existing cardio pulmonary dysfunction e) Arrhythmias

Dr Azam’s Notes in Anesthesiology 2013 20. Bronchoscopy. Dr Azam’s Notes in Anesthesiology 2013

• Anaesthetic technique depends to a great extent on the Disadvantages: equipment available and thus the knowledge of the type and 1. Blood and tissue debris may blown further down the bronchial tree. characteristics of bronchoscope being used is essential for the 2. Risk of generating high airway pressure and causing barotraumas safe management of bronchoscopy. especially in children. Two types of bronchoscopes • Rigid bronchoscopes are sized according to their internal diameter, 1. Rigid bronchoscope thus a 3.5 mm rigid bronchoscope has a 4 – 4.5 mm outer diameter 2. Flexible bronchoscope. to allow the patient to breathe through them. The rigid bronchoscope Rigid bronchoscope has two types. allows the passage of various instruments through them. This 1. Negus bronchoscope (rigid venturi type) includes suction catheter, forceps for biopsies and extraction of 2. Sturz bronchoscope ( rigid ventilating type) foreign bodies. Fogarty catheters to tamponade bleeding etc. • The bronchoscope has got the side openings at the lower end. Advantages: They provide ventilation to opposite lung when the scope is 1. Bigger foreign bodies can be removed as a whole. passed to one side. At the proximal end there is an eye piece 2. A large piece of tissue can be taken from growth in the bronchus. which can removed for suctioning or while taking a biopsy by Disadvantages: biopsy forceps. • The manipulation of rigid bronchoscope in tracheobronchial tree is • There are two side arm attachments to connect the light source poorly tolerated by the patient. Hence GA is essential in most of the on one side. On the other side, to connect the anaesthesia circuit cases. through which we can deliver anaesthetic gases. In addition in Sturz bronchoscope there is a narrow side arm attachment to provide jet ventilation. Rigid ventilating type: • Superior optical characteristics. • Can also be used with an injector. • Documentation of FiO2 is possible. Disadvantages: 1. When telescope / glass window is not in place controlled ventilation is not possible. 2. If the patient is allowed to breathe spontaneously, then there is an increased chance of sedation for surgeon due to exhaled gases. Rigid venturi type: • Inferior optical characteristics. • Relies on administration of high pressure O2 intermittently to inﬂate lungs. • Unobstructed, uninterrupted and unhurried view is available. 54

Dr Azam’s Notes in Anesthesiology 2013 21. Fiber Optic Bronchoscopy. Dr Azam’s Notes in Anesthesiology 2013

• The principle of fiber optics is the transmission of light and image Disadvantages: without distortion along the bundles of very fine flexible glass 1. It is expensive and delicate instrument so it is not available in all fibers. hospitals. • It contains fiber optic bundle transmitting light from a light source 2. Since the diameter is of small size, the foreign bodies have to be to the tip of the instrument, another bundle transmitting from the fragmented and biopsy material will be of small size. tip to the eye piece, and a suction lumen all contained with in a 3. Since it is a solid instrument it is not possible to ventilate the patient cylinder tube. through it. • The fiber optic bronchoscope is sized according to outer diameter and the patient must breathe around it.

These are available in various sizes and with various wide angles at the tip: ID (mm) ED (mm) Premature neonates 2.5 4 < 6 months 3 5 6 months to 1 year 3.5 5.7 1 year to adult 4 6.4

Advantages: 1. Smaller diameter so that it reaches the distal parts of bronchi, so visualization of bronchial tree is possible beyond the range of rigid bronchoscope. 2. It is ﬂexible so that it can be maneuvered in any direction. 3. It is very well accepted by the patient so LA will be sufﬁcient.

Dr Azam’s Notes in Anesthesiology 2013 22. Bronchography. Dr Azam’s Notes in Anesthesiology 2013

Bronchography is a method of delineating the bronchial tree with Anaesthesia: radio-opaque contrast medium. • Done ↓ local spray with 4% xylocaine catheter passed down the • It is now relatively uncommon investigation due to availability of trachea and contrast media is introduced through it. CT scan. GA: pre-op preparation • Was used earlier mainly for the diagnosis and evaluation of • Sputum for culture and sensitivity bronchiectasis. • Antibiotic • Usually it is done ↓ local anesthesia, but in children and • Physiotherapy unusually nervous adults may require GA. • Postural drainage • LA is preferred because bronchography requires patients co- • Sputum quantity should be reduced < 30CC/day operation to take pictures in different views and spontaneous Induction with IV agents or inhalational agents: breathing also helps in gradual spread of the drug. • Inhalational agents preferred • Hypoxia and some degree of obstruction to the airway is • Endotracheal intubation after IV scoline (1-2mg/kg) inevitable during bronchography with conventional media. So it is • Then maintained with N2O + O2 + halothane not done below 1yr of age because of risk of easy blockade of Once anaesthesia is established contrast medium is introduced smaller airways. through a catheter placed down the ETT via suitable inlet in Problems associated endotracheal tube connector. 1. Hazards associated with anesthesia in a poorly illuminated x- Spontaneous ventilation aids in gradual spread of contrast medium ray room. and depends upon the position required patient position is to be 2. Suboptimal respiratory function and further impaired with altered. introduction of contrast medium into the tracheo-bronchial tree. • If muscle relaxant given – gentle IPPV employed Drugs used • It is usually done on diseased side (one side). If bronchography 1. Dionosil (propyl iodine) – inert oily base required on both the sides. 2. Lipidol • First right side done as it required 3 position – PA view, right oblique 3. Carboxy methyl cellulose and right lateral. 4. Tantalum pentoxide • Left side as only oblique view is required. Right will not interfere with 5. Iohexol left. - Non-ionic • Right side – right lateral for upper lobe, head up for middle and lower - Commonly used lobe. - Non allergic • Left side – semi prone for middle lobe, left lateral. (Drugs – known of allergy and inducing anaphylaxis) • Pictures are taken in apnoea with full expansion of lungs. • At the end of procedure anesthetics terminated, suction and physiotherapy are used to remove contrast material from the respiratory tract. • ETT should be remained in place until there is an active cough reﬂex and patient should be nursed head down with healthier lung uppermost. 56

Dr Azam’s Notes in Anesthesiology 2013 23. Foreign Body aspiration & Anesthesia. Dr Azam’s Notes in Anesthesiology 2013

Foreign body aspiration in children occur most frequently between The FRC is less than that of an adult which is the reserve for oxygen. 1 to 3 yrs of age. These factors are important as the same narrow airworthy through the • Consists most frequently of peanuts, seeds and other food bronchoscope is shared for gas exchange and instrumentation. particles, less frequently of plastic and metal particles. Pre- medication: • More commonly in right main bronchus than in left • Anticholinergics: Atropine 0.02 mg/kg • Less frequently in the larynx & Trachea. • Glycopyrrolate 0.01 mg/kg Clinical features: • Decrease airway secretions, attenuate the vagal mediated • Bronchial aspiration – coughing, wheezing, dyspnea and bradycardia associated with mechanical stimulation of airway and decreased air entry on the affected side repeated doses of succinylcholine administration • Laryngeal/ Tracheal aspiration– Dyspnea, stridor, coughing and • Sedatives and Narcotics are avoided as they may cause respiratory cyanosis. depression Pre- operative Evaluation: • Antibiotics may be started if patient is febrile &septic • H/o Time of FB aspiration and time of onset of symptoms due to Monitoring: Routine airway obstruction. PR • H/o Last food intake. BP • H/o wheezing in the past – to anticipate hyper- reactive airways. Pulse oximetry • Physical examination – Focus on location and degree of air Pre cordial stethoscope obstruction ECG - Degree of gas exchange • Preoxygenation with 100% O2 for 3-5 min will increase the oxygen - Cardio vascular status. reserve and prevent any desaturation at the time of bronchoscopy • Review of the latest chest X-ray to a)Determine the location of • In a child with a more stable condition – I.V. catheter is inserted the Foreign body b)Evidence of secondary pathologic changes before induction like atelectasis, air trapping or pneumonia • Induced with Thiopentone (4-6 mg /kg) + Atropine (0.03 mg/kg) or • ABG may show extent of Hypoxia and Hypercarbia. with or without fentanyl (1-2micg/kg). Anaesthetic Management: • Followed by scoline (2mg) or atracurium(0.3-0.5mg/kg) or • Anesthesia for Bronchoscope in pediatric patients is challenging vecuronium (0.07 to 0.1 mg /kg) or mivacurium (0.2 to 0.3 mg/kg) for the depending in part on the expected duration of the procedure. Anesthesiologist and the Bronchoscopist. • Anaesthesia is maintained Halothane or isoﬂurane while the patient • Cricoid cartilage being the narrowest portion of the pediatric is ventilated manually airway necessitates the selection of appropriate size of the • Stomach is emptied and the patient is position for bronchoscope bronchoscope so that risk of trauma to the airway, subsequent • As soon as bronchoscope is passed through the glottis patient is development of sub-glottic edema can be avoided ventilated by means of jet ventilation • Oxygen consumption is almost twice that of adults and CO2 production is also accordingly increased. The pediatric patients are desaturated dramatically leading to arrest. 57

Dr Azam’s Notes in Anesthesiology 2013 Foreign Body aspiration & Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Maintenance - Intraoperative complication: • O2 + Halothane + Jet ventilation Laryngospasm • N2O (with held if signiﬁcant hyper inﬂation of one lung or Bronchospasm lobe due to the potential danger of further increasing the Arrhythmias (premature ventricular contraction PVCʼs) volume and rupture of the affected lung). Pneumothorax. • During the procedure, Anesthetist should monitor closely by the • PVCʼs is due to light anaesthesia, hypoxia and hypercarbia. breath sounds by the precordial stethoscope, inspiratory • Treatment: Ensure oxygenation, improve ventilation, administer IV respiratory excursions on both sides of chest and oxygen lidocaine.1.5 mg/kg iv. saturation by pulse oximeter. Pneumothorax: • Close communication and co-operation between the surgeon Must be kept in mind if acute deterioration of ventilation and gas and the anesthetist is very essential through out bronchoscope exchange occurs during bronchoscopy – CXR is diagnostic. since the same narrow airway & the bronchoscope is shared for • Chest tube is inserted to re expand the lung. gas exchange and instrumentation. • After the completion of bronchoscopy for foreign body removal the • If ventilation is inadequate due to the telescope being too large child is intubated for tracheobronchial suction to remove for the bronchoscope or bronchoscope engaged is in the distal accumulated secretions to prevent post obstructive pneumonia and portion of bronchus or apnoea is prolonged during attempts to for ventilation until adequate spontaneous breathing returns following grasp the foreign body – the Bronchoscopist is asked to reversal of N-M blockade with Neostigmine 0.05 mg /kg + Atropine momentarily pull back the scope so that patient can be 0.02 mg/kg ventilated. • Dexamethasone (0.4 – 1.0 mg/kg) is often given prophylactically for • Periods of Apnea or severe hypoventilation normally should not laryngeal edema exceed more than 1 minute. • Post operative croup is treated with inhalation of racemic epinephrine • When the foreign body or its fragment is successfully grasped (0.5 ml of 2.25% of sol diluted in 3 ml of saline) with the forceps, the forceps and bronchoscope are carefully • Post operatively: Close observation is required so that intervention pulled out of trachea and larynx should be totally relaxed and may be early in the event of respiratory compromise secondary to offer the least resistance for the foreign body to pass through airway edema or infection that may ensue. without being dislodged. • This maneuver may have to be repeated when the foreign body is fragmented. The patient is ventilated by mask and bag until the bronchoscope is re introduced.

Dr Azam’s Notes in Anesthesiology 2013 24. Post extubation Stridor. Dr Azam’s Notes in Anesthesiology 2013

Definition: Treatment: • Stridor is noisy respiration and is obstructed respiration Treatment of underlying cause Causes of post extubation stridor are: 1. Warmed, humidified oxygen • Noxious stimuli like blood, vomiting, foreign body laryngospasm 2. Nebulized racemic epinephrine 0.25-1 ml • Backward displacement of the tongue into pharynx with or 3. IV dexamethasone 0.5 mg/kg up to 10 mg without compression of the soft palate against pharynx 4. If severe, intubation in considered • Traumatic laryngoscopy and intubation 5. Tracheostomy may be necessary in severe cases • Use of larger endotracheal tube 6. Calcium gluconate if it is due to hypocalcemia but it manifests after • Use of cuffed tube in infants and children 6 hrs after thyroid surgery. • Over inflation of cuffs 7. Stridor due to recurrent laryngeal nerve palsy manifest immediately • Hypocalcaemia and require tracheal intubation and mechanical ventilation. • Recurrent laryngeal nerve injury after thyroid surgery • Laryngomalacia due to prolonged duration of compression and weakness of muscles. Prevention: 1. By proper suctioning of blood, vomitus at the time of extubation. 2. Visualization of glottis by laryngoscopy after extubation and removal of clots and any foreign bodies 3. Giving head low and lateral position to prevent tongue falling back and triple maneuver. I. Jaw thrust II. Chin lift III. Head tilt 4. Avoid frequent attempts at laryngoscopy and intubation 5. Use of appropriate ETT with preferably small leak in infants and children. Inspiration pressure of 14-20 cm H2O. 6. Use of uncuffed ETT and avoid over inflation of cuff in children 7. Prophylactic administration of steroids before extubation if post extubation stridor is suspected.

Dr Azam’s Notes in Anesthesiology 2013 25. Anesthesia for Microlaryngeal Surgery. Dr Azam’s Notes in Anesthesiology 2013

• LASER is an acronym for Light Amplification by stimulated Lasers commonly used in the Operating Room Emission of Radiation. WAVE LENGTH USER GENERAL CHARACTERISTICS Basic Principles: (nm) Laser produce coherent radiation, a form of light which has 3 Argon 488/515(blue/ Absorbed selectively by special characteristics. green) hemoglobin and melanin or other 1. Monochromaticity: All waves are exactly the same wavelength similar pigments. or colour. Transmitted through dear 2. Collimation: All waves are parallel to each other and do not substances diverge. Tissue penetration: 0.5 to 2 mm 3. Coherence: All waves travel in phase in the same direction. KTP 532 (green) Strongly absorbed by Coherent radiation can be focused into a spot size of energy (frequency- hemoglobin, melanin, and similar density high enough to vaporize tissue. doubled YAG pigments.- • Lasers are named from their lasing medium, a population of Transmitted through clear molecules that is stimulated to produce photons of coherent substances Tissue penetration: radiation For eg: CO2 laser uses CO2 gas molecules to produce 0.5 to 2mm coherent radiation which is also responsible for its wavelength. Nd;YAG 1065 (near More readily absorbed by dark • Laser beams are applied for their thermal effect, and can be infrared) tissues Transmitted through clear used to cut, coagulate or vaporize tissues as listed. fluids Tissue penetration; 2 to 6 mm C02 10,600 (tar Strongly absorbed by water and infrared) thus, by all tissue (pigmented or not). HeNe 632 (red) Used as a low power coaxial aiming beam for nonvisible lasers (C02andNd: YAG) Has no significant tissue interaction CO2 laser is the most commonly used in Microlaryngeal surgeries because of its shallow depth of burn and extreme precision and often referred to as the ʻWORK HORSE LASERʼ. This was introduced in Medical Practice by Yahr and Strully and first Surgery performed was on canine Larynx in 1972 by Jako, followed by clinical trials on human otolaryngology by Strong and Jako.

Dr Azam’s Notes in Anesthesiology 2013 Anesthesia for Microlaryngeal Surgery.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Risks associated with laser procedure: Laser Safety: 1) Eyes and skin of patient and medical personnel: 1. Identify the Operating Room • Eye injury depends on wavelength and exposure of laser- CO2 2. Eye protection (Goggle- particular to radiation used. For CO2 laser laser can cause cornea ulceration and scar. any type of glass or plastic glasses with side protectors should be • Human skin is less vulnerable to laser surgery than eye, direct used). high intensity exposure can result in burns. 3. Prevent reflection of laser beam from surgical instrument, 2. Pulmonary: preferably matted finish instruments Smoke produced by tissue vaporisation by laser beam. 4. Protection of patients skin immediately adjacent to operative field 1. Mutagenic by wet towel and drape. 2. Cause tracheal and bronchial irritation 3. Lacrimation, nausea and vomiting AIRWAY FIRE MANAGEMENT: • Since no method absolutely prevents fire when laser is used for 3. Fire and explosion: airway surgery, appropriate selection of airway appliances such as Laser is an intensive light that provides an ignition source, which tracheal tube and adherence to fire safety protocol minimises the can result risk. 1. Direct laser illumination and ignition Immediate: 2. Reflected laser light a. Disconnect 02source at Y piece and remove burning objects 3. Incandescent particles of tissue blown from ignition of from airway. cottonoids b. Irrigate site with water if fire is still smouldering Laser safety Committee: c. Ventilate the patient by mask or reintubate and ventilate with as • Risk of laser accidents can be reduced by implementing a formal low fraction of inspired 02 as possible. laser safety programme in the hospital include: Secondary: • Strategic planning a. Evaluate extent of injury by bronchoscopy/Laryngoscopy • Physician credentialing b. Reintubate/tracheostomy • Protocol formulation c. Monitor with ABG and Serial chest X Ray • Inservice education of health care and Personnel d. Ventilatory support, steroids and Antibiotics as needed.

Dr Azam’s Notes in Anesthesiology 2013 Anesthesia for Microlaryngeal Surgery.Continuation: Dr Azam’s Notes in Anesthesiology 2013

ANAESTHETIC REQUIREMENT FOR CO2 LASER ANAESTHETIC MANAGEMENT: PREOPERATIVE EVALUATION MICROLARYNGEAL SURGERY: • Routine preoperative investigations are mandatory for any • Conduct of anaesthesia poses a real challenge for Microlaryngeal laser surgery. Airway assessment should be done anesthesiologists as they have to share the airway with the with flow volume loops and CT scan only when it is indicated. surgeons which may be already compromised by the disease. PREMEDICATION: • Patients with no obstruction /stridor or on Tracheostomy can be give This is to provide: premedicant drugs like sedatives and antisialogogues. • Adequate depth of anesthesia to prevent circulatory responses • Adults with obstruction / stridor -no premedication. to instrumentation eg; laryngoscope, operating micro • Children with obstruction only-antisialogogues. laryngoscope. INDUCTION: • Immobile field • Induction technique mainly depends on the extent of obstruction of • Selection of nonflammable tube. the airway. Conventional relaxant technique comprises of • Adequate oxygenation and CO2 removal. preoperative check up, premedication, induction and maintenance • Prevention of airway fire and explosion. with thiopentone, muscle relaxant, O2, N2O, Halothane/isoflurane • Good post operative care. Watch for laryngospasm and laryngeal and narcotic analgesic is chosen for those with no airway oedema. obstruction. • Immediate return of reflexes after completion of surgery • In obstructed or compromised airway either inhalational or awake or • Scavenging of operating room gases and laser plume. fibreoptic bronchoscope technique is preferred. Tracheostomy followed by conventional technique is the choice for severely LARYNGEAL LASER OPERATIONS: compromised airway. Choice of anaesthetic technique: • All the patients are routinely monitored for ECG, B.P, SpO2 and • Anterior Commissure' lesions EtCO2. • Conventional and Jet ventilation • Posterior commissure lesions INTUBATION: • Apneic techniques • Tracheal intubation secures the airway and thus protects it from • Jet Ventilation aspiration of gastric contents, laser plume, inadvertant laser burn to • Laser alternates ventilation the trachea and also helps in controlling and monitoring ventilation. Patient with Tracheostomy The endotracheal tube of deliberately compromised diameter is used • Armoured tube to have an access to the lesions by the surgeon. The conventional • Inflate cottonoids above the cuff E.T. tubes composed of Polyvinylchloride (PVC) red rubber or • Conventional anaesthesia silicone are readily ignitable and flammable. • The chance of contact between laser beam and E.T. tube is about 50% of all upper airway laser cases.

Dr Azam’s Notes in Anesthesiology 2013 Anesthesia for Microlaryngeal Surgery.Continuation: Dr Azam’s Notes in Anesthesiology 2013

POLYVINYL CHLORIDE TUBES: (PVC) LASER RESISTANT-WRAPPING: • Since it is transparent, condensation of vapor as well as • In order to decrease the risk of fire, the conventional tracheal tubes evidence of combustion within the tube can be monitored can be wrapped with a metallic tape or metallic backed surgical visually. It requires a higher concentration of 02 to sustain flame sponges. This can prevent the laser from igniting the laser tube. due to its higher 02 index of flammability. Despite its advantages However, metallic tape has not been specially made for this use, so it can ignite if excess laser exposure occurs and can sustain a that clinicians must employ tapes designed for non medical usage. torch like flame. Hence unprotected PVC tubes are not generally Care must be taken when wrapping a tube to avoid gaps which may recommended. leave part of the tube exposed. Copper foil and aluminium tape are RED - RUBBER TUBES: widely applicable to wrap the E.T tubes. • Sustains combustion more readily than PVC tubes in room air. Commonly Available Laser Resistant Wrapping for Conventional Since it is more resistant to puncture by C02 laser energy than Tracheal Tubes PVC it is more susceptible to extraluminal fires than intraluminal LASER RESISTANT WRAPPING APPLICABLE LASER fires. If fire occurs, it could be undetected because of their Copper (3M) CO2,Nd: YAG.KTP opacity and cause more extensive damage. An advantage over Aluminium (3M) CO2.Nd,YAG,KTP red rubber tubes is that if ignited they are less likely than PVC to soften, deform or fragment into the tracheobronchial tree. Sensing foil (Radio Shack) CO2 SILICON: Metal backed sponge (Merocel) CO2,KTP • Can ignite in room air. If ignited becomes brittle, crumbles resulting in retained tube segments and the debris in the LASER RESISTANT TRACHEAL TUBES: tracheobronchial tree. • In order to assure a consistent level of laser resistance and general Combustion properties of Materials Composing Conventional safety anaesthesiologist prefers to use laser resistant tracheal tubes. Tracheal Tubes • These are 10-30 times more expensive than conventional tubes. It Times With A 10-W Laser Beam And 50% and 50% N, has its limitations like decreased flexibility and ease or intubation, MEAN TIME TO O2 INDEX OF PENETRATION increased likelihood of kinking or more difficult inflation and deflation MATERIAL IGNITION FLAMM ABILITY TIME (sec) properties. These are (sec) • Bovina with Polymethane cuff and a black pilot tube Polyvinyl 0.263+/- 0.004 0.77 3.06+/- 0.79 • Mallinckrodt double cuffed tube. chloride • Xomed single cuffed silicon tube. Silicone 0.189+/-0.009 Not tested No tested • Sheridon red rubber tube with copper foil tape. The cuff is filled with Red Rubber 0.176+/-0.003 41.48 33+/-1.01 saline or methylene blue to detect cuff puncture and saline acts as a fire extinguisher.

Dr Azam’s Notes in Anesthesiology 2013 Anesthesia for Microlaryngeal Surgery.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Advantages and Disadvantages of Commonly Available Laser APNOEC VENTILATION: Resistant Tracheal Tubes • Means apnoec anaesthesia with intermittent ventilation .This DESCRIPTION OF APPLICABLE technique is used for posterior commissure and subglottic lesions. All ADVANTAGES DISADVANTAGES RESISTANT TUBE LASER the patients of ASA grade II with moderate obstruction are Aluminium/silicone CO2 A traumatic Contains flammable anaesthetised and stabilized with conventional anaesthetic spiral with self- external surface; material technique. To give better access to the post commissure and to inflating foam cuff cuff maintains seal (silicone);cuff difficult subglottic lesions, the E.T tube need to be removed and here the (Bivona even if punctured to deflate if punctured apnea anaesthesia with intermittent ventilation starts. Before by laser; removing the E.T.tube, switch off N2O and ventilate with 100% O2 noninflammable inner surface and halothane/isoflurane mixture to achieve a high PaO2 besides an Airtight, stainless CO2,KTP Tube maintains Cuffed version SpO2 of 100%. Supplemental doses of muscle relaxant are given steel, corrugated shape well, after contains flammable when required. The E.T. tube is pulled up in favour of the surgeon to spiral with polyvinyl proximal cuff material (PVC) tubes proceed with laser excision. The E.T. tube is reintroduced through the chloride (PVC)tip and puncture; body of arc thick-walled; Operating Laryngoscope if double cuff tube is metal may reflect • SpO2 drops to 93% (allowing for an after drop to 90%) or apnea (Mallinckrodt) nonflammable; beam onto period extends beyond 7 min. noncuffed version nontargeted tissue available • Extremes of heart rate and B.P (HR <60 >120/ mt) (BP<80>180mm Silicone tubes CO2, KTP Wrapping protects Contains flammable of Hg) wrapped with flammable material material (silicone); • To allow suction evacuator to clear of excessive smoke and charred aluminium and and is smoother single cuff is tissue. Teflon, with, than manual tape vulnerable to laser • To allow the laserised area to cool methylene blue in wrapping; damage • The laser excision is completed. cuff (Xeromed) methylene blue aids in detection of • Ventilate the patient with 100% O2 till SpO2 reaches 100%, EtCO2 cuff perforation comes down to 30, patient is haemodynamically stable then allow the Red rubber tubes CO2.KTP Wrapping protects Contains flammable surgeon to start laserisation. wrapped with copper flammable material material (red rubber), • Apnoeic intervals progressively shorten from normal 7 mt with the foil tape and and is smoother tubes are thick walled reduction of respiratory reserve. polyester sleeve than manual tube (Sheridan) wrapping

Dr Azam’s Notes in Anesthesiology 2013 Anesthesia for Microlaryngeal Surgery.Continuation: Dr Azam’s Notes in Anesthesiology 2013

JET VENTILATION: • Is also favoured by many surgeons as it allows excellent visibility of the surgical field and fire is less likely as no flammable material is in the airway. Risk involved with Jet Ventilation are • High risk of hypoventilation in case of COPD, Bronchospasm, Obesity • Barotrauma: Pneumothorax, Pneumomediastinum • Unprotected airway: Aspiration of gastric contents, surgical debris, laser plume, inadvertant perforation of trachea.

EFFECT OF RESPIRATORY GAS MIXTURE. • Most Anaesthesiologist recognise the pertinent need to reduce the FiO2 below 0.40 or to the minimum concentration consistent with adequate oxygenation. Use of pulse oximetry is mandatory for keeping FiO2 to minimum compatible with adequate oxygen. N2O supports combustion to approximately the same as Oxygen. Use of air Oxygen mixture / Helium Oxygen mixture appears to be acceptable.

Dr Azam’s Notes in Anesthesiology 2013 26. NO & ARDS Dr Azam’s Notes in Anesthesiology 2013

• In ARDS, NO can be used to decrease PVR and increase oxygenation during permissive hypercapnea, and to prevent elevated PAP during armitrine bismesylate treatment. • Inhaled ʻNOʼ may also beneﬁt gravitations therapy and has synergistic effects with surfactant therapy. Possible beneﬁts of inhaled ʻNOʼ for ARDS include à • Decrease PVR • Decrease PAP • No effect on systemic hemodynamics • Improved oxygenation ʻNoʼ synthesis • ↓ venous admixture • ↓ true shut • ↑ perfusion to areas with normal VA/Q .

Dr Azam’s Notes in Anesthesiology 2013 27. Dental Anesthesia. Dr Azam’s Notes in Anesthesiology 2013

Anaesthesia for dental extractions: Anaesthetic machines: • Performed in outpatient clinics or dental surgical room • Intermittent or demand flow machines • Emergencies – poor preparation and assessment • BOC “Walton” serves and McKesson features with ability to change • Limited recovery facilities rapidly relative concentration Of O2 and N2O using single calibrated • Local anaesthesia – method of choice control Indications for general anesthesia: • Ability of the gas flow to follow the patientʼs inspiratory effort on Absolute indications: function and demand. • Young children with multiple extractions • High gas flows to be delivered to overcome high resistance to • Acute infections inspiration. • Previous radiotherapy to jaw Goldman nose piece – • Allergies to LA • Single wide bore tubing to overcome the high resistance to • Severe mentally and physically handicapped inspiration and use of low inspired gas flows. Relative indications: • Wall or cabinet mounted quantifies monitored dial mixture, suitable • Extremely nervous patients for both relative analgesia and GA • Previous faint reactions. • Smaller versions of conventional anaesthesia machines - reliable • Surgery in all 4 quadrants of mouth vaporizers are used. • Epileptic patients. • Atmospheric pollution is relatively high in dental anaesthesia. Mouth props, gags, packs and airways Contraindications: • Mouth props – large enough for assess to packing and surgery. • Severe medical disease – CVS, RS and others • Meckelson prop – for adults • Oral infections – severe trismus or edema of floor of mouth and • Devonshore prop – for children pharynx. • Mouth packs – To prevent airway complications • Incorrect packing – respiratory obstruction and aspiration of blood Position: and debris • Erect posture – fainting, CVS collapse • Mouth gags – in trismus and emergency • Supine position – CVS collapse, airway control, pulmonary • Nasopharyngeal airways inhalation, ↓ VC, airway obstruction. • Suction apparatus • Semi recumbent position with legs elevated Resuscitation equipments: • Ideal combination for RS and CVS conditions • Full range oral and nasal ETT • Good airway control. • Laryngoscopes • Defibrillator Dental chair: • ECG • Adjustable head rest allowing manipulation of head and trunk • Resuscitation drugs and others (fluid) • Should be able to place patient horizontally for CPR even there is power failure. 67

Dr Azam’s Notes in Anesthesiology 2013 Dental Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Anaesthetic management: Monitoring: • Preoperative preparation and premedication • Observation of reservoir bag • History • Colour of patient • CVS examination – Auscultation, BP, pulse, wt. • ECG • Airway assessment • Pulse • Lab investigations – Hb, Urine analysis • BP • Consent form • Precardial stethoscope • Escort person • Empty bladder and bowels Recovery: • Dentures and contact lens removed. • Observation Premedication: • Trolley –turned on sides with head low tilt • Avoided – sedatives, anxiolytics and anticholinergics • Street ﬁtness • Uncontrollable child between 5-10 years age – sedation with • Driving and operating machinery trimeprazine 4 mg/kg Induction: Post operative: • Semi-recumbent position with legs elevated, head rest adjusted • Clear instruction to keep head and neck on erect position • Analgesia • Small children with special rest to raise head to the level of head • Avoid alcohol rest. • Inhalational induction – Most commonly used in young children. Complications: • Halothane RS – Airway obstruction Laryngospasm • Intravenous induction – Older children and adults. Mouth breathing Bronchospasm Apnoea Aspiration Maintenance: CVS – Fainting • Mouth pack. Dysrrhythmias • Maintained via nose piece. Hypotension • Halothane / Enﬂurane

Dr Azam’s Notes in Anesthesiology 2013 28. Intraocular Pressure. Dr Azam’s Notes in Anesthesiology 2013

Definition of IOP 7. Pain. • Is defined as the pressure exerted by the contents of the eye 8. ↑ CVP. against its containing wall. 9. Blinking (↑ 5mm Hg). Normal IOP: 15 to 20 mm of Hg. 10.Squinting (↑ 26 mm Hg). 11.Laryngoscopy. Variables that affect IOP: ↑ • Aqueous humor fluid dynamics – Production • Intubation ( 10-20 mm Hg) • Choroidal blood volume – Drainage, autoregulation, CVP, • When the BP rises, the intra ocular pressure does not greatly alter chemical factors (PaCO2, PaO2 and PH metabolism) but when it is less than 85 mm Hg the intra-ocular pressure falls • Vitreous humor volume – Osmotic pressure • Systemically administered anticholinergics not associated with ↑ • Extra occular muscle tone – Neurogenic control IOP even in glauoma patients. Intraocular pressure helps to maintain the shape and therefore the The effect of cardiac and respiratory variables on intraocular pressure optical properties of the eye. (IOP): Variable Effect on IOP • Temporary variations in pressure are usually well tolerated in normal eyes. A) CVP • When the globe is open during certain surgical procedures or Increase ↑↑↑ after traumatic perforation, intra ocular pressure approaches Decrease ↓↓↓ atmospheric pressure. B) Arterial blood pressure Intraocular pressure may be lowered by: Increase ↑ 1. Mechanical methods – Preoperative use of a pressure pad or Decrease ↓ manual milking of fluid from the anterior chamber immediately prior to start of the operation. C) PaCO2 2. Hypocapnia. Increase ↑↑ 3. Hypotension. Decrease ↓↓ 4. Reduction of CVP. 5. Acetazolamide, timolol, mannitol, urea. D) PaO2 6. I.V. anaesthetics, volatile anaesthetics and narcotic analgesics. Increase 0 Decrease ↑ Intra ocular pressure is raised by: 1. Hypercapnia. 2. Coughing sneezing and straining. 3. Succinylcholine 4. Local atropine. 5. Local steroids. 6. Head low tilt. 69

Dr Azam’s Notes in Anesthesiology 2013 Intraocular Pressure.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Effect of anaesthetic agents on intra ocular pressure (IOP): Drug Effect on IOP A) Inhaled agents Volatile agents (↓ BP, ↓↓ relaxation of EO muscles, pupillary constriction) N2O ↓ B) I.V. anaesthetics (↓ by 15-50%) Thiopentone ↓↓ BZD ↓↓ Ketamine ? Narcotics ↓ C) Muscle relaxant Depolarization drug: scoline ↑↑ (↑ IOP by 5-10mmHg for 5-10min prolonged contraction of EO muscles) Non-depolarizers 0/↓

• Extra Ocular muscles contain cells with multiple NMJ. Repeated depolarization causes prolonged contraction results in increased IOP which has following effects: 1. Spurious increased measurements of IOP during surgery under GA – glaucoma patients 2. Extrusion of ocular contents – open surgical / traumatic wound. 3. Abnormal forced duction test for 20 min (cause Extra ocular muscle imbalance)

Dr Azam’s Notes in Anesthesiology 2013 29. Keratoplasty. Dr Azam’s Notes in Anesthesiology 2013

• Keratoplasty is a surgery on eye i.e., grafting of cornea. Corneal • Other agents that are used to reduce IOP include osmotic agents like grafting is frequently carried out as a semi-urgent procedure and mannitol 20% in a dose of 1-1.5 mg/kg over 30-60 minutes, Glycerol is being increasingly performed on a day-stay basis. However orally 50% solution in a dose of 1-1.5gm/kg. Patient should be there is enough time for proper pre-operative assessment and extubated deep under anaesthesia and avoid pressure response of preparation. extubation. Anti emetics like metoclopramide should be given to • Corneal grafting may be partial or full thickness. avoid post operative nausea and vomiting. Reversal with • General anaesthesia is preferable because the procedure may neostigmine and atropine is allowed. sometimes take upto 2 hours. • A good control on IOP with a soft eye is essential. The normal IOP varies between 10-20 mm Hg in adults. The pressure is lower in infants and young children. Pre-medication: • Diazepam and midazolam when given intravenously reduces IOP. Opioids reduces IOP moderately. Anticholinergic have no effect on IOP. But atropine may increase IOP in patients with glaucoma. Induction: • Administration of thiopentone causes decrease in IOP. Propofol causes greater ↓ IOP. Etomidate causes involuntary muscle movements. Ketamine may increase IOP it also causes nystagmus. Most inhalation agents except Nitrous oxide produces signiﬁcant reduction in IOP. • The depolarizing muscle relaxant succinylcholine increases IOP due to contracture of extra ocular muscles. So should be avoided. Non depolarizing muscle relaxants like vecuronium, atracurium pipecuronium, Rocuronium are indicated as they produces no change in IOP. • Intubation response should be attenuated by deep anaesthesia and with lignocaine 1.5 mg/kg I.V. • The reduction in IOP is greater under the conditions of controlled ventilation.

Dr Azam’s Notes in Anesthesiology 2013 30. Open Eye Surgery & Full Stomach. Dr Azam’s Notes in Anesthesiology 2013

Open eye injury and full stomach present the anaesthesiologist Anaesthetic management: with unique challenges. He must balance between the risk of aspiration against the risk of blindness resulting from elevated • GA is preferred (Disadvantage of RA - ↑ IOP – full stomach) IOP and extrusion of ocular contents. Goals: Goals: • To be aware of full stomach and take adequate measures to avoid • To prevent aspiration due to full stomach state aspiration. • To prevent rise in IOP • To prevent rise in Intra ocular pressure and extrusion of intra ocular Pre- operative evaluation: contents (prevent bucking, coughing, vomiting) • H/o regarding the mechanism and time of injury to the eye • To maintain a well relaxed patient for a lengthy operative period. • H/o recent ﬂuid and solid food intake and its relation to the injury (Pre oxygenation with 100% O2 for 3 min.) (gastric emptying time is delayed in stressful conditions) • Rapid sequence induction • Look for any other injuries – cerebral, abdominal, thoracic / limb • Injection Thiopentone 3-5 mg/kg injuries. • Injection rocuronium 0.6 mg/kg Premedication: • Cricoid pressure is applied by a trained assistant once the patient is • Premedication is indicated in these patients in the form of induced and maintained till the trachea is intubated and cuff inﬂated. sedation – to prevent crying and anxiety to avoid increase in IOP. • Supression of pressor response – IV lidocaine 1-1.5 mg/kg IV, Midazolam – Oral-- 0.3 to 0.7 mg/kg volatile anaesthetics, fentanyl 5-10µg/kg. Intubation done swiftly and IM-- 0.035 – 0.1mg /kg gently to prevent any trauma and bucking by the patient. IV-- 0.1 mg /kg • Cuffed ETT are used for older children (8-10 years) Injection fentanyl (2µg/kg/IV) • (Rapid sequence induction can be achieved by using the “Priming Prophylaxis against aspiration include: principle” for intermediate acting non-depolarising muscle relaxants 1. H2 receptor antagonists: IV / orally (Ranitidine / 0.3 M sodium like vecuronium) citrate) to ↓ Gastric acid production & to↑ Gastric acid pH. • In a patient with a full stomach, succinylcholine offers the clear, 2. Prokinetic agents: Metoclopramide to stimulate peristalsis and important advantages of rapid onset, excellent intubating conditions facilitate gastric emptying . and short duration of action. But will increase the IOP – so if succinyl 3. Antiemetics choline is given after pretreatment with a small dose of non Monitoring: depolarizing relaxant and an inducing dose of thiopental – succinyl • PR choline causes only slight increases in IOP above base line. • BP (NIBP) Maintenance: • Pulse oximetry • N2O + O2 + Halothane + IPPV + Inj. Vecuronium (Pancuronium / • ETCO2 Rocuronium) + Narcotic ( Fortwin). • ECG • Circuit: Jackson Rees Circuit (if < 20 kg), Bainʼs circuit (if more than 20kg) Reversal: • Neostigmine (0.05 mg/kg) • Glycopyrolate (0.008 mg/kg) 72

Dr Azam’s Notes in Anesthesiology 2013 Open Eye Surgery & Full Stomach.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Patient extubated after adequate reversal and thorough suction. Coughing and bucking at the time of extubation and after extubation cause increase in IOP – so patient extubated as soon as reﬂexes are regained and avoid coughing and bucking. Post operative care: • Post operatively the stomach is suctioned through a nasogastric tube placed intra operatively, good analgesia to prevent crying and antiemitic measures to prevent vomiting. Patient is nursed in lateral position.

Dr Azam’s Notes in Anesthesiology 2013 31. Anesthetic for Opthalmic Surgeries. Dr Azam’s Notes in Anesthesiology 2013

Ophthalmic surgery presents many unique challenge; including • Regulation of intraocular pressure • Prevention of occulocardiac reﬂex • Management of its consequences • Control of intraocular gas expansion • Dealing with possible systemic effect of ophthalmic drugs • Awakening without coughing, straining or vomiting • Akinesia • Profound analgesia • Minimal bleeding.

Ocular anatomy: The anesthesiologist should be knowledgeable about ocular • The supra orbital notch, the infraorbital foramen and lacrimal fossa anatomy to enhance his or her understanding of surgical • are clinically palpable and function as major landmark for procedures and to aid the surgery in performance of regional administration of anesthesia. block when needed. The laterals walls are at an angle of 450 to the medical wall, where Salient subdivisions of ocular anatomy include • as the ﬂoors pass upwards at as angle of 50. • Orbit The medical wall and roof are vertical and horizontal respectively. • Globe • • Orbital fat • Ocular muscle • Eyelid • Lacrimal systems Orbit: The wall of orbit is composed of: • Frontal • Zygomatic • Greate wing of sphenoid • Maxilla • Lacrimal • Ethmoid

Dr Azam’s Notes in Anesthesiology 2013 Anesthetic for Opthalmic Surgeries.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• The lateral orbital rim is 12-18 mm behind the cornea, allowing Orbital fat: easy access from the inferiolateral corner to equator of the globe The orbital fat is divided into a and posterior part of orbit. • Central (intracone, retrobulbar) space and Globe: • Peripheral (extracone, peribubar) space by the muscle cone of four • The volume of the orbit is about 30ml, while that of globe is 6.5 recd muscles. ml • However, orbit fat is continuous through the cone which is not well • The globe which lies closer to the roof of the orbit than the ﬂoor, developed. posteriorly. is normally 22-24 mm long but in myopic eyes may be longer • Thus the cone does not act as barrier to the spread of local than 30mm. anaesthetic. • Longer eyes tend to have thinner sclerae nd even the swelling of • As a result solution placed in the extra cone space (peribulbar sclerae. They are there fore at greater risk of perforation by injection) enter the intracone space rapidly. needle. • All the nerves to the extraocular muscle; and ciliary ganglion as well • Has 3 layer. as the branches of the ophthalmic division of the Vth nerve and the 1. Outer Fibrous layer – sclera terminal branches of VIIth nerve to the orbicularis occli muscle may 2. Middle vascular layer: uveal tract be blocked by injections into the orbital fat. 3. Inner nervous coat: Retina • The optic, occlornotor (which supplies the superior, inferior medial recd and inferior oblique muscle), abducens (which supplies the lateral rectal muscle) and the nasocilliar nerves (innervating the cornea and perilimbal conjuctiva) as well as the ciliary ganglion are all within the cone. • The lacrimal, frontal and infraorbital serves (which supply the peripheral conjuctiva.) and, trochlear nerve (which supplies the superior oblique muscle) are outside the cone. • The least vascular parts of the orbital fat are the inferotemporal and nasal areas and it is usual site to make injections into one or both of these regions.

• The globe is separated from other orbits, structure by Tenon's fascia

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Extra ocular muscles: 6 muscle • Superior rectus • Inferior rectus • Medical rectus • Lateral rectus • Venous drainage of the eye is achieved mainly through the central • Superior oblique retinal vein. • Inferior oblique. • All these veins empty directly into the cavernous sinus. Nerve supply: Blood Supply: • Mainly by the ophthalmic branch of trigeminal nerve. • Blood supply to the eye and its orbit is by means of branches of • Trigeminal nerve is divided into both the internal and external carotid arteries. • Opthalmic • Venous drainage of the orbit is accomplished through the • Maxillary multiple anastomoses of the superior and interior ophthalmic • Mandibular veins.

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• Ophthalmic division again divides into Frontal • Supra orbital • Lacrimal • nasocilliary

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Supra orbital: Carries sensation from the conjunctiva and skin of the central 2/3rd of the upper lid.

• Supratrochlear: In carries sensory ﬁbers from the medical 2/3rd of the upper lid. • Lacrimal nerve: It carries sensory input from the skin and conjunctiva at lateral aspect. Nasocilliary nerve • It carries sensory ﬁbres from the cornea, iris, ciliary body, perilimbal bulbar conjuctiva. • The infratrochlear branch of nasociliary nerve carries sensory input from the medical canthus medical portion of lower lid, skin and conjuctiva.

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Motor supply: • Choroid blood flow is usually, utoreeulated over a range of perfusion 1) Occulomotor nerver supplies pressures to keep IOP stable. a) Superior • Sudden increases in systolic arten,1 blood pressure cause a b) Medial transient swelling of CBV subsequent temporary out: low adjust IOP c) Inferior rectus muscle towards normal. d) Inferior oblique • Hypotension (systolic arterial blood pressure 90mm Hg) may reduce e) Levator palpebrae superior muscle IOP as CBV decreases. 2) The trochlear nerve supplies to the superior oblique muscles. • Sudden increases in CBV can farce vitreous gel forward in to anterior 3) The abducense nerve supplies lateral rectual muscle chamber during open eye surgery or can increase IOP in the intact 4. Zygomatic branch to the facial nerve eventually divides into an eye. upper branch supplying the frontalis and the upper lid orbicularis • Coughing, bucking, emesis, and die valsalva maneuver will increase and the lower branch which supplies the orbicularis of the lower central venous pressure, there by increasing both CBV and IOP. lid. • IOP will also tend to increase in response to respiratory acidosis. • The choroidal circulation may dilate in response to hypoxia and Ocular physiology: cause mild increase in IOP. • Because of control of IOP is often important to success of the • The CNS exert some degree of control over TOP diencephalons procedure, the anaesthesiologist must understand the have indicated area that affect TOP. Some responses seem to be physiologic effect of IOP and the implications of anaesthetic drug mediated neurovascularly, whereas others relate -,o increased and n aneuvers of IOP. extraocular muscle tone. Physiologic determinants of intraocular pressure: • These centers are usually depressed by sedatives barbiturates, and • Normal IOP is approximately 12 to 20 in Hg, with diurnal volatile inhaled anaesthetic. variation of 2 to 3m: n of Hg and position changes of I to 6 mm of • Hypocapnia decreases TOP through vasoconstriction at the Hg. choroidal blood vessels and • The most important influences on IOP are aqueous humor • The increased IOP associated with hypoventilation and hypercapnia dynamics, changes in choroidal blood volume (CBV), central occurs as result of vasodilatation of CBV and increase in central venous pressure, and extraocular muscle tone. venous pressure. • Aqueous humor dynamics, the main physiologic determinant of • Sudden external pressure on the eyeball will initially increase TOP IOP, is a balance between the production of aqueous humor and and may induce on ocularcardiac vagal reflex. The increased TOP its eventual elimination. promotes outflow of aqueous horror, thus returning TOP towards • Episcleral vein pressure is normally 8' to 11 mm of Hg. Any normal. increase in venous pressure will increase IOP. • Injecting a large volume (8 to 10ml) of fluid into orbit (e.g., a peribulbar block) may significantly increase TOP. • If TOP reaches the level of retina arterial pressure retinal ischemia can result.

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OCULO-CARDIAC REFLEX: Prevention and treatment: • It was described by Ashnur and Dagini in 1908. • Intramuscular administration of strop atropine, (0.02 mg/kg) gentle Definition: manipulation of extraocular muscles, and control of ventilation to • OCR is trigeminal-vagal reflex re3ponse that is manifested as maintain normocapnia should reduce the incidence and severity of cardiac arrhythmias (nodal, functional, ectopic atrial ventricular OCR. arythmias), bradycardia, hypotension and may be elicited by • The first step in treating OCR is to stop stimulation by the surgeon pain, pressure or manipulation of the eye ball, before the arrhythmia progresses to sinus arrest. Pathway: • If arrythmias persist, treatment with atropine 0.02mg/kg and local • The afferent pathway follows the long and short ciliary nerves to injection of lidocaine near the eye muscle may be necessary. the cilliary ganglion and then to the gaserian ganglion along the • If the patient still seems unusually sensitive to manipulation of the opththalmic division of the trigeminal nerve. extraocular muscles, the anaesthesiologist should ensure that the • This afferent pathways terminate it the main trigeminal sensory depth of general anaesthesia is adequate, the patient is normocapnic nucleus in the floor of the fourth ventricle. and surgical manipulation is gentle. • The efferent impulses starts in muscles of the vagal cardiac • The intravenous administration of atropine to prevent or treat OCR is depressor nerve and cause negative ionotropic and conduction controversial. Atropine may cause bigeminy and increase ectopic effects. beats, especially when halothane is the primary anaesthetic. Systemic effects of eye medication: Anaesthetic implications: • Both anaesthesiologist and the ophthalmologist must be aware, that • OCR occurs most often during strabismus surgery in children, eye drops are readily absorbed through hyperemic incised retinal surgery, at the time of injection of retrobulbar block. conjunctivae. • It can occur during nonophthalmic surgery if pressure is placed • Though small in volume these eyedrops contain highly concentrated on the eyeball. medication that can produce systemic results. • The reported incidence of OCR varies considerably from (32% to Phenyleprine: 90%) depending. upon intensity of observation and the definition • Can cause severe hypertension, arrhythmias, headache, of arrhythrnias. tremerlousness and myocardial ischemia. • Transient cardiac arrest may occur as frequently as one in 2200 • Because of single drops of 10% phenylephrine ophthalmologic strabismus surgeries. solution contains 4mg of phenylephrine. • The force and type of stimulus seem to influence the • 2.5% solution are recommended. incidence of OCR. • The more acute the onset and stronger and more sustained the traction, the more likely OCR to occur. • Medial rectus muscle is commonly believed to be the most sensitive in eliciting OCR. • Hypoventilation and increased arterial carbondioxide partial pressure significantly increase the incidence, of bradycardia during strabismus surgery. 80

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Epinephrine: Scopalomine: • Topical ocular epinephrine (92% solution contains 0.8 mg per • Is use to produce mydriasis and cyclopegia. drop) can cause tachyarrhythmias and premature ventricular • May cause disorientation and hallucinations in elderly and very beats, angina, HTN, nervousness. young patients. • It decrease the IOP by decreasing aqueous humor formation and Atropine: increase it drainage. • Used to produce mydriasis and cycloplegia • This effect last for 15 min. • The 1% solution contains 0.2 - 0.5 mg of atropine per drop. Echothiphate: • Systemic reactions seen mainly in children and elderly include • Echothiophate iodide eyedrops can reduce plasma tachycardia, flushing, thirst, dry skin and agitation. cholinesterase activity significantly. Choice of anaesthesia: • 4 to 6 weeks is required for activity to recover after cessation of • Regional anaesthesia may be the technique of choice for the whole the drops. range of adult patients, not just for those who are deemed unfit to • Patient treated with these eye drops may have prolonged undergo general anaesthesia. response to succinylcholine or to mivacurium and ester-linked • The trend over the last decade has been to increase the use of local local anaesthetics during this time. anaesthesia so that it is used in about 86% of cataract operation. Timolol: • This has coincided with surgical and anaesthetic advance and • It is beta blocker that lower IOP by &greasing aqueous humor increasin4 use of day stay facilities. production. • The patient must be able to lie still and to cooperate. Recovery time • It used to treat glaucoma preoperatively and postoperatively as is shorter after regional anaesthesia, the patient leaving promptly 0.5% solution. after the end of surgery, and there are saving with respect to space, • It produces systemic effects like bradycardia, hypotension, equipment, and staffing. congestive heart failure and exacerbation of myastheni, gravis • For longer operations; such as prolonged vitreoretinal surgery and and asthma. surgery in young patients, such as surgery for strabismus, general Acetylcholine: anaesthesia may be preferred. • Acetylcholine may be used to produce miosis after cataract • The choice usually clear but views the surgeon, anaesthetist and surgery. patient need to be considered. • Systemic effects include bradycardia, hypotension, bronchospasm, and increased bronchial secretion and salivation. • These undesirable effects may be prevented by the intravenous administration of atropine. Cyclopentolate : • Cyclopentolate eyedrops are used in a 2% concentration to dilate the pupils. • CNS toxicity result in effects such as discrimination, dysarthria and seizures has been reported. • Less concentrated (0.5%) solution are recommended for 81 pediatric use.

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GENERAL ANAESTHESIA FOR OCULAR SURGE: Premeditation: • Although patients may be in a high-risk category, ophthalmic • Premeditation is indicated for pediatric age group and for nervous surgery is low risk with respect to general morbidity and mortality adults. many procedures are suitable for day-case surgery. This is • Goals of premeditation include - to alley anxiety, minimize nausea, because this type of surgery cause minimal blood loss and vomiting, coughing and secretions. physiologic disturbance, lack of fluid shifts, little impact on the • Prophylactic antiemetic (metaclopromide 0.15 mg/kg) should be stress response and frequency or absence of post operative given to prevent any risk to the eye from postoperative vomiting. pain. • Opioids which increase the incidence of nausea and vomiting and • The aim of general anesthesia should be respiratory depression are better avoided. I. Smooth induction and maintenance of anaesthesia. • Atropine 0.02 mg/kg may be given to children prior to surgery to II.Maintenance of stable and low IOP prevent occulocardiac reflex. III.Avoidance or treatment of the occulocardiac reflex • Diazepam (0.1 to 0.2 mg/kg) or Lorazepam can be used. IV. A guaranteed airway Induction: V.Motionless surgical field • All intravenous induction agent (except ketamine, which raise blood VI.Smooth emergence without coughing, straining, nausea or pressure), ↓ IOP, although ethomidate and propofol seems to lower vomiting. more than of thiopentone. • The choice and does of induction of agent depends on the age, Indications for GA physical status and the perceived need for rapid recovery. • Uncooperative patients • Thiopentone sodium (3-5 mg/kg) produces reliably smooth induction. • Young children for strabismus surgeries, congenital cataract. It produces a transient fall in intraocular pressure. • Ketamine should not be used as it rises the blood pressure, TOP, Preoperative assessment: nystagmus, blephorospasm, and adventitious movements make it • The neonate and infant present special problems, and may have unsuitable in other situations. associated congenital anamolies that influence anaesthetic Propofol: management. • Induction of anaesthesia is rapid with propofol. • A management plan should be established for anaesthesia and • It produces muscle relaxation inc depression of airway reflexes and perioperative management of chronic medical problems such as, therefore occurs to he the host agent prior to the insertion of Diabetes. Hypertension, IHD. arrrythmias, chronic obstructive laryngeal mask airway. diseases, Asthma and may will be taking several drugs. An ECG • Maintainence of anaesthesia can he achieved by either continuous recording should be available for all patient older than 40 years. infusion or intermittent bolus injection. • Dose: 2-2.5 mg/kg induction close • Dose should be reduced in elderly patients and in patients with cardiac disease and hypovolemia. • An adequate depth of anaesthesia is required as if light anaesthesia the eye may look up, which may be hinder surgery. 82

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Muscle relaxants : • Atracurium (0.08-0.12 mg/kg) or vecuronium (0.04-0.06 mg/kg) are Succinylcholine: most widely used relaxants. • IOP is raised rapidly by 6-12 mm Hg by succinylcholine, as a • A nerve stimulator with train of four enables the depth of result of either increased tension in the tonic muscle, causing neuromuscular block to be monitered accurately and ensures that contraction of extraocular muscle, or an increase in choroidal increments are given to prevent any sudden offset. It allows a more blood flow. accurate assessment of the level of recovery from the relaxant drug. • The rise persist for up to 10 min. • The most important factor remains smooth anaesthesia without • Other adverse side-effects of succinylcholine include muscle straining or coughing. pain. None of the suggested preventive measures, such as the • Monitoring: ECG, Oxygen saturation ETCO2, NIBP, Nerve stimulator use of priming doses, precurarization or administration of • Reversal: Inj. Neostigmine 0.05mg/ kg iv with Inj. Glycopyrolate benzodiazepines or lidocaine is consistently effective. 0.01 mg/kg iv. • And drug should be avoided unless strongly indicated. • Extubation: Extubation should be performed without Non depolarizing muscle relaxants: coughing.Extubation should be done at deer level of anaesthesia to • Non depolarizing muscle relaxants like vecuronium 0.1 mg/kg, avoid bucking and coughing. atracurium 0.5 mg/kg and mivacurium can be used. It causes a • Oxygen should be given and particular care taken to detect fall in IOP by relaxing the extraocular muscle and by lowering the respiratory depression, hypoxia, and failure of adequate reversal of arterial pressure. neuromuscular blockade, arrhythmia or hypotension. Airway control; • Post operative analgesia: Following intraocular surgery, most An adequate depth of anesthesia and muscle relaxation is patient require only simple non-steroidal analgesics such as required before endotracheal tube or LMA is passed. paracetamol and diclofenac or ibuprofen. But more complex or • As small dose of opioid – Fentanyl (1µg/kg) as, Alfentanil - 10µg/ extraocular surgery may result in pain requiring opioids or local kg or lidocaine 1-1.5 mg/kg may be used to obtund the presser anaesthetic blockade. response to laryngoscopy and intubation. • Open eye injury with full stomach: Management of emergency • The preferred endotracheal tube is a south facing preshaped anaesthesia for a patient with a full stomach and a open eye injury RAE, which allow the connection, filter and gas sampling requires balancing the need to prevent aspiration of gastric contents connector to be well away from face. against the prevention of sudden significant increase in IOP that may Maintenance of anaesthesia: cause further eye damage and loss of vision. • Anaesthesia is maintained with inhalational agents like Halothane in 30% O2 with N2O. • Halothane lower IOP by drpression of mid brain and hypothalamiccenters. • Controlled ventilation with IPPV to maintain normocapnea or even mild hypocapnea to a level of 30mm Hg, aided by the administration of muscle relaxants.

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Anaesthetic management: Intravitreal Injection of Gas: • Early administration of Histamine recptor (H2) antagonist such • Ophthalmologists sometimes inject a small bubble of gas into the as Rantidine (50 mg iv) and anti-emetic like metaclopramide vitreal cavity during surgical reattachment of the retina. The goal is (0.15 mg/kg) will decrease the gastric volume and provide some to have a sustained bubble of stable size holding the retina in place. protection from gastric aspiration. The gases commonly used, sulfur hexafluoride (SF6) and carbon • Inj. Lidocaine 1.5 mg/kg iv and inj remifentanil 0.7 µg/kg iv 3-5 octafluorine (C6F8), are inert, very insoluble in water, and poorly mins before the induction may help to attenuate the increase in diffusible. Nitrous oxide (N6O) is 117 times more diffusible than SF6 IOP after tracheal intubation. and rapidly enters the gas tubble. If administration of N2O continues Modified rapid sequence technique: after the injection of gas into the vitreal cavity, the injected gas I. Preoxygenation of the patient with 100% O2 for 3-4 mins. bubble rapidly increases to three times its original size, which causes II. Induced with inj. Thiopentone 3-6 mg/kg or inj. Propofol 2-2.5 IOP to increase from 14 to 30 mm Hg. Within 18 minutes of mg/kg, will ensure adequate depth of anaesthesia for tracheal discontinuation of N2O, however, both the bubble size and IOP will intubation. decrease (from 29 to 12mm Hg). III. Relaxed with Non depoloriping muscle relaxant like • These rapid and wide variations in bubble size during general recuronium (rapidly acting ) – 0.6-0.9 mg/kg) or intermediate anesthesia may adversely affect the outcome of surgery. acting relaxants like vecuronium (0.2 mg/kg iv) or mivacurium • Washout of N2O from the lung is 90% complete within 10 minutes, can be used. so administration N2O should be discontinued at least 20 minutes IV. As soon as muscle relaxation perceived by the patient. before an intravitreal injection of gas. Bubble size and IOP should Cricoid pressure is applied. then remain stable. V. After relaxation tracheal intubation should be done. • Regional anesthesia: The regional techniques are relatively simple, VI. Cuff should be inflacted and cricoid pressure is released. have a high success rate, and should result in excellent operating VII. Maintained with O2 + N2O + Halothane + IPPV and inj. conditions with a wide range of safety. Recuronium (0.1 – 0.15 mg/kg • Regional anaesthesia: The regional techniques are relatively VIII. During surgery depth of anesthesia must be adequate (deep) simple, have a high success rate, and should result in excellent to ensure lack of movement and coughing. operating conditions with a wide range of safety. IX. Neuromuscular blockade reversed with inj. Neostigmine (0.05 • Regional anaesthesia is predominantly well tolerated by elderly mg/kg) and inj. Glycopyrolate (0.01 mg/kg). patients. X. Extubation should be done. • Frequency of intercurrent diseases and multiple drug therapy Examination under anaesthesia: make, the avoidance of GA more desirable. • Examination under anaesthesia is chiefly performed in infants and children. It involves limited manipulations of the globe. Inhalational anaesthesia ideal for this purpose.

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Preoperative assessment: • Adding bicarbonate to raise the pH of the local anaesthetic causes a • For minor procedure under topical or simple infiltrates greater proportion of the drug to exist in the uncharged form. This anaesthesia without sedation, little preparation is required. results in more rapid onset, and may lesser the need for • However if a formal eye block or sedation is planned, detailed supplemental injection. preoperative evaluation and preparation is desirable. • The patient should be in optimal condition with special attention Methods: paid to the control of blood pressure heart failure, diabetes • Topical mellitus. • Subconjectival injection • A failure of block is exceptionally rare, however in the event of • Retrobulbar (Intraconal) block failure of block, the operation must be postponed rather than • Peribular block changing to general anaesthesia. • Sub – Tennonʼs block Sedation : • Facial nerve blocks • Midazolam 7µg/kg and alfentanil 3µg/kg have been used to allay Contraindications for regional anaesthesia: anxiety to add analgesia and to enhance, not diminish • Young age an informed preference for general anaesthesia. cooperation. • Anticipated lack of cooperation • The patient must remain conscious and be able to respond • Severe involuntary movements command. • Inability to lie in required position for surgery Pharmacology and choice of solution: • Allergy to local anaesthetic. • The ideal anaesthetic would be safe, painless to inject, and • Presence of infection at site of injection would have a rapid onset of dense sensory and motor block and Relative contraindication: a predictable duration of action. • Operation lasting more than one hour. • High concentration of local anaesthetic seem to be required to • Long myopic eye (above 26mm) (Increased risk of globe perforation). ensure adequate penetration and intense motor block. Topical: • The traditional solution is an equal parts mixture of 2% lidocaine • Modern cataract surgical techniques allow the use of smaller and 0.75% bupivacains, giving rapid onset and long duration. incisions without necessity for total akinesia. • Lidnocaine 2% and prilocaine 2% are excellent agents if a • The cornea receives its sensory inneration through the long ciliary duration of no longer than an hour is but, it associated with nerve, which form interepithelial plexus. Terminal nerve ending are optical nerve damage. superficial, so topically applied local anaesthetic are easibly • Epinephrine 5 µg/cc and hyaluronidase 7.5 IU/CC beneficial in absorbed through the conjunctival membrane and effectively block term of spread quality, and duration of block and reduction of the sensory innervations of the cornea. pressure. • The drugs commonly used are amethocaine 1%, lidocaine 4% or • Clonidine (100µg), added to local anaesthetic prolongs the motor bupivacaine 0.75%, propavacaine, tetracaine. block. • Propavacaine is the least irritating on application. • Satisfactory anesthesia results, although the iris is not anaesthetized • More patient cooperation is required as there is no globe akirnsia 85

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Advantages: • A 25 gauge, 2.5 cm sharp needle is inserted with the bevel towards • No risk of haemorrhage, brain stem anaesthesia, opical nerve the globe close to the lateral canthus. damage, or perforation of globe. • The needle is passed away from the globe below it along the ﬂoor of • Recovery is more rapid. the orbit, post the equator and then upward and inward to the full Limitations: depth of 2.5 cm. This will allow the needle tip to enter the cone just • This method include lack of eye akinesis, treatment of behind the rear of the globe. uncomplicated cataract only and the need for cooperative, • After careful aspiration 2-5 ml of the solution may be injected communicative patients who are not anxious, claustrophobic, or monitoring any proptosis and pressure rise and .stopping the demented. injection if it rises excessively. • Pressure should be applied once the needle: bas been removed to control any venous bleeding to aid spread of the solution and to lower IOP. • Care must be taken to avoid penetration of the globe - especially in myopic Globe because of the large size of the globe. Signs of successful block: • Ptosis • No movement or minimal movement in all direction. • Inability to fully close the eyes once opened Advantages: • Single injection • Needs small amount of the drug Retrobular ( intracrainal) block: Quick onset (3-4 mins) because drug is placed directly into the nerve Anaesthesia and akinesia of the globe is obtained by depositing • • within the cone. the local anaesthetic solution into the muscle cone surrounding Disadvantages: the optic sheath. • It requires supplementary facial nerve block to produce akinesia of • Patient should be kept in lying down position. the tic, and orbicularis occuli. • Patient is asked to look straight ahead in the primary gaze position, to prevent rotation of the optic nerve, vasculature, and posterior pole of the globe towards the inferotemporal region. • The retrobulbar injection is made from the inferotemporal region of the orbit.

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Complications: Procedure: 1. Systemic toxicity • Patient lies supine and is asked to look straight ahead. 2. Subconjunctival edema (chemosis) • Palpate the junction of the medical 2/3rd and lateral 1/3rd of the 3. Bruising (Echymosis) inferior orbital rim where a groove is felt at the junction of the maxilla 4. Hemorrhage and zygoma. 5. Globe penetration or perforation • Topical application of 0.5% propavacaine followed by an initial 6. Optic nerve complication injection of local anaesthetic through the fornix of the conjuctiva. 7. Amaurosis (loss of vision)Central spread of LA – causes • Must lateral to this point and 1 mm above the rim insert a 25 G convulsion, respiratory depression, cardiac arrest 25mm standard hypodermic needle mounted on a 10 ml syringe and 8. Oculo cardiac reﬂex pass it slowly backwards perpendicular to all planes. 9. Brain stem anaesthesia • Advance the needle until it is about level with the posterior pole of the globe. Contraindications: • After aspiration slowly inject 6-8 ml of local ananesthetic. Stop 1) Sever involuntary movements injecting if globe becomes proposed or if upper lid falls. It is likely to 2)Bleeding disorders indicate retrobular injection. 3)Extreme myopia • Following injection digital massage or a compression device (Honam 4)Open eye injuries balloon) should be applied to dissipate the local anaesthetic and quickly normalize IOP. Peribulbar block: • Assess the block after 5-10 min and if greater degree of akinesia is • First described in 1986 by Dairs and mandel. required, a second injection should be performed. • Using a similar needle, entry is made at a point just medical to tile Caluncle. The needle is passes backwards with the bevel facing; the globe at an angle of 100 to the sagital plane directed towards the medial wall of the orbit. If the medial wall is contacted. the needle is withdrawn slightly and redirected laterally. • If both medial and lateral injection are planned. The volume of solution is 4-5ml for each. Disadvantages of peribulbar blocks versus retrobulbar block: • Large injected volumes (6 to 8 ml) causing a possible increase in IOP) • Slower onset (5 to 10 minutes) • Potential for perforation of the globe. • Vertical diplopia as a result of myotoxicity of the inferior rectus muscle by the local anaesthetic.

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Contraindications: Procedure: i) Severe myopic patients - axial length >26 mm. • Apply topical anesthesia to the conjunctiva and retract the lower lid ii) Perforated or infected eye. using speculum. Complication: • In the inferonasal quadrant, the conjunctiva is lifted with moor ﬁelds • Globe perforation - <0.1%. forceps at a point 5 to 7mm from the limbus. • Peribulbar haemorrhage • A small incision is made in the conjunctiva with round tippet scissors, • Blindness- optic nerve injury dissect inferomedially in a plane between the sclera and Tenonʼs • Ocular muscle pain. capsule. • CNS tracking of local anaesthetic along the optic nerve sheath. • Once in this plane a blunt curved Southampton cannula is passed Sub - tenon block: back wards beyond the equator and 3.5 ml of LA is deposited. • This technique is gaining popularity as an easy safe and • Sub - Tenons block can be used safety in patient with axial length effective alternative to retrobulbar and peribulbar anaesthesia. It 2-6mtn. has the • It is the block of choice in anticoagulated patients since any bleeding • advantage of avoiding blind needling to the orbit. point can be cauterized directly. • It effectively blocks the ciliary ganglion and short ciliary nerves. Facial Nerve Block: • Larder volumes depositea more posteriorly are required to block • Van lint Block the motor nerves and extraconal branches of the ophthalmic and • Atkinson Block maxillary nerves. • O'Brien Block • Nadbath-Rehman Block Vanlint block • 5 ml of a 1: 1 mixture to 2 or 4% lidocaine (Lignocaine) with 0.75% bupivacaine are injected subcutaneously in three directions at the lateral margin of the orbit. • A sharp 25 gauge 38 mm needle is used. • First injection is directed nasally along the lower margin of the orbit. • Second injection is directed upward along the supero temporal margin. • The third injection passes directly backwards towards the ear.

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Akinson block: • More proximal than won Lint's but more distal than a O Brier's • It is along the inferior edge of the zygomatic bone and upward across the zygomatic arch towards the top of ear. A 23G 3.5 cm needle with a rounded point. • Anaesthetic is injected 5-10 ml along the arch of needle is advanced.

O” Brien block: • The facial nerve trunk is injected where it leaves the sytlomastoid canal and where its branches are directed forward through the parotid gland.

Nadbathʼs proximal focial nerve block: • Blocking the main trunk of the nerve as it exit the stylomastoid foramen. • The needle inserted behind the posterior border of minus of the mandible in front of mastoid process. • The injection should be given with short 25 gauge disposable needle, • The needle enters the skin 2 cm front and I cm below the advancing it in an anteroccophaloid direction. external auditory canal. • It is crucial to aspirate before injecting 3 to 5ml of anaesthetic to • This point can be located (while the jaw is closed) as a palpable avoid intra vascular injection into the many blood vessels in this depression below the zygoma. Which ﬁlls with the anterior region. condyle of the mandible when the jaw is opened.

Dr Azam’s Notes in Anesthesiology 2013 32. Anesthetic Management of Cleft Lip & Cleft Palate. Dr Azam’s Notes in Anesthesiology 2013

INTRODUCTION: Embryogenesis: • Cleft of the lip, alveolus, hard and soft palate are the common Face / lip congenital abnormalities requiring surgical correction at early • The face develops from a series of five swellings or growth centers, age. Central one third of the face is distorted significantly. They generally termed as "Process". These are bilateral maxillary, frequently occur as isolated deformities but can be associated mandibular process, and one frontonasal process, which is clearly with other congenital abnormalities. visible by 5thweek. • Cleft lip and alveolus can be diagnosed reliably at 18-20 weeks of gestation by ultrasound scan allowing for earlier preparation and counseling of parents. However cleft of palate is difficult to diagnose by antenatal scan. Incidence: • 1: 600 - cleft lip and palate • 1: 1000 - cleft palate • The incidence increases in Oriental (Asian) group (1: -500), decreases in Black population (1: 2000). The highest incidence reported for cleft lip and palate in Native American tribes of Montana, USA (1: 276). Distribution: • Cleft lip alone - 15% • Cleft lip and Palate - 45% • Isolated Cleft Palate - 40% • Cleft lip and Cleft Palate predominate in mare whereas Cleft Palate appears more in female. In unilateral Cleft lip, tile deformity affects the left side in 60%. The racial processes probably do not fuse but rather merge, where • In general, the ratio being • by, as the mesenchyme grows and migrates, the epithelium ironed • Left: 60% Right: 30% out from between the elevations. Bilateral: 10% • By the 7 weeks, the facial processes are no longer separable. Aetiology : • The upper lip is derived from the maxillary process laterally and 1. A family history of CLIP in which the 1st degree relative is fronto-nasal process medially. The maxillary and lateral nasal affected ↑ the risk to 1: 25 live births. process merge, and mesenchymal continuity is established. 2. Maternal epilepsy 3. Drugs-(Steroids, Diazepam, Phenytoin) 4. Maternal alcohol, smoking. 5. Lower socio economic class. 90

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Anatomy of cleft lip: • The abnormality in Cleft lip is the direct consequence of disruption of the muscle of upper lip and nasolabial region. • The facial muscle can be divided into the three musculature rings of Delaire. Muscle chains of the face: A) Nasolabial muscles: 1.Transverse nasalis 2.Levator labi superioris alaque nasi. 3.Levator labi superioris B) Bilabial muscles: 1.Orbicularis oris (Oblique head) – upper lip 2.Orbicularis oris (horizontal head) – upper lip 3.Orbicularis oris – lower lip C) Labiomental muscles: 1.Depressor anguli oris 2.Depressor labi inferioris 3.Mentalis

Unilateral cleft lip: • In the Unilateral Cleft lip, the nasolabial and bilabial muscle ring are disrupted on one side resulting in an asymmetrical deformity involving the external nasal cartilage, nasal septum and anterior maxilla. Bilateral Cleft lip: • In the bilateral cleft lip the deformity is more profound but symmetrical. The two superior musculature rings are disrupted on both the side producing ﬂaring of the nose (due to lack of nasolabial muscle continuity), a protrusive premaxilla and an area of skin in front of pre maxilla, known as prolabium, devoid of muscle.

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Embryogenesis of palate: • The palate will separate the oral and nasal cavities, and so make sucking and breathing possible at the same time. • Embryologically, the primary palate consists of all anatomical structure anterior to the incisive foramen, namely the alveolus and upper lip. The primary palate derived from the medial nasal process and receives contributions from the maxillary mesenchyme. • The secondary palate is deﬁned as the reminder of the palate behind the incisive foramina divided into the hard palate and more posteriorly, the soft palate. The secondary palate develops from right and left palatine processes.

Anatomy of cleft palate: • Cleft Palate results in failure of fusion of the two palatine shelves. The failure may be conﬁned to the soft palate alone or involves both hard and soft palate. When the cleft of the hard palate remain attached to the nasal septum and vomer, the cleft is termed Incomplete. When the nasal septum and vomer are completely separated from the palatine process, the cleft palate is termed as Complete.

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Classification Anaesthetic implication Nagpur classification: • Difficult intubation. • Group I - Cleft lip alone • Neck flexion during laryngoscopy and intubation may result in • Group IA- Cleft lip and alveolar arch Atlanto occipital dislocation because of congenital laxity of • Group II - cleft of secondary palate alone ligaments. • Group IIS - sub mucous cleft of palate Primary management: • Group III - Cleft lip and Cleft palate Antenatal diagnosis: The Side of the cleft is described as ® for right, (L) for left and (RL) • An antenatal diagnosis of cleft lip, whether unilateral or bilateral, is for bilateral. possible by ultrasound scan after 18 weeks of gestation. Isolated Associated anomalies: cleft palate is difficult to diagnose on an 'antenatal scan. • Pierre Robin syndrome Feeding: • Treacher Collin syndrome • Due to the CP, the child can not develop the negative pressure to • Down syndrome suck at the breast. Inability to co-ordinate breathing and feeding • Pierre Robin syndrome: leads to inadequate nutrition. Difficulty in feeding leads to anemia, • 80% associated with cleft palate. malnutrition and failure to thrive. • Micrognathia • Some mothers are successful in breast feeding particularly when • Glossptosis - posterior displacement of tongue. cleft is incomplete and confined to the lip. • Anaesthetic implication: • Good feeding pattern can be established with soft bottles and • Airway obstruction - difficult airway. modified nipple, such as enlarging the hole in the nipple, often • Feeding problems - aspiration. suffices. • Treacher Collins syndrome: • Feeding plates, constructed from a dental impression of upper jaw, 1. 28% associated with deft palate are rarely necessary to improve the feeding. 2. Micrognathia & maxillary hypoplasia Airway: 3. Choanal Artesia • Cleft palate permits nasal regurgitation, chronic rhinorrhea and 4. Eye & ear malformations pulmonary aspiration. 5. Small oral cavity and air way with normal tongue • Major respiratory obstruction is uncommon and occurs exclusively in • Anaesthetic implication: babies with pierre Robin sequence. • Airway obstruction – difficult airway. • Intermittent airway obstruction is more common and managed by • Feeding problems - aspiration nursing the baby prone. • Downʼs syndrome: • More sever and persistent airway compromise can be managed by 1. High arched palate, narrow palate, cleft palate. retained nasopharyngeal intubation to maintain the airway. 2. Macroglossia, small mouth, narrow nasopharynx. 3. Subglottic stenosis 4. Hyper extensibility 5. Atlanto axial subluxation. 6. Short neck. 94

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Timing of surgery: Pre anaesthetic assessment: Timing of surgery is often dictated by the “Rule of Tens” Goal: • 10 weeks of age • Child with cleft lip and palate is more susceptible for increased risk of • 10 lbs anemia, malnutrition, failure to thrive, chronic otitis media, • 10gm/dl of Hb regurgitation, pulmonary aspiration, difﬁcult airway. Care should be • Soft palate should be repaired prior to speech development that taken evaluate these factors. is between 12- 15 month and hard palate up to 4 - 5 yr. Clinical history: • H/o Gestational age at birth, Feeding habits, Cleft lip along • Sleep apnea, ear discharge, Unilateral (one side) bilateral (Both side) • Regurgitation of food, snoring, ↓ • Running nose. One operation at 4-6 month • Previous medical illness, congenital defects, Cleft palate alone • Drug allergy, Soft Palate only BIRTH HISTORY: ↓ • HlO Birth weight, Birth asphyxia, cyanotic spells One operation at 6 month DEVELOPMENTAL MILE STONES: Soft and hard palate General physical examination: ↓ 1. Build: Two operations 2. Nutrition: ↓ 3. Weight: Soft palate at 6 month 4. Height: 5. Head circumference: ↓ 6. Chest circumference: Hard palate at 12-15 month 7. Peripheral veins visible? And prominent? Cleft lip and palate Unilateral or bilateral 8. Pulse rate: 9. Respiratory rate: ↓ 10.Temperature: Two operations 11.Blood pressure: ↓ 12.Airway: Cleft lip + soft palate4-6 months ↓ hard palate + gum pad + Lip revision 12-15 month

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SYSTEMIC EXAMINATION Children require premedication • CVS • Midazolam 0.25 - O.5mg/kg orally • RS • Promethazine 3 -4mg/kg orally, provide adequate drying of secretion. INVESTIGATIONS: It has sedative, antihistaminic, and anticholinergic effects. • Hemoglobin- • Antibiotic -because of increased chances of chronic otitis media, • Total leucocytes count chronic rhinorrhea. • ESR- • Baby shifted to OT with warm blanket covering. • Bleeding time Anaesthetic management: • Clotting time Pre anaesthetic preparation: • Blood group- for child of 12 month, 10kg coming for cleft palate surgery. • X-ray- mandible. • Operating room preparation. • ECHO- • Warm the operating room 27°c - 29°c • HlV, HBsAG, • Turn on warming devices • Hematocrit. • Warm the mattress - set at 35 - 37°c • Informed consent • Monitoring equipment (pulse oximeter, capnograph) turned on and Valid informed consent should be taken from the parent. checked. Preparation: • Precordial stethoscope with adhesive. • Preoperative fasting has been prerequisite for elective surgery. • Proper size face mask - 0 size Minimum fasting period (hours) for pediatric patients • Oral airways – 0/LMA-1 Age Milk & Solids Liquid • Tongue depressor • ETT-( 3, 3.5, 4 uncuffed RAE tubes) < 6 months 4 hours 2 hours • Stylet • Suction turned on with suction catheter- (size -6,8) 6 - 36 months 6 hours 3 hours • IV ﬂuids - 4-2-1 Formula. 4ml x 10kg = 40ml- (maintenance). > 36 months 8 hours 3 hours Fluid of Choice is RL taken in Burette of 200 ml. Fasting guidelines in neonates • Drugs drawn up and labeled. • Breast milk may be given until 4 h preoperatively. • Dextrose solutions may be given until 2 h preoperatively. • Formula milk feeds may be given until 6 h preoperatively. These milks contain cow protein and are more slowly digested than breast milk. • Babies having continuous feed via jejunal catheters should have these stopped 4 h preoperatively.

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Thiopentone Cuff size: • (7mg x 10 kg = 70mg. 3ml of 2.5% of Thiopentone taken in l0cc Neonate 2.5 cm syringe) Infant 5 cm Atropine. 1 – 8 yr 9 cm • (0.02mg x 10kg = 0.2mg. 0.5 ml of atropine taken in 2 cc syringe diluted to I ml i.e. 0.15mg/ml) 9 – 14 yr 12.5 cm • (Glycopyrrolate - 0.0 I mg x 10 kg = 0.1 mg.) ml in 2cc syringe • Temperature diluted to 2 ml i.e. 0.1 mg/ml) • Urine out put Succinylcholine Insertion of i.v. cannula: • (2mg x 10 kg = 20mg. 0.5 ml of Succinyl choline taken in 2 cc • Apply EMLA cream 60 - 90 min in advance. It should be applied at syringe i.e. 25mg/ml) least in two locations. ND NM blocker • I.V line can be secured after the child is sedated with Halothane (0.5 • (Vecuronium- 0.05mg x 10kg = 0.5 mg. 2mg of Vecuronium 1 %) + Nitrous oxide (70%) +Oxygen (30%) + with face mask. taken in 5 cc syringe and diluted to 4 m! i.e. 0.5 mg/ml) • Suitable vein should be selected, Opioid • Dorsum of hand • (Fentanyl -1µgm x 10 kg = 10 µgm. 1ml of Fentanyl 5.0mg • Medial aspect of foot taken in 5 cc Syringe diluted to 5 ml i.e. 10 µgm/ml) • Lateral aspect of foot Reversal- • Scalp vein • Neostigmine 0.05mg x 10kg = 0.5mg. I ml in 5 cc syringe to • Lateral aspect of wrist which inj Glycopyrrolate 0.01 mg x 10 kg = 0.1 mg. 0.5ml added. • After securing the vein, tape the cannula ﬁrmly in place and immobilize the limb in splint. Monitors: Cannula size and ﬂow rate • ECG Size (G) Length (inch) Flow (ml/min) • Pulse oximeter 24 0.75 14-15 • Precordial stethoscope 22 1 24-26 • Capnography • NIBP 20 1.25-2 38-42 Age Systolic Diastolic Infusion set: New born 62-86 35-55 • Micro drip infusion sets (60 dp/ml) allow the anaesthetist to more accurately deliver small volume of infusate .Fluids calculated in 6 wk – 9 yr 80-100 55-65 measuring chamber (Burette of 200m I). 10-19 yr 90-110 60-75 Premedication: • Inj Glycopyrrolate 0.01 mg/kg i.v given for antisialogogue effect. • Inj ondensetron 0.08mg/kg i.v as an antiemetic.

Dr Azam’s Notes in Anesthesiology 2013 Anesthetic Management of Cleft Lip & Cleft Palate.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Analgesic: Intravenous method: • Inj Fentanyl l µgm/kg i.v preferred because short duration of Advantages: action, rapid in on set, more potent. 1. Rapid in induction Preoxygenation: 2. Eliminates the use of face mask • Preoxygenation done with 100% oxygen with mask at for 3 - 5 3. Reduces the risk of excitement phase in inhalation induction. min. Inj Thiopentone - Induction: • Commonly used. Intravenous injection is pain less and produces the 1. Inhalational smooth induction. 2. Intravenous. • Dose - 7 -8 mg/kg - infants Inhalation induction: 5 - 6 mg/kg - children • Commonly used. Induction can be done with mask with Oxygen • The increased requirement in infants and children compared to adult (30%), Nitrous oxide (70%) and incremental doses of volatile is due to increased cardiac output, this would be expected to reduce agent (Halothane/sevoflurane) Volatile agent is added by the first pass concentration of Thiopentone arriving at brain. increasing the concentration by no more than 0.5 - 1 % every 3 - • Inj Propofol- 2.5 - 3 mg/kg i.v 5 breaths until unconsciousness is achieved. Sevoflurane is Relaxation: agent of choice for induction. • Succinylcholine 1 - 2mg/kg i.v is given to produce rapid NM block. Inhalational induction is preferred in children because of • Children require more Succinyl choline on the body mass bases Physiological Advantages because of larger total body water content 80 - 85% of the body 1. Higher alveolar ventilation 200mJlkg/min in neonate compared weight compared to adult 60 - 65 % of the body weight. to 100 ml/kg/min in adult. Thus uptake and elirnination of Intubation: inhaled unaesthetic is more rapid. • A laryngoscope with "C" section blade bridges the palatal defect 2. Lower FRC 25ml/kg compared to adult 40ml/kg So more of the when intubating the infant. Alternatively, the palatal gap can be filled gas in lungs is exchanged with each breath. by a gauze pack. 3. Higher cardiac out put 200rnJlkg/min compared to adult 100ml/ Position: kg min increases the rate of anaesthetic equilibration in the • The large head tends to place in flexed position prior to intubation. tissue. • Intubation is done in neutral position. This is easily corrected by 4. Higher blood flow to vessel rich organs. slightly elevating the shoulders with towels and placing the head on a These factors contribute for rapid induction and recovery by doughnut shaped pillow. Laryngoscope should be held in thumb and inhalational induction. index finger and the chin grasped with the ring and middle fingers of left hand. To improve the view of the larynx, pressure should be applied over the hyoid bone with small finger of left hand. Intubation done with appropriate size Endotrachial tube. • For infants, flat laryngoscope blade i.e. Magill is more suitable because it flattens out the curvature of epiglottis and can be used to lift it forwards to expose the larynx. • In children aged above 1yr, laryngoscopy can usually accomplished98 using medium sized Macintosh blade with tip-placed in vellecula. Dr Azam’s Notes in Anesthesiology 2013 Anesthetic Management of Cleft Lip & Cleft Palate.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Endotracheal tube: Diameter of distal joint of fifth finger Pre-curved, tracheal tubes of pie determined length are used (e.g. Length of the tube: RAE tube, Oxford tube) • Age (yr) /2+12 (cm) The following points should be considered while selecting ETT: • Height (cm) / 10 + 5 (cm) 1. In children cricoid is the narrowest part of the trachea and is • Weight (kg)/ 5+12 (cm) circular. So large tubes wiIl produce ischemia to the tracheal RAE tube – (Ring, Adair and Elwyn tube). mucosa. • Oral version of preformed tubes made up of PVC. It is bent toward 2. In neonate 1 mm edema causes 75% reduction in cross the concavity of the curve of the tube so that when it is in place it sectional area and 16% increases in resistance rests on the patient's chin. Size of tube: Approximate size and length of pediatric ETT Disadvantage: Appx age Id (mm) Lgth-oral (cm) Suction cath • Difficult in tracheal suction Premature –< 1000 2 5 • Flexion point is fixed. The intratrachial length may be inappropriate in gm 2.5-3.0 11 5 children whose cricoid diameter is larger or smaller than usual for > 1000 gm age, and their use may result in either accidental extubation or Neonate to 3 mth 3.0-3.5 12 6 bronchial intubation, especially when-mouth gag is inserted. Other tube is Oxford tube 3-9 month 3.5-4.0 12 6 • Position of the tube should be confirmed by 9-18 month 4.0 – 4.5 13 6 1. Direct visualization of vocal cords during laryngoscopy. 2 year 4.5 14 6 2. CO2 wave forms with Capnography 4 year 5.0 15 8 3. On auscultation Vesicular breath sounds on lung fields. 6 year 5.5 17 10 4. Bilateral Chest movement with each mechanical inspiration, 8 year 6 19 10 5. Condensation in the Err with exhalation. 10 year 6.5 20 10 6. Feel of the bag. • The position of the tube should be confirmed each time the patient's 12 year 7 21 12 head is moved because the distal tip of the tube moves towards the carina during flexion and toward the vocal cords during extension of Size can be calculated with pelingtonʼs formula: the neck. ≤ 6 years • • With the cleft lip/palate surgery, the tube should be taped against the Age (yr)/ 3+3.5 (mm ID) chin so that anatomy of upper lip is not distorted. ≥ 6 years • • The pack of wet gauge should be placed in deep hypopharynx for Age (yr)/ 4+4.5 (mm ID) cleft lip surgery. This will help in Absorbing dependent blood loss and secretion that could flow down besides tube into trachea.

Dr Azam’s Notes in Anesthesiology 2013 Anesthetic Management of Cleft Lip & Cleft Palate.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• To avert the eye injury, an ocular lubricant is placed in the eyes, Fresh gas flow and the eyelids are splinted with tape. Surgeon is asked to start 2.5 – 3 times the minute volume or minimum of 3-4 1 of flow the operation. Weight (kg) Mark (Lt) TT (Lt) • The surgeon usually places the "Dingman gag"to fix the tube 5 8 6 centrally along the tongue and to hold the mouth open. The 10 8 6 apparatus contains groove in which ET tube should sit without 15 10 7.5 being occluded. • Position: Correct positioning of the child is important for the 20 12 9 plastic surgeon, who sits at the head of the operating table. Advantages: • Head .extension must be maximal for the cleft palate surgery. • The system is simple, inexpensive. The entire body is raised with thick foam mat or folded blanket, • Low resistance allowing the head to drop back hyper extended into the head • Light weight hence not likely to cause excessive drag on to the ETT. support. Not only does this position provide good exposure but Blood loss: keeping the lungs in non dependent position, it also allows blood • Cleft lip repair is associated with only modest amount of blood loss to flow away from larynx, and towards the nasopharynx allowing The repair of cleft palate, however, may be associated with moderate it to be removed by suction. (10 60ml) of bleeding, but rarely is there a need for blood transfusion. Maintenance: • Small losses of blood in infants can cause significant changes in Hb • Anaesthesia is maintained with Nitrous (67%), Oxygen (33%), concentration and hemodynamic stability. Maximal allowable blood and with Halothane (0.5%), intermittent injection of muscle loss should be computed before the induction of anaesthesia. relaxant • ABL (allowable blood loss) can be calculated by • (Inj Vecuroniurn 0.015mg/kg) and IPPV, 18 - 25cycles/min with • ABL =EBV x (H0 – H1)/Ha Jackson and Rees circuit. • ABL - Allowable blood loss; EBV - estimated blood volume. Jackson and Rees modification of Ayerʼs T – piece: • H0 - original Hematocrit; HL -lowest Hematocrit; Ha, - average • Used for age < 5 year, or weight < 20kg. Hematocrit Component: Estimation of blood loss: • Ayerʼs T-piece with three open ports • Suction containers used to measure blood loss should contain • Corrugated tube capacity of 50-250 ml. • Reservoir bag with valve • The weight of the swab not moistened with saline is reliable • Connector • 4 x 4 inch sponge holds 10 - 15 ml of blood.

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EBL – estimated blood volume Fluid management: Age Blood volume (ml/kg) Fluid requirement is calculated by Holliday and Segar rule. a. Maintenance (4: 2: 1 rule) Premature 90-100 0 to 10 kg – 4 ml/kg/hr Full term 80-90 10 to 20kg - 40ml + 2ml/kg/hr 3 mth – 1 yr 75-80 >20kg - 60ml + 1ml /kg/hr b. Deficit: 3 yr – 6 yr 70-75 • Deficit is calculated by multiplying number of hours of fasting with > 6 yr 65-70 maintenance. Adult 60-65 • Pre operative fluid deficits are typically administered 50% in first hour and 25% in the second and third hour. • 10 Kg child • (child of 12 month of 10kgHo-35%, HL-25%, Ha-30% 10 kg x 4ml = 40ml (maintenance) ABL- 80 x 10 x (35-25)/30 = 266ml.) If the child is fasting for 4hr, pre operative deficit 4 x 40 = 160ml Thermoregulation: 1st hour 80 + 40 = 120ml Neonates and infants are prone to hypothermia because of large 2nd and 3'd hour 40 + 40 = 80ml ratio of body surface to weight. They have limited ability to cope Emergence: with cold stress. The heat loss can be minimized by • Once the surgery is completed, Emergence from anaesthesia begins • Warming the OT. as soon as the anaesthetist stops -inhaled anaesthetics, muscle • Warming mattress relaxants. Discontinuation of volatile agent, increasing the oxygen • Worming fluids and moderately increasing the manually controlled ventilation • Using plastic wrap to decrease water loss through skin increases pulmonary venous to alveolar concentration gradient of • Covering head with plastic cap inhaled anaesthetics and facilitates the elimination of residual inhaled Glycemic control: anaesthetics, where as excessive hyperventilation causes cerebral • A child of diabetic mother needs a Glycemic control. vasoconstriction and impedes the elimination of anaesthetics from • Hypoglycemia is defined as serum glucose is <30mg/dl in the brain. Further more, hyperventilation depletes the CO2 stores in the first day of life and <45mg/dl after 24hr. body tissues, delaying the onset of spontaneous breathing. • Treatment consists of giving 3 -4 mg/kg/min of dextrose-and titrate according to need.Hyperglycemia is considered if the Reversal of NM blockade: serum glucose is more than 150mg/dl. Treatment -Stop the • Once adequate efforts are observed, reversal of neuromuscular glucose infusion if it is> 250 - 300mg/dl and start insulin at a blockade is done with, dosage of 0.05 - 0.2 µ/kg/hr titrated to achieve normoglycemia. • Inj Glycopyrrolate 0.01 mg/kg iv Inj Neostigmine 0.05 mg/kg iv

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The criteria for adequate clinical recovery from NM blockade are • Maintain adequate, non paradoxical breathing • Sustain hip ﬂexion with leg elevation for 10 sec • Lift the head and / cough forcefully. After removal of throat pack, gentle suction should be done Extubation done in deep inspiration. Post operation care: • Baby shifted to recovery room in semi – prone position covered with warm blanket, Sp O2, pulse rate are monitored, shifted to postoperative ward. Pain control • Bilateral Infra orbital block • Paracetamol – 10- 15 mg/kg q4hr orally. • Ibuprofen – 4 -10 mg/kg q6-8hr • Diclofenac -1 -1.5 mg/kg q 12 hr

Post operative complications Air way obstruction • Air way obstruction results from the closure of cleft structure plus some edema secondary to trauma. • The infant should be placed in prone position with the head dependent, turned to the side, and hyper extended. A long traction suture is placed through the tongue and tied loosely. This can removed when the infant leaves the recovery room Nausea and vomiting • Factors contributing are Inhaled anaesthetics, inadequate analgesia, gastric distension, Treatment Ondensetron 0.1 - 0.15 mg/kg

Post extubation croup • Children are more prone for croup because the have narrow laryngeal and tracheal lumen. • Other complications are Hypothermia Post operative bleeding, aspiration, infection of wound. 102

Dr Azam’s Notes in Anesthesiology 2013 33. Polytrauma. Dr Azam’s Notes in Anesthesiology 2013

DEFINITION: • The hemoendocrine response to hypovolemia results in activation of • Polytrauma is defined as a clinical state followed by injury to the the sympathetic nervous system with the release of epinephrine and body with profound physio-metabolic changes involving multi nor epinephrine. The endocrine response is the release of multiple system. hormones from the hypothalamic pituitary adrenal axis which • Polytrauma patients are these who sustain any one of the augment the sympathetic response. The overall effects include following combination. vasoconstriction, sodium retention, insulin resistance, 1. 2 major system injuries + one major limb injury. gluconeogenesis and lipolysis. 2. 1 major system + 2 major skeletal injuries • Local endothelial injury can lead to activation of inflammation and 3. Instable # pelvis with associated visceral injury. coaglation at the site of injury which is essential for prevention of 4. 1 major system injury + 1 open grade III skeletal injury. infection and' for eventual healing and repair. INTRODUCTION: TRAUMA TEAM: It consists of • Trauma is epidemic in the modern world and has been the • Anaesthesiologist (Team leader) leading cause of mortality with increasing number of fast moving • Trauma surgeon vehicular traffic, there has been an increasing incidence of • Physician polytrauma. Most of these trauma's involve more than one • Radiologist system such as involving head injury and neck with chest, • Nurses and helpers. abdomen or orthopaedic injuries. Most of these injuries are caused by so called acceleration - deceleration injuries. The anaesthesiologist plays potential roles in the case of a trauma Unfortunately the victims of trauma are often young people, in patient as their best productive years. Apart from the vehicular accidents, • A trauma team member polytrauma is often the result of falls, riots, industrial accidents, • Trauma team leader fire arms and ballistics and others. • An anaesthesiologist • Trauma challenges the anaesthesiologist with additional • Critical care physician responsibilities and reminds us of our duties as a physician. It is • Pain relief physician a science of resuscitation amenesia and anaesthesia. Increased • Pre-hospital care physician number of vehicles, increased mass movement, alcohol and • Critical care transport physician drug abuse have increased the risk of serious injury. • Diasaster planning consultant BODY RESPONSE TO TRAUMA: • Whenever there is injury or insult to the body, it tries to maintain a normal homeostasis inspite of the increased metabolic demand by various mechanisms.

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• The anaesthesiologist is primarily concerned with preserving Yellow CNS function, maintaining adequate respiratory gas exchange • Requires close monitoring, care can be some what delayed. This and achieving circulatory homeostasis. category includes victims with: Role of trauma team leader Risk of shock • Compound fractures • Femur, pelvic fractures • Severe burns. • Unconscious, head injury. • All these victims will receive I.V. line, close monitoring for any complication and will receive treatment as soon as passable.

Green • Requires delayed or no treatment • Includes victims with minor fractures minor wounds and burns These patients after-,receiving dressing and /or splinting will be attended at the end.

Black: • For patients who are brought dead.

Death from trauma has a trimodal distribution Triage Peak (non-salvageable): • In a multiple casualty disasters identiﬁcation of victims needing • Death occurs within seconds to minutes as a result of major injuries prompt medical attention and those who can wait is performed to heart, brainstem, aorta and large vessels. The primary prevention by the ﬁrst aiders. is essential in avoiding death. • Prioritization of victims are done by color code tag. • Red – require immediate stabilization care and includes victims with • Shock status from any cause • Respiratory distress. • Head injury with unequal pupils • Major external bleeding.

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Peak (Salvageable): I) Over view • Death occurs within, minutes to hours, due to subdural or a. Perform visual scan of patent for obvious injuries epidural hematoma, hemo-pneumothorax, splenic laceration and b. Obtain history from prehospital personnel and patient (if major fractures. "Golden hour" is the first hour which begins able). when the victim is injured and not when the medial personnel arrive at the scene. The concept of golden hour was introduced II) Primary survey (ascertain "ABCDEs") by cowley indicating that these first 60 min were crucial to saving a. Airway maintenance (with cervical spine control) the patients life. This is the period where visceral injury or sever • Look for chest wall movements, retraction, and nasal flaring. fractures can cause continuing hemorrhage that eventually • Listen for breath sounds, stridor; and obstructed ventilation. result in hypovoluemia shock. During this window of opportunity, • Feel for air movement. appropriate treatment can save a life and reduce morbidity. Platinum 10 minutes is the first 10 minutes of pre hospital care b. Breathing (give supplemental oxygen) given to the patient at the site of Injury. Patients in second peak • Determine whether ventilation is adequate are amenably salvageable if they are rapidly assessed and the • Inspect chest to exclude open pneumothorax, or flail segment. process of resuscitation started at the. earliest. • Auscultation for bilateral breath sounds. Peak: • Provide assisted ventilation for ventilatory failure. • Death occurs from day to weeks due to sepsis, multiple organ c. Circulation (establish venous access) system failure, etc. in the high dependency areas like ICU's. • Check peripheral pulses, capillary refill, and blood pressure Improvement In the initial management will bring down the • Obtain electrocardiogram. mortality rate in this group. • Grade shock according to vital sign. Advanced trauma life support (ATLS) : • Correct hypovolemia and obtain blood samples. • The advanced trauma life support manual developed by the d. Disability to determine neurological status) committee on trauma of the American college of surgeons (ACS) • Evaluate central function are designated to Identify and correct the most-life threatening A: Alert problems first. It has five sequential components. V: Responds to vocal stimulus P: Responds to painful stimulus U.: Unresponsive • Evaluate pupil response to light. e. Expose patient for complete examination.

III) Resuscitation phase IV) Secondary survey V) Deﬁnitive care phase.

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I)OVERVIEW: II) PRIMARY SURVEY: • Initial evaluation: The orderly progression of history, physician • Primary survey aims at basic physiologic support and resuscitation. examination, diagnosis and treatment must often be abandoned The objective of primary survey Is to Identify life and limb threatening with trauma patients because resuscitation has priority over injuries and it consists of the ABCDE. diagnosis. A →Airway with cervical spine protection • Rapid overview: The initial moments following the patients B →Breathing and ventilation arrival In the emergency room are devoted to obtaining the most C →Circulation with haemorrhage control basic information about the overall condition of the patient and D →Disability / neurological status injuries injuries by visual scan. E →Exposure / environmental control. • History: - Accident History Airway with cervical spine protection: - patient history • Patency of the airway is assessed first, by looking for foreign bodies • Accident History: Information about the accident may help in and facial, mandibular fractures or tracheal/ laryngeal injures that evaluating the pattern and severity of injury. It can be obtained may result in airway obstruction. form the patient (if possible), trauma team members or from the • Suspect a cervical spine injury in polytrauma especially with an patients friends or relatives. altered level of consciousness or evidence of Injury above the level • Relevant questions should be asked In different types of trauma of the clavicle. like.Motor vehicle accident → about type of Impact, speed and • Manual in line traction is provided while securing the airway. Noisy size of the vehicle, location of the victim In the car etc. breathing suggest an obstruction. • Information should also be obtained about pre-hospital • If cervical spine injury is ruled out, a triple airway maneuver resuscitation and the condition of the victim on the scene and consisting of head tilt, chin lift and jaw thrust should be performed during transport. with suctioning of the mouth to clear the airway. In unconscious • Patient history: patients or with cervical spine injury only jaw thrush must be done • A brief and organized approach to obtaining the trauma patient's and an ore-pharyngeal airway Is required with C-spine protection. history' is characterized by the acronym AMPLE. • A cuffed endotracheal tube which ensures adequate ventilation and protects against aspiration is the definitive airway. A: Known allergies • Airway access can be oral/nasal or surgical. M: Medications used by the patient • Once airway is cleared and secured, 100% 02 at a flow rate of 15 P: Past illness or surgery liters/min can be delivered. L: Timing and content of last meal • Neck: It is quickly examined for wounds, tracheal position, venous E: Events preceding the accident. distension, surgical emphysema and crepitus. • Cervical spine should be stabilized with semi rigid collar, sand bags and tape.

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Table 3. grading system correlating the severity of upper Environment: Hypothermia, core temp <33°C. Respiratory obstruction and the resulting sings and symptoms Breathing and ventilation: Stage of obstruction Signs and symptoms • If the patient cannot maintain adequate tissue oxygenation n spite I No stridor at rest adequate quantities of O2 then artificial ventilation must be instituted. Mild or potential obstruction Cough • Some of the common causes of Inadequate ventilation. hoarseness Bilateral Unilateral II Stridor on slight exertion Moderate obstruction Rib retraction on inspiration 1. Obstruction of` upper respiratory 3. Intubation of right main dilation of alae nasi on inspiration tract bronchus use of accessory respiratory muscles 2. Leak between face and mask 4. Pneumothorax Indrawing of cervical soft tissues 5. Hemothroax Tugging of jaw and trachea on inspiration 6. Foreign body in main bronchi dyspnea 7. Lung contusion III Stridor at rest Severe obstruction apprehension Restlessness Immediate life threatening thorasic conditions must be noted and Sweating treated immediately. Pallor 1. Airway obstruction - must be relieved. increase in pulse rate and blood pressure 2. Tension pneumothorax - needle thoraco-centesis in second exaggerated excursion of neck veins intercostals space using a 14 guage needle. IV Slowed respiration Very severe obstruction Hypotension 3. Open chest wound - must be dressed. Cyanosis 4. Massive hemothorax - chest drain in 5th intercostals space anterior Impaired consciousness to mid axillary line. 5. Flail chest - Internal pneumatic fixation by intubation and positive Indications for a definitive airway: pressure ventilation / operative fixation of ribs. Airway Obstructed airway Inadequate gag reflex Circulation and haemorrhage control:

Breathing Inadequate breathing, Oz saturation less than 90%. • The aim is to evaluate the patients hemodynamic state while Circulation Inadequate circulation, systolic BP < 75mmHg despite controlling hemorrhage and restoring adequate perfusion. adequate ﬂuid resuscitation. • Shock can be classiﬁed as follows depending upon the blood loss Disability Coma, Glasgow coma scale <8/15. • Class I: < 15% Class II: 15-30% Class III: 30-40% Class IV: > 40%

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Watch for signs of shock: Table 6: Two level initial evaluation of consciousness: • ↑ respiratory rate Level 1 – AVPU system • ↑ heart rate A-Alert • ↑ capillary reﬁll time V-Responds to verbal stimuli • Skin pallor P-Responds to painful stimuli • Cold and clammy extremities U-Unresponsive • ↑ blood pressure Level 2 – Glassgow coma scale (GCS) • ↑ pulse pressure Eye – opening (E) • ↑ urine output spontaneous – already open and blinking 4 • ↑ level of consciousness. To speech 3 to pain 2 • Two wide bore 14-16G peripheral lines should be started immediately. None 1 Verbal response (V) • Pressure over bleeding site must be applied. Oriented 5 • Torinquet should not be used except in traumatic amputation of an extremity. Answers but confused 4 inappropriate, but recognizable words 3 • 2 liters of R.L (Hartmanʼs solution) or 1 liter of colloid bolus can be rushed and the patient condition is re-assessed. incomprehensible sounds 2 Rapid response < 20% blood loss. None 1 • Transient response: > 20% blood loss/active bleeding (+) / need Best motor response (M) blood transfusion and surgery. Obeys verbal commands 6 • No response: > 40% blood loss/bleeding is more than transfused Localizes painful stimulus 5 blood/needs immediate surgery. Withdraws from painful stimulus 4 DISABILITY (Neurologic evaluation): decorticate posturing (upper extremity ﬂexion) 3 • It refers to the initial assessment of neurologic function. decerebrate posturing (upper extremity extension) 2 • Rapid neurological evaluation using 2 level protocol to assess No movement 1 the level of consciousness should be done • An altered level of consciousness Indicates the need for Exposure: immediate reevaluation of the patients oxygenation ventilation • It involves completely undressing the patient for a through and perfusion status. examination, assessment & intervention. • Technique for removal of clothing to minimize patient movement. Clothing should be cut along the anterior midline of the garments. • Prevent hypothermia by covering the patient with warm blankets after examination

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RESUSCITATION: • Aggressive resuscitation and management of life threatening injuries, as they are identified, are essential to maximize patient survival. Adequacy of resuscitation is monitored by. • Airway - Pulse oxymetry/capnography. Breathing - Respiratory rate/capnography/ABG. Circulation - Assessing perfusion by blood pressure/pulse/temperature/central venous pressure & urine out put. Disability - Pupils/AVPU scale/Glasgow coma scale. Environment - Cone temperature. SECONDARY SURVEY: • Secondary survey begins after the primary survey is completed and while resuscitation is in progress. • Secondary survey involves the detailed head to toe evaluation of the patient, often described as "tubes & fingers in every orifice”. • The secondary survey should result in a complete list of injuries that allows the formulation of a management plan. 1. A detailed medical history. 2. Head to toe evaluation. 3. Complete neurological examination. 4. Sonography for trauma/Diagnostic peritoneal lavage. 5. Radiological evaluation 6. Laboratory studies MEDICAL HISTORY: A detailed history for following is taken. A-Allergies M-Medication P-Past medical history/ pregnancy L-Last meal E-Event leading to injury & environment

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Head to toe evaluation: Head: Thorax: • Entire scalp and head should be examined for lacerations, • Examination of thorax is done by reviewing the findings of the contusions and evidence of fractures. primary survey. • If scalp laceration is present, bleeding should be controlled • Auscultate for breath sounds high on the anterior chest wall for immediately since scalp is a highly vascular structure. pneumothorax and posterior bases for haemothorax. • Bleeding can be stopped by applying direct pressure or by • If intubated check endotracheal tube placement. suturing. • Intercostal drainage tubes may be necessary in the presence of • Look for evidence of bleeding or CSF leak from nose and ears to pneumo/ haemothorax. rule out cribriform plate damage and basal skull fracture. Abdomen: Eyes: • A thorough examination is done by inspection, palpation, percussion • Pupil size and reactivity are tested, and visual acuity is assessed and auscultation. if possible. • Exposed bowel is covered with warm saline soaked swabs to avoid • Look for any other evidences of Injury. hypothermia and fluid loss. • Contact lenses must be removed before orbital edema develops. • Focused abdominal sonography for trauma and diagnostic peritoneal lavage help us to assess the type and severity of injury and plan Mouth further management. • Look for lacerations which may be bleeding. • Look for urethral, renal, liver & splenic injuries. • Any vomitus or broken tooth should be removed Immediately to • Rectal examination - Sphincter tone; Rectal damage; Pelvic maintain a patent airway. fractures; Prostate position. • Look for any evidence of mandibular fracture which may cause Extremities: airway obstruction. • Long bone fractures can cause considerable blood loss. • Cervical spine should always be reinforced with sand bags, • Fractures of femur or humerus can cause 1.5 to 2 litres of blood loss, semirigid collar and tape during the airway monoeuvers. Signs of spinal cord injury • Cervical spine and neck: Patients with maxillofacial of head • Hypotension and bradycardia trauma should be presumed to have an unstable cervical spine • The compensatory mechanism in patients with hypovolemic shock injury and the neck should be immobilized until all aspects of the like tachycardia and peripheral vasoconstriction are absent in cervical spine have been adequately studied and an injury has patients with, spinal'cord injuries. This is because of loss of been excluded. sympathetic tone as well as disruption of cardio accelerator fibres. • The absence of neurological deficit does not exclude injury to cervical spine.Cervical spine tenderness, subcutaneous emphysema, tracheal deviation and laryngeal injuries must be evaluated because early intubation may be required before swelling compromises the airway.

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Table 7. NEUROLOGIC EVALUATION OF SPINAL CORD INJURY: Most frequently used scoring systems are Function Clinical finding Injured spinal cord i)Abbreviated injury scale (AIS) element ii)Injury severity score (ISS) Autonomic Loss of bladder control Prasympathetic iii)Glasgow coma scale (GCS) Loss of rectal control pathways iv)Trauma score. Priapism 1) Abbreviated injury scale (AIS ): Reflex Areflexia initially Reflex arcs within • Abbreviated injury scale was published in 1971 by the American Hyperreflexia after a few weeks the spinal cord Medical Association, the American Association for Automotive Sensory Loss of superficial pain and Spinothalamic tract Medicine, and the Society of Automotive Engineers. temperature on the side opposite Posterior columns, • AIS provides a uniform grading for persons injured in motor vehicle the injury transmitting crashes, penetrating trauma and other causes of blunt trauma. Loss of position sense of the proprioceptive • AIS scoring system is revised every 5 years. fingers and toes on the side of impulses • In the present form AIS assigns a score form 1 to 6 to injuries that injury Posterior colums are coded bayed on their anatomic site, nature, and severity. Loss of vibration sense on the 2) Injury severity scoreIt was developed from abbreviated injury scale side of injury and published in 1974. Motor Loss of voluntary muscle Corticospinal tract I. This score provides a summary severity score for patients with contractions on the side of injury multiple injuries. Loss of involuntary response of Corticospinal tract II. Each injury is given an abbreviated injury scale code and pain on the side of injury classified into one to six body regions. III. ISS is the sum of the squares of the highest AIS scores from the Definitive care: three most severely injured body regions. • Successful implementation of the ATLS protocols should result in IV. Highest AIS score is used if a region, has more than one injury. the rapid, accurate, and effective assessment, management, and V. Score range is from 1 to 75. continuing care to the trauma patient. VI. ISS of 16 or more is taken as defining major trauma and • Completion of the previous phases should provide information to corresponds with an average mortality rate of 10%. plan definitive management, which may be surgical or non VII. ISS scale has been used for road traffic casualties In relation to surgical or involve transferring the patient. mortality, time of death, hospital treatment time, and disability. Trauma scoring: • First civilian trauma unit was established at cook county hospital in Chicago in 1966. • No individual scoring system is applicable to all age groups in all settings when prior disease states and mechanism of Injury are considered.

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Disadvantages: Revised Trauma score: 1. Any error in scoring the AIS increases the ISS error. • Trauma score has several disadvantages like capillary refill and 2. A wide diversity of injuries yield the same ISS score. respiratory efforts are difficult to assess in the field under adverse 3. Values for injuries to different body regions are not conditions and in poor lighting. differentiated. • Trauma scoreunderestimates the severity of some had injuries. 3) Glasgow coma scale • Revised Trauma score eliminates these assessments and requires It was introduced in 1974 by Teasdale and Jennett. only three of the five parameters of the trauma score i.e. Glasgow • It is the most frequently used neurologic scoring system and is come scale, systolic blood pressure and respiratory rate. also a component of several other scoring systems. • A range for each parameter is allocated a value that is multiplied by • It allows the grading of Impairment of consciousness in both an assigned weight. trauma and nontrauma situations. • The sum of resulting values ranges from 0 to 7.8408. The higher the • It provides an accurate indication of the patients neurologic value, the better the prognosis. status, out come and prognosis. • The Glasgow coma scale component carries most of the weight in • Scores range from 3 to 15, with higher scores indicating the revised trauma score, which allows identification of severe head increased level of consciousness. injury in the absence of multisystem injury or major physiologic • GCS score may have to be modified depending on changes. circumstance. FLUID RESUSCITATION IN POLYTRAUMA: • Example - (i) Patient with gross periorbital edema may not be • Circulatory shock is the most common complication of polytraunla testable for eye opening rather than scoring 1. (ii) Intubation in a that requires treatment during the initial phase. patient does not permit verbal response testing. • Prolongation of shock, even for a brief period, is likely to contribute to • Paediatric testing may be more difficult therefore a non verbal the development of organ failure and death during the later stages of pediatric coma scale has been advocated for use in small care. children. • Hemorrhage is the most common etiology of traumatic shock contributing to inadequate perfusion. Trauma score: • Prompt recognition of the mechanism of hypotension is essential so • Trauma score is based on the GCS, capillary refilling, blood that appropriate treatment can be promptly instituted. pressure, respiratory rate and effort. • Fluids are effective initially in all types of shock, they gradually lose • The sum of the values can range from 1 (worst) to 16 (normal) their effectiveness if definitive treatment of any non hemorrhaggc • Patients with score less than 12 to transferred to a trauma cause is' delayed. center. • The clinical signs of hemorrhage are classified into four categories depending on the response to the volume lost.

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Table 5. Advanced trauma life support classiﬁcation of hemorrhagic shock Class I Class II Class III Class IV Blood loss Up to 750 750-1500 1500-2000 ≥ 2000 (Ml) up to 15% 15% - 30% 30% - 40% ≥ 40% Blood loss (% blood volume) Pulse rate < 100 > 100 > 120 ≥ 140 Blood Normal Normal Decreased Decreased pressure Normal Decreased Decreased Decreased Pulse Nomal or Posivitive Positive Positive pressure increased (mm Hg) Normal Capillary reﬁll test Respiratory 14-20 20-30 30-40 > 35 rate ≥ 30 20-30 5-15 Negligible Urine output (mL/hr) CNS – Slightly Midly Anxious and Confused, mental anxious confused lethargic status Fluid Crastalloid Crystalloid Crystalloid Crystalloid replacement blood blood (3.1 rule)

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• Manifestations of the adequacies of 3 regional micro circulations are observable in the early assessment of trauma patients. • Poor blood flow • To skin is immediately evident as cool, pale, sweating peripheries. • To brain is manifested as altered consciousness (anxiety confusion, and restlessness). • To kidneys is observable as oliguria. ROUTES FOR FLUID ADMINISTRATION 1) Peripheral intravenous route: • One or more large bore (16-gauge or larger) peripheral intravenous catheters for the administered of fluids and blood should be placed as quickly as possible In the management of the trauma patient. • First choice for cannulatlon is a vein that is visible. • Second choice is the external jugular vein. • Third choice, although invisible, is the femoral vein. The pulsations of, which are palpable during spontaneous circulation in shock and 'during cardiac compression. A larger # 14- #8 cook interaosseous infusion needle is percutaneously cannula (8.5 to 12 French gauge) can be placed by means of • inserted Into the flat portion of the proximal tibia just below, and the Seldlnger technique in to the femoral vein. medial to, the tibial tuberosity the depth of the needle insertion The last choice in adults for peripheral venous cannulatlon is • should be planned before placement. If it advanced too far, the a rapid venous cut down. needle will penetrate the posterior cortex and will not allow Infusion. The last choice for cannulation in children is the itnrasseous route. Aspiration of bone marrow identifies adequate needle position. Fluids Which is ideally done with an 18- gauge, 4cm jamshedi bone may be infused, by the intraosseous route, at rate up to 40ml/min marrow needle (using 300 mmHg pressure). • Needle is placed 2 cm below the tibial tuberosity from an anterior approach and directed towards the feet to avoid the tibal growth plate.

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Central venous route: • blood cells. Rapid, massive infusion of isotonic salt or colloid • The superior vena cava is the preferred vessel for central venous solutions can be life-saving, particularly in patients with severe catheterization. external or, internal blood loss. • Many consider the right internal jugular vein the preferred • To restore and maintain the extracellular extravascular volume, approach to superior vena cava catheterization. predominantly with crystalloids, since this internal redistribution is • Superior vena cava is preferred because a catheter in the related more to the degree of tissue trauma and ischemia than to superior venacava is less dysrhythmogenlc than one in the right blood loss per se. atrium or pulmonary artery. • To keep an intravenous route open for drug administration and also • Air embolism must be avoided whenever the catheter is opened provide basic hydration. This may be accomplished by a continuous to the atmosphere and particularly in hypovolemic patient by infusion of 5% dextrose in 0.75% to 0.5% sodium chloride, 20 to 25 slightly lowering the head end, the conscious patients should be ml/kg/24 hr for adults and children, and 100ml/kg/24 hr for infants. asked to hold the breath, where as the un conscious patient Hyperglycemla caused by massive infusion of dextrose containing should receive positive pressure ventilation. fluids should be avoided, since it may worsen, cerebral edema and • Catheterization through the subclavian vein remains a last neurologic outcome. choice because it is associated with a slightly higher incidence of • To adjust this therapy promptly for increased or decreased diuresis, lung puncture leading to pneumothorax. keeping urine flow greater than 0.5ml/kg/hr. Catheter location in relation to the site of injury • To change intravenous fluids to achieve normal serum electrolyte • Location of the injury must be considered when choosing a site concentrations, osmolality, and colloid osmotic pressure, serum for venous access. albumin (3 to 5g/dl); hematocrit (30% to 40%); and serum glucose • Avoid venous access in injured limbs (100 to 200mg/dl). • In patients with injuries below the diaphragm at least one IV Total amount and rate of intravenous infusion depend on the total should.be, placed In a tibutary of superior vena cava because volume and rate of estimated blood loss and the type of fluid selected. vascular disruption of the inferior vena cava may be present. FLUID RESUSCITATION IN CHILDREN: Infusion strategies: • Most significant pathophysiologic defect in traumatized children is • Rapid volume infusion accompanied by packed red blood cells hemorrhagic shock. continues to be the mainstay. • Earliest manifestations of shock are – • During emergency resuscitation and post resuscitative life • Delayed capillary refill support, Intravenous fluids should be administered with the • Mottled skin following objectives. • Cool extremities • To restore normal circulating blood volume immediately after fluid • Tachycardia losses, using combinations of electrolyte solutions, colloids, and solutions containing red

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• In children systolic and diastolic blood pressure remains Hypertonic solutions: relatively constant because of peripheral vasoconstriction and • 3% and 7.5% hypertonic saline are commonly used. may be maintained until there is a 30% to 40% loss of circulating • IT restores the blood volume by maintaining a contracted interstitial blood volume and therefore the hypovolernic patients may have space. a narrow pulse pressure. Advantages: • Arterial pH is a good indicator of circulatory status in children. • Lesser infusion volume. • If pH is low, in the presence of normal or low carbondioxide, it • Positive inotropic effect should be assumed that circulating blood volume is inadequate, • Direct vasodilatory effect until proven otherwise. • It causes increase in mean arterial pressure and cardiac output • If the pH fall's below 7.2 in a child with adequate ventilation, followed by peripheral vasodilatation with an increase in renal, sodium bicarbonate may be added to fluid replacement which mesenteric, total splanchnic and coronary blood flow. can be caliculated by Dose = body Wt In kg x 0.15 mEq x base Disadvantages: deficit, given as an IV bolus, followed by reassessment of the • Transient increase in blood pressure and vasodilatation may pH. increase hemorrhage from open blood vessels. • For initial fluid resuscitation, Ringer's lactate is administered as a • Potential for hypernatremia and hyperchloremic metabolic acidosis. bolus (20ml/kg). 3 for 1 rule • If vital signs fail to improve, boluse of RL may be repeated three • Isotonic electrolyte solutions are used for initial resuscitation. times. • A rough guideline is to replace each ml of blood loss with 3ml of • If, despite the infusion of RL, hypotension or shock continues, crystalloid fluid, thus allowing restitution of plasma volume lost into either '0' or type specific red blood cells are administered interstitial and intracellular space. (10ml/kg increments upto 30-40 ml/kg.) Crystalloid administration - clinical problems: Types of fluids: • It reduces viscosity thereby enhancing bleeding from injured vessels. • All plasma substitutes and electrolyte and colloid solutions • It lowers the hematocrit and dilutes the clotting factors. produce hypercoagulability by diluting the clotting factors. • Resuscitation with large volume of cold crystalloids aggravates Crystalloid solutions: hypothermia. Crystalloids are divided into • Impairment of immure system is seen as a consequence of rapid • Isotonic bolus of crystalloids. • Hypertonic. Isotonic solutions: • There are normal saline and ringer lactate. • They freely equilibrate through intravascular and interstitial spaces but do not promote intracellular fluid shifts. • Advantages of these fluids are, less expensive, availability and effective interstitial fluid deficit replacement. • Normal saline may cause hypernatremia and hyperchloremic metabolic acidosis. 117

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COLLOIDS: Hypertonic saline – Dextron (HSD): 1) Hydroxy ethyl starch: • Hypertonic saline dextran is 7.5% saline solution in 6% dextran 70. • It is a branched glucose polymer with variable molecular weight • HSD provides 12 times the volume expanding capacity of an equal and clearance.Clearance rate is 46% of the dose cleared in 2 volume of isotonic crystalloid. days and 64% in 8 days but detectable starch may be present as • HSD causes a temporary fluid shift from the interstitial and many as 17 weeks. intracellular space to the Intravascular space. • Recommended dose is 20ml/kg/d as a volume expander and • Half life of HSD is 8 hours. dose in excesses of >20ml/kg results in coagulopaty. • HSD preserves regional blood flow and capillary diameter as • It doesn't carry the risk of transmitting Infectious diseases and compared with hypertonic saline solution alone. has the lowest rate of anaphylactold reactions. • HSD Improves pulmonary blood flow and renal function. 2) Albumin: 5% / 25% solution: • HSD maintains pulmonary artery pressure and pulmonary vascular • Its a major serum protein accounting for 80% of plasma resistance at baseline values. concentration of protein. • Main disadvantage of HSD is hypernatremia and acute vasodilatation • Intravascular half life of albumin in 16 hours. when infused rapidly, but this is a transient phenomenon. • Doses in excess of 20ml/kg result in intravascular volume Gelatins: Haemaccel , Gelofusine: increases by more than the volume infused because the high • Haemaccel does not impair coagulation and does not interfere with concentration of protein draws in interstitial water. blood typing and is eliminated unchanged via kidney and intestine. • It presents a risk of dilutional reduction in fibrinogen and other Colloids vs clotting factors. crystalloids • Albumin binds calcium and there by has a negative inotropic Trait Colloids Crystalloids effect. Cost Relatively expensive Inexpensive Duration of action Several hours (or Short lived to few hours Dextron: Dextron 40 / Dextron 70 more • Mixtures of glucose polymers of various sizes and molecular Urinary flow Decreased GFR Greater Urinary flow weight. Infusion volurne Less More • Oxygen delivery is improved by Improvement In microcirculatory Peripheral edema Minimal when Peripheral edema blood flow distribution resulting from lower blood viscosity. capillaries intact • Dextron 70 has a 30% intravascular retention after 24 hours and Effect on coagulation Platelet abnormality Dilutional may reduce the incidence of ARDS. thrombocytopenia factor • Dextron 40 has a shorter retention time but does, not elevate dilution sedimentation rate and may have a more potent antiplatelet effect. • Dextron 40 should, however, be given only after urine flow has been restarted with infusion of electrolyte solution, because it may worsen renal tubular function. 118

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Resuscitation fluid comparisons BLOOD PRODUCTS: Packed red blood cells Best volume expansion best Needs cross – matching short bood Blood component therapy: oxygen transport bome pathogens risk dilutional coagulopathy with massive • Banked blood or packed red blood cells should be used to sustain transfusions immunosuppressive the hematocrit at 25% to 30%. Isotonic crystalloids (NS, LR) Immediately available Distribute rapidly into extracellular • The main purpose of transfusing blood is to restore the oxygen area Low cost Take up a lot of storage space carrying capacity of the intra vascular volume. Pasteurized plasma preparation like 5% plasma protein fraction are Hypertonic crystalloids Intravascular volume many Increase heart rate increase heart • time the volume infused easy contractility reduced peripherval safe but, may occasionally contain vasodilator substances. transportable vascular resistance • Fresh - frozen plasma or cryoprecipitate is indicated for replacement Albumin Naturally occurring colloid Expensive 5% no risk of blood born of isolated factor deficiencies, reversal of warfarin effect, and pathogens transport functions massive blood transfusion. 25% free radical savaging Blood should be warmed to near body temperature. anticoagulant properties • Dextrain 6% dextran 70 Naturally occurring Reduces platelet adhesivenss • Packed red blood cell solutions, because of their high hematocrit 10% dextran 40 Reduced blood viscosity Enhances fibrinolysis increased value, should be diluted with isotonic saline solution in the bag to bleeding above 1.5g/kg increase the infusion flow rate and to decrease hemolysis. Association with acute renal failure • Undiluted packed red blood cells should be infused slowly and Mild anaphylactic reactions Hydroxyethyl starch high Synthetic polymers Degraded by amylase judicious diuresis are recommended in cases of anemia associated Stays intravascular 24 hrs reduces factor VIII and von with heart failure. willebrand Medium Intravascular 4-6 hrs Above 20mL/kg/d Coagulopathy in Low Intravasculr less than 4 hrs higher doses above FLUID RESUSCITATION FOR TRAUMA PATIENTS IN 21ST CENTURY. 33 mL/kg / day for HEs 200/0.5 Oxygen therapeutic agents: Minimal effect of coagulation Ideal blood substitute would be disease free and have a long life anaphylactic reactions rare • Fractionated HES May be able to plug leaky universal ABO compatibility and a similar oxygen carrying capacity. capillaries Gelatin solutions (widely From bovine collagen Withdrawn by FDA in 1978 for used in the UK) intravascular for 2 -3 hrs anaphylactic reaction little effect on clotting formation Oxygen therapeutic agents No cross-match needed long Short half-life limited substrate shelf life (human derived) No viral contaimination HES (bovine derived) Lower viscosity than blood Oxygen unloading (PFCs) No immunosuppressive effectsLimited clinical trial experience

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SHORT AND LONG TERM GOALS FOR RESUSCITATION Perflurocarbons: Parameter Short term Long term They are inert substances with linear oxygen unloading characteristics. 1. Systolic blood pressure 80-100 mmHg > 100 mgHg • Fluosol DA was shown to be ineffective in the treatment of severe 2. Heart rate < 120 bpm < 100bpm anemia due to hemorrhage. 3. Arterial pH > 7.20 Normal • Perflubron is a second generation perflurocarbons appears to be a 4. Hematocrit > 25% > 20% more effective transporter of oxygen. 5. Serum Lactate < 6 Normal It is thicker than blood. 6. Urine output > 1.5 m/kg/hr • 7. Pulmonary artery Not usually > 3 ml/kg/h • It Is stable upto 2 years refrigerated and has a half time of about 4 occlusion pressure measured > 18mm Hg days. 8. Cardiac Index ” > 3L/min/m2 • When inspired atmosphere contains 90-100% oxygen, this solution 9. Oxygen delivery (DO2) ” > 600 ml/min/m2 releases about twice the oxygen of the normal blood. 10. oxygen consumption (VO2) ” > 150 ml/min/m2 Disadvantages: 11. Mixed – VenousSaturation (SVO2) ” > 70% • A high FI02 is required to provide adequate tissue oxygen delivery because the perfluorocarbon oxygen dissociation curve is linear, Intra venous fluid replacement in hemorrhagic shock Class I : 2.5 L RL (or) 1 L Polygelation unlike the sigmoidal hemoglobin - oxygen curve. Class II : 1.5L RL + 1 L Polygelation • Perfluorocarbons at a dose of 25 ml/kg body weight produces Class III : 1 L RL + 0.5 L Polygelation + 1-1.5 L while blood (Or) bradycardiay hypotension, reduction in WBC, pulmonary 0.1 – 1.5 L equal volume of concentrated Red cells + polygelatin insufficiency, reticuloendothelial blockade, decrease resistance to Class IV : 1 L RL + 1 Polygelatin + 2 L whole blood(or) 2 L equal bacterial infection, anaphylactic reactions. Glutaraldehyde - polymerized bovine hemoglobin product: volume concentrated Red cells and polygelation (or) hetastarch. This bovine derived solution has reduced oxygen affinity which Responses to fluid resuscitation • promotes the unloading of oxygen. Rapid response Transient No response Response • It has a reduced viscosity similar to crystalloid solutions about one Vital signs Return to Normal Transient Remain abnormal third that of blood and can be stored at room temperature for 2 years. improvement BP Polyheme: Estimated blood Miniral (10-20%) Moderate and Severe (> 40%) • It is a human polymerized hemoglobin based blood substitute has loss ongoing (20-40% similar oxygen transport and oncotic characteristic to those of Need for more Low High High banked red cell and does not appear to cause pulmonary or systemic crystalloids hypertension. Need for blood Low moderate to high Immediate Hemolink: Blood preparation Type and cross Type specific Emergency blood • A human red cell substitute . match release Need for operative Possibly Likely High likely intervention

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Hemoglobin: • Hemoglobin based red cells substitutes of three derivatives are currently being studied. 1. Human hemoglobin - Synthesized from out dated blood. Primary advantage is production from a natural product. Disadvantage is the limited amount of discarded blood for substrate. 2. Animal hemoglobin - It is inexpensive and potentially widely available. Purification remains a concern as pathogenic transmission remains uncertain. 3. Recombinant hemoglobin - Synthesised from culture formation has a high associated cost and requires stringent purification methods. Synthetic erythrocytes: • They are also called lipid - encapsulated hemoglobin or liposome - encapsulated hemoglobin. • Synthetic erythrocytes are made by incorporating stroma free hemoglobins into liposomes. • Their oxygen dissociation curve is virtually identical to that of red blood cells, and they are slightly more viscous in solution than blood. • Large dose suppress the reticuloendothelial system. • Half-life is greater than 24 hours. • Synthetic erythrocytes are difficult to sterilize, especially against viruses.

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Dr Azam’s Notes in Anesthesiology 2013 34. Tourniquet & Anesthesia. Dr Azam’s Notes in Anesthesiology 2013

Introduction: • Ischemic Injury: Ischemia develops rapidly after cuff inflation and • The use of tourniquets to reduce blood loss during extremity results in progressive lactic acidosis with the accumulation of carbon surgery is an old and effective technique, but it is potentially dioxide, extracellular potassium and myoglobin and inflammatory hazardous. Even newer automatic (as opposed to older mediators, such as thromboxane. Capillary integrity is breeched and pneumatic) devices can be associated with complications that following cuff deflation, extravascular fluid increases in the ischemic range from minor and self limited to debilitating or even fatal. limb. The resultant edema is responsible for post – tourniquet Localized complications may result from either direct pressure to syndrome, a frequently dismissed condition that can have a underlying structures or ischemia in tissues distal to the deleterious impact on surgical recovery. When extreme oedemal tourniquet. Systemic effects are usually related to the inflation or formation obstructs normal capillary perfusion, a vicious circle of deflation of the tourniquet. tissue ischemia and edema formation develops, producing a limb – Complications with Tourniquet use threatening compartment syndrome. This depends upon the degree Pressure Related Injuries of inflation pressure and the duration of inflation time. • Pressure related injuries to the underlying skins, as well as SYSTEMIC EFFECTS: nerve, muscle, and vasculature, are dependent on both the • Hemodynamic Alterations: Hemodynamic changes with tourniquet magnitude (inflation pressure) and duration (inflation time) of inflation or deflation are usually minimal in healthy patients. tourniquet use. Tourniquet inflation is associated with rise in systemic vascular • Skin: Erythema of the skin is a common finding and is of little resistance. This may increase intra-cranial pressure in patients with consequence. Bullous lesions are observed after very long prior head injury or it may precipitate congestive cardiac failure in tourniquets inflation times. However, the bullous lesions are to be patients with poor cardiac reserve. Tourniquet release can be differentiated from abrasive or allergic skin injuries resulting from associated with severe hypotension, believed to be due to removal of a felt cast protector and chemical burns from iodine – based tourniquet stimulation, as well as direct myocardial depression and preparation solutions. vasodilation produced by products of anaerobic metabolism (Lactic • Nerve: Nerve injury is caused by shearing forces set up across acidosis). the proximal cuff edge, and this is the most frequently recognized • Pulmonary Thromboembolism: Pulmonary embolism can occur in tourniquet complication. Axonal dysfunction(neurapraxia) as well two situations: 1) A thrombous becomes dislodged during Esmarch as prolonged neurologic deficits due to the axonal disruption wrap exsanguinations and tourniquet inflation in patients with venous have been observed. Severe nerve injury may occasionally lead thrombosis following prolonged orthopedic immobilization; or 2) to incomplete recovery of function or a causalgia syndrome. tourniquet – related pulmonary embolism occurs in a patient with a • Muscle: Pressure necrosis of underlying muscle is less clinically hypercoagulable state (such patients appear to have a higher apparent than are other pressure – related complications. The incidence of embolism). myoglobinuria is easily overlooked, and muscle weakness may be attributed to a nerve palsy. • Vascular Injury: Tourniquet – related arterial or venous injury can cause thrombosis with distal embolization of atheromatous material. Spontaneous venous or arterial thrombosis has been reported in patients with hypercoagulability. 122

Dr Azam’s Notes in Anesthesiology 2013 Tourniquet & Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Complications with use are summarized in the tabular form • A brief neurologic examination of the effected extremity should be Pressure Related carried out following emergence from anaesthesia. Profound motor • Skin Injury and sensory deficits characteristic of a severe nerve injury should be • Nerve Injury readily apparent. Less severe nerve injury may result in variable - Mild (Neurapraxia) motor weakness and or variable sensory loss. With regional - Severe (axonal disruption) anaesthesia, there can be considerable delay in the diagnosis or - Delayed (causalgia) nerve injury, especially with postoperative regional analgesia • Arterial Injury • Embolism results in hypoxemia, reduced end – tidal carbon dioxide, • Rhabdomyolysis hypotension, and signs of myocardial ischemia. Ischemia – related • Compartment syndrome has been observed to occur both • Post tourniquet syndrome immediately after surgery and after a delay of several hours. The • Compartment syndrome limb is typically quite swollen, tense and painful, although the pulse Systemic complications may be intact. Measurement of intra compartmental pressures is a • Hemodynamic perturbations useful diagnostic procedure, especially in patients with residual - Cuff inflation – congestive heart failure regional anesthesia of the extremities. - Cuff deflation – cardiovascular collapse • The post – tourniquet syndrome is characterized by swelling, • Intracranial hypertension stiffness and mild degree of weakness and numbness that develops • Pulmonary embolus several hours after tourniquet deflation. • Post operative causalgia is the only complication of tourniquet use Recognition of complications: that presents weeks or months after surgery. Burning pain and The intraoperative recognition of tourniquet complications is limited autonomic dysfunction develop; followed by distal extremity to the sudden hemodynamic changes (discussed above) and the dystrophic changes in the absence of treatment. following: Risk Assessment: • Skin injuries usually manifest in the immediate postoperative • Conditions that increase risk for tourniquet related complications are period. When the cuff is removed, the cuff site should be listed in the following table up to 60% of peripheral nerve injuries can periodically inspected for ecchymoses, persistent erythema, and be directly attributed to malfunctioning pneumatic tourniquets. bullae formation. Automatic microprocessor controlled devices appear safer than older • Arterial injury with obstruction to blood flow should be suspected pneumatic cuffs and should be used whenever possible. when cuff deflation does not result in reperfusion of all or part of • Patients at increased risk for complications with use of extremely the extremity. tourniquets

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Medical Conditions Potential Complications Management s of complications: 1. Pressure – caused skin lesions are treated on the basis of clinical • Obesity, conical proximal • Peripheral nerve injury( Radial appearance. Lesions with intact skins are treated expectantly, extremity, nerve) where as those with bullae require burn care. • Previous humeral head • Pulmonary embolism with 2. Nerve injuries that do not resolve quickly should be evaluated by a fracture, Esmarch wrap exsanguination neurologist, and nerve conduction studies should be performed. • Delayed surgery after and / or cuff inflation, Septic / Cautious physical therapy should proceed to improve the potential immobilization tumour emboli with Esmarch for full recovery from the operative procedure. • Infection / tumor of extremity, wrap exsanguination and / or 3. Post –Tourniquet syndrome is managed with elevation of the Severe cuff inflation, extremity, close monitoring of wound healing, and physical therapy. • Left ventricular dysfunctional • Cuff inflation – left Ventricular 4. Causalgia syndromes are managed with sympathetic blockade, Hypercoagulable failure, Cuff deflation- physical therapy, and possibly, neurolytic sympathectomy. Early • States, Previous extremity hypotension, intervention is most efficacious. vascular surgery • Thromobembolic events, 5. Compartment syndrome is a surgical emergency requiring urgent • Arterial occlusion decompression of the affected compartments by fasciotomy. 6. Pulmonary embolism is managed with controlled ventilation, Implications: oxygen, vasopressors, and cardiopulmonary resuscitation, if 1. Most tourniquet – related compressive nerve injuries involve required. Systemic anticoagulant or thrombolytic therapy and neuropraxia and resolve completely over hours to days with no surgical thrombectomy are helpful in selected patients. treatment. With nerve disruption, recovery can extent to weeks 7. Arterial thromboembolism is also serious. Surgical exploration and / or months. Occasionally recovery is incomplete, or a causalgia or thrombolytic therapy may be necessary to prevent tissue loss syndrome develops. The latter may cause considerable and disability. disability. Extremity paralysis or paresis may have a negative impact on postoperative rehabilitation efforts. 2. Weakness and swelling associated with post – tourniquet syndrome interfere with rehabilitation, would healing, and the skin normal function as a barrier to infection. 3. Unrecognized arterial occlusion results in necrosis of bone and soft tissue, often necessitating surgical excision or amputation. 4. Pulmonary embolism can cause right ventricular strain and cardiovascular collapse. Nonfatal embolism causes respiratory failure, stroke and myocardial infarction. 5. Compartment syndrome carries a significant risk of ischemic necrosis and permanent contracture of involved muscles.

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Dr Azam’s Notes in Anesthesiology 2013 Tourniquet & Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Prevention of complications: Pneumatic Automatic The concept of minimum effective pressure is important for • Mechanical pressure regulator Microprocessor regulates preventing pressure related skin and nerve injuries. This is the have malfunctions. Aneroid Pressure to ± 6mm Hg. Excellent minimum tourniquet pressure that prevents bleeding. It varies pressure gauge varies with time pressure accuracy, with automatic directly in relation to the patientʼs systolic blood pressure and the (Must recalibrate with each self – calibration. Audio and visual circumference of the extremity. For normotensive, average – use).No pressurization or elapses pressure and elapsed time alarms sized adults. Minimum effective pressure for pressure for upper time alarms. No fail – safe 500mm Hg fail – safe pressure and lower extremity tourniquets is approximately 200 and 250 overpressure limit. limit. mmHg, respectively. Narrower tourniquets must be inflated to relatively higher pressures to be effective and should be avoided in obese or hypertensive individuals. • Inflation time should be limited to 2 hours. This is not always possible, and several strategies have been proposed to safely prolong inflation time. Induced hypothermia of the extremity prior to cuff inflation is time consuming but it is effective for tissue protection during prolonged procedures. Intermittent cuff deflation and re-inflation will provide ischemic recovery time, but this makes surgical visualization difficult owing to discoloration and edema. Double – cuff tourniquets may be alternately inflated and deflated to relieve pressure on underlying structures. Inflation time has been safely prolonged to almost 4 hours with double – cuff technique, but the relatively narrow cuffs employed require higher inflation pressures and should not be used in obese or hypertensive patients. • Patients at high risk of arterial injury or thrombosis should not be considered for the tourniquet use without prior vascular surgery consolation. Tourniquets should not be used in patients with hypercoagulable states. • Deep vein thrombosis should be suspected in patients under going delayed repair of lower extremity fractures. Noninvasive evaluation of the immobilized extremity, simple exsanguinations and preoperative low – dose heparin prophylaxis are useful preventive measures. Safety of Pneumatic Vs. Automatic (Microprocessor – Controlled) Tourniquets.

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Dr Azam’s Notes in Anesthesiology 2013 35. Tourniquet. Dr Azam’s Notes in Anesthesiology 2013

• Tourniquets are applied around upper or lower extremities to Muscle changes: eliminate intra operative bleeding and thereby provide better 1. Cellular hypoxia develops with in 8 min operative conditions. 2. Cellular creatinine increase. • Used in IVRA. 3. Progressive cellular acidosis • However application of tourniquets is not without danger. The 4. Endothelial capillary leak >2 hrs. major complications being directly relates to either. 5. Limb becomes progressively colder 1. Duration of Ischemia Systemic Effects of Tourniquet Inflation: 2. Pressure generated by the cuff 1. Elevation of arterial and pulmonary artery pressure. The tissues most at risk of damage are nerve and muscle. 2. Can increase CVP. • Nerve is most susceptible to pressure injury and Systemic Effects of Tourniquet Release: • Muscle is vulnerable to Ischemia 1. Transient fall in core temperature • The suggested “SAFE” duration of tourniquets inflation varies 2. Transient metabolic acidosis from 45min-4 hrs. With 2hr being the most accepted time. 3. Transient fall in central venous organ tension UL – 1 hr 4. Transient fall in systemic and pulmonary art pressure LL – 1&1/2 hr. 5. Transient increase in ETCO2. Prerequisites: 6. Increased O2 consumption 1. Cuff width should exceed half the diameter of the limb and 7. Hypotension after release of tourniquet - Due to acid metabolites. should be long enough. 2. Organic iodine solutions should be avoided at the site of Tourniquet Pain: tourniquets applications • Tourniquet applied with >100mm of Hg of systolic pressure for more 3. The duration of the surgery should be well below the safe than 45-60 min are usually associated with ill defined aching / duration. burning sensation of uncertain etiology. (Not blocked by spinal / 4. The gauges used in the tourniquets inflation system should be Epidural) accurate. • Tourniquet pain is carried by unmyelinated fibres which are relatively 5. Inflation pressure should be limited to that needed to block resistant to local anaesthetics. arterial flow. Usually 50-100 mm Hg greater than patients • Tourniquet pain sometimes becomes so severe, that patients may systolic pressure. require supplemental analgesia. Under GA it can be reverted as a Physiologic changes caused by limb tourniquets: gradually increasing MABP 45 min – 60 min after cuff inflation. Neurological Effects: • Cuff deflation invariably and immediately relieves the sensation of 1. Abolition of somatosensory evoked potentials and Abolition tourniquet pain and its hypertension. SSEP nerve conduction occurs within 30 min 2. Application for > 60 min causes tourniquet pain & HTN. 3. Application for >2 hrs may result in postoperative neuropraxia. 4. Evidence of nerve injury may occur at skin level underlying the edge of tourniquet. 126

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• Signiﬁcant decrease in systolic and Diastolic BP when tourniquets are employed in patients who receive GA may be offset by deepening GA and when patientʼs well being is threatened, β - blockers, vasodilators like SNP may be used.

Complications: • Neuropraxia may follow the use of pneumatic tourniquets Electrophysiological testing and thorough neurological examination should be done to distinguish between proximal injuries that might be attributed to spinal / epidural anesthesia. • Ischemia induced tourniquets of lower extremity may lead to development of DVT.

Contraindications: 1. Sickle cell disease: May lead to circulatory stasis, hypoxaemia and acidosis →Triad known as Precipitate sickling 2. Peripheral vascular Diseases 3. Ventricular dysfunction 4. Calciﬁc Arterial disease

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Dr Azam’s Notes in Anesthesiology 2013 36. Grading of Nerve Injury. Dr Azam’s Notes in Anesthesiology 2013

Grade I injury [Neuropraxia]: Complications associated with patient positioning • Loss of function without anatomic injury. Complication Position Prevention • Most likely injury related to positioning. Air embolism Sitting, prone, reverse Maintain venous pressure • Recovery in 6 weeks. Trendelenburg above 0 at the wound. Grade II injury (Axonotmesis): Alopecia Supine, lithotomy, Normotension, padding • Anatomic disruption of axon but preservation of nerve sheath Trendelenburg and occasional head and connective tissue. Degeneration and regeneration occurs turning. and function gradually returns. Grade III injury (Neurotmesis): Backache Any Lumbar support, padding, • Axon sheath, connective tissue disruption seen. Degeneration and slight hip flexion. occurs. Regeneration does not occur. Compartment Especially lithotomy Maintain perfusion syndrome pressure and avoid external compression. Corneal Especially prone Taping and lubricating eye. abrasion Digit Any Check for protruding digits amputation before changing table configuration. Nerve palsies Avoid stretching or direct Brachial plexus Any compression at neck or Common Lithotomy, lateral axilla. Pad lateral aspect of peroneal. Decubitus upper fibula. Radial Any Avoid compression of Ulnar Any lateral humerus. Padding at elbow, foream supination. Retinal Prone, sitting Avoid pressure on globe. Ischemia Skin necrosis Any Padding over bony prominences.

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Dr Azam’s Notes in Anesthesiology 2013 37. Spinal Surgery. Dr Azam’s Notes in Anesthesiology 2013

Indications 1. IVDP and nerve root compression (L4 –L5 / L5 – 51) 2. Spondylosis L5-6 or L4 – L5. 3. Scoliosis 4. Tumors 5. Vascular malformations 6. Abscess 7. Traumatic compression of spine due to fall. 8. Meningomyelocoele

Pre-op consideration 1. Neck mobility, TMJ mobility etc 2. Ventilatory changes due to scoliosis 3. Neurologic deﬁcits documented 4. Premedicate with analgesics. These patient have pain.

Intra-op Management • Anterior cervical fusion involves injury to esophagus, trachea, RLN, carotid vessels, sympathetic chain etc. • Injury to RLN has been diagnosed intra-op by Electromyographic testing of vocal cord function using special ETT with built in Electrode wires. • Transthoracic approach to anterior thoracic spine requires a DLT& OLA. • Prone position: Its limitations, problems etc. excess bleeding from engorged epidural plexus. • Epidural • Surgical short for short surgery • Continues for moderate • IBP, CVP, neurological monitor – MEP, SSEP, wake-up test • Decrease bleeding by hypotension technique, epinephrine

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Dr Azam’s Notes in Anesthesiology 2013 38. Total Hip Replacement. Dr Azam’s Notes in Anesthesiology 2013

Anatomy of Hip Joint: Joint – ball and socket joint. Contraindications: • Ball – upper end of femur. Absolute: • Socket - part of the hip bone called acetabulum. The ends of the • Active infection of hip joint or any other region. bones are covered with a smooth layer of cartilage, which allows Relative: frictionless and pain free movements. • Any process that is rapidly destroying the bone • When this cartilage is damaged clue to disease process like • Neurotrophic arthritis arthritis, joints become stiff and painful. • Absence/relative insufficiency of abductor musculature • Most patients for THR are elderly with osteoporosis and young • Rapidly progressing neurological disease patients suffering from rheumatoid arthritis or obesity or Hip replacement options: ankylosing spondylitis. THR, also called THA (Total hip arthroplasty): Indications: • The hip socket and ball of the femur is replaced with a metal / • Pain with distructive process of joint as evidenced on ceramic ball on the stem fitted into a cut with a plastic liner. roentigenogram indicates for THR. • Revision of hip replacement • Disorders of the hip joint for which total hip arthroplasty may be • Re-operation on a previously performed hip replacement which has Arthritis Renal disease failed or become loose. Rheumatoid Cortisone induced • Part or whole of the previous implant is removed and replaced with a Juvenile rheumatoid (Still disease) Alcoholism , new one. Importance - Prolonged operation with significant blood Ankylosing spondylitis Caissons disease loss. Degenerative joint disease (osteoarthritis, Lupus Bilateral hip replacement: hypertrophic) Gaucher disease Primary Nonunion, femoral neck and trochanteric • Both hips are replaced simultaneously. Secondary fractures with head involvement • Has a longer recovery time. Slipped capital femoral epiphysis Pyogenic arthritis or osteomyelitis Hip resurfacing: Congenital dislocation/dysplasia of hip Hematogenous • Ball of the femur - resurfaced with a metal shell rather than being Coxa plana (Legg-Perches disease) Paget Postoperative disease Tuberculosis removed and replaced. Traumnatic dislocation Congenital subluxation or dislocation • The socket is replaced as a traditional replacement without cement Fracture acetabulum Hip fusion and pseudoarthrosis • Importance - preserves more of the patients own bone → there by Hemophilia Failed reconstruction more anatomical load bearing on the femur. Avascular necrosis Osteotomy Postfracture or dislocation Cut arthroplasty Idiopathic Femoral head prosthesis Slipped capital femoral epiphysis Girdlestone Hemoglobinopathies Total hip replacement (Sickle cell diseases) Resurfacing arthroplasty Bone turmour involving proximal femur or acetabulum

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Girdle stone procedure: Spine is often involved, • Indicated if revision hip replacement is not an option. • Neck positioning during intubation should be as gentle to avoid nerve • Loosed Loosened prosthesis is removed altogether → Scar root compression or nuscleus pulposes protrusion. tissue develops between the upper end of femur and the hip • Pose a problem in performing a epidural or spinal anaesthesia in this bone →allows person to move with little pain. groups of patients. • Drawback - Femur is shortened, leg is weak, walking with aid b. Rheumatoid arthritis: crutches is usually necessary. • Immune mediated joint distruction with chronic and progressive inflammation of synovial membrane, as opposed to articular wear Minimally invasive arthroplasty: and tear. • Computer assisted, • It typically involves multiple joints like - cervical spine, hips, shoulders Minimal invasive, knees, elbow, ankle, metacarpophalangeal joins in symmetrical Cementless hip replacement surgery. fashion. • Approach Lateral - decubitus position • Inserting invasive catheters and even gaining intravenous access are Anterior - supine position a challenge in patients with severe deformities. Surgical steps in THR: • Extreme cases of RA can involve almost all synovial membrane, • Postioning of the patient usually → lateral decubitus position. including those in the cervical spine and te4aronrandibular joint. • Dislocation and removal of femoral head. • Atlanto axial subluxation which can be diagnosed radiologically, may • Reaming of the acetabulum and insertion of a prosthetic plastic lead to protrusion of the odontoid process into the foramen magaum or ceramic acetabular cup with or without cement. during intubation, compromising vertebral blood flow arid • Reaming of femur with insertion of a femoral component (metal/ compressing the spinal cord or brain stem. ceramic femoral head and metal stem) into the femoral shaft with • This can be evaluated by flexion W extension lateral X-ray of cervical or without cement. Metals used include stainless steel, alloys of spine / neck. cobalt amid chromium and titanium. Wear resistant polyethylene is used for socket replacement. Bone cement with or without antibiotics may be used to anchor the prosthesis into the bone. Joint replacements implanted without cement are designed to fit and lock into the bone directly. IMPORTANT CONSIDERATIONS: • Most patients undergoing THR suffer from osteoarthritis or rheumatoid arthritis, ankylosing spondylitis. a. Osteoarthritis: Degenerative disease affecting the articular surface of one or more joints, mainly wear and tear seen in obese.

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Systemic manifestations or rheumatoid arthritis c) Geriatric problems: Organ system Abnormalities • Most of the replacement surgeries are undergone by elderly Cardiovascular Pericardial thickening and effusion, individual. Hall mark of ageing is decrease in functional reserve and myocarditis, coronary arteritis, conduction inability of organ system to respond to external stress. defects, vasculitis, cardiac valve fibrosis CVS: (aortic regurgitation)conduction • Decreased arterial elasticity due to fibrosis of media → increase in defects,regurgitation) systolic blood pressure - LVH. Pulmonary Pleural effusion, pulmonary nodules, interstitial pulmonary fibrosis • Decreased adrenergic activity → lesser ability to respond to Hematopoietic Anemia, eosinophilia, platelet dysfunction hypovolemia, hypotension (from aspirin therapy) thrombocytopenia. • High incidence of diastolic dysfunction if associated HTN, CAD, Endocrine Adrenal insufficiency (form steroid therapy), cardiomyopathes. impaired immune system • Diminished cardiac reserve → Dermatologic Thin and atrophic skin from the disease and immunosuppressive drugs • Manifested as drop in blood pressure during induction of general anesthesia. Anaesthetic implications: • Prolonged circulation time → • A thorough pre-operative airway assessment needed in the RA • Delayed onset of action of IV anaesthetic agents. Faster induction patient, evaluation of with inhalational anaesthetic agents. • Mallampatti classification • Increased risk of developing CHF. Thyromental distance • RS Mouth opening Decrease pulmonary elasticity → increase in residual volume and Neck movement closing capacity. • Function-al evaluation of heart and lung is necessary. V/Q mismatch • Hematocrit should be performed to assess the degree of anemia. Decrease arterial O2 tension • Basic electrolytes including sodium, potassium, BUN, and • Increase anatomic and physiologic dead space creatinine will reveal the extent of renal dysfunction because on • Increased chest wall rigidity. NSAID's. • Decreased muscle strength → decreased cough, decreased • Preoperative evaluation of joint movements helps to determine, maximum breathing capacity and inability to spit out the secretions. how the extremities should be positioned. • Blunted response to hypercapnoea and hypoxia. • Regional anaesthesia is the preferred choice of anaesthesia, as • Chance of aspiration pneumonia is three due to deceased laryngeal lumbar spine is often not involved in rheumatoid arthritis. reflexes. • GA is preferred then, Prevent flexion of neck Maintain stability of cervical spine Tracheal intubation using fibro optic bronchoscope under topical anaesthesia is preferred. • Cautions use of narcotics. 132

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Renal system Pharmacological changes: • Decreased renal blood flow and GFR - Increased risk of ARF in • Decrease in muscle and increase in body fat post operative period. • Decrease TBW • Decreased tubular function. • Higher plasma concentration of water soluble drugs and lower • Impaired Na+ excretion plasma concentration of fat soluble drugs. • Decreased concentrating and diluting capacity. • Altered protein binding • Predisposition for dehydrations, fluid overload. • Decreased albumin → increase free drug levels of acidic d rugs. • Decreased ability to reabsorb glucose. • Increased acid glycoprotein → decreased line levels of basic drugs Metabolic and endocrine function • Inhalational anaesthetics → Decreased MAC Heat production decreased, heat loss is increased, hypothalamic • → Rapid onset of action temperature regulating centres reset to a lower level. → Myocardial depressant effect, exaggerated • Increased insulin resistance. Hepatic system → Recovery from anaesthesia prolonged • Decrease in hepatic mass, blood flow and function. • Muscle relaxants →decreased cardiac output and slow muscle blood • This results in decrease rate of biotransformation, decreased flow. albumin production, decrease plasma cholinesterase level. • Two fold prolongation of onset of neuromuscular blockade. GIT • Decreased hepatic excretion → prolongs duration of action of • Gastric emptying time prolonged. rocuronium and vecuronium. CNS • Decreased renal clearance → prolonged action of pancuronium. • Does requirements for local anesthetics and inhalational agents Ankylosing spondylitis: decreased epidural and spinal – more cephalad spread. • Involves ossification of ligaments joint cartilage and disc space of • Post operatively acute confusional stage, delirium and cognitive axial skeleton with eventual ankylosis. dysfunction may be seen. • Involves hips, shoulders and costovertebral joints. Skin • Importance – Costovertebral joint involvement • Prone to trauma from adhesive tapes, electrocautery and ECG • Regidity of ribcage electrodes. • Impaired lung function • Peripheral nerves are more superficial so proper padding after • Vital capacity is minimally reduced if diaphragmatic activity is positioning is mandatory. preserved. • Veins Frail and easily ruptured by iv infusion Arthritic joints • Interfere with positioning e.g. lithotomy

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Anaesthetic implications: Physical examinations: • Careful positioning in operating room as there is ever present 1. Pallor, dehydration and anemia - investigations and interventions risk of spine fracture and cervical spine instability. required and to be corrected before surgery. • Fiber optic techniques of tracheal intubation. 2. Blood pressure - optimized preoperatively and associated cardiac • Position the patient while awake. risk factors need to be investigated appropriately. • Vertebral column is usually fuse → lumber epidural or spinal 3. Weight /BMI and shape of the back may determine the type of difficult. anaesthetic used. Pre-operative evaluation 4. Physical examination should be done for heart, lung, abdomen, To assess vascular status of lower extremities, status of upper extremities and • Possible catastrophic and fatal complications during and after its ability to use crutches. Spines, hip joint range of movements surgery. and any other bony or muscular deformity. • Co-existing pathological conditions and patients tolerance for a 5. Cervical spine should be assessed for pain during movement and major surgery. restricted movement. History: 6. Patients with rheumatoid arthritis and osteoarthritis should be • Current problem and activity of the patient examined thoroughly for cervical spine abnormalities. • Personality, activity and age often dictates the type of 7. Check preoperative nerve dysfunction anaesthetics. Laboratory investigations; • Underlying medical fitness and review of organ systems, • Full blood count and Hb level especially in the elderly. Enquire about respiratory and CVS • Creatimine and blood urea and electrolytes problems. • RBS, ECG • Drug history: Warfarin, aspirin, NSAID's has implications for the • Clotting studies if on anticoagulants anaesthetists in regard to neuraxial blocks. A high proportion of • ABG, urine analysis elderly patients are on cardiovascular treatment particularly β- • Lung function test, echocardiography and x-ray should be done in blockers and ACE inhibitors. patients with reduced cardiopulmonary reserve. • Allergies: Enquire specifically about antibiotic allergies and • The CVS status of patients unable to exercise, yet at risk of CAD, cheek the type of cement being used. Aseptic loosening of (e.g. history of angina, diabetes mellitus, CHF, MI) can be evaluated cemented THR has been linked to allergies to some of the With components of the cement. • Dipyridamole thallium scanning • Surgical history, previous anaesthetics: Anaesthetics records • Dipyridamole echocardiography may detail difficulties in spinal/epidural insertion, airway • Dobutamine echocardiography assessment with intubation and other problems encountered. • History of past illness: cardiac, pulmonary, genitourinary diseases, goat, glaucoma, diabetes, gastric ulcer, embolism, dependent' edema, malignancy, epilepsy, stroke, HTN, bleeding tendency, emotional problems and hepatitis. 134

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Anaesthetic technique: EPIDURAL ANAESTHESIA • Choice of anaesthesia depends on some factors like • EA alone or combined spinal epidural is done - Duration of procedure • Lumbar epidural is done - Surgeons preference • Site of epidural needle entry is between L2 to L4-5 spines. - Practice pattern in the hospital • Sensory block till T10 is required. - patient preference • Test dose 3cc of xylocaine with adrenaline to rule out inadvertent - Previous anaesthetic experiences spinal or intravenous injection. Surgery can be done under • Followed by Inj. Bupivacaine 0.5 (I) 5cc given through epidural 1)Central neuraxial blockadeSA catheter followed with an incremental dose. Epidural, Spinal or Combined Spinal-Epidural • Combined spinal epidural is done where in spinal anaesthesia has 2)General anaesthesia more rapid and predictable onset, more intense block. Epidural SPINAL ANESTHESIA: analgesia postoperatively helps in early ambulation and pain relief. • SA is preferred choice for THR. • Epidurally 0.125% bupivacaine with tramadol used for postoperative • Secure a 18G I.V. cannula and preload with I.V fluids priorly analgesia. • Premedication GENERAL ANAESTHESIA • Benzodiazepines to alloy anxiety - inj. midazolam 1-2mg i.v. • GA is preferred in patient with ischemic heart disease, fixed output • Antiemetic – inj. Ondensetron 0.1 mg/kg i.v. states, diabetes mellitus. • Analgesic inj. Fentany1 2µg/kg iv (if not given through SAS) • Pharmacodynamics and pharmacokinetics changes associated with • Spinal anaesthesia under asceptic precaution 3-3.5 ml 0.5% (H) aging must be taken into account. bupivacaine is used. • Difficulties in airway management to be anticipated and managed • 10-25 µg inj. Fentanyl added to spinal drug fastens the onset of • 18 G I.V. cannula secured action, lengthens the duration of action of spinal anesthesia. • Premedication • T10 sensory level block is desirable • Benzodiazepines inj. Midazolam 0.05 mg / kg iv to • Target controlled infusion (TCI) propofol with a target infusion of • Allay anxiety 1.5 – 3 µg / ml for the lateral position, using face mask • Reduce induction drug requirement supplemented oxygen. • Anticholinergics for Antisialagogues effect – inj. Glycopyrrolate 0.01 • Patients who are uncomforatable due to pain from arthritic mg / g i.v. shoulders and other joints, intermittent doses of midazolam, • Inj. Ranitidine 1mg / kg i.v cautious narcotics are used. • Inj. Ondensetron 0.1 mg / kg i.v. • Fluid management should be appropriate by assessing the blood • Analgesic inj. Fentanyl 2 µg /kg i.v. loss by observing the volume of blood collected in suction bottle • Induction agent – inj. Thiopentone 3 – 5 mg / kg i.v. or inj. Propofol 2 and weighing the soaked mops. mg / kg i.v. • Intubate with inj. Succinylcholine 1.5 to 2 mg / kg i.v. • Intubated with maintaining cervical spine stability with snuggly fitting cuffed ETT orally. 135

Dr Azam’s Notes in Anesthesiology 2013 Total Hip Replacement.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Maintenance – O2 (33%) + N2O (665) + halothane (0.5%) + Advantages of regional Advantages of general anaesthesia intermittent inj. Vecuronium 0.05 mg / kg i.v. techniques • Reversal – Inj. Neostigmine 0.05 mg / kg i.v. + Reduced blood loss, reducing the Easier for patients that cannot Inj. Glycopyrolate 0.01 mg / kg i.v. need for transfusion tolerate lying flat • Patient extubated once the surgery is over. Vitals are monitored Avoids effects of general Safer in patients with fixed output and maintained. anaesthesia on pulmonary states where maintenance of normal Postoperative management function sinus rhythm, heart rate and • Postoperative antiemetics and analgesic protocol followed. intravascular volume is critical. • Postoperative oxygenation is advisable by oxygen msk 3 – 4 lits / (Remember these patients need min for 4 - 6 hrs. cardiology review preoperatively. • Fluid prescription to be given. Echocardiography can determine • Pulse rate, blood pressure, oxygen saturation and urine output the size of the stenosed orifice, the monitored. transvalvular gradient and peak Other regional anaesthesia blood flow velocities distal to the • A femoral 3 in 1 block or a obstruction). • Psoas lumbar plexus plus lateral cutaneous nerve of thigh block May avoid intubation Patient preference used for analgesia. Good early post operative May be safer for patients with • When GA is considered, the pharmacodynamics and analgesia ischaemic heart disease as stable pharmacokinetic changes of drugs associated with ageing must cardiovascular conditions may be be taken into account. easier to maintain • Difficulties in airway management should be anticipated and Reduced incidence of post managed. operative venous thrombosis and • If central neuraxial blockade is contraindicated pulmonary embolism • A femoral 3 in 1 block or a (sympathectomy mediated • Psoas lumbar plexus plus lateral cutaneous nerve of thigh increase in lower extremity blood block can be used to supplement GA. flow, and amelioration of the hypercoagulable state associated with surgery). Lower cost Simple technique in rural set-up

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Intra operative problems with THR Controlled hypotension Blood loss Can decrease intraoperative bleeding • • Hypothermia Improves prosthetic cementing by providing a dry bone surface • • Bone cement implantation syndrome Shortens the duration of surgery • • Fat embolism Improves surgical results • • Venous thrombosis and thromboembolism Ensure adequate iv loading prior to cementing of femoral • • Air and gas embolism component • Positioning Blood loss Commonly THR is done in lateral decubitus position • Blood loss in patients managed with no special precautions is It can cause • • expected to about 1000 – 1500 ml. Potential V/Q mismatch and hypoxemia • Hypotensive or regional anaesthesia reduces blood loss by 30 – Compression of axillary artery, branchial plexus and vessels in • • 50%. the femoral triangle. Lowering intraoperative mean arterial pressure to 50mm of Hg Compression of lateral femoral cutaneous nerve of thigh, femoral • • reduces blood loss more effectively than a MAP of 60mmHg. nerve and common peroneal nerve. Benefits of reduced blood loss. Hence adequate padding should be provided. • • When blood kept to a minimum, patients benefits because their THA is also done in supine position by anterior approach. • • exposure to blood obtained by others is reduced. Advantage – site of incision is more aseptic but changes of Increase rate of infection raises the fear of bacterial infections of venous thrombosis is more on the same side. • implanted prosthesis. Monitoring Reduced bleeding in the operative field not only facilitates surgery, • Extensive invasive hemodynamic monitoring is required for • elderly and medically compromised patients when complex and but might also improves surgical results. revision surgery is required • Blood loss less than 300ml exhibited improved penetration of the - Urine output cement into the bone. - NIBP • Modalities to reduce blood loss - Pulse oximeter • Maintain normotension and normal pulse rate intraoperatively. - ECG • The donor patientʼs Hb should be no less than 11g / dl or the - Temperature hematocrit 33% before each donation. The last donation should - Invasive intra arterial line for BP monitoring (In case occur not less than 72 hours before surgery. hypotensive technique is used) • Controlled hypotension – differences in the resulting vasodilatation of - CVP for fluid management the venous and arterial vasculature systems leading to redistribution - Trans esophageal echocardiography of blood flow. By providing a dry bone, improve prosthetic cementing - Capnography and shorter duration of surgery. - Pulmonary capillary wedge pressure

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Dr Azam’s Notes in Anesthesiology 2013 !"#$%&'()#*+,-)#./#$/-),0-)1+2+34######!"#"$ 56-7+/8#981,1+/# Total Hip Replacement.Continuation: # Dr Azam’s Notes in Anesthesiology 2013 #

• Regional anaesthesia (due to vasodilatation of the venous and #!"#"$%#"&'%#()#"$%## *%'%+"#$,-.%+&+/#,+.#%01,+2&(+## arterial systems leading to redistribution of blood flow). • Maintaining normal body temperature mild hypothermia (35o C) 3%,'&+/#()#4%'5-## ,/,&+2"#1-(2"$%"&6#6('1(+%+"## has been associated with an average increase of 500ml of blood loss during THR. # • Revision hip replacement patients require perioperative blood transfusion, perioperative autologous blood donation and 7&2-51"&(+#()#8(+%#',--(9## :+"-,#'%.5;;,-<#=>?#@ABCC#''#=/D## intraoperative cell salvage should be considered. Reinfusion of autologous red cells lost during surgery. # • High dose aprotinin – a protease inhibitor of fibrinolytic activity and intrinsic coagulation pathway by decreasing activation of E'8(;&F,"&(+#()#),"#G#8(+%#',--(9#G#6%'%+"## plasminogen. ,&-#&+"(#"$%#)%'(-,;#H%+(52#6$,++%;2# • Recombinant human erythropoietin 600 IU/kg SC weekly beginning 21 days before surgery ending on the day of surgery. # Hypothermia I,-/%#%'8(;&#',<#8%#(2%-H%.#&+## J',;;#%'8(;&## • It can be difficult to prevent perioperative hypothermia. Fluid warmers, hot air blowers, humidifcation systems are important -&/$"#2&.%#()#"$%#$%,-"## because intraoperative hypothermia can contribute significantly to coagulopathy and perioperative blood loss. # Bone cement implantation syndrome 3=4#$<1("%+2&(+#(-#6,-.&,6#,--%2"## K,<#-%,6$#;5+/2#,+.#6,52%## • This is a space filler used to improve the fit of implanted orthopaedic prosthesis to the bone. # # &+6-%,2%#&+#15;'(+,-<#,-"%-<## • It fixes the components securely in bone and helps in distributing # # 1-%225-%## the load evenly from the surface of the prosthesis to the bone • In patients with patent foramen ovale, emboli may pass into systemic surface, there by reducing stress in the supporting bone. 5circulation# ./#?&,1-/,)#=1,0#?&,-/,#@+"&'-/#+A&2-B#-'C+21#'&4#?&))#1/,+#)4 causing myocardial infarction or stroke. ),-'17#71"7D2&,1+/# 7&D)1/3#'4+7&"81&2#1/@&"7,1+/#+"#),"+E->## • Bone cement is polymethylmethacrylate (PMMA). Clinical features !"#$#%&"'()&*+,)-# • Intra operative hypotension: Profound hypotension immediately Hypoxia (increased pulmonary shunt) • 5# F4?+G1&#H1/7"-&)-8#?D2'+/&"4#)0D/,I## after insertion of cemented femoral prosthesis may be due to • Hypotension (decreased SVR) • Direct vasodilation / cardiac depression from methyl 5# F4?+,-/)1+/#H8-7"-&)-8#6JKI## • 5Dysarrythmias# !4)&""4,0'1&)#H1/72D81/3#0-&",#C2+7E#&/8#)1/D)#&""-),I# (including heart block and sinus arrest)# methacrylate monomer. • 5Pulmonary# LD2'+/&"4#FM*#H1/7"-&)-8#?D2'+/&"4#A&)7D2&"#"-) HTN (increased pulmonary vascular1),&/7-I# resistance)# Forced entry of air, fat or bone marrow into the venous system with .&$&/)0)$*'# resultant pulmonary emboli. 5# ./7"-&)-8#1/)?1"-8#+G43-/#7+/7-/,"&,1+/#?"1+"#,+#7-'-/,1/3## • It is noted usually – after extensive reaming of femur 5# N&1/,&1/1/3#-DA+2-'1&#C4#'+/1,+"1/3#7-/,"&2#A-/+D)#?"-))D"-## • After insertion of cemented femoral component 5# ./#&7D,-#04?+,-/)1+/## • With relocation of hip :;<# 138 # ===>!"$%&'>7+'# Dr Azam’s Notes in Anesthesiology 2013 # Total Hip Replacement.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Management • Minor • Increased inspired oxygen concentration prior to cementing Tachycardia (> 110 beats / min) Maintaining euvolemia by monitoring central venous pressure • Hyperthermia • In acute hypotension • Retrieval of fat emboli • Iv epinephrine (4 – 50 µg) stat. • Urinary fat globules • In high risk group, epinephrine (10 – 20 µg) is injected • Decreased platelets / hematocrit (unexplained) through the distal port of the pulmonary artery catheter, the • Increased erythrocyte sedimentation rate moment a decrease in arterial pressure is noted. • Fat globules in sputum • Post operative hypoxia is managed by nasal oxygen, monitoring with pulse oximeter, judicious use of narcotics to Diagnosis of FES requires at lest one sign from major and four signs provide analgesia and yet avoid hypoventilation / airway from minor criteria categories. obstruction. • Methods to minimize bone cement implantation syndrome The Signs during GA include use of plug in the femoral shaft to limit the distal spread of • Decline in ETCO2 cement in the femur. • Decline in arterial O2 saturation • Venting of entrapped air • Rise in pulmonary artery pressures • Waiting for cement to become more viscous before its • ECG ischemic changes appearing in ST segment and right sided insertion heart strain • performing high pressure lavage of the femoral shaft to Treatment remove debris (potential microemboli) • Reversal of possible aggravating factors such as hypovolemia • Respiratory support Fat Embolism • Corticosteroid therapy may be beneﬁcial • Fat embolus syndrome (FES) is caused due to entering of fat goblets to systemic circulation during reaming of medullary can Deep vein thrombosis (DVT): and when the prosthesis is implanted. • DVT is common after THR (30 – 50%) Major • Proximal DVT (popliteal, femoral or iliac vessels) is more common. • Axillary / subconjuctival petechia • During THR,obstruction of the femoral vein is relieved after hip • Hypoxemia (PaO2 < 60mmHg; FiO2 < 0.4) relocation an increase in markers of thrombosis is noted and • CNS Depression echogenic material can be seen on echocardiography. • Pulmonary edema

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• Efforts to reduce DVT during surgery should be directed during Effects are these phases of venous occlusion. Maneuvers include • Increase in pulmonary vascular resistance • Reducing duration of surgery • Impaired gas exchange due to increase in alveolar dead space due • Augmenting lower extremity blood flow during surgery to to vascular obstruction and hypoxemia from alveolar hypoventilation. reduce venous stasis. • Increased airway resistance due bronchoconstriction. • Administering anticoagulants during this phase of surgery 15 • Decreased pulmonary compliance due to lung edema, lung – 20 U/kg of unfractionated heparin administered before haemorrhage and loss of surfactant. surgery reduce • Right ventricular failure due to sustained increase in right ventricular the DVT rates to 6%. after load. • DVT rates during THR performed under epidural / spinal reduces Symptoms and Signs the incidence by 40% and epidural anaesthesia with concurrent • Tachypnoea use of low dose epinephrine infusions to 10% (mechanism of • Dyspnoea epinephrine is unknown, but it does augment the blood flow, • Chest pain thereby minimizing venous stasis) • Hemoptysis • Post operative modalities to reduce DVT that can be safely used • Tachycardia in conjunction with epidural anaesthesia are • Hypotension • Pneumatic compression foots • Wheezing • Foot pumps and foot exercises • Hypoxemia • Early ambulation • Respiratoy alkalosis • Aspirin and low dose warfarin started the day after surgery • Wide fixed S2 split In high risk cases venecava filters may be placed • In ECG preoperatively. • Tachycardia • Pulmonary embolism • Right Axis deviation • Emboli most frequently occur during insertion of the femoral • Tall peaked T waves prosthesis. Venous stasis or hypercoagulability is often Investigation contributory in such cases. When venous thrombi (DVT) • Chest X-ray becomes dislodged from the site of formation, they embolise to • Pulmonary angiography the pulmonary arterial circulation or paradoxically to the systemic • Ventilation perfusion scan circulation through a patent foramen ovale which is rare in THR • Helical CT scan or TKR. • Intraoperative pulmonary embolism • sudden hypotension • Hypoxemia • Bronchospasm • Decrease in ETCO2 • Increase in CVP and PAP 140

Dr Azam’s Notes in Anesthesiology 2013 Total Hip Replacement.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Bilateral hip arthroplasty can be safely performed in one session, INFECTIONS assuming absence of significant PE after insertion of first • Infection in implant placement can be catastrophic. prosthesis. Pulmonary artery monitoring reliably signals • Prophylactic antibiotics should be given before skin incision. embolization by increase in pulmonary vascular resistance • Recently antibiotic loaded bone cement (ALBC) are available usually indicated by an increase in pulmonary artery pressure commonly used antibiotics in cement include (PA) in the face of unchanged pulmonary artery occlusion Tobramycin Cefazolin pressure (PAOP) and fall in cardiac output. GentamycinCefotaxime • PVR = PA – PAOP / Cardiacoutput x 80 VancomycinCefamandole • If PAP rise > 200 dynes / sec / cm-5 during 1st hip arthroplasty, TicarcillinErythromycin the contralateral surgery should be postponed. NafcillinClindamycin Treatment: Cafelothin Best treatment is prevention • The indiscriminate use of ALBC include the occurrence of an allergic • Mini dose heparin (5000 IUq 12 hours preoperatively or or toxic reaction to the antimicrobial agent and emergence of immediate post operatively) antibiotic resistant bacteria. • Oral anticoagulants (Warfarin) Other complications • Aspirin and dextran therapy (less commonly used) • Aseptic loosening of the joint • Early ambulation post operatively • Osteolysis around the prosthesis • High elastic stockings and pneumatic compression • Allergic dermatitis (due to nickel, chromium and cobalt) • The most popular method of thromboprophylaxis after THR is • Ion release and metal toxicity – systemic toxicity to metal ions used oral anticoagulation with warfarin with the 1st dose administered in implants and some metals are potential carcinogenic. in the evening before surgery and a target INR of 2.0 – 3.0. Low • Neurovascular injury – injury to external iliac A., Femoral artery or molecular weight heparin (enoxaparin 30 mg SC) has been vein, femoral nerve can occur. demonstrated to be equally effacious. A minimum of 7 – 10 days • Contralateral hip injury due to improper positioning. prophylaxis is required. • Cardiac arrest Air embolism: Revisions of THR • Heat generated by the cement as it hardens the pressure of air • The general principles are same as for THR. Patients are more trapped in the femoral shaft by 20% force it through the elderly and usually have more medical problems. damaged sinusoids into extraosseous veins pulmonary air • Operation takes longer, at least 2- 3 hours, often more. embolism. • Epidural combined with GA is the best option. • Air trapping beneath the cement and extent of air embolism are • Blood loss can be significant upto 2 liters perioperatively. reduced by using plug in femoral shaft or by using long nozzle to • Post operative pain can be a significant problem introduce the cement into the bottom of femoral canal.

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Dr Azam’s Notes in Anesthesiology 2013 Total Hip Replacement.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Summary of hip replacement anaesthesia Procedure THR Revision of THR Prosthetic Revision of previous replacement of THR – may include femoral head and one or both acetabulum components Time 2 hours 2- 6 hours Post operative pain +++ +++ / ++++ Position Lateral or supine Lateral or supine Blood loss 300 – 500 ml, G & S 1 litre, occasionally considerably more, crossmatch 2 units Practical techniques Spinal or GA. GA + Epidural or combined ETT with never block spinal epidural with or epidural or opioids sedation or GA / LMA, or IPPV + ETT + epidural or opioid arterial line +/- CVP may be indicated for complex revision or high risk patient.

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Dr Azam’s Notes in Anesthesiology 2013 39. Total Knee Replacement. Dr Azam’s Notes in Anesthesiology 2013

• Aim to relive pain, provide motion with stability and to correct Tourniquet related problems: deformity. • Perioperative bleeding is minimal when a tourniquet is used, • Indication – painful joints with / without deformity. although expect to lose upto 500ml (and frequently more) from the • Eg: rheumatoid arthritis osteoarthritis and traumatic arthritis. drains in the first hour post operatively. Contraindications: • Break through of tourniquet pain may be seen after about 1 hour Relative causing CVS stimulation and hypertension. This is treated by • Poor general health deepening anaesthesia / adding iv narcotics. • Untreated metabolic disorders • When cemented TKR is performed bone cement implantation Absolute syndrome is delayed unto the deflation of tourniquet at the end of • Sever osteoporosis operation. • Recent / current sepsis of joint This is prevented by an infusion of fluid before and as the tourniquet is • Neuropathic joint etc released along with vasopressors and oxygen as required. • Knee arthritis is frequently bilateral and patients appreciate to Thromboembolic prophylaxis: have both replacements preformed at the same time so that they • Thromboembolic complications occurs after TKR despite aggressive have only one period of rehabilation and can get over with it. On measures. Intermittent pneumatic compression devices may be the other hand postoperative complications are higher and need effective, but must be applied during surgery and worn continuously much more peri operative intervention. after surgery except during ambulation. Patient intolerance limit their Anaesthetic management use, however. • Preoperative examination and evaluation are similar to THR. • Therefore, the two most common anticoagulant based methods of Anaesthetic technique thromboprophylaxis after TKP are LMWH and warfarin • Usually done in supine position Dose • Combined spinal / epidural or spinal / femoral and sciatic nerve LMWH: blocks avoids the need for GA. • Enoxaparin 3000U starting – 12 hours post operatively or 4000 U od • GA supplemented by an epidural with postoperative epidural starting 10 – 12 hours preoperatively. infusion is a common technique. Warfarin: Femoral and sciatic nerve blocks have the following advantages • Fixed low dose 2 mg / day or as a monitored dose (target INR – 2.0 – • Good post operative pain relief in the first 24 hours. 3.0) • Avoids need for a urinary catheter • Allows more mobility, in bed for the patient Avoids difficulties and complications of an epidural (but the pain relief may be inadequate perioperatively for use with sedation and hence is usually combined with spinal / sedation)

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Postoperative analgesia: Type to enter text 1. Successful outpatient recovery depends on early ambulation, adequate pain relief and minimal nausea and vomiting. 2. Effective postoperative analgesia is essential for early rehabilitation to maximize post operative range of motion and prevent joint adhesions following joint replacement. 3. Post operative pain is usually the most signiﬁcant problem and this is the main determinant of the anaesthetic technique. 4. Epidural analgesia for 24 – 72 hours effectively controls the pain. 5. Femoral / sciatic blocks or can be used to provide analgesia for 8 -24 hours. 6. Femoral nerve catheter technique can be used for 48 hours. 7. Systemic OPIOIDS and NSAIDs should also be considered.

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Dr Azam’s Notes in Anesthesiology 2013 40. Speciﬁc problems of Orthopedics. Dr Azam’s Notes in Anesthesiology 2013

Rheumatoid Arthritis: Ankylosing Spondylitis: • Rheumatoid arthritis is a disease of unknown origin • This disease, more common in men involves ossification of ligaments characterized by immuno mediated synovitis. These patients at their attachment to bone. Progressive ossification involves the have deformity, instability, and destruction of many joints through joint cartilage and disc space of the axial skeleton with eventual out the body which pose a significant challenge to the ankylosis. These patients are likely to have impaired lung function anaesthesiologist. All the joints are effected in Rheumatoid due to rigidity of Rib cage. Aortic Regurgitation and BBB may Arthritis. develop. There is an ever present risk of spine fracture cervical • The immediate concern of the anaesthesiologist is technical. spine instability in these patients so careful positioning in Operation Arterial cannulation may be difficult because of small calcific theatre is important. radial arteries which may be unaccessable due to flexion Anaesthetic consideration include: deformities of the wrist. Carpel runnel compression may 1. Use of Fibre optic technique for tracheal intubation. preclude extension of wrist. CVP line insertion may be difficult 2. Positioning while awake because of fusion and flexion of the neck. However the lumbar 3. Choice of Axillary Block rather than interscalene when using spine is not often affected in Rheumatoid arthritis hence spinal Regional Analgesia in upper extremity. and epidural are usually straight forward. Other technical problems of concern are airway management and cervical spine POSITIONING FOR ORTHOPEDIC SURGERY instability. Patients are placed in a variety of positions for orthopedic procedures. • Atlanto axial instability develops in many patients with adult Improper positioning may result in intra and post operative problems Rheumatoid Arthritis and the symptoms include neck pain, head such as ache or neurologic symptom in arm or leg with neck movements. 1. Air Embolism: This occurs when the operative field is above the Atlanta – Axial subluxation develops from erosion of ligaments by level of the heart. This may be a problem in surgery of cervical Rheumatoid involvement of the bursae around the Odontoid spine, or shoulder in sitting position, in total hip replacement in process of C2. Subluxation occurs with flexion of the neck. lateral decubitus position or in lumbar spine surgery in prone Anaesthetic Management must prevent flexion of the neck and position. Air replacement in lateral decubitus position or in lumbar maintain stability of the cervical spine. This may be spine surgery in prone position. Air Embolism is suspected if accomplished by tracheal intubation under topical anaesthesia untoward circulatory compromise occurs in any of these settings. and positioning of patients when awake. 2. Stretch of Malposition of joints may occur in Anaesthesia and might • Rheumatoid Arthritis patients are apt to develop post operative account for a variety of non specific post operative discomforts in airway obstruction from narcotics or sedatives. Post operative the back or extremities. nasal O2 should be administered. Post operative monitoring of 3. Direct Pressure over bony prominence may cause tissue Ischaemia peripheral O2 saturation with pulse oximetry is mandatory. CPR Direct Pressure on soft tissue of orbit in prone position may lead to is difficult in Rheumatoid Arthritis patients and tracheostomy is retinal artery occlusion and direct pressure over peripheral nerves almost impossible in severe cases. may result in post operative Neurapraxia.

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4. Compression of Veins / Arteries: Of upper or lower extremities Sites of Peripheral Nerve Injury in Orthopaedics may occur in lateral decubitus position. Nerve injury site Cause Comment 5. Malposition of Extremities may lead to various stretch or compression induced neurapraxias. Upper extremity Abduction, external Usually resolves, but may ANAESTHETIC PROBLEMS OF THE PRONE POSITION Bronchial plexus rotation or extension require several months Airway of shoulder. Traction Endotracheal tube kinking or dislodgement. Edema of upper of shoulder airway in prolonged cases may cause post operative respiratory Ulnar nerve Pressure at the Not uncommon post obstruction. elbow. Traction of operative palsy results in Blood Vessels C8-T1 dermatomes numbness of ring and fifth • Arterial or venous occlusion of the upper extremity (check with over the 1st rib fingers pulse oximeter on the finger) Radial nerve Pressure behind the Resulsin wrist drop • Kinking of the femoral vein with marked flexion of the hips, this arm may predispose to post operative deep vein thrombosis. Head Supra orbital Pressure on the Results in numbness of • During lumbar laminectomy, abdominal pressure increases may nerve supra orbital ridge forehead cause elevation of epidural venous pressure contributing to intra when lying prone operative bleeding. Lower extremity Pressure over Results in numbness of Nerves Lateral femoral anterior iliac crest in the lateral aspect of the • Branchial plexus stretch or compression cutaneous lateral or prone thigh and knee Ulnar nerve due to pressure on the olecranon Nerve of the high position or over Peroneal nerve compression due to lateral pressure over the lateral thigh head of the fibula. Femoral nerve Pressure to the groin Results in numbness of Lateral femoral cutaneous nerve trauma due to pressure over of the dependent limb the anterior thigh and the iliac crest in the lateral medial aspec toflower leg • Head and neck decubitus position • Gross hyperflexion or hyperextension of the neck Common peroneal Pressure below the May be due to External pressure over the eyes may result in retinal injury due to nerve head of the fibula compartment syndrome compression. Results in foot drop • Lack of lubrication of coverage of eyes may result in corneal Check list abrasion. Head rest may cause pressure injury of supraorbital Check preoperative nerve dysfunction nerve. Excessive rotation of the neck may contribute to brachial Check tourniquest problems duration and pressure plexus problems. Check postoperative position, splints, tight bandages, rule out compartment syndrome Check intraoperative surgical factors Risk of neumpraxias is more common in prolonged surgery

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COMPLICATIONS OF ORTHOPAEDIC SURGERY • Release of acid metabolites into central circulation (e.g. 1. Tourniquet Damage thromboxane) 2. Fat Embolisin Transient fall in pulmonary and systemic arterial pressures 3. Deep Vein Thrombosis Transient increase in end-tidal CO2. 4. Hypotensive Response to Methylmethacrylate Fat Embolism • A certain degree of lung dysfunction occurs in all patients following Tourniquet Damage: long bone fractures, due to release of bone marrow or fat into • Tourniquets are applied around upper and lower extremities to circulation but clinically significant fact embolism syndrome develops eliminate intra operative bleeding in order to provide better in 10 to 15%. The signs include hypoxia, tachycardia, mental status operative conditions. However application of tourniquet is changes nad potechiae on the conjunctiva, axilla or upper thorax, associated with number of disadvantages. lung infiltrates on X-ray confirms the presence of lung injury. Physiologic changes cause by Limb Tourniquets Treatment includes early recognition, O2 administration, and Neurologic effects judicious fluid managements. • Abolition of somatosensory evoked potential and never condition Deep vein Thrombosis: within 30 min. Application for more than 60 min causes • DVT is another complication of orthopaedic surgery and may develop tourniquet pain and hypertension. Application for more than 2 h following fracture of the Femoral Head, or following total hip or total may result in postoperative neurapraxia. Evidence of nerve knee arthroplasty. Decreased Cardiac output, deliberate hypotensive injury may occur at a skin level underlying the edge of the anaesthesia, intra operative hypovolemia, excessive blood loss, tourniquet. hypothermia all play a role in DVT formation. Many patients receive Muscle changes anticoagulants peri operatively to prevent post operative DVT. This • Cellular hypoxia develops within 10 mins influences anaesthetic management favoring a choice of general • Cellular creatine declines over spinal or epidural anaesthesia, and discouraging placement of • Progressive cellular leak develops after 2 h CVP or pulmonary artery catheter. • Limb becomes progressively colder Hypotensive Response to Methyl Methacrylate Systemic effects of tourniquet inflation • Following insertion of freshly prepared acrylic bone cement into • Elevation in arterial and pulmonary artery pressure develops. newly reamed bony cavities such as femoral canal or acetbular cup a This is usually slight to moderate if only the limb is occluded. decrease in arterial pressure accompanied by increase in heart rate The response is more severe in patients under balanced is observed. This is due to absorption of the bone cement through anaesthesia that does not include a potent anaesthetic vapor. raw bony surface. This bone cement is a known peripheral Systemic effects of tourniquet release vasodilator and direct myocardial depressant. Severe reactions have • Transient fall in core temperature resulted in cardiac arrest. Adequate fluid replacement and if • Transient metabolic acidosis necessary a vasopressor with α and β activity like ephedrine, • Transient fall in central venous oxygen tension (but systemic Dopamine or epinephrine should be given if necessary. hypoxemia unusual)

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Conclusion: • Perioperative morbidity and mortality in the elderly patients will continue to be an important problem. Pre-operative clinical assessment to recognize patients at intermediate and high risk of post operative events by careful history taking, physical examination and functional capacity assessment is important to guide anaesthesia management. • Speciﬁc intraoperative and post operative anaesthesia management in terms of maintenance of hemodynamic stabilization and normothermia, effective post operative pain control and prevention of hypoxaemia will minimize post operative adverse events in the elderly. Incorporating each of these elements into decision making for perioperative management of elderly patients can only beneﬁt outcome in this rapidly growing and increasingly vulnerable surgical population.

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