Regional Anesthesia

Dr. Azam’s

Notes in Anesthesiology

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

Regional Anesthesia

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. Principles of regional Anesthesia - 5 29. Lumbar Sympathetic Block - 52 2. Describe the course of Sciatic Nerve and any one approach to 30. Inter costal Nerve block - 53 block the nerve - 9 & 65 31. Interpleural block - 56 3. Describe the anatomy of Stellate ganglion. Discuss indications 32. Perineal Anesthesia - 58 technique & implications of stellate ganglion block - 11 & 45 33. Cutaneous innervations of the lower limb - 59 4. Describe Anesthetics concerns for regional anesthesia in a 34. Cutaneous innervations of upper limb - 60 patient on anticoagulants - 13 35. Psoas Compartment block 61 5. Describe the clinical manifestation of LA toxicity & its 36. Femoral Nerve Block - 62 & 100 management - 15 37. Obturator Nerve Block - 63 6. Describe regional block for removal of infected corn foot - 17 38. Inguinal Paravascular technique - 64 7. Anatomy of Epidural Space & the methods of identiﬁcation - 19 39. Blocks around the Knee Joint - 68 8. Phantom limb pain - 21 40. Saphenous nerve block - 69 9. Cauda Equina Syndrome - 22 41. Common Peroneal Nerve - 70 10. Total Spinal Anesthesia - 23 42. Tibial Nerve - 71 11. Spinal Needles - 24 43. Complications of Spinal & Epidural Anesthesia - 72 12. Post Dural Puncture Headache - PDPH - 25 44. IVRA - 73 13. Differential Blockade - 29 45. Anatomy of vertebral column & physiology of spinal anesthesia - 76 14.Nerve Classiﬁcation And Sequence Of Block - 31 46. Epidural Anesthesia - 87 15. Supraclavicular Block - 32 & 47 47. Caudal Anesthesia - 92 16. Hernia Block - 33 48. Guidelines on regional anesthesia in patients treated with heparin 17. Field Block for tonsillectomy - 35 oral anti-coagulations, anti platelets and others - 94 18. Celiac Plexus Block - 36 49. FACIAL NERVE BLOCK - 95 19. Interscalene Block - 39 & 46 50. Brachial Plexus - Applied Anatomy - 96 20. Gasserian Ganglion Block - 40 51. Post Operative Analgesia - 101 21. Maxillary Block- 41 52. Patient Controlled Analgesia (PCA) - 102 22. Mandibular Block - 42 53. Assessment Of Pain - 106 23. Glossopharyngeal Nerve block - 43 54. Preemptive Analgesia - 109 24. Superior Laryngeal Nerve block - 44 55. Chronic Pain Management - 112 25. Axillary Nerve Block - 48 56. Mixture of Local Anesthetics - 119 26. Wrist Block - 49 57. Spinal Anesthesia In Children - 121 27. Autonomic Blockade - 50 58. Bromage score - 123 28. Sympathetic Blocks - 51 59. Blocks of Eye - 126

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

Dr Azam’s Notes in Anesthesiology 2013 1. Principles of regional Anesthesia. Dr Azam’s Notes in Anesthesiology 2013

Definition: Anatomic consideration: • Is defined as reversible blockade of nerve conduction by L.A. in • Landmarks: the part where it is applied. • Superficial • Deep Types of RA: Nerve Fibres: 4 types: Diameter Velocity Type Myelin Location Function • Topical anaesthesia: Surface application to skin or mucous. μm (m/sex) • Infiltration anesthesia: Injecting LA into the tissue to be cut Aα 15-22 + 70-120 to & from Motor, muscle • Field block: Injecting LA into the area to be operated. muscles and proprioceptors Ex: Inguinal field block. • Aβ 8-13 + 40-70 joints Touch. • Conduction block: (Referred to RA): Accomplished by depositing a solution along the course of nerve supplying a region of the Aγ 4-8 + 15-40 To muscle Touch, pressure, body where elimination of sensory and / or motor innervation is spindles tone of muscle required. Aδ 1-4 + 5-15 Afferent Pain, temp, • Ex: Spinal / Epidural analgesia. sensory nervespressure Pre-block evaluation: B 1-3 + 3-14 Preganglionic Preganglionic Last dose of Heparin & low molecular weight heparin. • sympathetic sympathetic • Patient on T.clopidogrel activity • Aspirin ingestion (consider RA with BT < 10 minutes) CS 0.3-1.3 - 0.7-1.3 Postganglionic Postganglionic • Coagulopathies Pre-medications: sympathetic sympathetic • Benzodiazepines, narcotics, antihistamines, anticholinergics, activity diversion and distraction. γ 0.4-1.2 - 0.1-2 Afferent Pain, temp, • These provide: comfort, protection from CNS toxicity, protection sensory nervestouch from allergy, from reflex bradycardia. • Facilities: proper room, ventilation, light, equipments for CPR etc.

Asepsis: • Hexachlorophene or tincture of zephiran used over face, scrotum, perineum. • Betadine, 70% ethyl or isopropyl alcohol used. Skin preparation: • Soap water scrub or 70% ethyl alcohol for 5 min. • Normally skin contains 200-600 bacteria / inch2 of surface area. • Above measure decrease it by 20-40 bacteria / inch2.

Dr Azam’s Notes in Anesthesiology 2013 Principles of regional Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Pharmacologic considerations: Summary of chemical factors: • LA blockade depends on 4 factors: • Degree of hydrolysis determines penetrability. 1. Diffusion to nerve and into bundle: Depends on solubility. • Effectiveness is a linear function of pH of tissues. 2. Penetration into nerve cell: Depends on non-ionized (base) • Alkaline pH of solutions increases activity. form. • Buffering to an alkaline pH has a greater effectiveness. 3. Distribution in a nerve fiber cell: Solubility. • Acid media neutralize anesthetic action. 4. Fixation: Affinity of cation form to channel receptors. Minimum anesthetic condition (Cm): Recovery from LA block depends on 4 factors: • Lowest concentration of drug that blocks conduction is called • Absorption: Into circulation. Cm. • Release process: Nerve fibers releases fixed drug as Differential block (Cm): gradient of concentration reverses with time. • Small fibres blocked by low concentration whereas myelinated • Redistribution: to other organs after absorption. ones need high concentration of L.A. This is due to differing Cm • Metabolism and elimination. values of L.A. for different nerve fibres. Transitional block (Wedensky block ): Dissociation constants (pKa): • A latent period required for a L.A. to change the function of a nerve from an unblocked state to the blocked state. During this • It is defined as a pH at which equal concentration of acid and basic forms of a substances exist. time, one conceives of either a partial or threshold block and repetitive stimuli may be conducted. During this time patients • The base or nonionized form is responsible for penetration of nerve and the ionized or cation form is responsible for the feels skin incision but with less intense. action of LA on nerve. Order of block: Amount of base form present is inversely proportional to pKa • • Sympathetic block: of that agent at pH 7.4. Ex: Lidocaine pKa is 7.74 has 65% • Vasomotor ionized and 35% in Non-ionized form at pH 7.4. • Cold • Tetracaine and procaine have high pKa, hence slow onset • Warmth bupivacaine: 8.1 pKa. • Slow pain • Benzocaine: with pKa 3.5 has rapid onset of action. • Fast pain • Outside nerve PH 7.4 à once the base form gets into the • Motor axon where PH is 7.2 à the base form converts into ionized • Joint sense form which is now required for its action on nerve. • Pressure Mechanism of action: • Block of ionic channels: It prevents Na to enter into cells following stimulation hence blocks action potential. • Receptor expansion. • Prior depolarization: also blocks K channels, but its affinity towards Na channels is great. 8

Dr Azam’s Notes in Anesthesiology 2013 Principles of regional Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Glucose in L.A impair its action due to hypo-osmotic effect. Pharmacokinetics: • Contact of L.A on nerve surface: Atleast 3-4 mm of nerve Absorption: surface has to come in contact with L.A or atleast 3 node of Gets absorbed into blood stream after injection into tissue and depends on: Ranvier blocked. 8 to 10 mm surface contact is more Site of application: Mucous, SC , IM practical. • Blood supply to the site Pharmacodynamics: • Presence & absence epinephrine etc. • L.A activity is related to its chemical properties. •

• Diffusibility is related to water solubility. 1. Disposition: When interstitial level decreases, L.A from neural • Onset: Related to pKa of L.A and pH of tissues. tissue enters interstitial and ﬁnally into blood. • Duration: Related to protein binding and lipid solubility. 2. Protein binding: Determines duration of action and protection against high free drug in plasma thus decreasing toxicity. Protein Duration pH L.A Chemical pKa Onset Bupivacaine > Etidocaine > Mepivacaine > lidocaine > binding (min) prilocaine. 6.5 Lidocaine Amide 7.7 2-4 min 64% 100 3. Redistribution: Occurs to all other organs depending on blood 5.5 BupivacaineAmide 8.1 5-10 min 95% 175 supply. Metabolism: • If pKa – pH of medium is > 1, percentage of ionized will be • Esters: In plasma. almost complete à penetration of cell membrane is delayed. • Amides: In liver. • Ex: Bupivacaine, tetracaine. • Esters: By cleavage of ester linkage and enzymatic hydrolysis. • If pKa – pH < 1, increased unionizedà penetration of cell • Chlorprocaine> procaine > tetracaine. membrane fast à rapid onset. • Metabolite-- PABA (Paraamines benzoic acid) • Ex: Lidocaine, mepivacaine. • Amides: Oxidative dealkylation and later hydrolysis in liver. • Potency: depends on lipid solubility. Bupivacaine, Prilocaine > etidocaine > c tetracaine, etidocaine are examples, hence require only low • Elimination: conjugated and excreted in urine. concentration. Enhancement of action: • Alkalization: by increasing nonionized forms • Carbonated L.A.

Dr Azam’s Notes in Anesthesiology 2013 Principles of regional Anesthesia.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Technical consideration: Nerve damage can be decreased by using: • Instruments: Tray, sterilization (avoid chemicals) by • Small bore needles. autoclaving, boiling or pasteurization. • Short beveled (450) • Tests of instruments. • Parallel to fibres. • Holding the needle: held like a dart. Procedure: • Insertion of needle. • Amides are stable, without preservatives. • Identification of nerve: • Metabisulfates Na 0.1% (antioxidant) prevents breakdown of • Proper landmarks. epinephrine. • Paresthesia. • Methyl – paraben (antimicrobial) • Nerve stimulator • Do not inject L.A into tumor sites. • X-ray guidance. • Aspiration test. • Radiographic aid Nerve stimulator: 1913 by Perthes. • Stereoscopic films 1. Use minimal intensity stimulus, output current between 0 • 2 view studies. and 6 MA and a twitch stimulus rate from 1/10th sec to • Use of contrast media. 1sec. • Use radio-opaque drugs: Diadrast. 2. Goal is to achieve maximum response to very low current ie 0.5 MA. 3. The standard blockade monitor or hand unit can be used. 4. Failure rates: 4 – 6%. 5. Small dose of L.A is given and loss of motor power gradually to current is established before injecting full dose. 6. Complications

Nerve Damage: I. Transient II. Permanent a. Mechanical b. Ischemic c. Chemical or Toxic

• Endoneural injection: Nerve damage

Dr Azam’s Notes in Anesthesiology 2013 2. Describe the course of Sciatic Nerve and any one approach to block the nerve. Dr Azam’s Notes in Anesthesiology 2013

Anatomy & Course: • The sciatic nerve is the largest nerve in the human body, originating from the lumbo-sacral plexus (L4-5 and S1-3) and providing sensory and motor innervation to the lower extremity. • The sciatic nerve exits the pelvis via the greater sciatic foramen below the piriformis muscle. In the gluteal region, the sciatic nerve courses between muscle layers. The nerve is deep (anterior) to the gluteus maximus muscle and is superﬁcial (posterior) to the inner muscle layers (superior and inferior gemellus muscles, obturator internus muscle, quadratus femoris muscle). • It courses down the midline of the posterior thigh and branches into the tibial and common peroneal nerves usually in the popliteal fossa. Sciatic nerve block is most commonly performed for foot or ankle surgery.

PROCEDURE: Landmarks. • In Labatʼs classic approach, the patient - in lateral decubitus position (operative side up), and the leg is flexed at the knee. • If the patient is unable to flex the leg, the leg should be extended at the hip as far as possible without producing patient discomfort. Landmarks for the posterior approach of sciatic nerve: • Draw a line between the greater trochanter to the posterior superior Needles iliac spine (PSIS). • 21-gauge, 10-cm insulated needle for the majority of patients. • Draw a second line from the greater trochanter to the patientʼs sacral For obese patients, 15-cm needles may be needed. hiatus (Winnieʼs modification). • 18-gauge, 10-cm insulated Tuohy needle for catheter • Determine the point of initial needle insertion by drawing a line placement. Insert catheters 5 cm beyond the needle tip. perpendicular from the midpoint of the first line to its intersection with Local Anesthetic. the second line. • In most adults, 20 to 30 mL of • A fourth line can be drawn along the “furrow” formed by the medial • local anesthetic is suficient to block the plexus. edge of the gluteus maximus muscle and the long head of the biceps femoris muscle (Figure 17-4). • The furrow represents the course of the sciatic nerve toward the lower leg. • The triangle formed by the first, second, and fourth lines further defines initial needle placement, and subsequent adjustments of the needle within the triangle can improve success at sciatic nerve stimulation. 11

Dr Azam’s Notes in Anesthesiology 2013 Describe the course of Sciatic Nerve and any one approach to block Dr Azam’s Notes in Anesthesiology 2013 the nerve.Continuation:

Equipment: A standard regional anesthesia tray is prepared with the following equipment: • Sterile towels and 4"x4" gauze packs • 20-mL syringes with local anesthetic • Sterile gloves, marking pen, and surface electrode • One 1½" 25-gauge needle for skin inﬁltration • A 15-cm long, short bevel, insulated stimulating needle • Peripheral nerve stimulator

Dr Azam’s Notes in Anesthesiology 2013 3. Describe the anatomy of Stellate ganglion. Discuss indications technique & Dr Azam’s Notes in Anesthesiology 2013 implications of stellate ganglion block.

Anatomy: Anterior approach: • Fusion lowest 3 cervical C6,7,8 T1 ganglion + 1st thoracic • Locate a point 2cm above medial end of clavicle. ganglion. • At cricoid level is upper border of C6 vertebrae and palpate • 1-3 cm long. Chassaignac tubercle just lateral here. • Differs in same person on 2 sides • 2 cm below is C7 vertebrae. • Leriche and pontaine – 1934 – for CVA. • Palpate trachea and carotid vessels here. • Usually cervical – stellate – T2, T3, T4 are also block • Insert needle lateral to trachea until it impinges on body of C7 interruption of sympathetic fibers of head and neck, arm vertebrae about 2-3 cm deep. Inject 10cc. and thorax. Supplies: Landmark: • Gray rami to C7, C8 • C7, 1st rib, T1 transverse process. • Inferior cervical / cardiac nerves • Behind subclavian artery and origin of vertebral artery. • May communicate with vagus. • Posterior to carotid sheath. • Anterior to C8, T1 nerves. Signs of stellate block: (Horner-Bernasds sign/syndrome) • Right side – anterior relation – apex of lung and dome of A) Principal signs: Miosis, Enophthalmos (Bernards sign), Ptosis pleura (Hornerʼs law), Narrowing of palpebral fissure. • Left side these are 2.5cm lower. B) Supplementary signs: Technique 1) Conjuctival injection Anterolateral: 2) Congested nostril • Locate midpoint of clavicle, raise skin wheal 1 cm above. 3) Flushed face • Palpate transverse process of C6 (anterior tubercle or 4) Anhidrosis Chassaignac tubercle or carotid tubercle) 5) Improved blood flow to arm: warmth • Insert needle here and direct it medially, backward and downward to contact 1st rib neck or C7, transverse vertebra. • Now redirect more medially to contact body of C7 vertebrae and inject 10ml.

Dr Azam’s Notes in Anesthesiology 2013 Describe the anatomy of Stellate ganglion. Discuss indications technique & Dr Azam’s Notes in Anesthesiology 2013 implications of stellate ganglion block. Continuation:

Indications: 1. Vascular Pain relief 2. Accidental injection of thiopentone in artery 3. Raynaudʼs disease 4. Vascular anastomosis 5. Thromboembolism 6. Occlusive vascular disease 7. Phanthom limb pain 8. Pain due to CNS lesion 9. Herpes zoster 10.Causalgia 11.Neoplasms

Contraindications • Coagulopathy • Recent myocardial infarction • Pathological bradycardia • Glaucoma

Complications Misplaced needle • Haematoma from vascular trauma • Carotid trauma • Internal jugular vein trauma • Neural injury • Vagus injury • Brachial plexus roots injury • Pulmonary injury • Pneumothorax • Hemothorax • Chylothorax (thoracic duct injury) • Esophageal perforation • Hoarseness (recurrent laryngeal nerve) • Elevated hemidiaphragm (phrenic nerve) • Epidural block • Intrathecal 14

Dr Azam’s Notes in Anesthesiology 2013 4. Describe Anesthetics concerns for regional anesthesia in a patient on anticoagulants. Dr Azam’s Notes in Anesthesiology 2013

Guidelines based on literature, case studies, and consensus statements . • The morbidity of spinal hematomas can be greatly reduced with early diagnosis and intervention. • Neurological monitoring at least every 2hrs should be considered in high-risk situations. • Consider using neuraxial infusions with low doses of local anesthetic in higher risk situations. • This will enhance early detection of spinal hematoma • Combined therapies, which attack unique components of the coagulation cascade, may increase the risk of bleeding complications. (e.g. Heparin AND coumadin) • Approach new agents affecting coagulation with caution.(e.g.Fondaparinux)

Regional anesthesia in a patient on anticoagulants

Thrombolytics Heparin- Unfractionated Low Molecular Weight Heparin • Consider avoiding neuraxial Subcutaneous Heparin (LMWH) blocks, except in extreme • No contraindication for neuraxial techniques circumstances. Time block at least with mini-dose SQ heparin High Dose-BID LMWH 10 days after, and 10 days before • Time insertion of needle or removal of (e.g. enoxaprin 1mg/kg q12hr, or 1.5mg/ thrombolytics given. catheters 4 hours after last dose, and 2-4 kgQD) ! • If thrombolytics are given around hours before subsequent dose. • First dose should be given >24hrs after the time of neuraxial puncture, • Consider checking a platelet count in patients the block, and 2 hrs after catheter monitor patients at least Q2hrs, and receiving SQ heparin for greater than 4 days, removal use solutions with weak local to rule out heparin-induced thrombocytopenia • Indwelling catheters should be removed anesthetic. (HIT.) prior to initiating therapy • No recommendation for timing of Low dose intra-operative heparin LowDose-QDLMWH catheter removal after unexpected • Delay heparin dose for 1 hr after needle (EuropeanRegimen) thrombolytics use. placement. Remove catheter 1 hr before any • Indwelling neuraxial catheters can be • Use caution and consider checking subsequent dose, or 2-4 hrs after last dose. safely maintained. ﬁbrinogen levels. • Consider postoperative monitoring (q2hr • First dose of LMWH should be given 6-8 neuro checks) and using weak local hrs after block. anesthetic concentrations. • Catheter should be removed >10-12 hrs Prolonged therapeutic heparinization after the last dose. o!Subsequent dose of • Neuraxial blocks should be avoided in this LMWH given >2 hrs after removal of situation catheter. 15

Dr Azam’s Notes in Anesthesiology 2013 Regional anesthesia in a patient on anticoagulants Dr Azam’s Notes in Anesthesiology 2013

Fondaparinux Coumadin/Warfarin: Anti-platelet Medications • Anti-thrombotic effect through factor Xa • Chronic oral anticoagulation should be • Includes NSAIDS inhibition, actual risk unknown. stopped 4-5 days prior to block, and PT/INR (motrin,naproxen),thienopyridines(ticlopidine • Consensus recommendations based on the checked before procedure performed. and clopidogrel), glycoprotein IIb/IIa antagonists sustained and irreversible anti thrombotic effect, • If initial dose given >24 hrs prior to (abciximab, tirofiban) early postoperative dosing, and report of spinal procedure,or if 2 or more doses given, check • Bleeding time not a reliable test. Risk for hematoma reported during initial clinical trials. PT/INR before block. bleeding increased in females, elderly, and those • Recommend single needle pass, atraumatic • Catheters can be safely maintained on low with a history of easy bruising/excessive needle placement, and avoidance of indwelling dose (5mg) warfarin therapy CheckPT/INR bleeding. neuraxial catheters QD for indwelling catheter in pts on warfarin • NSAIDS-no added risk or timing concerns for • If INR>3, with hold or reduce coumadin neuraxial techniques when used alone. dose. Ticlopidine,clopidogrel, and platelet GP antagonist • Catheters can be removed when INR < 1.5. may represent significant risk: • Minimize local anesthetic concentration; • Ticlopidine- discontinue 14 days prior to block Herbal Preparations: monitor neuro status during therapy and for Clopidogrel- discontinue 7 days prior to block Of concern to the anesthesia provider is the side effect of bleeding in the patient who consumes herbal preparations. 24hrs after catheter removal • Abciximab- discontinue 2 days prior • Eptifibatide and tirofiban- discontinue 8hrs prior to block Mechanism of action: varies with the preparation. Garlic, ginger, feverfew: inhibit platelet aggregation Cox-2selective inhibitors(rofecoxib, celecoxib, • valdecoxib) • Ginseng: antiplatelet components • Minimal effect of platelet function. • Alfalfa, chamomile, horse chestnut, ginseng: contain a • Consider in patients requiring anti-inflammatory coumadin component peri-operatively. • Vitamin E: reduces platelet thromboxane production • Ginko: inhibits platelet activating factor

The risk for epidural/spinal hematoma is unknown. Surgical patients should be advised to stop herbal products 5-7 days before surgery. One of the crucial aspects of preoperative assessment is the concomitant use medications that alter coagulation. In addition, the patient should be screened for bleeding tendencies

Dr Azam’s Notes in Anesthesiology 2013 Dr Azam’s Notes in Anesthesiology 2013 5. Describe the clinical manifestation of LA toxicity & its management.

• Toxicity is deﬁned as an adverse reaction in an organism to a given dose of an agent. • Systemic and localized toxic reactions can occur, usually as a result of accidental intravascular or intrathecal injection of ver small or high volume exceeding the therapeutic range.

Types:

CNS TOXICITY: CVS TOXICITY: MISCELLANEOUS:

Site of CNS action: • Hippocampus and limbicsystem of brain particularly Factors inﬂuencing CNS toxicity amygdala is the trigger foci for seizures. They are Hypoxia selectively excited by LA agents. • Acid Base imbalance - Metabolic and Respiratory . acidosis Hypercarbia. Mechanisms of CNS toxicity • High concentration of LA agent. • Hyperkalemia - Increase both cardiotoxicity and convulsive activity of lignocaine & bupivacaine. ↓ Signs and Symptoms: Early blockade of the amygdaloid complex Pre-excitation stage (4 µg/ml) ↓ • Light headedness - Early symptom – tinnitus Blockade of inhibitory pathway in cerebral cortex 44, • Visual disturbance - Difﬁculty in focussing, diplopia. 76, 142. • Slurring of speech, talkativeness. ↓ Thus facilitatory neurons function in an unopposed Excitation stage fashion. • Muscle twitching, fasciculations GTCS (10 µg/ml) ↓ Depressant Stage Irritation • Coma, Respiratory arrest. (20 µg/ml) ↓ Convulsions • General order of CNS toxicity of LA ↓ Bupivacaine > tetracaine > etidocaine > prilocaine > lidocaine > mepivacaine > procaine CNS depression most toxic is bupivacaine, least toxic is procaine.

Dr Azam’s Notes in Anesthesiology 2013 Describe the clinical manifestation of LA toxicity & its management. Continuation: Dr Azam’s Notes in Anesthesiology 2013

CVS TOXICITY: MISCELLANEOUS:

• They occur at a dose higher than the CNS toxic dose. I. Allergy - common with esters because of PABA • They are seen at 25 µg/ml II. Local tissue toxicity: Skeletal muscles are more susceptible III. Methemoglobinemia: prilocaine & benzocaine --> Treatment • Mechanism of CVS toxicity: is IV methylene blue High Plasma concentration of LA agent. IV. Additive toxicity: Methylparaben which are used in multi-dose ↓ vials, has chemical structure similar to PABA, which is a direct effect on heart & peripheral blood vessels neurotoxic. Metabisulfite used in epinephrine containing LA solution is also a toxic agent. ↓ Depress the pace maker activity of SA node Treatment of LA toxicity: ↓ • C-A-B Sinus Brady cardia & arrest • Start chest compressions if cardiac arrest occurs. Ensure an adequate airway, give oxygen in high concentration if Factors influencing CVS toxicity: • available. • Pregnant patient more sensitivity to CVS toxicity of bupivacaine Ensure that the patient is breathing adequately. Ventilate the patient Sign & Symptoms: with a self inflating bag if there is inadequate spontaneous • Increased PR interval respiration. Intubation may be required if the patient is unconscious • Increased QRS duration and unable to maintain an airway. • Decreased cardiac output • Decreased Blood pressure • Administer 20 % lipid emulsion (values in parenthesis are for 70kg): • Bolus 1.5 mL/kg intravenously over 1 minute (~100mL) • Continuous infusion 0.25 mL/kg/min (~500 mL over 30 minutes) CC/CNS Ratio: • Repeat bolus Q 5 minutes for persistent cardiovascular collapse. • It is defined as the dose in (mg/kg) that cause cardiovascular collapse vs • Double infusion rate if blood pressure returns but remains low. the dose in (mg/kg) that causes CNS system collapse. • Continue infusion for a minimum of 30 minutes. • Lignocaine = 7.1 ± 1.1 • Atropine - 2 to 3 mg stat • Bupivacaine = 3.7 ± 0.5 (decreased to 2.7 ± 0.4 in pregnant patients) • Ephedrine 12.5 to 25 mg • Epinephrine, dopamine - If no blood pressure • Convulsions: Thiopentone 2 mg/kg, Lorazepam 4 mg, Midazolam 2 to 5 mg, Diazepam 5 to 10 mg.

Dr Azam’s Notes in Anesthesiology 2013 6. Describe regional block for removal of infected corn foot. Dr Azam’s Notes in Anesthesiology 2013

Ankle Block The ankle block involves blockade of 5 nerves. The ankle block is a common peripheral nerve block. It is useful Four of the five nerves are terminal branches of the sciatic nerve and for procedures of the foot and toes, as long as a tourniquet is include the following: not required above the ankle. It is a safe and effective • Posterior tibial nerve - continues as an extension of the tibial nerve technique. entering the foot posterior to the medial malleolus where it branches into the lateral and medial plantar nerves. It is located behind the Indications posterior tibial artery level adjacent to the medial malleolus. • The ankle block is suitable for the following: • Sural nerve - continues as an extension of the tibial nerve entering the • Orthopedic and podiatry surgical procedures of the distal foot. foot between the Achilles tendon and lateral malleolus. • Infected Corn • Superficial peroneal nerve - continues as an extension of the • Diabetic foot debridment. common peroneal nerve entering the ankle lateral to the extensor Advantages include the following: digitorum longus. • Easy to administer • Deep peroneal nerve - continues as an extension of the common • Safe technique when used appropriately. peroneal nerve entering the ankle between the flexor hallucis longus • Rapid onset of anesthesia Avoids complications related to tendons.!"#$%&'"&($')'*+(,%&-%( neuraxial or general anesthetic techniques The./&*+(,%&-% saphenous( nerve is a terminal branch of the femoral nerve. Disadvantages include the following: Saphenous./0%&1'2'*+(0%&",%*+(,%&-% nerve- located( anterior to the medial malleolus. 3%%0(0%&",%*+(,%&-%( • Is a superficial block and purely sensory. ( • The patient will still be able to move their toes and foot. • Requires at least 3 separate injections Placing an ankle block Schematically Drawn Division of the Sciatic Nerve is uncomfortable. • The patient may require conscious sedation for analgesia and amnesia. Sciatic Nerve

Contraindications • Few contraindications exist. • Should not be used when the foot is infected. Common Peroneal Tibial Nerve • Local anesthetic does not work in an acidotic environment. Nerve • In addition, there is the risk of introducing infectious agents to healthy tissue. • Young children Superficial Peroneal Posterior Tibial Nerve • Compromised circulation to the foot Nerve

Deep Peroneal Nerve Sural Nerve

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Describe regional block for removal of infected corn foot.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Patient positioning: Superficial Peroneal, Sural and Saphenous Nerves: • Position the foot on a footrest so that an access to all nerves to be blocked is maintained. • Superficial Peroneal Nerve. Inject a subcutaneous wheal of local • Walk from one side of the foot to the other while performing anesthetic (3ml to 5 mL) from the anterior border of the tibia to the the block procedure instead of bending and leaning to lateral malleolus reach the opposite side. • Saphenous Nerve. Inject a subcutaneous wheal of local anesthetic (3ml to 5 mL), directing it posteriorly from the tibial Equipment: ridge to the medial malleolus . Sural Nerve. Insert the needle between the Achilles tendon and A standard regional anesthesia tray is prepared with the • the lateral malleolus, and subcutaneously infiltrate 3ml to 5 mL of following equipment: local anesthetic along this course. • Sterile towels and 4"x4" gauze packs • Three 10-mL syringes with local anesthetic Drug: NEVER USE EPINEPHRINE! • Sterile gloves, marking pen, and surface electrode • One 1½" 25-gauge needle 0.5% Onset in Anesthesia Analgesia Technique: Ropivacaine (min) (Hrs)4-8 (Hrs)5-12 Deep peroneal nerve: 5-30 • The finger of the palpating hand is positioned in the groove Complications: just lateral to the extensor hallucis longus. The needle is • Infection inserted under the skin and advanced until stopped by the • vascular puncture bone. At this point, the needle is withdrawn back 1-2 mm • Nerve injury and 2-3 mL of local anesthetic is injected. • Infection • Instead of relying on a single injection, a "fan" technique is • Hematoma recommended to increase the success rate. Posterior tibial nerve: Note: • Posterior tibial nerve is anesthetized by injecting local Be careful with the total volume of local anesthetic. anesthetic just behind the medial malleolus. • The needle is introduced in the groove behind the medial malleolus and advanced until contact with the bone is felt. At this point, the needle is withdrawn back 1-2 mm and 2-3 mL of local anesthetic is injected.

Dr Azam’s Notes in Anesthesiology 2013 7. Anatomy of Epidural Space & the methods of identiﬁcation. Dr Azam’s Notes in Anesthesiology 2013

Epidural space (mm) Thickness of dura (mm) Anatomy of Epidural Space: • The epidural space is the circular space surrounding the dural Cervical 1.0 – 1.5 2.0 – 1.5 sac and all of its contents. Upper thoracic 2.5 – 3.00 1.0 Extends from the foramen magnum to the sacral hiatus. • Lower thoracic 4.00 – 5.00 1.0 • The space is more extensive and easily discernible posteriorly, while anteriorly, the dura adheres closely to the periosteum of Lumbar 5.00 – 6.00 0.66 – 0.33 the vertebral bodies. • Lateral boundaries and the intervertebral foramina and the peduncles of the vertebrae. • The space extends laterally accompanying the spinal nerves Distance to epidural space: through the intervertebral foramina into the paravertebral space • The over all median distance in normal adult female is 4.7 cm at up to the angle of the ribs. L3 – L4 level. • This communication between the extradural and paravertebral • The maximum depth occurs at L3 – L4 inter space. spaces explains the – ve pressure in epidural space. • The depth decreases above L3 and below L4 level. The contents of the epidural space: • Aeriolar tissue, fat and 4 spinal nerve roots with their dural Epidural space in children: sleeves. • In children under 6 yrs of age, the epidural space has spongy, • The spinal arteries. gelatinous lobules and distinct space. (This is contrast to densely • The venous plexus and capillary network packed fat globules and ﬁbrous strands characteristic of the • There are strong lateral attachments of the dura at the cervical mature epidural space). and lumbar areas to the spinal canal wall. • Because of this difference there is a more rapid longitudinal spread • Posteriorly, in the midline, a distinct connective tissue, named of drugs within the juvenile epidural space. “Plica mediana dorsalis” connects dura matter to ligamentum – Flavum. To reach the epidural space in the midline sagittal plane, the following structures are penetrated from outside to inside: • Skin and subcutaneous tissue. • Supraspinous ligament • Inter spinous ligament • Ligamentum ﬂavum Size of epidural space: • In the anterior region it is almost non existent. • Posteriorly it is measured readily in the midline, as shown in the table 21

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of Epidural Space & the methods of identiﬁcation. Dr Azam’s Notes in Anesthesiology 2013

Negative pressure techniques: 1. Hanging drop sign: After the needle has been introduced Disappearance of resistance technique: to the level of resistance indicating the beginning of 1. Syringe technique: Sicard and rorester in 1921. Sudden loss of ligamentum flavum, a small drop of sterile distilled water resistance to a pressure exerted on the plunger of a syringe filled with is placed on the hub of the needle. When needle is H2O. advanced through ligamentum flavum à drop will be “sucked into” epidural space. 2. Spring – loaded technique – (Visual technique) when epidural space is entered, syringe automatically unloaded itself by virtue of the 2. Capillary tube method – odomʼs devised a small capillary diminished resistance in the space syringe is heavy. tube filled with sterile saline in which 1 or 2 bubbles of air were placed. These acted as meniscus. As needle enters 3. Balloon technique of macintosh – small light balloon mounted on a epidural space, saline sucked in, and air bubbles glass adapter is attached to the needle when it reaches lig flavum. advanced into space. Balloon inflated with 2-3 ml of air. As needle advances and penetrates into epidural space balloon collapses. (Pressure 50 mm Hg). 3. Manometer technique – small ʻUʼ shaped glass tube about 3 to 4 inch height is used as a H2O manometer. As 4. Books device – (Visual technique) odomʼs indicator / capillary tube the needle advances into the intraspinous lig. the sterile sealed at one end filled with water or saline and few bubbles are glass manometer is attached. As it advances into the placed in tube part. Attached to epidural needle when it reaches lig epidural space – immediate movement of liquid signifying flavum – bulb is heated to create a slight positive pressure. Needle negative pressure. penetrates epidural space – meniscal bubble advances into epidural a. Lower lumbar area à 0.5 cm H2O or less space. b. Upper lumbar area à 2.0 cm H2O c. Lower thoracic area à 2.0 cm H2O 5. Vertical tube of Dawkins – (Visual technique)

• A slight positive pressure is created by a short vertical column of H2O in tube less than 10cm high-connected at right angles to needle a bubble of air also may be placed in H2O. Force of gravity on the column of H2O produces pressure. When epidural space is entered the level of column of H2O drops indicating disappearance of resistance.

Dr Azam’s Notes in Anesthesiology 2013 8. Phantom limb pain Dr Azam’s Notes in Anesthesiology 2013

• This is the sensation of the continued presence of an amputated New treatments: limb. • An electrical prosthetic limb moved by signals from the • It is most common after arm amputation and if the amputation is patient's muscle reduced the pain if used for several hours delayed after the initial injury. per day. • It is associated with tingling or pain, which is severe in 15% of cases. • The perceived limb may be felt to be in an abnormal position. Visual trickery: • It is believed to be a state of central pain. • Stimulation of the motor cortex can reduce phantom limb pain. Mechanisms • These new approaches are all based on a shift in emphasis in phantom limb pain away from the site of damage – the There may be many mechanisms underlying phantom limb pain: stump – to the centre of pain processing: the brain. It • Damage to nerve endings is often important; subsequent erroneous appears that disordered inputs from the limb's sensory regrowth can lead to abnormal and painful discharge of neurones in systems, combined with disrupted motor signal back to the the stump, and may change the way that nerves from the amputated limb, generate a mismatch between the brain's built-in map limb connect to neurones within the spinal cord. of the physical body and what is actually perceived. It would • There is also evidence for altered nervous activity within the brain as appear that this mismatch results in pain. a result of the loss of sensory input from the amputated limb. • Phantom limb pain is generable intractable and chronic; once it develops, it persists and is rarely improved by present medical treatments.

Traditional treatment of phantom limb pain: Traditional treatments include: • Phenytoin, carbamazepine, sympathetic nerve blocks, transcutaneous electrical nerve stimulation (TENS), dorsal column stimulation and cordotomy. Pre-emptive analgesia with epidurals has been claimed to prevent the development of phantom limb pain when instituted before surgical amputation.

Dr Azam’s Notes in Anesthesiology 2013 9. Cauda Equina Syndrome Dr Azam’s Notes in Anesthesiology 2013

• After the conus medullaris, the canal contains a mass of nerves Clinical features: (the cauda equina or "horse-tail") that branches off the lower end • Bowel and bladder dysfunction. of the spinal cord and contains the nerve roots from L1-5 and • LMN type of injury with peresis of logs. S1-5. The nerve roots from L4-S4 join in the sacral plexus which • Anaesthesia in posterior thigh, saddle / great toe perineal area. affects the sciatic nerve, which travels caudally (toward the feet). • Pain characteristic of nerve root compression. • It is suspected, when for fails to regain sensory and motor power within Cauda equine syndrome: usual time after spinal anaesthesia Is characterized by • Return of function is usually slow over several months or these effects may (a) urinary and fecal incontinence coupled with. be permanent. (b) localized sensory loss in the perineal area with varying degrees • Tidal drainage is recommended as an early form of therapy. of (c) leg weakness due to injury to cauda equine. D/D: • Transverse myelitis Aetiology: As a rare complication of spinal anaesthesia. Surgical manipulations I. Use of micro-catheter for repeated dose / continuous infusion of • sub-arachnoid local anaesthetic. • Difﬁculties in evacuation while in bed II. Pooling (maldistribution) of hyperbaric solutions of lidocaine. • Disc prolapse III. Neurotoxicity due to chlorprocaine. • Tumors or hematomas IV. Damage to conus medullaris V. Direct injection of local anaesthetic to spinal cord. Investigations for diagnosis VI. Accidental injection of alcohol into spinal cord during intrathecal • Previous records administration. • CT/MRI of spinal cord VII. Detergents used clear disposable syringes and their • Myelogram contaminants. • CSF examination Precautions: • Histology to r/o other systemic disease. (auto antibodies) Following are recommended to decrease maldistribution and neurotoxicity of local anaesthetic: Treatment: 1. Decreasing dose of lignocaine < 60 mg. 1. Bed rest with passive muscle activity. 2. Avoid repeated doses 2. Steroids and antibiotics. 3. Decreased lidocaine concentration to 1.5% 3. Physiotherapy 4. Use of isobaric solutions. 4. Care of bowel and bladder 5. Diluting L.A. with aspiration of C.S.F. 5. Surgery if hematoma / tumor 6. Substituting bupivacaine for lignocaine / whichever possible. 7. Avoid spinal epinephrine.

Dr Azam’s Notes in Anesthesiology 2013 10. Total Spinal Anesthesia Dr Azam’s Notes in Anesthesiology 2013

1. Total central neurological blockade. 2. This is one of the major hazards to be encountered in performing Management: epidural anaesthesia. • Turn the patient into supine position. • It can also occur during interscalene block of Brachial plexus. • Trendelenburgʼs position à elevate legs. • Incidence for the epidural à 1 in 1000 cases. • Ventilate with 100% O2. • It is the result of unrecognized spinal puncture and the infection • It is important to ventilate the patient by mask before of large volume of anaesthetic solution à during epidural proceeding to ETT intubation. anaesthesia. • If ventilation with 100% O2 by mask is very difﬁcult (or) • It usually comes on soon after injection. It may be delayed for impossible à rapid intubation. 30-45 mins. • No muscle relaxant (or) hypnotic agent necessary. • Intravenous ﬂuid bolus. Signs and symptoms. • Vagolytic dose of atropine à 2 – 3 mg. 1. Profound bradycardia - because of total sympathectomy and • Ephedrine à 10 – 25 mg. relative increase in vagal tone. • Epinephrine à 10 – 100 µg.→ If hypotension (or) 2. Profound hypotension bradycardia not resolved. • Vasodilation of capacitance vessels. • Surgical procedure à • Decrease venous return to heart and • Continued • Decrease systemic vascular resistance • Airway is secured à 3. Apnea for considerable time blockade of C3 – C5. Phrenic nerve • Hemodynamic response managed and patients is block (Diaphragmatic paralysis). stable. à 4. Dilated pupils due to sympathetic blockade. • Postponed: If there is doubt about hemodynamic (or) 5. Loss of consciousness CNS status of patients. 6. Motor blockade – muscle paralysis.

It can be avoided by: • Careful technical application. • Aspiration for spinal ﬂuid. • Test dose • Incremental doses

Dr Azam’s Notes in Anesthesiology 2013 11. Spinal Needles Dr Azam’s Notes in Anesthesiology 2013

1. Vary in regard to the outside diameter (OD), inside 11. Conveniently, it is also possible to tear the dura, producing a large hole even diameter (ID) and shape of their tip. with a small needle. 2. These differences are important because they affect 12. The dura is made chiefly of collagen fibers and some elastic fibers. the size and shape of the puncture hole made in the 13. The collagen fibers are oriented in diverse directions while the elastic fiber dura mater and the speed with which CSF appears generally run longitudinally. in the hub after the SAS is entered. 14. The dura is also variable in its thickness (0.5 – 2 mm) in the same individual. 3. Gauge 22, 25, 26, 27 & 29 The thicker it is, the grater the retraction. 4. OD (mm) 0.7, 0.5, 0.45, 0.34 15. Of the hole, the typical “tin-lid” hole is produced by all needle tips with a cutting 5. ID of spinal needles also varies considerably for the edge. same size of OD. 16. When a non-cutting needle is used or when a cutting needle is inserted, With the 6. ID is important as it affects the rate of flow of CSF point parallel to the longitudinal fibers, an ellipsoidal hole is produced, compared down the needle, which is related to the CSF to a more round hole when the needle top is at right angles to the fibers. pressure at the needle tip. With a 26 gauge needle, 17. Because the shape of the needle tip several different typer are available. it can take 10 to 60 seconds for CSF to appear at the needle hub. It is seen sooner if the hub is translucent rather than opaque. It addition the, flow will be faster if the patient is sitting up rather than in the lateral decubitus position, as the pressure at the needle tip is greater. 7. 22 gauge needles can be used without the aid of an introducer, but thinner needles usually require an Parts: introducer which is first inserted into the ligamentum • Stylet flavum. • Cannula - Hub & tip 8. The shape and sharpness of the needle tip affects the shape and size of the hole produced in the dura. This hole is not simply the same size as the OD of the needle. 9. Often there is a flap similar to that of an opened “tin can” whose lid has not been completely removed. 10.This flap may move back into the hole, partially or totally preventing CSF escape, even after puncture with large-bore needles.

TYPES: 26

Dr Azam’s Notes in Anesthesiology 2013 12. Post Dural Puncture Headache - PDPH Dr Azam’s Notes in Anesthesiology 2013

Post spinal headache was first documented by August Bier 2) High CSF pressure theory: due to bacterial or chemical arachnoiditis in1899. Any breach of the dura may result in PDPH – may follow a) Diagnostic LP b) Myelograma c) Spinal anesthetic Description: Headache is bilateral frontal or retro orbital, occipital d) epidural ʻwetʼ tape) Epidural catheter may puncture dura. extending into neck – throbbing / croissant – association with photophobia Incidence: The incidence is about 3-30%. In inadvertent dural and nausea / association with body position à aggravated by sitting or puncture, during extra dural block with Tuohy needle, has its standing, relieved or lessened by lying down lat. maximum incidence of headache. The incidence will vary Onset and duration: Soon after assumption of a head up position i.e. according to size of needle used. 12-72 hrs following the procedure / duration à range from / day to 1 yr. • 16 G needle -24% usual period 4 days by end of 1 week 75% would have subsided. • 20 G needle-14% Severity classiied into 3 categories. • 24 G needle- 6% • Mild: Incidence 8%, no significant inconvienience, patient mobile, • 25 G needle-3.5% hydration + analgesics / codeine – sufficient. • 32 G needle-1.4% • Moderately severe: incidence 3% some degree of inconvenience, only partially mobile, does not like to recline. AETIOLOGY: • Severe headache: incidence 2.3%, interruption of normal activity, prefers to remain supine, treatment with blood patch. Low CSF pressure theory:

The pressure of CSF in sub dura space is 150 mm of H2O. But the pressure in the lumbar epidural space is sub Factors affecting PDPH: atmospheric. So some escape of CSF will invariably occur after 1. Sex – Frequent in females – young females – nearly twice as in-men obstetric deliveries ↓ SA 20% incidence. L.P. and will continue until the hole become occluded. It is 2. Menstruation second part of menstrual cycle à lower frequency calculated that average, CSF leakage is about 10 ml/hr. This may (higher estrogen and rising progesterone levels à H2O and salt lead to decreased CSF pressure as low as 50 mm of H2O. The retention). healing of the dural puncture hole may take up to 3 weeks. So a 3. Onset of menses and subsequent preovulation period à more large guage needle and any thing which increases CSF pressure frequent. like pregnancy increases the leakage and so incidence of post 4. Age: 20-40 yrs à greatest frequency puncture headache. When the rate of leakage exceed the rate of 5. After 50 yrs à sharp ↓ in incidence (higher pain threshold, ↓ physical formation it results in change in hydrodynamics of the CSF. This sensitivity, diminished elasticity of cerebral blood vessels). 6. Psyche: spinal taps done with great fan, many precautions and lead to loss of cushioning of the brain and pressure or traction on warnings à headache incidence of 16%. vessels and pain sensitive structure like basal dura and tentorium, producing headache. 27 Dr Azam’s Notes in Anesthesiology 2013 Post Dural Puncture Headache - PDPH. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Mechanism of PDPH: Imbalance in CSF dynamics. • Type of agent: No difference in incidence with procaine, tetracaine or dibucaine or lidocaine or bupivacaine. • Continuos loss of CSF occurs – rate of loss greater than rate of • Size of needle: small needle make small holes. Less production. (30-50 ml loss critical point, 10 ml/hr loss). leakage with 25 guage Quincke than 22 guage Quincke • Diminished CSF – fall in spinal / CSF pressure – brain loses its “water needle. cushion” and sags especially in upright position – Traction on pain – • Type of needle: Whitacare pencil point or Greene conical sensitive supporting structures including blood vessels. needles produce less leakage than needles that have a • Stimuli from superior surface of tentorium cerebelli transmitted through V. bevel with a cutting edge, Quincke – Babcock or Pitkin CN. needle. • Pain in anterior part of head. • Orientation of needle: A 22 guage needle parallel to • Stimuli arising from below the tentorium and transmitted through IX and longitudinal dural fibers produces lesser leakage than when X. CN. And upper 3 cervical nerve à pain in posterior part of head and it is perpendicular to the dural axis. nuchal region. • Angle of approach to dural puncture: Less leakage at an • Vascular component – to fill space backing in fluid, vasodilation of the angle of 300 than at an angle of 600 or 900. intracranial vessel occurs and is accompanied by perivascular edema – • Altitude: more frequent at high altitude than at sea level. pain stimuli arising from dilated vessels. • Enforced post-spinal bed rest. ↑incidence, Barly ambulation recommended practice with ↓ incidence. Avoid excessive strain. • Procedural factors hyperflexing the patient – stretches dura – larger opening ↑ incidence of PDPH. • Introducer for advancement of needle ↓ incidence of PDPH minimizes the contamination of deeper structures and SAS.

Dr Azam’s Notes in Anesthesiology 2013 Post Dural Puncture Headache - PDPH. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Prevention: Prophylaxis depends on a) proper care of patient b) minimizing spinal fluid leakage c) maintaining normal CSF volume. Recommendations: (1) Allay patients fear (2) Prelimnary hydration oral 2,500 ml/day, parenteral if needed (3) Use fine guage needles 24 or smaller (4) Use of needle introducer (5) Spinal needle bevel parallel to longitudinal dural fibers. (6) Expeditious performance of tap without fan fare. (7) Encourage early ambulation (8) Maintain CSF volume – equalizing any general loss and maintaining TBW. 9) cough and straining should be avoided Treatment: Aimed at restoring normal CSF dynamics. Conservative measures are • Psychological support and positive reassurance. • Confinement to Bed – Head down positin. • Application of Ice bag to head. • General body hydration – oral / I.V. • Sedation and / or analgesia: chloral hydrate, sod amytal asprin codeine. • Caffeine sodium benzoate 0.5G iv/im (effective in 70-75 % patients, caffeine causes marked cerebral vasoconstriction). • Cardiovascular stimulants: Ephedrine sulfate 50 mg .iv, Amphetamine sulfate 5-10 mg TID, Ergotamine tartrate orally 1mg. • I.V. fluids – dext 50% - 5ml every 6-12 hrs, 5% DW infusion • O2 inhalation • Abdominal compression – toraise peri dural venous plexus and thus increase CSF pressure.

Special therapeutic measures: • Subarachnoid saline injections: small guage needle inserted à5%glucose, - physiologic saline solution introduced in 5ml fractions 15-20 ml restores normal CSF pressure, relief immediate but short with recurrences risk of second dural puncture. • Peridural saline solution injection performed at site of original puncture, caudal injections are also effective, relief short lived. • Epidural blood patch: ﬁrst proposed by Gromely in 1960 seals holes or defects in spinal dura by means of a blood clot “patch”. • Patient positioned – lumbar area aseptically prepared for epidural puncture. • Venous blood (10-20 ml) withdrawn from antecubital vein. • Epidural puncture performed – at original puncture. • Epidural space identiﬁed – autologous blood is slowly injected and needle removed. Optimal volume of blood – 10 ml is critical (89% relief). volumes of 12ml or more( 12-15ml) recommended in adults 96-98% relief. Rate of injection is – 10 seconds for 10 ml. 1. Patient kept supine for 1 hour. 2. Thereafter movement and ambulation are encouraged.

Dr Azam’s Notes in Anesthesiology 2013 Post Dural Puncture Headache - PDPH. Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Epidural spread of blood: spreads homogenously in all directions away from point of needle – more so cranially extends over 7 to 14 segments. Caudal spread stops at S1 – S2, cephalad spread between T5 and L1. • Mechanism of relief (1) Immediate “pressure effect” – compresses dura mater – decrease SAS pressure and restores CSF dynamics. Saline – 15 ml blood – 10 ml critical volumes. (2) “Sealant effect – 2 to 4 days injected blood forms gelatinous patch in area of original spinal dural puncture allowing healing of puncture hole. • Other uses (a) after myelography (b) chronic headache. • Adverse responses: Possibility of bacterial contamination, backache, neckache, vestibular and cerebellar disturbances and nerve root compression.

Dr Azam’s Notes in Anesthesiology 2013 13. Differential Blockade Dr Azam’s Notes in Anesthesiology 2013

• Differential blockade refers to the gradual and sequential Differential blockade: Results in sympathetic blockade (judged by temp block of the different type of nerve fibres when they are sensitivity) that may be 2 segments higher than the sensory block (pain, light exposed to a local anesthetic. touch) which in turn is 2 segments higher than motor blockade. • It is the existence of differential sensitivity of different types of nerves to the blocking actions of local anesthetics. Autonomic Blockade: Etiology is multifactorial. • Sympathetic outflow - Thoracolumbar 1. Frequency – dependence on local anaesthetic action means • Parasympathetic outflow - Cranioscral that even under basal conditions different types of nerves with different frequencies of nerve impulse transmission • Sympathetic pre-ganglionic fibers exit spinal cord from T1 to L2 level have different sensitivities to local anesthetics. • Neuraxial block does not block vagal nerve 2. Duration of exposure of nerves to local anesthetic solutions Neuraxial block primarily results in varying degree of sympathetic block & alters perceived sensitivity to local anesthetic action. • 3. Most-investigators believe that axonal diameter is by itself, physiological response, resulting from decrease sympathetic tone and/or not a determinant of nerve sensitivity to the blocking action unopposed parasympathetic tone. of local anesthetics. 4. Results of in vitro studies of sensitivity to local anesthetics CVS Manifestation: depend in part on whether nerves normally sheathed remain • Neuraxial block typically produce variable decrease in blood pressure that intact or whether they have been desheathed. may be accompanied by a decrease in heart rate & cardiac contractility. 5. The ability to demonstrate differential sensitivity of nerves to local anesthetics varies with the type of local anesthetic • Vasomotor tone is primarily determined by sympathetic fibers arising from (amide or ester-linked) as well as within the same type of T5 to L1, innervating arterial & venous smooth muscle. anesthetic (e.g.. amide vs amide). Blocking these nerve causes: 6. Local anesthetics block myelinated nerves at the nodes of Ranvier. Axonal conduction block is produced only when • Vasodilation of venous capacitance vessels several, not just one, nodes are exposed to • Pooling of blood pharmacologically active concentrations of local anesthetics. • Decrease venous return to heart Length of nerve exposed to local anesthetic also therefore • Arterial vasodilation may decrease SVR - these effects of which may be influences sensitivity to local anesthetics. minimized by compensatory vasoconstriction above the level of block. Zone of differential T6↔ sympathetic blockade. Blockade: T8↔ sensory blockade.

T10↔ motor blockade.

Dr Azam’s Notes in Anesthesiology 2013 Differential Blockade. Continuation: Dr Azam’s Notes in Anesthesiology 2013

High Spinal block: • Prevents compensatory vasoconstriction • Blocks sympathetic cardiac accelerator ﬁbers that arise at T1 - T4. Profound Hypotension may result from: • Vasodilation • Bradycardia • Decrease contractility Treatment: • Preloading 10 - 20 ml/kg of IV ﬂuids • Excessive bradycardia should be treated with Atropine • Hypotension with Vasopressor • Direct α adrenergic agonist ( phenylephrine); Increases venous tone, arteriolar constriction • Direct β adrenergic effects (Ephedrine); increases Heart rate & contractility, indirect effect - vasoconstriction. • Epinephrine

Dr Azam’s Notes in Anesthesiology 2013 14. NERVE CLASSIFICATION AND SEQUENCE OF BLOCK Dr Azam’s Notes in Anesthesiology 2013

3. LOCAL ANESTHETICS TABLE 3-1 NERVE CLASSIFICATION AND SEQUENCE OF BLOCK WHEN EXPOSED TO LOCAL ANESTHETIC INTRODUCTION Fiber Type Myelin Diameter Function Conduction Velocity Time to Block Compared to general anesthesia with opioid- (µm) based perioperative pain management, regional DQHVWKHVLDFDQSURYLGHEHQHÀWVRIVXSHULRUSDLQ $_ Yes ² Somatic motor and proprioception Fast Slow FRQWUROLPSURYHGSDWLHQWVDWLVIDFWLRQGHFUHDVHG $` Yes ² /LJKWWRXFKDQGSUHVVXUH VWUHVVUHVSRQVHWRVXUJHU\UHGXFHGRSHUDWLYHDQG postoperative blood loss, diminished postopera- $a Yes ² 0XVFOHVSLQGOH VWUHWFK WLYHQDXVHDDQGYRPLWLQJDQGGHFUHDVHGORJLVWLF UHTXLUHPHQWV7KLVFKDSWHUZLOOUHYLHZWKHPRVW $b Yes ² 3DLQ IDVWORFDOL]LQJ WHPSHUDWXUHÀUPWRXFK FRPPRQORFDODQHVWKHWLFVDQGDGMXQFWVXVHGLQWKH % Yes ² 3UHJDQJOLRQLFDXWRQRPLF 86PLOLWDU\IRUWKHDSSOLFDWLRQRIUHJLRQDODQHVWKHWLF WHFKQLTXHVZLWKSDUWLFXODUHPSKDVLVRQPHGLFD- C 1R ² 3DLQ QRQORFDOL]LQJDFKH WHPSHUDWXUHWRXFK Ø Ø WLRQVXVHGIRUSHULSKHUDOQHUYHEORFN 31% DQG SRVWJDQJOLRQLFDXWRQRPLF Slow Fast FRQWLQXRXVSHULSKHUDOQHUYHEORFN &31%

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11 The complete brachial plexus diagram: 15. Supraclavicular Block. Dr Azam’s Notes in Anesthesiology 2013

• Mainly two types, classical Kulenkampff and plumb bob approach. • Indication: • Operations of the upper arm lower arm and hand.

Contraindications: • Haemorrhagic diathesis • Contralateral phrenic nerve paralysis • Contralateral recurrent laryngeal nerve paralysis • Contralateral pneumothorax • Children (relative contraindication) • Narrow-chested patients • Bilateral supraclavicular brachial plexus block

Technique: Patient position: • Supine with the head turned to the opposite side, arm as Endpoint: down as possible, that is hand touching the knee. • Eliciting twitches or paraesthesia or click

Landmarks: Drug: • Midpoint of the clavicle • 8-10 ml of local anaesthetic per division • Subclavian pulsation • External jugular vein Missed nerve: • Median nerve may be missed. Needle: • 25 G insulated needle or a 22G, 2 inch needle. Practical Tips: • Coughing by the patient while paraesthesia is being sought may indicate Puncture site: pleural puncture, and the procedure must be discontinued. A chest X-ray • Immediately dorsolateral from the palpated pulsation of will reveal any possible pneumothorax. The patient should be observed the subclavian artery 5H cm posterior to the midpoint of for24 hours. the clavicle. • Puncture of the subclavian artery indicates that the needle has been Direction of needle: inserted too far medially. The plexus should be sought more laterally. • Caudal direction and slightly lateral, parellel to the scalene muscles to contact the ﬁrst rib.

Dr Azam’s Notes in Anesthesiology 2013 16. Hernia Block. Dr Azam’s Notes in Anesthesiology 2013

• Indications: I. Iliohypogastric nerve: • Inguinal or genital operations – inguinal herniorrhaphy, • L1–T12 – emerge posteriorly to the psoas major muscle, lie on Orchiopexy (or orchidopexy) . the anterior surface of quadratus lumborum – do not enter the • Post operative pain relief. pelvis-penetrates the transersus abdominis at the level of iliac crest then lies beneath internal oblique – penetrates Anatomy: aponeurosis. The inguinal region is supplied by: • Splits in 2 branches before becoming cutaneous • Iliohypogastric nerve • Lateral branch à sensory to lateral part of buttock and Hip. • Ilio inguinal nerve • Anterior branch à becomes superﬁcial just medial to • Genitofemoral nerve anterior superior iliac spine. • Innervates the lower abdomen. II. Ilioinguinal nerve: • Follows same course – exits peritoneum to enter inguinal canal à sensation to scrotum, penis and medial thigh in male or equivalent area of Labia and mons pubis in female. III.Genitofemoral nerve: • L1 – L2: Femoral branch travels with the femoral artery à cutaneous sensation just below inguinal ligament. IV. Genital branch • travels in inguinal canal à scrotum (men) labium majus (women)

Land marks: • Pubic tubercle • Anterior superior Iliac spine.

Dr Azam’s Notes in Anesthesiology 2013 Hernia Block. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Technique: • Raise skin wheal 2-3 cm medial to the upper aspect of anterior superior iliac spine. • (22 G / 3.5 inch spinal needle) insert needle perpendicular to the skin through wheal to bone and inject 5 ml LA sol. • Redirect the needle along the incision but downward and medially and inject 15 ml of LA solution. • Palpate public tubercle and raise skin wheal 2 cm lateral to this point. • Insert needle perpendicular to skin until bone is hit inject 5 ml of LA solution. • Redirect the needle laterally and superiorly along the line of incision for 2 inches and inject 15 ml of LA sol. LA agent: • 1.2% of lignocaine (Max dose 5 mg/kg) • 0.25-0.5% of Bupivacaine (max dose 3 mg/kg)

Complications: Pain when cord is pulled – prevented by inﬁltrating the superior portion of the cord. Patient discomfort Persistent paresthesia from intraneural injection.

Contraindications: 1. Patient refusal 2. Uncooperative patient 3. Mentally unstable patients 4. Obesity 5. Anxiety 6. Irreducible hernia 7. Coagulopathy.

Dr Azam’s Notes in Anesthesiology 2013 17. Field Block for tonsillectomy. Dr Azam’s Notes in Anesthesiology 2013

Nerve: Other approach: • Lesser palatine • Anterior approach • Lingual nerve • Lateral approach • Glossopharyngeal • Posterior approach • Pharyngeal plexus • Tissue displacement approach • These plexus are called circulus tonsillaris. Complications: Technique: • Pleural shock • Amethocaine lozenges 60mg. ½ hr before • Perforation of esophagus • Mouth and pharynx sprayed with 4% xylocaine (cough reflex abolished) some • Intrathecal injection – Total spinal prefer active cough reflex. • Intravascular injection • 3 to 5 ml xylocaine with adrenaline 1.5% • Pneumothorax 1. Upper part of posterior pillar • Cardiac arrest 2. Upper part of anterior pillar • Hoarsness of vice RLN block 3. Δle fold of lower pole. • Pnernic nerve block 4. Supra tonsillar fossa after drawing tonsil medial • Branchial plexus block. • Mediastinitis Position: Sitting and well supported in chair. Disadvantages: Signs of successful block • Depression of tongue cause discomfort. • Horners syndrome. • Fainting • Flushing of cheek face neck arm and increased Paratracheal approach: skin temp. • 2 finger breath lateral to supra sternal notch. • Flushing of conjunctiva and sclera. • 2 finger breath above clavicle. • Anhidrosis of face and neck. • This is at medial border of sternocleidomastoid at level of C7 transverse • Lacrimation. process. • Stiffness of nostril. • Position checked by palpating cricoid cartilage and chassaignac tubercle (C6 • Muellerʼs syndrome - injection of tympanic – Tr) membrane and warmth of face. • 22G needle 5-8 cm length à push sternocleidomastoid carotid art downward and backward. • Advance needle directly backwards. • Make contact with bone C7 transverse process – needle withdrawn 0.5 to 1cm. • Aspiration for blood and CSF. • 15 to 20 ml of 0.5% lignocaine injected. • Block ganglia and Rami for C2 to T4 • 30 min later Hornerʼs syndrome (Miosis, Enophthalmos and Ptosis) and vasodilation of arm. 37

Dr Azam’s Notes in Anesthesiology 2013 18. Celiac Plexus Block. Dr Azam’s Notes in Anesthesiology 2013

CELIAC PLEXUS BLOCK Physiology of celiac plexus block: Anatomy: Blockade of afferent nociceptive fibres: • Celiac plexus lies anterior to aorta at the level of 1st lumbar • Any pain originating from visceral structures innervated by celiac vertebra. plexus can be effectively alleviated by this blockade. This include Nerve fibers reach the plexus from: pancreas, liver, Gall bladder, omentum, mesentery, alimentary • Preganglionic sympathetic fibres from splanchnic nerves. tract (from the stomach to transverse colon). • Pre ganglionic parasympathetic from vagus. Blockade of sympathetic fibres to GIT: • Some sensory fibres from phrenic and vagus. • The complete sympathetic denervation of GIT allows unopposed • Afferent fibres concerned with nociception. parasympathetic activity and increased peristalsis, increase in • There are 3 pairs of splanchnic nerves which descend to the gastric motility and relaxed sphincters lead to increased gastric celiac plexus. They are: emptying. 1) Greater splanchnic nerves arises from T5-T9 (sometime T4 • Diarrhea may develop. Nausea and vomiting seen in GIT and T10 also) spinal segments. malignancy may be abolished after celiac plexus block. 2) Lesser splanchnic nerves arises from T10 and T11 spinal Blockade of sympathetic fibres to splanchnic vessels: segments and • Secondary to vasodilatation of large splanchnic bed, hypotension 3) Least splanchnic nerve arises from T12 spinal segment. may develop after well placed celiac plexus block. Drugs used for celiac plexus blockade: • These nerve fibre synapse in the ganglia of celiac plexus. 1. Local anaesthetic alone • There are 3 pairs of ganglia exist within the plexus. They • are: 0.5% sensorcaine with 1: 200,000 dilution of adrenalin. • 1. Celiac ganglia 15ml on each side (Total 30 ml). • 2. Superior mesenteric ganglia Used in non malignant conditions. 2) Local anaesthetic + steroid 3. Aortico-renal ganglia Commonly used steroid is Betamethazone The Nociceptive afferent fibres travel from viscera along the • • In chronic abdominal pain following multiple surgeries it will give sympathetic fibres, through the ganglia, splanchnic nerve, • good results. sympathetic chain, white rami communicants and then 3) Neurolytic blockade: synapse in the dorsal root ganglia. • Most commonly used compounds are alcohol or phenol. • The proximal axon of these cell bodies synapse in the dorsal horn of spinal cord.

Dr Azam’s Notes in Anesthesiology 2013 Celiac Plexus Block.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Alcohol: 3) Premedication: • 50-100% used. • I/V premedication for patients who are anxious and patients with severe • Disadvantage – immediate severe pain. pain. • This can be abolished by using 0.5% bupivacaine and • Avoid premedication if the block is performed for diagnostic purposes. absolute alcohol at a ratio of 1: 1 (Total amount of 50 ml) Procedure: to be used 25 ml on each side). • Sterility has vital importance. Phenol: • Land marks to be marked are: • used as 6% aqueous solution or 12% phenol prepared in 1. Spinous process of T12 and 11 vertebrae. renografin. 2. Inferior border of 12th rib Indications: 3. Site of needle entery is 7-8 cms lateral to the spinus processes in the 1. Pain relief in upper abdominal malignancies originating inferior border of 12th rib. from stomach, pancreas, gall bladder and liver. Needle used: Neurolytic block is indicated. • 12-18 cm long 20-22 G needle with an attached skin marker. 2. Pain after multiple abdominal surgeries. • Infiltrate the skin and muscle with local anaesthetic solution. 3. Local anaesthetic and steroid is usually indicated. • Introduce the needle at the point of needle entry and advance. The 4. For evaluation of upper abdominal pain local direction is towards the L1 spine and proceeds to hit on the 11 vertebral anaesthetic alone is indicated. body. After the vertebral body has reached, a skin marker is placed on 5. Non-malignant pain of upper abdomen e.g. chronic the needle, 2-3 cm from the skin. pancreatitis. • The needle is then withdrawn to the subcutaneous plane and make minor • Here also neurolytic block is indicated. But its long term adjustments and reintroduce laterally until it just slip from the lateral effect is variable. Regeneration of new pathways result in surface of the vertebral body. After the lateral aspect of vertebral body development of different pain syndromes in these has passed a “POP” is often felt when the needle passes through the patients after 6-12 months. psoas fascia. At this point needle approaches the great vessels and should advance slowly. The needle should pass 2-3 cm beyond the Technique: lateral part of vertebral body. 1) Preparation: • After proper placement of the needle a careful aspiration is performed. If • Informed consent to be obtained. blood is encountered, the needle is slowly withdrawn until negative • I/V cannula to be introduced and start an I/V infusion. aspiration is achieved. Alternatively, on the aortic side the needle can be • Resuscitative equipments and drugs must be readily advanced through the aorta until no blood is returned, and injection is available. made at this location. 2) Position: • Prone position with a pillow under the lower abdomen to remove lumbar lordosis. Block can be performed in lateral position also, but needle placement is difficult.

Dr Azam’s Notes in Anesthesiology 2013 Celiac Plexus Block.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Same procedure can be repeated on the other side also. After proper needle placement, 2-3 ml of local anaesthetic containing epinephrine is injected for Celiac Plexus: further test of either I/V or intrathecal placement. If this is negative full dose of local anaesthetic or neurolytic drug can be injected. • Image intensification techniques like radiography, fluoroscopy and CT scan increase the accuracy of celiac plexus block. • Catheter placement can be done in non malignant conditions and can give local anaesthetic infusion for prolonged blockade. • Single needle approach using left side needle and injecting the drug posterior and anterior to aorta is also described. Complications: • Due to blockade of sympathetic fibers. • Hypotension: Can be avoided or minimized by giving I/ V infusion of 500-1000 ml of R.L before the block. Orthostatic hypotension may persist after a neurolytic block. But in most cases, it is self limiting with in a week. Complications due to the technique: • Backache • IVC damage • Injury to blood vessels à retroperitoneal haematoma • Injury to spinal nerves • Injury to kidney • Renal hemorrhage. • Nephro cutaneous fistula Complications due to local anaesthetic/neurolytic agent 1. I/V injection can lead to toxicity. 2. Intrathecal injection can produce total spinal block.

Dr Azam’s Notes in Anesthesiology 2013 19. Interscalene Block: Dr Azam’s Notes in Anesthesiology 2013

INTERSCALENE BLOCK. Drug: Indications: • 20-30 ml of (mixture of 1 – 1.5% lignocaine with adrenaline 1 in • Shoulder joint surgeries, reduction of shoulder dislocation 2 lakhs with 0.5% bupivacaine. • Surgery on the clavicle • Soda bicarbonate can be added to the solution to hasten the • Surgery on the humerus onset of block. Contraindications: Complications: • Severe lung disease with decrease in vital capacity • Phrenic nerve injury (30% decrease in vital capacity) • Coagulopathies • Recurrent laryngeal nerve damage • Infection at the site of injection • Hornerʼs syndrome • Uncooperative patients • Inadvertent extradural/spinal injection Technique: • Inadvertent vertebral artery injection (Avoid bilateral blocks) Patient position: • Local anaesthetic toxicity • Supine, head turned to the opposite side, arm by the side of • Haematoma, Ecchymosis the patient, snifﬁng or lifting the head by the patient to • Total spinal identify the interscalene groove. Missed nerves: Anatomical Landmarks: The ulnar nerve may be missed • Cricoid cartilage • Level of C6 • Lateral border of sternomastoid • Interscalene groove Needle: • 25 G insulated needle if nerve locator is used or a 22 G 1 ½ inch needle. Puncture site: • In the interscalene groove at the level of cricoid.

Direction of needle: • Medial, caudal (at an angle of 30 degree to the sagittal plane) and slightly dorsal, directed to the transverse process of C6. End point: • Eliciting twitches (at a current of 0.4mA or less) or paraesthesia or click.

Dr Azam’s Notes in Anesthesiology 2013 20.Gasserian Ganglion Block. Dr Azam’s Notes in Anesthesiology 2013

GASSERIAN GANGLION BLOCK: (Meckelʼs cave) Technique: 1. Sitting / supine • Its also called as trigeminal ganglion block. 2. Insert a 10 cm,22G needle, 3-inch, lateral to the angle of the • Used for trigeminal neuralgia mouth or immediately medial to the masseter muscle which is Anatomy: deﬁned by asking the patient to clench his teeth. • The trigeminal ganglion is located intra-cranially, 3. It is advanced posteromedially and angled superiorly towards posterior & superior to the foramen ovale. midpoint of zygomatic arch à for nearly 5 cm depth. • It is partially contained in the reﬂection of duramater 4. Contact with infra temporal plane obtained. called the Meckels cave. • Now withdraw and slightly elevate to reach foramen ovale. • Exit through foramen ovale present in the base of • Inject 1cc procaine or alcohol lateral pterygoid plate just in front of TMJ. • Can be done under propofol anesthesia to ↓ pain. • The Ganglion divides into 3 principle divisions namely: Complications: • Opthalmic division • Pain • Maxillary division • Hematoma formation • Mandibular division • Dry eye due to paralysis of ophthalmic division. • Sub Arachanoid injection. • They supply: • Blockade of other C.N. • Forehead, upper jaw, mandibular nerve gives a motor branch to the muscles of mastication.

Landmarks: • Skin over lying upper 2nd molar tooth a wheal is raised. • Midpoint of zygomatic arch • Pupil

Agents used: • LA • Bupivacaine • Lignocaine

Dr Azam’s Notes in Anesthesiology 2013 21. Maxillary Block. Dr Azam’s Notes in Anesthesiology 2013

Maxillary Block: Complications: • Haematoma formation • Due to close association of the maxillary nerve with the infra orbital ﬁssure, the local anaesthetic can spread into the orbit and cause temporary blindness.

Indication: • To evaluate facial neuralgia. • To facilitate surgical procedures in its cutaneous distribution.

Anatomy: • The nerve exits through the foramen rotundum and passes through the pterygopalatine fossa medial to the lateral pterygoid plate on its way to-enter the infra orbital ﬁssure.

Techniques: • The patient is positioned supine, with the head and neck rotated to the opposite direction. • The mandibular notch is palpated by asking him to open and close his mouth. A 22G, 8 cm needle is inserted through the notch in a slightly cephalomedial direction. • The needle will contact the lateral pterygoid plate at a depth of approximately 5 cm. • The needle is withdrawn and in a stepwise manner walked off the plate into the fossa. 3-5 ml. of the solution can be injected.

Dr Azam’s Notes in Anesthesiology 2013 22. Mandibular Block. Dr Azam’s Notes in Anesthesiology 2013

Mandibular Block Anatomy: • It exits from the cranium via the foramen ovale and is parallel to the posterior margin of the lateral pterygoid plate and descends inferiorly and laterally towards the mandible. • The nerve innervates the skin overlying the lower jaw and antero superior to the ear. • The branches are: 1. Buccal nerve 2. Auriculotemporal nerve 3. Lingual nerve

Technique: • Patient in supine, head and neck turned to the opposite direction, mandibular notch is identiﬁed. • Needle is inserted in the mid point of the notch and directed cephalomedial to reach the lateral pterygoid plate. • The needle is withdrawn and redirected stepwise to walk off the posterior border of the lateral pterygoid plate 5 ml of solution is injected.

Complications: • Haematoma formation • Subarachnoid spread

Dr Azam’s Notes in Anesthesiology 2013 22. Glossopharyngeal Nerve block. Dr Azam’s Notes in Anesthesiology 2013

Glossopharyngeal Nerve Block. • Leaves skull through Jugular foramen along with X and XI CN. • Supplies: pharynx, tonsils, soft palate, posterior 1/3 of tongue.

Technique: • Mark point midway between mastoid and angle of mandible. • Insert needle 2-4 cm depth to reach styloid process. • With draw and slip backward about 0.5 cm to block the N. Indications: 1. Surgery on tongue. 2. Neuralgia 3. Awake intubation 4. Ca tongue to relieve pain.

• Gag reﬂex: elicited by touching root of tongue and posterior wall of pharynx. • Afferent: glossopharyngeal nerve. • Indication: direct laryngoscope and awake intubation. • Inject: 2 cc 2% lidocaine at the base of anterior tonsillar pillar (palatoglossal arch).

Dr Azam’s Notes in Anesthesiology 2013 23. Superior Laryngeal Nerve block. Dr Azam’s Notes in Anesthesiology 2013

Superior laryngeal nerve block: • Supplies sensory to supra glottic region. Anatomy • branch of vagus. • It can be blocked before it enters larynx through thyrohyoid M.

Technique: • Locate greater cornu of hyoid with index ﬁnger. Insert needle to touch the bone and then slip back and inject 2 ml 2% Lidocaine.

Indication: 1. Awake intubation. 2. Laryngectomy. 3. T.B. 4. Laryngitis 5. Ca larynx.

Complications: • Injury to surrounding structures. • Difﬁcult in phonation, cough, deglutition.

Dr Azam’s Notes in Anesthesiology 2013 24. Stellate Ganglion Block Dr Azam’s Notes in Anesthesiology 2013

• It is also called as cervico thoracic sympathetic block Supplies: • Gray rami to C7, C8 • Inferior cervical / cardiac nerves Anatomy: • May communicate with vagus. • Fusion lowest 3 cervical C6,7,8 T1 ganglion + 1st thoracic ganglion. • 1-3 cm long. Indications: • Differs in same person on 2 sides • Vascular Pain relief • Leriche and pontaine – 1934 – for CVA. • Accidental injection of thiopentone in artery • Usually cervical – stellate – T2, T3, T4 are also block interruption of • Raynauds disease sympathetic ﬁbers of head and neck, arm and thorax. • Vascular anastomosis • Thromboembolism Landmark: • Occlusive vascular disease • C7, 1st rib, T1 transverse process. • Neoplasms • Behind subclavian artery and origin of vertebral artery. • Phantom limb pain • Posterior to carotid sheath. • Herpes zoster • Anterior to C8, T1 nerves. • Causalgia • Right side – anterior relation – apex of lung and dome of pleura • Pagetʼs disease • Left side these are 2.5cm lower. • Pain due to CNS lesion

Technique Signs of stellate block: (Horner-Bernasds sign/syndrome) Anterolateral: I. Principal signs: Miosis, Enophthalmos (Bernards sign), • Locate midpoint of clavicle, raise skin wheal 1 cm above. Ptosis (Hornerʼs law), Narrowing of palpebral ﬁssure. • Palpate transverse process of C6 (anterior tubercle or Chassaignac II. Supplementary signs: tubercle or carotid tubercle) 1. Conjuctival injection • Insert needle here and direct it medially, backward and downward 2. Congested nostril to contact 1st rib neck or C7, transverse vertebra. 3. Flushed face • Now redirect more medially to contact body of C7 vertebrae and 4. Anhidrosis inject 10ml. 5. Improved blood ﬂow to arm: warmth Anterior approach: • Locate a point 2cm above medial end of clavicle. • At cricoid level is upper border of C6 vertebrae and palpate Chassaignac tubercle just lateral here. • 2 cm below is C7 vertebrae. • Palpate trachea and carotid vessels here. • Insert needle lateral to trachea until it impinges on body of C7 vertebrae about 2-3 cm deep. Inject 10cc. 47

Dr Azam’s Notes in Anesthesiology 2013 24. Interscalene Block. Dr Azam’s Notes in Anesthesiology 2013

INTERSCALENE BLOCK. End point: • Eliciting twitches (at a current of 0.4mA or less) or paraesthesia Indications: or click. • Shoulder joint surgeries, reduction of shoulder dislocation • Surgery on the clavicle Drug: • Surgery on the humerus • 20-30 ml of (mixture of 1 – 1.5% lignocaine with adrenaline 1 in 2 lakhs with 0.5% bupivacaine. Soda bicarbonate can be Contraindications: added to the solution to hasten the onset of block. • Severe lung disease with decrease in vital capacity • Coagulopathies Complications: • Infection at the site of injection • Phrenic nerve injury (30% decrease in vital capacity) • Uncooperative patients • Recurrent laryngeal nerve damage • Hornerʼs syndrome Technique: • Inadvertent extradural/spinal injection Patient position: • Inadvertent vertebral artery injection (Avoid bilateral blocks) • Supine, head turned to the opposite side, arm by the side of • Local anaesthetic toxicity the patient, snifﬁng or lifting the head by the patient to identify • Haematoma, Ecchymosis the interscalene groove. • Total spinal

Anatomical Landmarks: Missed nerves: • Cricoid cartilage • The ulnar nerve may be missed • Level of C6 • Lateral border of sternomastoid • Interscalene groove

Needle: • 25 G insulated needle if nerve locator is used or a 22 G 1 ½ inch needle.

Puncture site: • In the interscalene groove at the level of cricoid. Direction of needle: • Medial, caudal (at an angle of 30 degree to the sagittal plane) and slightly dorsal, directed to the transverse process of C6.

Dr Azam’s Notes in Anesthesiology 2013 25. Supraclavicular Nerve block. Dr Azam’s Notes in Anesthesiology 2013

Mainly two types, Endpoint: • classical Kulenkampff and • Eliciting twitches or paraesthesia or click • plumb bob approach. Drug: Indication: • 8-10 ml of local anaesthetic per division • Operations of the upper arm lower arm and hand. Complications: • Contraindications: Phrenic nerve damage • Haemorrhagic diathesis • Recurrent laryngeal nerve damage • Contralateral phrenic nerve paralysis • Homer's syndrome • Contralateral recurrent laryngeal nerve paralysis • Subclavian artery puncture • Contralateral pneumothorax • Pneumothorax • Children (relative contraindication) • • Narrow-chested patients Missed nerve: • Bilateral supraclavicular brachial plexus block • Median nerve may be missed. Technique: Practical Tips: Patient position: Coughing by the patient while paraesthesia is being sought may indicate • Supine with the head turned to the opposite side, arm as • down as possible, that is hand touching the knee. pleural puncture, and the procedure must be discontinued. • A chest X-ray will reveal any possible pneumothorax. Landmarks: • The patient should be observed for24 hours. • Midpoint of the clavicle • Puncture of the subclavian artery indicates that the needle has been • Subclavian pulsation inserted too far medially. • External jugular vein • The plexus should be sought more laterally.

Needle: • 25 G insulated needle or a 22G, 2 inch needle.

Puncture site: • Immediately dorsolateral from the palpated pulsation of the subclavian artery 5H cm posterior to the midpoint of the clavicle.

Direction of needle: • Caudal direction and slightly lateral, parellel to the scalene muscles to contact the ﬁrst rib. 49

Dr Azam’s Notes in Anesthesiology 2013 26. Axillary Nerve Block. Dr Azam’s Notes in Anesthesiology 2013

AXILLARY BLOCK Perivascular injection: • Major nerves are blocked at the level of the third part of the • A needle is advanced superior to the artery, till a fascial click is felt. axillary artery. Subclavian artery, at the lateral border of the • The proximity of the artery within the sheath can be observed by 1st rib continues as the axillary artery . seeing the transmitted pulsation. 30-40 ml of solution is injected after • Pectoralis minor divides the axillary artery into 3 parts at the negative aspiration. lateral border of the muscle. • Alternatively, 15-20 ml solution can be injected above and below the • The median nerve lies anterosuperior to the artery, the ulnar artery, after placing the needle in the sheath. nerve lies anteroinferiror and the radial nerve lies posterior . • The musculocutaneous nerve has already left the sheath Disadvantage: and lies in the substance of the coracobrachialis. • Musculocutaneous nerve is missed, which can be blocked by injecting 5 ml of local anaesthetic into the substance of the Technique: coracobrachialis. • Position the patient supine with the arm at right angle to the body and the elbow ﬂexed at 90 degrees, The dorsum of the hand rests on a pillow to prevent forward displacement of the humerus. • The artery is palpated as proximally in the axilla as possible.

Transarterial technique: • A 22/25G needle is introduced till bright red blood is aspirated and is then advanced posterior to the artery. • Drug is injected posterior to the artery or half the solution is injected posterior and half anterior, the total volume being 40 ml.

Elicitation of paraesthesia: • This can be done by inserting the needle near the location of the nerve and 10 ml is injected at each nerve.

Dr Azam’s Notes in Anesthesiology 2013 27. Wrist Block. Dr Azam’s Notes in Anesthesiology 2013

• Median nerve: • It lies deep between the flexor carpiradialis and the palmaris longus tendon, which is identified by asking the patient to flex his wrist after making a fist. • A small gauge needle is inserted between the tendons at a point 2-3 cm proximal to the wrist crease; loss resistance will be felt as the needle passes through the retinaculum. 2-4 ml of solution injected.

Ulnar nerve: • It lies immediately lateral to the tendon of ﬂexor carpi ulnaris and medial to the ulnar artery. • The tendon and artery are palpated immediately proximal to the styloid. • A small gauge, needle is inserted perpendicular to the wrist at this point and 3-5 ml of solution is injected after eliciting paraesthesia or in a fan like manner.

Radial Nerve: • Field block is performed at the subcutaneous level in and around the anatomical snuff box. • The extensor pollicis longus tendon is identiﬁed and the needle is inserted above the tendon at the base of the ﬁrst metacarpal. 2-3 ml is injected proximally along the tendon, which crosses the anatomical snuff box.

Dr Azam’s Notes in Anesthesiology 2013 28. Autonomic Blockade Dr Azam’s Notes in Anesthesiology 2013

AUTONOMIC BLOCKADE Treatment: • Sympathetic outflow – thoraco lumbar • Preloading 10-20 ml/kg of IV fluids. • Parasympathetic outflow - cranio-sacral. • Excessive / symptomatic bradycardia should be treated with Atropine. • Sympathetic preganglionic fibers exit spinal cord from T1 to • Hypotension with vasopressors. L2 level. • Direct α adregnergic agonist (phenylephrine ↑ venous tone, arteriolar • Neuraxial block does not block vagal nerve. constriction. • Neuraxial block primarily results in varying degrees of • Ephedrine (direct β adrenergic effects) ↑HR and contractility indirect sympathetic block and physiological responses, resulting effects – vasoconstriction. from ↓ sympathetic tone and / or unopposed parasympathetic toe.

CVS manifestations: • Neuraxial blocks typically produce variable ↓ in BP that may be accompanied by a ↓ in the HR and cardiac contractility. • Vasomotor tone is primarily determined by sympathetic ﬁbers arising from T5 to L1, innervating arterial venous smooth muscle. • Blocking these nerves causes • Vasodilatation of venous capacitance vessel. • Pooling of blood. • venous return to heart

Arterial vasodilatation may ↓SVR à the effects of which may be minimized by compensatory vasoconstriction above the level of block.

A high spinal block: • Prevents compensatory vaso constriction. • Blocks sympathetic cardiac accelerator ﬁbers that arise at T1- T4. • Profound hypotension may result form • Vasodilation • Bradycardia • ↓ contractility.

Dr Azam’s Notes in Anesthesiology 2013 29. Sympathetic Blocks. Dr Azam’s Notes in Anesthesiology 2013

SYMPATHETIC BLOCKS Testing the completeness of sympathetic blockade. General description. Sympathetic function: Continuation: Benefits of sympathetic blockade • Doppler technique • To produce pain relief. • Electromagnetic flow meter • To improve blood flow in vasospastic disorders • Laser Doppler flowmetry • To improve drainage of local edema. • Pulse wave • Temperature Indications for sympathetic blockade: • Distal perfusion pressure 1. Obliterative arterial disease. • Capillary O2 tension 2. Renal colic • Metabolism. 3. Acute pancreatitis 4. Pancreatic cancer pain Pain: Pain score, analgesic requirements, activity. 5. Cardiac pain 6. Pagets disease of bone Contraindications of sympathetic block: 7. Reflex sympathetic dystrophy • Patient on heparin. 8. Phantom limb pain • Bilateral blocks avoided. 9. Central pain • Bilateral injection in the lumbar region for permanent blockade 10.Raynaud's disease cause loss of ejaculation. 11.Accidental intra arterial injection of thiopentone 12.Early frostbite Agents used for sympathetic blockade: • For short term: local anaesthetics used. For permanent block Testing the completeness of sympathetic blockade. (chemical sympathectomy). Sympathetic function: 1. 6 – 7% phenol in water. • Skin conductance response (SCR) 2. 7 – 10% phenol in water soluble contrast medium. Or Ex: Angiographin, omnipaque. • Sympathogalvanic response (SGR) 3. 50 – 100% alcohol. • Skin potential response 4. Aluminum salt • Sweat test 5. Sulpate. 1. Ninhydrin test – relies on sweat protein to change color to yellow 6. Glycerol 50% 2. Cobalt blue test – filter papers which are saturated with cobalt blue; sweat changes paper color to pink For Celiac Plexus refer question on celiac plexus: 3. Starch-iodine test – relies on color change • Skin plethysmography and ice response • Blood flow • Plethysmography (Muscle and skin) • Xenon – 133 clearance • Sodium – 24 clearance 53

Dr Azam’s Notes in Anesthesiology 2013 30. Lumbar Sympathetic Block. Dr Azam’s Notes in Anesthesiology 2013

Indications Lumbar sympathetic blockade is indicated for diagnosis, prognosis, and therapy of circulatory and painful conditions such as:

Circulatory Inoperable peripheral vascular disease and vasospastic disease of the lower extremities

Anatomy: • Ganglion lie on anterolateral surface of the body of lumbar vertebrae. • Inject at L2 or L3 level. • Injection 25 ml 0.25% bupivacaine. • 22G, 15cms needle used. Drugs • Volume of at 15 – 25ml must be injected Technique: • Short-acting local anesthetic, such as 1% • Ttwo needle. lidocaine, is commonly used for diagnostic • Single injection technique sympathetic block • Bryce smith technique • Longer-acting agents, such as 0.25%- 0.375% Neurolytic agents should be given under x-ray control using bupivacaine, is advantageous for both diagnostic radiopaque contrast medium or therapeutic block • Angiographin • Higher percentages of bupivacaine are typically • Omnipaque not used related to chance of motor block • Epinephrine (adrenaline) or Clonidine may be Indications: added to prolong the effects of the injection. • Artheriosclerotic disease: E.g: gangrene pain, claudication, For Neurolytic Blockade: diabetic gangrene, Buergerʼs disease • Volume of 2 – 4ml at both L3 and L4, using 6 – • TAO 10% phenol or 50 – 100% alcohol • Arterial embolus • Renal Colic Contraindications • Complex regional pain syndrome ( CPRS) • Patients on anticoagulant therapy • Herpes zoster • Hemorrhagic disorder • Phantom limb • Allergies to medications injected • Urogenital pain • Local infection • Hyperhidrosis • Chronic back pain • Tench foot • Failure of ejaculation. 54

Dr Azam’s Notes in Anesthesiology 2013 31. Thoracic Sympathetic Block. Dr Azam’s Notes in Anesthesiology 2013

Technique: In thoracic region somatic block • Locate spine in midline • Measure 5cm lateral from midline • Insert 10cm needle perpendicular to skin to hit rib. • Withdraw and incline 450 so that needle is advanced medially, forward and upward. • Needle will be at intervertebral foramina, inject 5 – 8 cc.

Current Indications: • Painful neuropathic conditions • Certain visceral pain syndromes

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!"#$%&'()) # # # # # # # # # 32. Inter costal Nerve block. Dr Azam’s Notes in Anesthesiology 2013 # Anatomy:# • E"1'&"4#"&/1#+F#P>#,+#P>># # >R#E&1"-8#3"-4#&/8#<01,-# • Q"&/70-)## BR#E+),-"1+"#7?,&/-+?)#7+''?/17&/,)# # :R#N&,-"&2#7?,&/-+?)#I"&/70#I"&/70## #

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Bilateral block is called Bartlett’s block.

Dr Azam’s Notes in Anesthesiology 2013 Inter costal Nerve block.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Indications: Surgical Nonsurgical • Breast surgery • Pain relief from fracture rib. • Lithotripsy • Pleuritic pain • Pacemaker insertion • Pain from ﬂail chest • Umbilical/incisional hernia repair • Thorocostomy / gastrostomy tube • Intra abdominal along with Celiac (ICD) block • Hespes zoster pain • Intra thoracic along with stellate • Differential diagnosis block • Post operative relief in Ex: T10 11 12 appendicectomy.

Complications: • Hypotension • Epidural / spinal • Pneuemothorax • Toxic effects • Catheter can be placed for continuous block.

Technique: • Lateral or semi prone. • 18G Tuohy needle with luer lock syringe used.

Dr Azam’s Notes in Anesthesiology 2013 33. Interpleural block Dr Azam’s Notes in Anesthesiology 2013

Ideal inter costal space is 6th or 7th. Anatomy: • After sterile preparation and drape, the skin is first anesthetized at a • Interpleural block is nothing but placing the local anesthetic • solution in between the two layers of pleura. point 8 to 10 cm lateral from the midline, overlying the top edge of the rib. • Commonly tuohy type of needle is used to place the catheter inside the pleural cavity. • Infiltration is carried deeper with a 4 cm, 22G needle until rib is contacted. • Detected by loss of resistance to air technique. After recontacting the rib with tuohy needle, maintaining firm contact • Avoid during IPPV, since it can mislead U and cause tension • pneumothorax. with the patients back, the needle is gently walked cephalad until it is felt to slide off the superior edge of the rib. • Maintain position for 20-30 minutes to settle the drug. The needle syringe unit is then advanced slowly until entrance into • Analgesia for 5-8 hrs, hence repeat every 8 hrs. • the inter pleural space is detected. ! • The plunger will be pulled in as the negative pressure sucks the air from the syringe.

Drug & Dosage: • Bupivacaine is used either 0.25% and 0.5% • Volume of 20 - 30 ml may be used. (0,4-0.5ml/kg) • Adrenaline is added to decrease the plasma level of the drug. • A continuous infusion can be used. "#$%&'#!()'*$+!,-./-!0#!-1,23!4%)56'*'57$!859:! $)57$):&57(! Indications: Surgical applications: • The needle passes through the skin, subcutaneous tissue, • When combined with general anesthesia, acts pre-emptive analgesia external intercostal muscles, internal intercostal muscle, • It provides postoperative pain relief for: intercostalis intimus & parietal pleura. • Open cholecystectomy • Renal surgeries Technique of Interpleural block: • Unilateral breast surgery • Performed by placing the epidural catheter in the interpleural space. Non-surgical Applications: • The hall mark of this technique is detection of the negative • Multiple rib fracture inter pleural pressure. • Upper limb ischemia, reﬂex sympathetic dystrophy Posterior Approach: • Post herpetic neuralgia • Positioning: • Tumour invasion of brachial plexus, vertebral metastasis. • Lateral or prone: Arms should be in front of the body or off the table to retract the scapula as far anteriorly as possible. 58

Dr Azam’s Notes in Anesthesiology 2013 Interpleural block. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Contraindications: • Lack of consent • Pleural ﬁbrosis • Pleural effusion • Hemo/pneumothorax.

Dr Azam’s Notes in Anesthesiology 2013 34. Perineal Anesthesia Dr Azam’s Notes in Anesthesiology 2013

Perineal anesthesia requires block of 3 nerves: Drugs: Lidocaine 1% • Pudendal nerve • Mepivacaine 1% • Posterior femoral cutaneous nerve • Chlorprocaine 1% • Ilio inguinal nerve •

• Anatomy: formed by anterior divisions of S2 3 4 • Pudendal nerve à S2 3 4 anterior primary divisions. • It passes through à greater sciatic foramen à lesser sciatic Indications: à à foramen ischial spine enters perineum. • Rectal and perineal surgery. • It is blocked just medial and posterior to ischial tuberosity. • Vaginal delivery with episiotomy and outlet forceps • Differential diagnosis of pain. Indication: • Relief of pain form Ca cervix. • Delivery (labour pain, episiotomy pain) • Hemorrhoidectomy • Surgery on perineum. • Anal dilatation. • Forceps delivery Technique Transperineal: by Muller in Germany in 1908. • Lithotomy position, palpate posterior medial margin of tubersity of ischium. Fusest 8cm needle medially and posteriorly to ischium for about 1 inch, inject 5cc L.A., then advance it linch into ischio-rectal fossa & inject 10cc L.A. Bilateral block is necessary. Transvaginal: by wilds in 1954. • Ischial spine located by index finger vaginally. Sacrospinous ligament palpated (attached to spine) needle inserted at these point lateral to finger to avoid fetal parts. Contact spine and go medial and posterior to it and inject 2-3 cc L.A. • Later advance it further through ligament and inject 8cc L.A. Rt finger to block Rt pudendal and vice-versa. Complications: 1) Rectum punctures. 2) Hematoma of thigh 3) Intra vascular injection 4) Fetal damage

Dr Azam’s Notes in Anesthesiology 2013 35. Cutaneous innervations of the lower limb. Dr Azam’s Notes in Anesthesiology 2013

Nerves arising from lumbar plexus are: • Lateral femoral cutaneous nerve (L2, L3) • Femoral nerve (posterior rami of L2-L4) • Obturator nerve (anterior rami of L2-L4) Nerves arising from (Lumbosacral plexus) include: • Posterior cutaneous nerve of the thigh (S1-S3) • Sciatic nerve (L4-L3)

Dr Azam’s Notes in Anesthesiology 2013 36. Cutaneous innervations of upper limb. Dr Azam’s Notes in Anesthesiology 2013

Dr Azam’s Notes in Anesthesiology 2013 37. Psoas Compartment block. Dr Azam’s Notes in Anesthesiology 2013

PSOAS COMPARTMENT BLOCK Complications: • Epidural/ subarachnoid / intravascular injection Anatomy: Peripheral nerve damage • The psoas compartment block utilises a technique in which a needle • is placed between the psoas major and quadratus lumborum • Development of sympathetic block secondary to extravasation muscles. of the local anaesthetic. • It blocks the lumbar plexus at the level of L4-L3 and anesthetizes the Choice of local anaesthetic, dosage and volume: hip and anteromedial thigh. Volumes of less than 20 ml have been associated with Cadaveric dissections have revealed that the lumbar plexus is within • • increased failure rates and volumes greater than 40 ml may the substance of psoas muscle at the level of L5. introduce the risk of local anaesthetic toxicity and central Indications: neuraxial spread. • Used in combination with other nerve blocks for surgery of the thigh The current recommended volume is 30 ml. For the • Used for neuralgia of the thigh and fascia lata pain syndrome. • continuous technique, ropivacaine 0.2% with basal infusion • Postoperative pain relief rates of 6-10 ml h'1 are used. Technique: • With the patient lying in the lateral position and the operative side up, hips and knees are maximally ﬂexed. A line is drawn joining the upper border of the iliac crests (intercristal line). A mark is made where the intercristal line crosses the spine or the spinous interspace of L4. • From this, a mark is made 3 cm caudal and 4 cm lateral. After skin preparation, a wheal is raised and a 22G spinal needle is advanced perpendicular to the skin entry site until it contacts the L5 transverse process. • The needle is then redirected cephalad until it slides off the transverse process. At this point, a needle with a 20 ml syringe attached is slowly advanced until loss of resistance to injection of air is detected. • The depth of the psoas compartment is about 12 cm. 30 ml of local anaesthetic solution can be injected. A nerve stimulator may be used to verify correct needle placement. • While using a nerve stimulator, optimal needle position is conﬁrmed by contraction of the quadriceps muscle. • If contraction of hamstring muscle is elicited, the needle is directed too far medially. • If local anaesthetic is injected at this location the risk of epidural spread is real and should therefore be avoided. 63

Dr Azam’s Notes in Anesthesiology 2013 38. Femoral Nerve Block Dr Azam’s Notes in Anesthesiology 2013

Anatomy: Complications: • The femoral nerve is the largest branch of the lumbar • The femoral nerve block is notable because it is simple to perform plexus. It arises from the dorsal branches of the anterior and has a very low incidence of complications such as peripheral primary divisions of L2, L3, L4 and descends through the nerve injury, haematoma, infection and local anaesthetic toxicity. psoas major to emerge at the lower part of its lateral border. • It passes along the pelvic wall on the iliacus muscle to reach Medial to Lateral: :Vein Artery Nerve the superior pubic ramus and crosses over this beneath the inguinal ligament. • On parsing into the thigh, it lies lateral to the femoral artery and divides into anterior and posterior divisions. • In the thigh, cutaneous branches, arise that innervate the skin of medial and anterior parts as far as the knee.

Indications: • When combined with the lateral femoral cutaneous nerve block, the femoral nerve block provides anaesthesia for many orthopaedic and plastic surgical procedures on the anterior and lateral parts of the thigh and femur. • When combined with a sciatic nerve block, this block provides anaesthesia / analgesia for surgeries on the lower limb.

Landmarks and technique: • With the patient lying supine, the following landmarks are identiﬁed; anterior superior iliac spine, public tubercle, inguinal ligament and femoral artery pulsations. • The inguinal ligament is located between the anterior superior iliac spine and the pubic tubercle. • The femoral artery is palpated and marked below the inguinal ligament. • The needle insertion is 1 cm caudad to the inguinal ligament and 1 cm lateral to the femoral artery. The contraction of quadriceps muscle is sought with the nerve stimulator 20 to 30 ml of local anaesthetic solution is injected. • Evidence of successful block is achieved when the patient is unable perform knee extension. 64

Dr Azam’s Notes in Anesthesiology 2013 39. Obturator Nerve Block. Dr Azam’s Notes in Anesthesiology 2013

OBTURATOR NERVE BLOCK

Anatomy: • The obturator nerve is derived from the lumbar plexus and arises from the ventral divisions of L2, L3 and L4. • The chief contribution is from L3. It descends through the psoas major muscle over the brim of pelvis into the lesser pelvis where it runs along the lateral wall to the upper part of the obturator foramen. • As the nerve enters the thigh, it divides into two branches, anterior and posterior. • The anterior branch supplies the adductor longus, adductor and gracilis and sends a main branch to the hip joint. • The posterior branch supplies the obturator externus, adductor magnus and adductor brevis and sends a branch to the knee joint.

Indications: • Useful as a diagnostic, prognostic or therapeutic procedure in patients with adductor spasm. • For surgeries at the level of or proximal to the knee.

Technique: • The patient is placed supine, the pubic tubercle e is identiﬁed and a skin mark is made 2 cm lateral and 2 cm caudad from this point. • A skin wheal is raised at this point and a 22 G, 3-inch needle is inserted perpendicular to the skin. It is advanced until contact is made with the bone at an approximate depth of 1 to 2 inches. • This is usually the inferior or the horizontal ramus of the pubic bone. • The needle is withdrawn and redirected laterally so that the needle slides off the pubis into the lateral portion of the obturator foramen. • If a nerve stimulator is used, adductor muscle contraction should be sought to correctly locate the obturator nerve 10 ml of local anaesthetic solution is injected and the adequacy of the block conﬁrmed by demonstration of adductor muscle paresis.

Dr Azam’s Notes in Anesthesiology 2013 40. Inguinal Paravascular technique Dr Azam’s Notes in Anesthesiology 2013

INGUINAL PARAVASCULAR TECHNIQUE OF LUMBAR PLEXUS • The anatomical basis for the “3-in-l block” is the concept of a single ANAESTHESIA (WINNEʼS 3 – IN – 1 BLOCK) sheath for a fascial compartment forming a closed space which • Regional anaesthesia of lower limbs has been simpliﬁed by encloses all the nerves involved in the lumbar plexus. a technique that involves blocking three or the four nerves. • Study of the anatomy shows that when these nerves emerge from • Femoral, obturator and the later femoral cutaneous nerves the lumbar plexus, they are sandwiched between the fascial can be blocked with one injection of a large volume of local covering of the quadratus lumborum muscle posteriorly and the anaesthetic into the femoral nerve sheath, just below the psoas major muscle anteriorly. inguinal ligament (Figure 3). • The fascial sheaths of these muscles enclose the three major • The main advantage of this block is that three nerves can be branches of the lumbar plexus. blocked using one injection and the success rate is also • The compartment so formed continues with the femoral nerve and high. extends below the inguinal ligament. • Drugs injected into the femoral sheath will travel upwards along Anatomy: this sheath provided enough volume (more that 2o to 25 ml) is injected and sufﬁcient pressure applied below the site of injection so that cephalad spread is promoted. • The femoral, obturator and the lateral femoral cutaneous nerve will be reached by the solution in this sequence with a similar onset of the block. Indications: • Surgeries on the anterior part of high • Management of fracture shaft of femur • In combination with sciatic nerve block for acute knee injuries. • For knee arthroscopy Technique: • The technique of a 3-in-1 block is very similar to femoral nerve block. When paraesthesia is elicited, at least 20 to 25ml of local anaesthetic solution is used to block the lateral femoral cutaneous nerve which is at the highest level. • Digital pressure is applied below the injection site to promote cephalad spread. The lateral femoral cutaneous nerve is often only partially blocked. • Hence, it is recommended that it be blocked separately at the anterior superior iliac spine

Dr Azam’s Notes in Anesthesiology 2013 41. Sciatic Nerve block. Dr Azam’s Notes in Anesthesiology 2013

• Sciatic nerve block is usually indicated for providing surgical The sciatic nerve and its branches: anaesthesia as well as for postoperative analgesia of the lower Course of the nerve: extremity. Contrary to common belief, this nerve block is relatively • In the pelvis, the nerve lies in front of the pyriformis muscle. It simple 10 perform. enters the gluteal region through the greater sciatic foramen • However, the deep location of this nerve mandates proper training below the pyriformis muscle and runs downwards passing and adequate knowledge of anatomy of the region. between the ischial tuberosity and greater trochanter. • When performed under adequate sedation it has a reported • The nerve enters the thigh at the lower border of the gluteus success rate of 95% when paraesthesia is elicited. maximus and then runs vertically downwards to the popliteal • The use of a nerve stimulator is associated with an even higher fossa where it terminates as the tibial and common peroneal success rate and is therefore recommended for these blocks. nerves. • Motor supply: To the semitendinosus, semimembranosus, long Anatomy: and short head of biceps femoris and ischial head of adductor • The nerve originates from both the lumbar and sacral plexuses and magnus muscle. consists of two major nerve trunks enclosed in a common sheath. • Sensory supply: Cutaneous innervation of the entire lower limb • The tibial nerve trunk consists of ﬁbres from the ventral divisions below the knee (with the exception of a medial strip of the leg) and the common peroneal nerve ﬁbres arise from the dorsal and the foot. divisions of the anterior rami of L4,5S1,2,3 roots . • Articular branches: To the hip joint. Indications: • Surgical procedures on the lower limb in combination with the lumbar plexus or femoral nerve block. • Surgery below the knee combined with a saphenous nerve block • Surgery on the ankle and foot as a sole anaesthetic • Postoperative pain management following surgery on the lower extremity.

Dr Azam’s Notes in Anesthesiology 2013 Sciatic Nerve block.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Techniques Of Sciatic Nerve Block: • Following local skin preparation and identification of the entry point, a • The sciatic nerve can be blocked using several approaches 15 cm-long insulated needle (connected to a nerve stimulator) is and can be performed in the following positions: introduced after infiltration with local anaesthetic (LA). With an initial 1) Supine current intensity of 1.5 mA, the needle is introduced to a depth of 8–13 • Anterior approach cm. The sciatic nerve lies 4-6 cm beyond the anterior surface of the • Lateral approach femur. If the bone is contacted, the needle is withdrawn up to the skin. 2) Lateral • The skin is then moved medially 1.5 to 2 cm and the needle • Posterior parasacral reintrodnced. If bone is contacted again, this is likely to be the lesser • Gluteal and subgluteal approach trochanter. Internal rotation of the foot helps to swing the lesser 3) Prone trochanter posteriorly and allows the passage of the needle. The • Popliteal approach needle position is adjusted to elicit a discernible muscle contraction 4) Lithotomy (extension or plantar flexion of the toes, foot eversion or inversion) with • Raj approach the lowest possible current intensity (0.5 mA for 100 µsec stimulation). • It is hazardous to inject when neural stimulation is still present at 0.3 Anterior approach: mA as the needle tip may lie in the nerve itself. After confirming twitch • This approach is convenient especially in painful conditions, response, 20 to 25 ml of local anaesthetic solution is injected. e.g., following trauma. • This position also allows for the performance of the femoral Lateral approach: nerve block without having to change the position of the High lateral approach: patient. • The greater trochanter is identified and the needle entry point is 3 cm • Since the nerve lies medial and posterior to the lesser distal to the lateral prominence of the greater trochanter. The needle is trochanter of the femur, it can be approached anteriorly near introduced close to the posterior margin of the femur until periosteum the lesser trochanter. is contacted. It is then partially withdrawn and redirected posteromedially to slide posterior to the femoral shaft. The sciatic nerve is Landmarks and technique: contacted at a depth of 10-13 cm. Nerve location is confirmed by • A line is drawn connecting the lower border of the anterior contractions of the calf muscles or the anterior compartment muscles superior iliac spine and the superior aspect of the pubic on nerve stimulation. 20 ml solution is injected. tubercle. This line overlies the inguinal ligament. • A perpendicular is then drawn at the junction of the medial third and lateral two thirds of this line. • The greater trochanter is identified and a third line is drawn parallel to the first line. • The point of intersection of this third line and the perpendicular line is the point of entry of the needle .

Dr Azam’s Notes in Anesthesiology 2013 Sciatic Nerve block.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Low lateral approach: Landmarks for sciatic nerve block by the posterior approach • The groove between the biceps femoris and lateral border of Gluteal and subgluteal approach: the vastus lateral is identified and marked. • These approaches have been more recently described. • A vertical line is drawn from the tip of the patella and the • They involve the identification of the greater trochanter of the point where this line intersects this groove line is the point of femur and the ischial tuberosity as landmarks. needle entry. Gluteal approach: • A 10 cm-long needle connected to a nerve stimulator, is • A straight ling is drawn between the above mentioned two points. introduced at a 30° angle directed posteriorly, after local The entry point of the needle is at the midpoint of this line where it infiltration with LA. is introduced perpendicular to the skin. • Initially, contraction of the biceps femoris and vastus lateralis • At a depth of 5-7 cm, the sciatic nerve is stimulated. 20-30 ml of is elicited due to direct stimulation of the muscles. When the LA is injected. needle is 4-6 cm deep, these contractions disappear. Subgluteal approach: • On further introduction of 1-3 cm, the sciatic nerve • This approach has been found to be simple and reliable. A line is stimulation is observed. drawn between the ischial tuberosity and greater trochanter. • From the midpoint of this line, a perpendicular line is drawn Posterior approach: caudally for 4 cm. • This is the most commonly performed approach and it • At this level, a skin depression can be palpated representing the blocks the nerve at the level of the sciatic notch using the groove between the biceps femoris and semitendinosus muscle. piriformis muscle as the landmark. • A 10 cm insulated needle connected to a nerve stimulator is 0 Position: introduced at an 80 angle and the sciatic nerve located at a depth of 5-7 cm.(20-30 ml of LA is injected.

Lithotomy position (Raj approach): • This approach is useful in obese patients, as they can remain supine with the hip ﬂexed and the leg supported by an assistant. • The patient is positioned in the lateral A line joining the greater trochanter of the femur and the ischial position with the side to be blocked uppermost. The knee of tuberosity is drawn. this limb is ﬂexed with the heel of the foot placed at about • The needle is inserted at the midpoint of this line and the sciatic the level of the contralateral knee. nerve is usually stimulated at a depth of 4-6 cm. A total volume of 18 to 20 ml of local anaesthetic is injected .

Dr Azam’s Notes in Anesthesiology 2013 42. Blocks around the Knee Joint. Dr Azam’s Notes in Anesthesiology 2013

BLOCKS AROUND THE KNEE JOINT • To achieve anaesthesia for surgeries on the foot, branches of sciatic nerve and the saphenous nerve can be conveniently blocked around the knee joint. This technique is particularly useful in situations where edema or inﬂammation around the ankle jeopardizes the success of the ankle block. Indications: • It can be used for all surgeries on the ankle and foot. It can also be used for the diagnosis of myotonia and as an adjunct to physiotherapy for severe equines deformities. Anatomy: • The following nerves are blocked around the knee joint a) tibial nerve and b) common peroneal nerve (branches of sciatic nerve,) and c) saphenous nerve, the terminal branch of the femoral nerve.

Nerves in the popliteal fossa

Dr Azam’s Notes in Anesthesiology 2013 43. Saphenous nerve block. Dr Azam’s Notes in Anesthesiology 2013

SAPHENOUS NERVE BLOCK (L3 – L4) Anatomy: • It courses along the medial side of the knee behind the sartorius muscle and becomes subcutaneous between the tendons of the sartorius and gracilis muscles distal to the medial condyle of the tibia. It has no motor component (no ʻMʼ in saphenous). Cutaneous supply: • Medial, anteromedial and posteromedial aspects of the leg from above the knee to the level of medial malleolus.

Technique:

Distal approach: • A horizontal line is drawn from the tibial tuberosity to a point just distal to the medial tibial condyle. • Along this line, 3-5 ml of local anaesthetic (LA) is inﬁltrated subcutaneously. A nerve stimulator cannot be used to identify this nerve as it has no motor component. Proximal approach: Saphenous nerve block- distal approach • The nerve can be blocked beneath the sartorius muscle. • The needle is inserted at the superior border of patella and 10 ml LA is injected deep to the sartorius muscle between vastus medialis and sartorius muscles. • Alternately, a trans-sartorial approach can also be used. • A Tuohy needle attached to the syringe is inserted one ﬁnger-breadth above the patella through the sartorius muscle till a loss of resistance is encountered and 10 ml of LA is injected.

Dr Azam’s Notes in Anesthesiology 2013 44. Common Peroneal Nerve. Dr Azam’s Notes in Anesthesiology 2013

COMMON PERONEAL NERVE BLOCK (L4-S3) Anatomy: • It traverses along the lateral part of the popliteal fossa just below the biceps femoris tendon. • Motor supply: Extensor muscles of the foot • Cutaneous supply: Lateral aspect of the leg, heel and ankle • Articular branches: To the knee joint. Technique: • Feel for the head of the fibula and palpate for the common peroneal nerve on the neck of the fibula the nerve can be blocked by subcutaneous infiltration of 3-5 ml of local anaesthetic. • If not palpable, the needle is advanced to reach the periosteum of the fibula. It is then slightly withdrawn and 5-7 ml of local anaesthetic is injected. • A nerve stimulator can be used to elicit contraction of anterior compartment muscle.

Common peroneal nerve at the knee joint

Dr Azam’s Notes in Anesthesiology 2013 45. Tibial Nerve. Dr Azam’s Notes in Anesthesiology 2013

TIBIAL NERVE BLOCK (L4 - S2) Anatomy: • The tibial nerve runs along the middle of the popliteal fossa just lateral to the popliteal artery. Motor supply: Flexor muscles on the back of knee joint and calf muscles. Cutaneous supply: Popliteal fossa and posterior portion of leg up to the ankle. Technique: • The nerve lies in the midline of the triangle formed by the tendons and the popliteal crease.

Surface marking and point of needle entry for tibial nerve block

• With the patient lying in prone position, a small pillow is placed under the leg and the knee is mildly flexed. • The medial and lateral borders of the triangle are marked. The popliteal crease is marked to complete the triangle. • A perpendicular is drawn from the midpoint of the line along the popliteal crease. • The point of entry is marked 5 cm proximal to the popliteal crease on this perpendicular line and 1 cm lateral to this line. The needle is advanced at a 45-60° angle in an antero-superior direction. • At a depth of 1.5-2 cm, the nerve is identified by paraesthesia in the posterior aspect of the leg. A nerve stimulator can be used to elicit plantar flexion of the foot. 5 to 7 ml of local anaesthetic solution is injected. • A successful nerve block is confirmed by sensory 73

Dr Azam’s Notes in Anesthesiology 2013 46. Complications of Spinal & Epidural Anesthesia. Dr Azam’s Notes in Anesthesiology 2013

1. Hypotension > 25% (on < 90% in normotension). 2. Cardiac arrest 3. Respiratory failure 4. Failed spinal blockade 5. High or total spinal blockade (subdural injection) 6. Post dural puncture headache (PDPH) – nuchal rigidity 7. Backache 8. Neurological complications o Trauma to spinal cord o Cauda equina syndrome. o Spinal cord infarction o Space occupying lesion o Meningitis 9. Transient neurologic symptoms: • Urinary retention (S2, S4) Immediate complications – (1) to (5) + 9 Delayed or late complications (6) to (8) I. Hypotension: treatment II. Head down III. I.V. ﬂuid (preload 10-15 ml/kg) IV. O2 V. Vasopressor therapy VI. HTN treatment sodium Nitroprusside 30- 60gm NTG > 0.6 g. VII. Respiratory insufﬁciency; O2 therapy and ventilatory support.

COMPLICATIONS OF EPIDURAL ANAESTHESIA Above 1 – 9 + • Epidural abscess. • Spinal or epidural hematoma. • Sub dural injection

Dr Azam’s Notes in Anesthesiology 2013 47. IVRA Dr Azam’s Notes in Anesthesiology 2013

• 1908 - Bier, local anaesthetic introduced intravenously. Tourniquet application: • 1908 - Ramsohoft, introduced agent intra-arterially. • Cuff placed proximal end of surgical site and inflated 50-100 mg Hg above systolic pressure. Never deflate cuff 20-30 mins have Mechanism: elapsed ofter injection of LA. No cuff should be placed > 2 hrs. • Local anaesthetic administered intravenously have • Holemar introduced two cuff technique, a second one is placed just direct action on blood vessel walls causing distal to primary one. vasodilatation. • st • These agents diffuse into tissues and produces Tourniquet discomfort of 1 cuff may be due to tightness and it can be anaesthetic block to small nerve fibers and nerve alleviated by subcutaneous infiltration or applying a 2nd tourniquet. trunks. • Injection of a dilutent solution of LA through the cannula, usually • Greater localization seen towards traumatized tissues used is lidocaine (2 hrs). (8-10 times) • Bupivacaine (contraindicated because of risk of cardiac toxicity). • Rapid and intense analgesia à tetracaine. Indication: • Pre-warming of LA up to 300C lessens patient discomfort. • Below elbow and below knee operations. • Ketamine à 40 ml of 0.5% limited use (development of • Tendon operation, hand abscess, FB removal, colles unconsciousness with in few min). fractures, carpal tunnel release. • Pentazocine + pancuronium potentiate action of LA. • Elderly and children ASA I, II, III Dosage: Technique: • A volume dose relationship is involved. • Reassurance to the patient • Procaine or lidocaine 1.5 – 3 mg/kg. • I.V. canula is inserted (in the distal vein to operative • Upper limbs 3mg/kg of 0.5% (40-50 ml) site). • Lower limbs 3 mg/kg of 0.25% (80-100 ml) • Production of ischaemic limb • Blood volume of upper limbs 3% of total blood volume. • Exsanguination • Blood volume of lower limbs 9% of total blood volume. • Gravity (elevation of limb 2-3 mins) Response: • Esmarch bandage (distal to proximal) • Pale skin à excellent exsanguination (Cutis marmorata) • This enhances the effectiveness of technique. This • Successful blocks à Complete sensory block. ischemic period will decrease the amount of LA. à Motor paralysis of extremity à Absence of subjective complaints à Desirable that patient awake and responsive

Dr Azam’s Notes in Anesthesiology 2013 IVRA. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Kinetics of distribution of drugs: Adverse effects: • Venous system à peripheral superficial veins and fills large CNS: superficial veins à small veins of muscles à deep veins à • Temporary dizziness, nystagmus, drowsiness, mild seizures and perforating veins à retrograde filling of venules à convulsions. capillaries à extravascular space by diffusion à tissues. EEG: Reduction in alpha activity • Largest concentration à nerve tissue. • • Increase in low frequency. The amount of drug that enters the general circulation on • High amplitude waves. ECG: release of tourniquet depends on Mild bradycardia 1. Concentration of agent • Decrease in ʻTʼ wave amplitude 2. Volume injected •

3. Duration of regional vascular containment Effect of NMJ: When nerves are considered, the fibres for distal distribution • LA produces a definite pre-junctional block and a curare like are blocked first so that anaesthesia develops from the • attachment to cholinergic receptors at the muscle end plate. finger tip upwards. • Advantage: Simple, rapid recovery, rapid onset, muscular relaxation and controllable extent of anaesthesia,patient awake, oral feeding Release of tourniquet: can be allowed, early ambulation. • Planned cyclic intermittent release of tourniquet: It is excellent technique for most procedure (< 90 mins) both for open • Deflation of tourniquet to zero and immediate reinflation. • and closed reductions of bony fractures. • After 1 min, 2nd deflation to zero for 10 sec then reinflation. • After 2 min, 3rd deflation to zero for 30 sec and reinflation. • After 3 min, last deflation to zero and no reinflation.

During deﬂation we see complaints such as a) Buzzing b) Dizziness c) Metallic taste

Recovery: • After complete release of tourniquet. • Return of sensory nerve function à 1-5 min • Anaesthesia seldom present after à 10 min • Reactions occurs when LA enters general circulation • Release of tourniquet too early • Release of proximal cuff when distal one in not fully inﬂated.

Dr Azam’s Notes in Anesthesiology 2013 IVRA. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Complications: • Toxic reactions after release of tourniquet • Post operative pain due to rapid recovery • Tourniquet pain • Restricts surgery time because of tourniquet • Oozing of LA into the surgical ﬁeld of large volume used. • Nerve injury at edges of tourniquet • Neuropraxia • Axonotmesis • Neurotmesis Lower extremity Beir type blocks (Lehman Jones Block): A failure rate of about 15% occurs with thigh tourniquet technique. A large volume of drug is needed and because the concentration is low to use with in 80 ml dose range the anaesthetic block is often incomplete.

IVRA: - Upper limb – Bierʼs blow - Lower limb – Lehman Jones Block

Dr Azam’s Notes in Anesthesiology 2013 48. Anatomy of vertebral column & physiology of spinal anesthesia. Dr Azam’s Notes in Anesthesiology 2013

Vertebral column: There are 7 processes: • The vertebral column (The spine or back bone) forms the central axis of the skeleton and forms a canal which • 3 muscular processes: 2 transverse, 1 spinous functions to protect the spinal cord. • 4 articular processes: 2 upper and 2 lower.

Made up of 34 vertebra: There are certain gaps between any two vertebrae these are: • 7 – cervical 1. The lateral intervertebral foramen: the spinal nerves emerge • 12 – thoracic through this gap. • 5 – lumbar 2. The posterior inter laminar gap. • 5 – sacral and • In extended position: it is triangular and small. • 4 to 5 – coccygeal vertebrae. • In flexed position: Diamond shaped. • It is the site where spinal puncture is done for spinal or epidural In the adult normal spinal column has 4 curves when patient is space. supine and horizontal. Articulation of the vertebrae is by ligamentous connections: • Cervical curve – convexity anterior There are 5 ligaments. • Dorsal curve – convexity posterior • Supraspinous ligament: Strong thick fibrous band connecting the • Lumbar curve – convexity anterior apices of the spines. • Sacrococcygeal curve – convexity posterior. • Interspinous ligament: Thin, fibrous structure connecting adjacent spines. • The high point of spinal curve when the patient is supine • Ligamentum flavum: Consists of yellow elastic tissue, extend between laminae. and horizontal is at L3 vertebra and low point at T5 vertebra. • Thus solution heavier than spinal fluid deposited at L3 will • Posterior longitudinal ligament. flow away both cranial and caudad. • Anterior longitudinal ligament.

Abnormal curves may be: • Kyphosis – an exaggerated A-P dorsal curve. • Lordosis – an exaggerated lumber curve. • Scoliosis – an exaggerated lateral curve.

A typical lumbar vertebra: composed of two parts. • Body or base anteriorly which bears weight. • The arch – which surrounds the cord laterally and posteriorly consisting of lamina and pedicles.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

• Ossification of vertebra: 3 primary centers ( 7-8 wks)- 1 for body and Primary curves: 1 • Present from birth • each for vertebral arch. • Thoracic sacrococcygeal • 3 secondary centers: 1 each for transverse process (16 th yr ) and 1 for spinous process Secondary curves: Topographic line of tuffier: • Develop later in life • A line across the back between the crests of ilica passes over the th • Cervical lumbar concave spine of the 4 lumbar vertebra in upright position. • It passes over the interspace between 4th and 5th lumbar vertebrae when patient is lying in the lateral position. • This line serve as a surface landmark on the back for the identification and numbering of the interspaces between the spinous process of the vertebrae.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Intervertebral disc: SPINAL CORD Present between bodies of the vertebrae. • • It is the cylindrical mass of nervous tissue. Each disc consists of a fibrous outer covering “annulus • • Length 42-45 cms. Weight – 30 gm. fibrosus”, which encloses a core of gelatinous material “the • Occupy upper 2/3 of the vertebral canal. nucleus pulposus”. • Rostral end is continuos with the medulla oblongata. Acts as a shock absorbed and gives flexibility to the vert- • • Extends caudally to either lower border of L1 vertebra or upper column. border of L2 vertebra. ʻProlapsed discʼ: A protrusion of the nucleus pulposus can • • Form the conical lower end – ʻconus medullariesʼ. occur following careless technique of lumbar puncture. • “The filum terminale” – a delicate filament stretches from conus medullaries to the first segment of the coccyx. Venous plexus of the vertebral column: These are: Developmental anatomy: External plexus: Marked in cervical region. • At birth the tip of the spinal cord lies at the level of lower border of - Lie outside the vertebral canal. 3rd lumbar vertebra and dural sac at the 3rd sacral vertebra. - They communicate freely. • After birth, the lengthening and growth of the cord as well as Internal plexus: meninges lag behind the growth of the bony vetebra. Lie inside the canal between dura matter and the vertebra. • • This differential growth rate results in the development of the • Get tributaries from spinal cord and bone. epidural space and the caudal space. Freely communicate each other. • • The spinal cord becomed relatively free of itʼs dura, but is surrounded by arachnoid and is engulfed in the CSF in the SAS. Basivertebral veins: Results in the downward fanning of the spinal nerves, forming Present in the substance of the bodies. • ʻcauda equineʼ. Communicate through openings on vertebral surface to external vertebral plexus and dorsally with internal vertebral Internal structure: plexus. • On cross section, spinal cord consists of The intervertebral veins: A central grey matter (cell bodies) Accompany the spinal nerves through intervertebral • • Outer white matter (fibres) foramina. • • Tributaries are spinal cord veins, internal and external vertebral plexus. • End is segmental veins – they are: vertebral, intercostals and sacral veins. • These finally drain into Azygous and Hemiazygous veins à Superior venacava.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Spinal nerve roots: Posterior spinal arteries: • There are 31 pairs of spinal nerves attached to spinal cord. • 4 longitudinal running vessels – 2 on each side. • Each nerve arises form a ventral and dorsal nerve roots – • One lies in front of the dorsal nerve root and the other behind it. which unite in the intervertebral foramina to form spinal • Derived – either directly from vertebral artery or from primary branch of nerve trunks – which soon divide into anterior and posterior posterior inferior cerebellar artery. primary divisions. • Supplies posterior 1/3 of spinal cord. • It is block of spinal nerve roots which produces typical effect in spinal analgesia. Reinforcement of arterial supply: Formation of spinal nerves: • Spinal radicular branches: arises from local segmental arteries like • The dural sac consisting of the dura mater and the vertebral, ascending cervical, posterior intercostals, spinal lumbar and arachnoid mater: the pia mater coverage the spinal cord lateral spinal arteries – these enter vertebral canal through and projecting laterally as the denticulate ligaments intervertebral foramina. separating the rows of dorsal and ventral rootlets. • One of the radicular branch is considerably larger termed. ʻArteria • Cerebrospinal fluid circulates between pia and arachnoid. In radicularies Magnaʼ or ʻArtery of Adamkeiwiczʼ. It may be responsible the subarachnoid space: for major blood supply of lower 2/3 of spinal cord in 50% of population. • On each side, two rows of rootlets attach to the cord; the dorsal filaments carry sensory information to the central Venous drainage: nervous system; the ventral filaments convey motor Veins of the spinal cord are situated in the pia matter, and drain information from the central nervous system to the parenchyma of the cord. periphery: They are 6 in number and form longitudinal plexiform channels. • A number of rootlets combine to form at each segment They are 1) Two median longitudinal veins: anterior and posterior. dorsal and ventral roots: 2) 4 lateral longitudinal veins. • The swollen area on the dorsal root the spinal (dorsal root) • These veins communicate with internal vertebral plexus and drain ganglion contains cell boodles of sensory neurons: finally into external vertebral plexus. • Dorsal and ventral roots unite to form a spinal nerve: • At the base of the skull, some veins drains into internal vertebral plexus • Dura (and arachnoid) continues as a sheath around nerves and others drain into cranial venous sinuses – ending in inferior leaving the spinal cord. petrosal sinuses. Blood supply: • Arterial supply: from one anterior and two pairs of posterior Blood flow: spinal arteries. • Perfusion pressure range à 60 – 120 mm Hg. Anterior spinal artery: • Average flow à 60 ml/gm/min at 60 mm Hg pp. • Formed at the foramen magnum. • Gray matter flow à 40 ml / 100 gm / min. • Branch of terminal portion of each vertebral artery. • White matter flow à 8 – 12 / 100 gm min. • Lies in the midline on the anterior median fissure. • Supplies anterior 2/3 of the spinal cord.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Regulation of spinal cord circulation: Arachnoid matter: The circulation to spinal cord and cord perfusion dependent on: • It is membrane of spider web delicacy, which lines the dural • MAP sheath and sends prolongations along each nerve root. • Integrity of circulation • Above it is continuous with cerebral arachnoid. • Autoregulation at the micro circulatory level. • If P.P. is reduced to 50 mm Hg Spinal cord blood flow is The pia matter: reduced. • It is the innermost of 3 membranes. • Intrinsic regulation is dependent largely on normal tissue Co2, • It is a vascular connective tissue sheath which closely invests PaCo2, Po2 and PH and cord temperature. the brain and spinal cord and projects into their sulci and • Hypoxia and hypercarbia – increases blood flow. fissures. • Hypocarbia and hypothermia – decreases blood flow • Anteriorly it is thickened into ʻlinea splendensʼ along the length of the anterior median fissure. On either side it forms Meninges of the spinal cord: ligamentum denticulatum, which is attached to dural sheath. • Spinal cord has 3 covering membranes or meninges: The Dura • Posteriorly it forms posterior subarachnoid septum passing matter, Arachnoid matter and Pia matter. from the posterior median sulcus of the cord back wards to the dura. Dura matter: • Inferiorly it continues as filum terminale, with a covering sheath • Dural covering of the brain is double membrane. of dura attached to the coccyx. • Dural covering of spinal cord is a continuation of the inner layer (meningeal layer) of the cerebral dura. Nerve supply of meninges: • Made up of dense fibrous tissue. The posterior (unlike the anterior) aspect of the drua and nd • • Dural sac extends to the level of 2 sacral segment. arachnoid are not supplied by the afferent nerve fibres, so that • Occasionally ends as high as L3 or extends to S3 vertebra. pain is not felt when the dura is pierced by L.P. Needle. • The dural sac then continues as the covering of filum terminale to end by adhering to the periosteum on the back of the coccyx. • The sac widens out in the cervical and lumbar regions corresponding to the cervical and lumbar enlargements of the spinal cord. • It lies loosely in the spinal cord, but it attached at the following points to its bony surroundings: I. Above to the edges of the foramen magnum and to the posterior aspect of the 2nd and 3rd cervical vertebra. II. Anteriorly to posterior longitudinal ligament. III. Laterally blend with the epineurium of the spinal nerves. IV. Inferiorly by the filum terminals to coccyx. V. Posteriorly it is completely free. 82

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Dr Azam’s Notes in Anesthesiology 2013 Continuation: Control of production: COMPARTMENT RELATED TO SPINAL MENINGES • Is under sympathetic control. These are • Increased sympathetic stimulation, increases production and • Sub arachnoid space. fluid pressure. • Subdural space • Carbonic anhydrase enzyme is essential for active secretion. • Extra dural space In children: THE SUB ARACHNOID SPACE: • 4 – 12 yr.. of age, formation of CSF is 0.35 ml/min with standard • The SAS is lined externally by the arachnoid matter and error of 0.02 ml/min. internally by the pia matter. • Mean CSF volume (5-10 yr.. age) – 75 ml. (66 – 100 ml) • It contains innumerable cob web like trabeculae. • It is traversed by the cranial and spinal nerves. Absorption of CSF: • It contains the main blood vessels of the CNS and extends • Through cerebral arachnoid villi to venous sinuses. along the capillaries and small arteries into the nervous tissues • For absorption intraventricular pressure should be more than of the spinal cord and brain. sinuses pressure. • It contains CSF, which functions as the lymph found in other parts of the body. SUBDURAL SPACE: • In cervical and thoracic region, the space is annular and the • It is potential one only. distance between the arachnid and pia is only 3 mm, hence the • The arachnoid is in close contact with the dural sheath. danger of injuries the cord if spinal tap is done here. • Contains thin film of serous fluid. • Below the L1 vertebra (where cord ends) the space is circular ad has diameter of 15 mm. The lumbar puncture below L1 is easy and constituent nerve roots of cauda equina escape damage on account of their relative mobility and the absence of cord greatly increases the cross sectional area of the SAS. • In the skull the pia and arachnid membranes are for the most part is in fairly close apposition.

Cerebrospinal ﬂuid (CSF): • CSF is analogous to the lymph in other parts of the body. • Volume: • Total volume in adults à 120 – 150 ml. In spinal SAS à 25 – 30 ml. Formation of CSF: • By process of ultra ﬁltration through choroids plexus. • About 0.4 ml/min (25 ml/hr) or 600 ml/day. 83

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

PHYSIOLOGY OF SPINAL ANAESTHESIA INDIRECT EFFECTS There are three sites of action of local anaesthetics placed in • Due to paralysis of nerves. subarachnoid space. In order of importance are: • Sympathetic blockade is major determinant • Primary: On nerve roots of spinal cord I. Hemodynamic changes as shown in the table: • Weaker concentration – cause sensory block Low High • High concentration cause – motor block Mean brachial arterial pressure Decreased 21% Decreased 44% • Secondary: On dorsal root ganglia and posterior and anterior horn Systolic Decreased 50% synapses. Diastolic Decreased 43 % • Limited and incomplete: In spinal cord parenchyma on ascending and descending tracts. Right auricular pressure Decreased 36 % Decreased 53 % Pulmonary artery pressure Decreased 15 % Decreased 35 %

Determinants of nerve fibre susceptibility: Cardiac rate Decreased 8 beats Decreased 10 beats 1. Fibre size: Small fibres are more sensitive than large fibres. 2. Degree of Myelination and distance between the nodes of Stroke volume Decreased 73 to 68 cc Decreased 57 to 43 m Ranvier: The greater the Myelination and the distance between Minute output Decreased 16 % Decreased 31 % the nodes, the greater will be the resistance to drug action. Peripheral resistance Decreased 14 % Decreased 18.5 % 3. A functional characteristic: The axons with a high frequency of Calculated left ventricular work Decreased 30% Decreased 62 % impulse traffic are more sensitive to local anaesthetic blockade. Peripheral blood flow Decreased Increased Difference of levels of block according to fibre type: Fingers Toes Decreased Increased • Sympathetic paralysis is more diffuse and will extend 2 – 4 Oxygen consumption

segments above the sensory block. A-V O2 difference 2.8 to 4.2 3.9 to 5.0 • Motor blockade, 1 – 4 segments below the sensory level. Art. O2 saturation None None Oxygen consumption Decreased Decreased Sequence of nerve modality block: Hematocrit Decreased 1 % Decreased 2 % • Vasomotor block – dilatation of skin vessels and increases Estimated hepatic blood flow Decreased 24 % Decreased 33 % cutaneous blood flow. Brachial Art – Hepatic V O2 diff. Increased 16% Increased 35% • Block of cold temperature fibres • Sensation of warmth by the patient due to above Splanchnic vascular resistance Slightly increased Increased 7% • Temperature discrimination. Splanchnic oxygen consumption Decreased 4 – 6% Increased 2-8%

• Slow pain Venous pressure Decreased 12% Decreased 35% • Fast pain • Tactile sense Circulation time Increased Increased 20% • Motor paralysis • Pressure sense abolished • Proprioception and MTJ sense 84

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Theories to explain these circulatory changes are: IV. Bronchial effect: Hematogenous intoxication: Rapid absorption into blood • • Sympathetic fibres to bronchial musculature comes from upper steam of anesthetic drugs precipitates the lowering of B.P. 5 or 6 thoracic segments. Direct action on medullary centers. • • High block cause: • Paralysis of adrenal nerve. • bronchospasm • Respiratory depression. The hypoxia due to decreased • Affective dyspnea ; due loss of the MTJ ventilation will cause these circulatory changes. • sense or position sense in the thoracic cage • Loss of skeletal muscle tone: This effect diminishes • structures. intraabdominal pressure and causes splanchnic pooling and V. GIT effect: diminishes support and milking action on veins, à impair • The gut gets contracted after spinal anaesthesia. Intestines are venous return à decreases cardiac output. usually active and show segmental movements as well as slow peristalsis. Primary mechanism of hypotension: • With high spinal antiperistalitic movements seen which can result in regurgitation. Paralysis of vasoconstriction nerve Fibres. Effect o gastric emptying: ↓ • S.A promote gastric emptying which was delayed by surgery. Arteriolar and venous dilation VI. Ventilatory effects: ↓ • S.A. to sensory level of at least T4 does not affect pulmonary Peripheral pooling of blood ventilation in unpre-medicated patient. ↓ VII. Enodocrine effects: ↓ Venous return Endocrine effects of surgical stress are: ↓ • Increased plasma epinephrine and nor epinephrine. ↓ CO • Increased production of ADH. Increased production of growth hormone. ↓ • Increased production of cortisol. Hypotension • Increased cyclic AMP à proportional to severity of stress. II. Autonomic nervous system: • Increased prostaglandins, Renin • Blocks sympathetic out flow. • Endorphin activation • Parasympathetic – vagal action becomes more prominent • and hence cause the physiologic disturbances in the heart, • Increased prolactin à six fold more in females bronchi and GIT. These neuroendocrnine responses are inhibited by regional III. Cardiac effect: anaesthesia i.e., spinal or epidural. • In high spinal block of upper five thoracic spinal roots cause Mechanism: Regional anaesthesia block afferent impulses to block of cardio-accelerator fires, with the vagus intact will the CNS specifically to hypothalamic pituitary axis, so that cause bradycardia. release of endocrine substances are inhibited. In addition they block peripheral efferent sympathetic out flow.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

VIII. Reduction of blood loss: Pharmacokinetics: • Is related to the redistribution of blood flow to other parts • Peak plasma concentrations of bupivacaine show an insignificant (mainly splanchnic bed and pulmonary bed) of the body increase. away from the operative site. • Peak plasma times are prolonged and terminal half life is increased. IX. Thromboembolic complication: reduced • Plasma clearance slowed. X. Effect on Carbohydrate metabolism: • Glucose tolerance is minimally affected compared to surgery INFANTS AND CHILDREN: done under GA. • Duration of spinal motor block is shortest. XI. Fat metabolism: • After 2 yrs there is linear increase in duration upto about 15 yrs, • Decreases plasma glycerol and free fatty acids. when duration attains adult value. XII. Effect on pulmonary function and pulmonary complication • Dosage of anaesthetic depends on body weight or body surface area post operatively. (unlike in adults where dosage depends or body height) Regional anaesthesia (particularly post operative epidural • • Factors modifying the dose are analgesia) will promote breathing more efficiently. • Larger circumference of the spinal cord. XIII. Effect on mental function: • Greater filling of vert. Canal Particularly in elderly, post operative confusion and • • Smaller volume of CSF and low density of CSF. disorientation are reduced following RA compared to GA. EFFECT OF AGE ON SPINAL ANAESTHESIA Effect of epinephrine: (Kinetics and Dynamics) Spinal sub arachnoid bupivacaine 0.5% (15 mg), isobaric • Absorption from the SAS is slowed à Sclerotic vessels. • anaesthesia is prolonged by the addition of epinephrine. à Decreased blood flow • Optimal dose – 100 µg / ml or dilution of epinephrine of 1: 10,000. • Specific gravity of CSF more: Hyperbaric solutions may act more like isobaric à Spread is less. • Decreased CSF volume. • Changes in curvature of lumber and thoracic spine à greater upward spread and pooling in the thoracic cavity in the presence of exaggerated lumbar lordosis or thoracic kyphosis. • Slightly higher levels of analgesia. • An increased latency time to maximal spread. • Faster onset of motor block.

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

DIFFERENCE BETWEEN SPINAL AND EPIDURAL Spinal Epidural Speed of onset Very rapid Delayed Upper limit of block Variable unpredictable Can be controlled Intensity of block Profound Variable agent depended Lower limit of block Satisfactory S4 Variable( sacral space ) Motor blockade Complete Incomplete Systemic absorption Negligible Substantial toxicity possible. Hypotension Common, rapid onset Variable, gradual onset Provision of post operative Nil Ideal roots for continuous analgesia analgesia Dose Small Large

Testing for levels of block for different nerve modalities: A. Testing for sensory level of anaesthesia: • Using loss of recognition to pinprick using a sterile needle. • It occurs 2-3 dermatomes more cephalad than the sense of touch • Using cold stimulus – such as alcohol sponge • particularly recommended in elderly, debilitated or those with delicate skin. B. On set and assessment of motor block: • Motor block develops after sensory block. • Sequence and onset of motor block, can be assessed by a modified Bromage scale as shown in table. BROMAGE SCORE: Scale Criteria Degree of block 0 Free movement of legs and feet with ability to raise None extended leg 1 Inability to raise extended leg and knee flexion is Partial 33% decreased but full flexion of feet and ankles is present 2 Inability to raise leg or flex knees ; flexion of ankle and Partial 66% feet present 3 Inability to raise leg, flex knee or ankle, or move toes Complete paralysis 87

Dr Azam’s Notes in Anesthesiology 2013 Anatomy of vertebral column & physiology of spinal anesthesia. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Recovery from motor block: • Recovery is reverse of onset.

C. Sympathetic block: • 2 – 3 segments higher than sensory block. • Due to blockade of preganglianic sympathetic B-ﬁbres.

Test for sympathetic block: • Using sympatho – galvanic reﬂex (SGR) • Principle: Skin conductance is directly related to the activity of the sympathetic nervous system. Method: Using the electro cardiograph direct writer. • when sympathetics are intact – A biphasic response seen 1st phase – Direct nerogenic response. 2nd phase – Hormonal response. • when sympathetics blockaded by RA – Graph becomes ﬂat line or amplitude of response decrease.

Other factors affecting skin conductance are: • Skin moisture • Electrolyte content • Degree of sweating

By testing skin temperature: • It is more reﬁned and sensitive technique of observing level of sympathetic block. • The temperature in area of sympathetic block may be increased by 0.8 to 1.60C, allowing for core cooling effect. • Level of elevated skin temperature is cephalad to sensory block.

Dr Azam’s Notes in Anesthesiology 2013 49. Epidural Anesthesia. Dr Azam’s Notes in Anesthesiology 2013

• Epidural anaesthesia (peridural or extradural) is anaesthesia Epidural space (mm) Thickness of dura (mm) obtained by blocking spinal nerves in the epidural space as the Cervical 10 – 15 2.0 – 1.5 nerves emerge from the dura and then pass into the intervertebral Upper thoracic 2.5 – 3.0 1.0 space foramina. • Anaesthetic solutions are deposited outside the dura. Lower thoracic 4.0 – 5.0 1.0 • Segmental block – spinal sensory and sympathetic nerve Lumbar 5.0 – 6.0 0.66 – 0.33 fibers. • Motor fibers may be partially blocked. Distance to epidural space: • Thoracic epidural block or thoracic segmental epidural • Overall median distance in normal adult female patients is 4.7 anaesthesia. cm at L3 – L4 level. • Lumbar epidural block or spinal epidural block • Perineal or extremity surgery – 15 ml Factors altering depth: • Lower abdominal surgery – 20 ml 2% lidocaine a) Weight • Upper abdominal surgery – 20 ml b) Technique – loss of resistance closer than hanging drop. • Caudal epidural block or caudal anaesthesia sacrococcygeal c) Angle of needle ligament. d) Position of patient e) Edema Peridural space: f) Ethnic origin. • Circular space surrounding the dural sac and all its extensions. • Thoracic à 1 to 3 cm H2O (2 cm H2O) • Extends from foramen magnum to coccyx. • Lower lumbar à 0.5 cm H2O • Upper limit foramen where the periosteal layer of spinal vertebral • Upper lumbar à 1.0 cm H2O canal fuses with dural layers. • Lower limit: sacrococcygeal ligament. • Posteriorly: more extensive and distensible • Anteriorly: dura adheres closely to the periosteum of vertebral bodies. • Lateral: intervertebral foramina and peduncles of vertebrae. • Potential space – areolar tissue, fat and spinal nerve roots spinal arteries, and a capillary network forms a rich venous plexus. • “Plica mediana dorsalis” of the dura mater connects dura to lig. flavum in midline.

Midline suggital plane – following structures are penetrated • Skin subcutaneous tissues. • Supra spinous ligaments • Inter spinous ligaments • Ligamentum ﬂavum. 89

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

Negative pressure: • Cone theory – tenting of dura FATE OF EPIDURAL AGENTS: • Transmission theory – intrapleural negative pressure transmitted through intervertebral foramina to ! 2*#+3)%&'#"415$#("' peridural space. • Described in 1928 by Heldt and Moloney. 6("7#$3+#"%&'-*)1%+'#"'1*#+3)%&'-*%51'' • Greatest in patients with firm attachments • Greatest at thoracic region 61%8%71',9' 61%8%71'$0)3' =#;;3-#("'$0)3' =#;;3-#("'$0)3' • Less in lumbar area :%-53&%)' #"$1):1)$1,)%&' +3)%&')(($' +3)%'<%$1)'''' • Least or absent in sacral area %,-()*$#("'' ;()%<#"%'' -&11:1-''' • Factors that increase negative intra pleura pressure A!/BC>!?'' and decrease CSF pressure à increase negative /%)%:1)$1,)%&',&(58'(;' >3,+3)%&'-*)1%+'''' "1):1'$)3"8-''' extra dura pressure. !"#$#%&'()' >&(D1)' • Marked flexion of spinal column. )%*#+'%,-*.' %,-*-' /0%-1' *0%-1'' ?1"$)#*1$%&'-3,@ >*#"%&')(($',&(58''''' *1)#"13)%&'-*)1%+'''' Site of action: ?>E' 1. On the nerves as they traversal the epidural space. 2. On the nerves as they pass out thru the >3,'*#%&'-*)1%+''''' /1)#*01)%&'5()+',&(58'' intervertebral foramina. 3. On the nerves in SAS – by diffusion through dura. • Sensory anaesthesia of all modalities complete Factors in extent of EA: sympathetic fibers block partial motor block incomplete. Dispersion = + gravity 1. Volume of solution (10 ml will diffuse over 6-8 segments). 2. Selection of appropriate interspace. 3. Speed of injection – slower rates decrease spread 4. Position of patient 5. Effect of gravity 6. Specific gravity of anaesthetic agent

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

Detection of epidural space: Inﬂuence of age on absorption: Disappearance of resistance Elderly patients: Negative pressure techniques technique 1. Peak serum level of anaesthetic agent is increased. 1) Hanging drop sign 1) Syringe technique 2. Time to C5 max is signiﬁcantly reduced 2) Capillary tube method 2) Spring – loaded syringe 3. Slower onset of block 3)Manometer technique 3) Balloon technique 4. Increase hydrostatic pressure with age. 4) Brooks device 5) Vertical tube of Dawkins Principal determinants of dosage: 1. Volume of anaesthetic solution Volume capacity of epidural space: o - Age / segment factor • Volume of solution required for an epidural anaesthetic depends on o - Height factor • Site of injection 2. Selection of interspace • No of segments to be blocked 3. Spread of solutions • Capacity of the lower part of peridural space is larger. 4. Speed of injection • Per segment volume of anaesthetic solution necessary in sacral and 5. Position of patient lower lumbar region is greater than in thoracic region. 6. Extra dural pressure and compliance factors of epidural • Segmental dose – “dose spread” volume of analgesic solution space injected in ml/no of dermatomes blocked Or ml/spinal segment. 7. Sp. gravity of anaesthetic solutions 1. Cervical à 1.5 ml (each pair of spinal segments) 8. Clinical modifying factors 2. Thoracic à 2.0 ml o Obstetric patient à decrease dose vol by 30%. 3. Lumbar à 2.5 ml o Abdominal distention or extremely obese. I. Single injection – 15 to 20 ml o Arteriosclerosis decrease dose vol by 50%. II. Continuous technique – initial dose 8 to 12 ml later 5 to 7 ml every o Anatomic factors – elderly. hr. III. Poor risk, frail or very old patients – dose volume halved. Volume of Extent of Type of surgery Space injection (ml) anaesthesia Perineal L3 – L4 10 – 12 4 – 6

Extremity L2 – L3 12 – 14 8

Lower abdominal L1 or L2 14 – 16 10

Upper abdominal T2 or L1 16 – 18 12

Thoracic T12 20 -22 or 14 Catheter

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

Volume of anaesthetic solution: Speed of injection: • Age/sex factor: • More rapid the injection wider is its spread. From 4years to 18 years à steady increase from 0.2 to 1.0 • Recommended rate of injection 0.5 to 0.7 ml/sec 1.0 ml/1.5 sec is ml/segment optimal. 1. 20 – 40 years à 1.0 to 1.6 ml / seg (plateau) • Fast (1.0 ml/sec or more) injection 2. 40 years – 60 years à slight decrease 0.5 to 1.0 ml/seg • Increase ht of dermatome / block 3. > 60 years à 0.3 to 0.6 ml/seg. • Discomfort on injection • Hypobaric activity Height factor: • Drainage thru azygos system • 5 ft (150 cm) à 1.0 ml/seg. • (Bypasses liver) SVC à heart cardiac effects dramatic) • 6 ft (180 cm) à 1.6 ml/seg. • 5 ft à + 2 inches (5 cm) à + 0.1 ml/seg. Position of patient: • Epidural space is a potential space, and solutions do not readily flow Selection of interspace: in this space because of low compliance, hence gravitational 1. 2nd most important factor influences minimal. 2. Site of injection should correspond as closely as possible to the middle of the area to be anaesthetized. Lateral position: then to supine à little different in spread or onset of Spread of solutions: block onset of sympathetic blockade is slightly more rapid on • Spread symmetrically to both sides (sitting / lateral dependent side. position) • Most intense and earliest onset of block at site of Retaining lateral position: Intense anaesthesia on dependent side for injection. relatively major block – approx 15 minutes. • Spread is related 2 anatomic factors o Size of epidural space Sitting position: o Size of nerve roots • Obese patients • Onset of anaesthesia at L5 and S1 and also other sacral • Perineal anaesthesia segments – delayed, intensity and duration – less. (Nerve • Upper thoracic and cervical region block. roots are larger than at other segments). • L1 or L2 lumbar epidural – spread both caudal and cranial Prone position: cervico-thoracic block with head flexed to chest. L4 T8 equal in the onset of blockade. Extradural pressure and compliance factors of epidural space: • Pressure in epidural space is a specific determent of spread. • Pressure is determined by 1. Epidural venous pressure 2. CSF pressure 3. Amount of connective tissue and fat in space.

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

Breathing pattern: • Increase inspiratory negative pressure transmitted to epidural spread àincrease cranial spread of solutions.

Specific gravity of anaesthetic solutions: • Has limited influence as gravitational influences are not a major factor. • Bupivacaine – dissolved in 10% dextrose and plain bupivacaine – overall dermatomal spread is similar. • Rate of injection determine whether sol. Behave as a hyper or hypobaric mixture. Rapid rate à hypobaric activity.

Clinical modifying factors: • 2 imp clinical conditions require a downward adjustment in dosage • Obstetric patient – dose vol. – decrease by 30% (decrease in size of epidural space from distention of epidural veins – venacaval compression in supine position). • Abdominal distention or extremely obese – decrease dose by 30%. • Arteriosclerosis and / or occlusive vascular disease – decrease dose by 50%. • Early diabetes when widespread angiopathy of arterioles.

Anatomic factors – aging process. • With advancing age – the intervertebral foramina are progressively occluded à limits on-towards spread of solutions à greater volume available to spread in peridural space. • Dose volume should be reduced in older patients. • Connective tissue changes – increase permeability of connective tissue. Complications: • Subarachanoid injection results in unconsciousness. • Haematoma formation.

Dr Azam’s Notes in Anesthesiology 2013 50. Caudal Anesthesia. Dr Azam’s Notes in Anesthesiology 2013

Caudal Anesthesia: The Sacral canal contains: • Is one of the most commonly used regional techniques in • Terminal part of dural sac, ending at S2, on a line joining the pediatric patients. posterosuperior iliac spines. • Can be also be used in adults. • The 5 sacral nerve roots and the coccygeal nerves. • The sacral epidural venous plexus. Anatomy of Sacrum: • Filum terminale. • The typical sacrum is a triangular shaped bone dorsally • Loose areolar fat convex formed by gradual fusion of the lamina of the 5 • Lymphatics. sacral vertebral segments, which is completed by the 20th year of life. Physiology of Caudal block: th • The bone articulates cephalad with the 5 lumbar vertebra • Anesthesia occurs slowly and caudad with coccyx. • Anaesthesia usually is first noted on the buttocks about the sacral • The concave anterior surface is smooth and in part supports hiatus. many important structures such as the iliac vessels, rectum • Pain is the first modality of sensation to be lost, followed by touch and and fetal head. temperature. • The posterior surface is rough, because of fusion of spinous • Pain is usually lost two segments higher than touch loss. processes. • Motor ibers are affected last • The 5th sacral vertebra is unfused. • There are four foramina, the fifth being absent. Systemic Effects: • Failure of fusion of the lamina of the 5th vertebral segment CVS Changes: results in a hiatus, that communicates with epidural space. Hypotension • The sacral hiatus is a v shaped or U-shaped notch formed Bradycardia by sacral cornua. Respiratory system: • Hiatus is covered by sacrococcygeal ligament. Respiration is not affected to that extend by caudal anaesthesia. • The first foramen is 0.5cm from midline and 2.5cm above Endocrine system: the level of the posterosuperior iliac spine, while the fifth No changes in ACTH, immunoreactive beta-endorphins, ADH, cortisol, foramina is expected to be 1cm from the midline. catecholamines, insulin and GH levels. • The third foramina is commonly the largest. • Distance between the apex of hiatus and the dural space is 47 mm. Anomalies of the Sacrum. • Deficient lateral wall • Trauma deformity • Extended hiatus.

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

Technique: 3 techniques: Indications: I. The conventional technique • Surgery of anus and rectum II. The simpliﬁed technique • Gynecological perineal procedure III. The continuous technique • Obstetric delivery • The patient may be placed in lateral or in prone position. • Management of vasospastic disease of lower extremity • Posterior superior Iliac spine • Management of pelvic & extremity pain. • sacral cornua identiﬁed. • Circumcision • The hiatus between the sacral cornua, this is about 1.5 to 2 • Herniorrhaphy inches above the tip of coccyx and it is either V or U shaped • orchidopexy notch. • A 19G disposable needle is inserted immediately caudal to Contraindications: the thumb at a cephalad angle of about 450. • Active disease of CNS, except idiopathic epilepsy. • Resistance is felt after a few millimeter as the needle • Inter vertebral disc engages in the ligament followed by sudden loss of • Infection at the site of block resistance as it penetrates which is felt as a ʻPOPʼ as it • Pilonidal sinus or cyst. enters the sacral extradural space (1st position). • Abnormalities of Sacrum. • “Whoosh test” can be used to predict successful needle • Obesity placement. This involve listening with a stethoscope over the midline lumbar spine for a characteristic whoosh sound on Complications: injection of 2-3ml of air through caudal needle. • Dural puncture • vascular puncture Anesthetic Solution: • Breakage of the needle or catheter • Lignocaine 2% • Infection • Bupivacaine 0.5%, • Toxic reaction to local anesthetics. • Ropivacaine 0.75% • Hypotension • Headache. Dose recommended: • For low caudal block include T11 = 30 ml. Spiegel Formula: • For moderate caudal block include T7 = 45 ml • For high caudal block include T4 = 60 ml. V = 4 + D-15/2; V=Volume of drug; D=Distance in cm from C7 to hiatus.

Dr Azam’s Notes in Anesthesiology 2013 51. Guidelines on regional anesthesia in patients treated with heparin oral Dr Azam’s Notes in Anesthesiology 2013 anti-coagulations, anti platelets and others.

1. Patients should not receive i.v unfractionated heparin within 1 hour of administrating a central neuraxial block. 1. If dilution has been done without stenting postpone all elective 2. The last dose of fractionated heparin should be given at surgeries 2-4 weeks. least 4 hour before the block. 2. If a bare metal stent has placed, postpone elective surgeries for 6 3. LMWH should be given at least 12-24 hours before NAB. weeks and chose a window between 6 and 12 weeks of stent The first dose should be given at least 4 hour after the placement after which restenosis can occur. block and removal of the catheter should be 12 hour after 3. If a drug eluting stent is inserted postpone elective surgery for 12 the last dose and atleast 4 hours before the next doses. months. These guidelines may apply to the newer longer acting 4. If surgery is unavoidable a risk benefit balance should be made LMWHs. Which are becoming available and the reader is between continuation and stoppage of Clopidogrel and aspirin choices urged to consult the package inserts for guidance these include, drugs . 5. Continuing the surgery while continuing to give Clopidogrel and 4. With regards to warfarin INR should be < 1.5 prior to discussing the risks of surgery and NAB with patient and surgeon. performing the block. The risk of thrombosis due to 6. Stopping Clopidogrel 5 days in advance, bridging perioperative period stoppage of warfarin is unacceptably high bridging therapy with GP IIb/IIa inhibitors (eptifibatide or tirofiban)which can be stopped with heparin should be considered. Although short term on the morning of surgery. stoppage of Warfarin seems fairly benign with respect to 7. Stopping clopidogrel 7 days in advance and accepting the risk of stent complications. thrombosis. Very high risk: • Major surgery in patient > 40 years plus previous venous thromboembolism or malignant disease or hypercoagulable state desire major orthopedic surgery or hip fracture or stroke or spinal cord injury. • Certain herbal medicines especially garlic may increasing the tendency to bleeding. It is advisable to stop garlic 7 days in advance or other such medications ginkgo and ginseng 36 hours in advance. • The use of anti platelet drugs is brought with controversy NSAIDs soon fairly safe with respect to NAB and need not be stopped for this reason. Clopidogrel should be ideally stopped 7 days before surgery. This may however lend to an unacceptably high risk of stent thrombosis. Choices include the following in the patients in whom central NAB would be advantageous or in whom continuation of antiplatelet drugs would pose an unacceptable risk of bleeding. 96

Dr Azam’s Notes in Anesthesiology 2013 52. FACIAL NERVE BLOCK Dr Azam’s Notes in Anesthesiology 2013

AIM: • To paralyze orbicularis oculi muscle to prevent blephrospasm ! which causes a rise in IOP

Different Techniques: 1. Brien technique-commonly used 2. Van lint technique 3. Atkinson method 4. Nadbaths technique

Procedure – O brien technique: 1. Patient in sitting or lying position 2. Locate the position of the condyle and temperomandibular joint. 3. Ask the patient to open the mouth. 4. 25 G. needle is inserted anterior to the tragus over the condyle. 5. 4ml 0f 2% lignocaine is given after negative aspiration and after closing the mouth. 6. Firm pressure and local massage to the skin.

COMPLICATIONS: 1. Laryngospasm 2. Dysphagia

Dr Azam’s Notes in Anesthesiology 2013 53. Brachial Plexus - Applied Anatomy. Dr Azam’s Notes in Anesthesiology 2013

ANATOMY • The roots are situated in the subclavian triangle of neck. They emerge • This is a plexus of nerves situated in the root of neck, in the between scalenus anterior anteriorly and scalenus medius posteriorly angle between the clavicle and lower posterior border of and lie on the scalenus medius. The roots communicate with the sternomastoid, the braches of which are mainly distributed to sympathetic ganglia. supply the upper limb. It extends from the lateral aspect of • C5 & C6 communicate with middle cervical ganglion by grey ramus the cervical vertebral column, between the scalenus anterior communicates and scalenus medius, downwards and laterally, deep to the • C7 & C8 communicate with inferior cervical ganglion by grey ramus midpart of clavicle, to the axilla. communicates • T1 communicate with ﬁrst thoracic ganglion by grey and white rami The plexus can be divided into ﬁve stages communicates I. Root stage II. Trunk stage The following branches are given off from the root stage. III. Division stage 1. Branch to phrenic nerve – C5 IV. Cord stage 2. Nerve to Rhomboids (Dorsal scapular nerve) – C5 V. And Branches stage 3. Nerve to serratus anterior (Long thoracic nerve of Bell) – C5,6,7 4. Branches to scalene muscles 5. Branches to longus colli ROOT STAGE • The contribution to the phrenic nerve can descend for a variable Five roots contribute to the plexus. They are distance and then join the nerve proper. It may come out along with the 1. APR C5 nerve to subclavius from the upper trunk, descend and join the phrenic 2. APR C6 nerve as accessory phrenic nerve. In avulsion of the phrenic nerve as 3. APR C7 it lies on scalenus anterior to put diaphragm out of action, the 4. APR C8 procedure may be a failure, if accessory nerve is spared. 5. APR T1 • The nerve to rhomboids supplies levator scapulae, rhomboidus minor and major. A small twig from C4 can join the plexus (C5) and a branch • The nerve to serratus anterior can undergo amyotropic neuropathy from T2 can join T1. • resulting in paralysis of the muscle and winging of scapula. • The entire APR C4 can contribute to the plexus and the contribution of T1 may be absent. This is the PRE FIXED TRUNK STAGE TYPE. This may be associated with a cervical rib. The The C5 and C6 unite to form the upper trunk. contribution of T2 may be complete, while the contribution of C7 continues as the middle trunk. C5 may be absent. This is the POST FIXED TYPE of C8 and T1 unite to form the lower trunk. plexus.

Dr Azam’s Notes in Anesthesiology 2013 Brachial Plexus - Applied Anatomy.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• The trunks alos are in the subclavian triangle. They lie on the • Damage to this point results in Erbʼ paralysis. Here the muscles scalenus medius and related anteriorly to nerve to supplied by C5 and C6 are paralysed. The limb is in the following subclavius, superficial branch of transverse cervical artery, postion. inferior belly of omohyoid, supraclavicular nerves, external • Adduction at shoulder – paralysis of supraspinaturs, deltoid jugular vein, fasciae, platysma and skin. The trunks lie above • Medial rotation at shoulder – paralysis of short lateral rotators – the third part of subclavian artery.ʼ infraspinatus, teres minor • The upper trunk gives off the nerve to subclavius (C5,6) and • Extension at elbow – paralysis of biceps, brachialis, brachioradialis suprascapular nerve (C5,6). • Pronation forearm – paralysis of supinator • The nerve to subclavius deep to the clavicle. The • Flexion – Wrist, metacarpophalangela joining and interphalangeal suprascapular nerve accompanied by suprascapular vessels joining – paralysis of extensors and inferior belly of omohyoid, reaches the suprascapular • The lower half of brachial plexus may be injured in Klumpkeʼs paralysis. notch, passes deep to the suprascapular ligament. It This part can also be affected in apical carcinoma of lung – Pancoast supplies the supraspinatus in the supraspinous fossa, runs in tumour. the spinoglenoid notch to enter the infraspinous fossa an supplies the infraspinatus. DIVISION STAGE • Supraspinatus initiates abduction (15ʼ). Infraspinatus is a • Each trunk divides into anterior and posterior divisions. The divisions lateral rotator of shoulder joing. are situated deep to the clavicle. The third part of the subclavian artery • Each trunk, deep to the clavicle divides into an anterior is related medial to the nerve divisions. Anteriorly the divisions are division and a posterior division. related to the clavicle, subclavius, suprascapular vessels and posgteriorly to first digitations of serratus anterior and subscapularis. ERBʼs POINT: • This is the outermost and the most vulnerable point in the CORD STAGE brachial plexus, when stretched. • The anterior divisions of the upper and middle trunks unite to form the Six nerves meet at this point in the upper trunk. lateral cord of the brachial plexus. APR C5 • The anterior division of the lower trunk forms the medial cord APR C6 • The posterior divisions of all the three trunks unite to form the posterior Anterior division of upper trunk cord. The cords of brachial plexus are related to the first and second Posterior division of upper trunk parts of the axillary artery. The medial and posterior cords are lateral Nerve to subclavius and the medial cord posterior to the first part of the axillary artery, while Suprascapular nerve the cords are in their respective positions – lateral cord alteral, posterior cord posterior and medial cord medial to the second part of the axillary artery.

Dr Azam’s Notes in Anesthesiology 2013 Brachial Plexus - Applied Anatomy.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• The cords with the axillary vessels are enclosed by the • The posterior cord gives off axillary sheath derived from the prevertebral fascial of neck. • The upper subscapular nerve (C5,6), nerve to latissimus dorsi – dorsal In relation to the ﬁrst part of the axillary artery, the cords are scapular nerve (C6,7,8) and related anteriorly to the clavipectoral fascia and pectoralis • The lower subscapular nerve (C5,6) as collateral branches and the major muscle and posteriorly to the subscapularis. The cores exillary (C5,6)and radial (C5,6,7,8 T1) nerves as terminal in relation to the second part of the axillary artery, are related branches. to the pectoralis minor anteriorly and to subscapularis, • The upper subscapular nerve supplies subscapularis, the dorsal latissimus dorsi and teres major posteriorly. At the lower scapular nerve supplies the latissimus dorsal and lower subscapular border of pectoralis minor, the cords terminate as branches. nerve suuples subscapularis and teres major. • The axillary nerve supplies deltoid, teres monor and the skin in the BRANCHES STAGE upper lateral aspect of arm. • The branches given off from the cords at the lower border of • The radial nerve supplies triceps, anconeus, lateral part of brachialis, pectoralis minor are the terminal branches. The branches brachioradialis, extensor carpiradialis longus, extensor carpi radialis given off from the cords proximal to it are the collateral brevis, extensor digitorum, extensor carpi ulnaris, abductor pollicis branches. The branches of the cords are covered by the longus, extensor pollicis longus, extensor pollicis brevis, extensor pectoralis major muscle proximally, but only by fasciae and indicis and extensor digiti minimi. It also supplies the skin in lower skin distally. The terminal branches are related to the third lateral part of arm, posterior aspect of arm, forearm, lateral part of part of the axillary artery, similar to their cords. – dorsum of hand, lateral three and half digits in dorsal aspect except the musculocutaneous and lateral root of median nerve lateral to nail bed region. the artery, axillary and radial nerves from posterior cord • The medial cord gives off the medial pectoral nerve as collateral behind the artery and the branches of the medial cord, branch and the medial cutaneous nerve of arm (T1,2) medial cutaneous medial to the axillary artery. nerve forearm (C8, T1) ulnar nerve (C7,8,T1) and medial root of • The posterior cord and its branches, especially radial nerve median nerve (C8,T1) as terminal branches at the lower border of may be involved in crutch paralysis. pectoralis minor. • The lateral cord give off the musculocutaneous nerve • The medial pectoral nerve supplies the pectoralis minor and pectoralis (C5,6,7), lateral root of median nerve (C5,6,7) as terminal major muscles. The medial cutaneous nerve of the arm is situated branches and the lateral pectoral nerve (C5,6,7) as the medial to the third part of the axillary artery and also the axillary vein collateral branch. and supplies the skin of the medial aspect of arm. • The musculocutaneous nerve supplies the • The medial cutaneous nerve of the forearm lies in between the third coracobrachialis, biceps brachii and major part of brachialis. part of the axillary artery and the axillary vein and supplies the medial It supplies the skin of the lateral aspect of forearm. The aspect of the forearm. lateral root of median nerve is joined by the medial root to from the median nerve. The lateral pectoral nerve supplies the pectoralis major after piercing the clavipectoral fascia.

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Dr Azam’s Notes in Anesthesiology 2013 Brachial Plexus - Applied Anatomy.Continuation: Dr Azam’s Notes in Anesthesiology 2013

• The ulnar nerve lies between the third part of the axillary • MP = medial pectoral, artery and the axillary vein, deep to medial cutaneous nerve • MBC = medial brachial cutaneous, of forearm, supplies the flexor carpi ulnaris and medial half of • MABC = medial antebrachial cutaneous flexor digitorum profundus in the forearm, palmaris brevis, • SS = subscapular hypothenar muscles, third and fourth lumbricals, all palmar • TD = thoracodorsal nerve. and dorsal interosseii and adductor pollicis in the hand, and • DSN = dorsoscapular nerve; supplies the skin of the palmar and dorsal part of the medial • SS = suprascapular nerve; aspect of hand and medial one and a half fingers. • LP = lateral pectoral nerve. • The median nerve supplies pronator teres, flexor carpi • LTN = long thoracic nerve. Theradialis, palmaris complete longus, flexor digitorum brachial superficialis, flexor plexus • MC = musculocutaneous, pollicis longus, lateral half of flexor digitorum profundus, • M = median pronator quadratus muscles in the forearm, adductor pollicis • U = ulnar diagram:brevis, flexor pollicis brevis, opponents pollicis, first and • R = radial second lumbricals in the palm and the skin over the lateral • AX = auxiliary half of palm and lateral three and a half fingers including the nail bed region.

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Dr Azam’s Notes in Anesthesiology 2013 54. Femoral Nerve Block. Dr Azam’s Notes in Anesthesiology 2013

ANATOMY OF FEMORAL NERVE (L2,L3,L4) • When the needle reaches the depth of the artery a pulsation of the hub • It is the largest nerve of lumbar plexus. It is formed from the is visible. Local anaesthetic solution 20ml injected fanwise lateral to the dorsal divisions of L2, L3 and L4. It supplies the muscles and artery. If the paraesthesia is obtained, 7 to 10 ml of solution should be skin of the anterior compartment of thigh. It emerges from injected at that site. the lateral margin of psoas, passes downwards in the groove USES between iliac crest and psoas, and then enters the thigh • Muscle biopsies of the quadriceps muscle or other surgical procedures beneath the inguinal ligament. At the base of the femoral limited to the anterior thigh. triangle, the nerve lies on iliacus, a finger breadth lateral to • Knee arthroscopy the femoral artery from which it is separated by a portion of • Pain relief for mid femoral shaft fracture, surgical repair the psoas. Almost at once within the triangle it breaks up into • Fracture neck of femur along with LCN and Sciatic Nerve Block its terminal branches which stem from an anterior and • May be combined with sciatic nerve block of operation on leg and foot posterior division. • With lateral femoral cutaneous and obturator nerve block for operations Anterior - Muscular Branches to pectieus and sartorius on or above the knee on medial side. division - Intermediate cutaneous nerve ADVANTAGES Cutaneious of thigh 1. It is a simple, easy technique branches Medial cutaneous nerve of 2. Success rate is high thigh Posterior - Muscular - Quadratus femoris LIMITATIONS division branch • With isolated femoral nerve block procedures on the anterior aspect of - Cutaneous - Saphenous nerve thigh can only be done. branch - Articular - HIP and Knee SIDE EFFECTS branches • Intravascular injection and haematoma (due to close proximity of the LAND MARKS femoral artery) Inguinal ligament • Peripheral nerve damage can occur if the local anaesthetic is injected Femoral artery directly into the substance of the nerve. PROCEDURE: • Define the inguinal ligament by drawing a line between the anterior superior iliac spine and the pubic tubercle. Palpate the femoral arterial pulse and at a point approximately 1 cm lateral to the pulse and 1-2 cm below the inguinal ligament insert a 22 G short bevel needle and advance it lateral to the artery. Two distinct “pops” can be identify as the tip of the needle penetrates first the fascia Lata and then the illo- pectinel fascia. 102

Dr Azam’s Notes in Anesthesiology 2013 55. Post Operative Analgesia. Dr Azam’s Notes in Anesthesiology 2013

INTRODUCTION • How should physicians use their understanding of nociception in the • The international association for the study of pain has management of acute pain. The most effective pain management defined pain as “unpleasant sensory and emotional strategy includes: experience, associated with actual or potential tissue 1. Inhibition of peripheral inflammatory response to tissue injury (non- damage”. Pain following surgery is often underestimated and steroidal anti inflammatory drugs) under treated. Pain and its intensity vary widely among 2. Neural blockade of transmission of pain impulses (regional analgesia) people. Inadequate knowledge regarding the necessity and 3. Prevention of central sensitization (administration of regional adequate knowledge regarding the necessity and adequacy anesthesia before tissue injury). of pain relief, combined with the difficulty in assessment of 4. Enhancement of descending inhibitory pathways (neuraxial pain, has resulted in under treatment of pain. administration of opioids or < - adrenergic agonists) • The primary goal of acute pain management is to ʻimprove 5. Prevention and management of anxiety (Preoperative teaching and patient outcomeʼ. This begins with providing effective pain postoperative anxiolysis) control and includes increasing patient satisfaction, The discussion will cover the following areas minimizing therapy induced side effects, facilitating recovery • What causes post-operative pain? and shortening hospital stay. • How do we assess postoperative pain? • Neuroendocrinal responses, tissue catabolism and Techniques of postoperative pain management, with special emphasis on: postoperative pulmonary function are favorable altered by I. Patient – controlled analgesia various techniques that provide postoperative analgesia. II. Epidural analgesia, patient – controlled epidural analgesia There is increasing evidence to suggest that inadequate III. Combined spinal epidural technique analgesia may be detrimental. IV. Intrapleural analgesia • Between the site of active tissue damage and the centre for Current views on preemptive analgesia perception of pain that follows lie a complex series of Drugs used for postoperative pain control with special reference to: physiological events collectively termed nociception. • Morphine pethidine fentanyl tramadol bupivacaine, levobupivacaine, Nociception can be divided into four processes: clonidine, paracetamol. I. Transduction • Multimodal analgesia II. Transmission Postoperative pain control in children: III. Modulation • Role of nerve blocks IV. Perception • Paracetamol Postoperative pain control in the elderly; • Special problems in this age group

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Dr Azam’s Notes in Anesthesiology 2013 56. Patient Controlled Analgesia (PCA). Dr Azam’s Notes in Anesthesiology 2013

• Patient controlled analgesia is the self – administration of The steep sigmodial dose-response curve for opioid analgesics small does of analgesics by patients when they experience pain. Patient controlled analgesia is a simple method of Serum opioid concentration (Arbitary units) arranging a dose or opioids to be administered at the Loading dose Basal infusion PCA Lockout time appropriate time for optimal pain relief with minimum intervention. Morphine 3 – 10 mg 0.5 – 1.5 mg/h0.5 – 1.5 mg 6 – 8 min • It provides a clear proﬁle of drug dosage needed in each (0.1%) patient to achieve comfort. In addition PCA allows patient to Pethidine (1%) 25 – 50 mg 5 – 40 mg/h 5 – 15 mg 6 – 8 min take an active role in the management of their pain. The goal is a comfortable non-sedated patient. Fentanyl 30 – 100 µg 10 – 20 µg/h 10 – 20 µg 5 – 6 min PCA Delivery system: (0.01%) Concept of PCA as a closed loop feed back system Tramadol 100 mg 12 mg/h - - ! .#,-!/'0%*%$1&)1%2*!2-! :--#81! ()%*!+#,%#-!34!(5/! "#$%&#'!! ()%*! Epidural PCA +#,%#-! Morphine 2 – 5 mg 0.1 – 0.8 mg/h0.1 – 0.3 mg 30 min (0.1%) 56)*7#!%*!()%*! Pethidine (1%) 30 – 50 mg 10 – 30 mg/h 10 – 30 mg 20 min (#&8#91%2*! Fentanyl 50 – 100 µg 30 – 50 µg/h 10 – 30 µg 10 – 15 min (0.01%) Indication of PCA 1. Acute postoperative pain relief 2. Cancer pain Side effect (%) of commonly used opioids 3. Labour pain Agent Nausea Vomiting Sedation PsychologicPruritus 4. Pain management in multiple trauma problems 5. Acute episode of chronic pain Alfentanyl 30 15 30 18 0 6. Burns pain 7. Sickle cell crises Fentanyl 47 37 1 5 4 Meperidine 8 5 13 0 0 Morphine 26 11 5 8 3 Sufentanil 50 33 3 13 0 Buprenorphi 42 17 0 10 11 ne Naibuphine 18 8 0 11 0 104

Dr Azam’s Notes in Anesthesiology 2013 Patient Controlled Analgesia (PCA).Controlled: Dr Azam’s Notes in Anesthesiology 2013

PCA adjuncts used for prophylaxis and treatment of side Developments in patient controlled analgesia devices effects • Reduced size Drug Advantages DisadvantageAdministered • Lighter weight s • Can run on batteries Promethazine Less opioid Increase Recently, IM, IV PRN • Tamper prooﬁng requirement sedation Mixed with opioid in • Robustness Stepper motors PCA • Droperidol Less nausea, Increase 0.62 mg IV drip PRN • Digital pulses • Microprocessors Vomiting sedation X 2 • Memory and / or printouts Potentiate • Programs to control infusions analgesia Analgesic regimens Metoclopramide Nausea and Oculogyric 10-20mg IV drip q4 Continuous infusions Bolus regimens vomiting crisis 6th TDS Less nausea, Increased Retroauricular patch Fixed doses Variable doses (Transdermal vomiting sedation, placed Discontinuous regimens Scopolamine) disorientation prophylactically or Fixed bolus or visual PRN Variable bolus Fixed time intervals changes, not Variable time intervals recommended Factors causing delay in onset of analgesia from next dose of pain killer in patients less 1. Reluctance by patients to let the nurses know that discomforts has returned than 16 or more 2. Delayed recognition of a patientʼs distress by busy ward nurses than 60 years of 3. Delays in ﬁnding a second registered nurse to witness the preparation age and administration of the analgesic Diphenydramine Less pruritus Variably 25mg IV drip PRN x 4. Delayed absorption of analgesic from an intramuscular depot. effective 2 Naloxone IV Less pruritus May decrease 0.25 - 1 µg/kg/hour infusion analgesia

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Dr Azam’s Notes in Anesthesiology 2013 Patient Controlled Analgesia (PCA).Controlled: Dr Azam’s Notes in Anesthesiology 2013

Types of patient controlled analgesia infusion Causes of overdosage with patient controlled analgesia 1. Background infusions Machine related 2. Adaptive infusions • Programming errors 3. Target seeking infusions • Deprogramming of the pump Advantages of patient controlled analgesia over conventional • Faulty technique when refilling the machine analgesia • Siphoning effects. 1. Consistently high patient satisfaction Human factors 2. Equal or superior analgesia compared with other regimens • Programming errors 3. Minimal or reduced sedation • Incorrect refilling of machine 4. Delay in the initiation of onset of pain relief by personnel is • “Phantom hands” avoided • Deliberate tampering 5. Patient retains a sense of being “in control” Morphine Difficulties in managing postoperative analgesia Advantages Wide variations between patients in their responses to: • Widely prescribed • Painful stimuli • High efficacy • Analgesics • Medical staff are familiar with its use Substantial variations within individual patients in their • Readily available responses to analgesics over time • Inexpensive Recognition of a patientʼs distress by nursing or medical staff Disadvantages may be delayed by: • Controlled drug • Low staff levels on the wards • Causes dose-dependent respiratory depression • Personal or social bias • Sensitivity to dose-dependent sedation varies • Poor training or inexperience • Histamine release may precipitate bronchospasm, peripheral • Cultural or language differences vasodilation and itching • Ward routines – staff rounds, shift changeover, mealtimes • Given intravenously, morphine causes nausea and vomiting in up to Administration of drugs may be delayed by: two thirds of patients. • Controlled drugs stored in a locked cupboard Pethidine • Time taken to prepare and load syringes with analgesics Advantages • Lack of availability of two trained nurses to witness drug • Medical staff are familiar with its use, inexpensive preparation and administration. Disadvantages Histamine release affects cannula site Norpethidine may accumulate, causing risk to Patients with impaired renal function Those taking monoamine oxidase inhibitors

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Dr Azam’s Notes in Anesthesiology 2013 Patient Controlled Analgesia (PCA).Controlled: Dr Azam’s Notes in Anesthesiology 2013

Fentanyl Non-steroidal anti-inﬂammatory drugs Advantages Slow onset Highly soluble in lipids Relatively long duration Rapid onset of analgesia Used with opiates to improve pain relief and decrease side effects Does not release histamine Increase tendency to bleed and gastric discomfort Disadvantages Affect renal blood ﬂow Expensive Infusion rates vary between patients Bupivacaine with low dose fentanyl Advantages Useful in segmental epidural analgesia Few side effects Disadvantages Optimal mixture not yet determined

Other opiates used in patient controlled analgesia Alfentanil • Intravenous • Rapid onset • Short duration of effect; poor quality analgesia in ﬁrst 12 hours after surgery

Nalbuphine Less likely to cause respiratory depression Ceiling effect – unsatisfactory for server pain Causes considerable sedation Buprenorphine Slow onset and offset of effect Very soluble in lipids 30 times as potent as morphine Ceiling effect – unsatisfactory for very severe pain Causes considerable sedation and nausea

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Dr Azam’s Notes in Anesthesiology 2013 57.ASSESSMENT ASSESSMENT OF PAIN OF PAIN. Dr Azam’s Notes in Anesthesiology 2013 Linear analogue scale Pain behavior chart Linear analogue scale No Pain At all • Crying Will not be consoled 2 • WortNo Painpain at allimaginable Worst pain Imaginable Responds to comforting 1

Not crying 0 WordWord category category scale scale Worst Worst pain pain imaginable imaginable 4 4 Movement Thrashing about 2 SevereSevere pain pain 3 3 Restless 1 Moderate pain2 Moderate pain 2 Slight pain1 Calm 0 Slight pain 1 No pain0 Mood Hysterical 2 No pain 0 Agitated 1 SmileySmiley face face chart chart Clam/asleep 0

Worst Pulse rate > 30% above preoperative level No pain possible Pain 3 > 20% above preoperative level 2 > 10% above preoperative level 1 Preoperative level 0 Sedation scale Pain behaviour chart Asleep (Unrousable) 4 Crying Will not be consoled 2 Asleep (Rousable) 3 Responds to comforting 1 Not crying 0 Drowsy (Responds to speech) 2 Movement Thrashing about 2 Slightly sedated (But looks awake) 1 Restless 1 Wide awake (Clear headed) 0 Calm 0 Mood Hysterical 2 Agitated 1 Clam/asleep 0 Pulse rate > 30% above preoperative level 3 > 20% above preoperative level 2

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Dr Azam’s Notes in Anesthesiology 2013 ASSESSMENT OF PAIN.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Alternative Strategies Observation chart Psychological Date Time BR Pain Sedation Nausea Succesive Total Volume Obervers • Relaxation with the help of music, mental imagery and score score score demands demands remaining initials control of breathing Physical 1. Surgery, such as covering burns with skin graft, or Examples of achievable standards include. amputation of ischaemic limbs 1. At lease 90% of postoperative patients should leave the recovery 2. Changing blood ﬂow patterns by elevation or depression of ward with “Little or no pain” the affected part 2. 100% of all postoperative patients should have a pain chart 3. Cooling or warming the effected part 3. More than 90% of all postoperative patients should have completed 4. Transcutaneous nerve stimulation; acupuncture pain charts 5. Ultrasound 4. Less than 10% of patients may have severe pain for 2 successive 6. Soft tissue mobilization hours Pharmacological 5. No more than 5% of patients may have unrousable sedation at any 1. Local anaesthetic time 2. Reversible blockde of the peripheral system, preferably 6. No more than 5% of patients with severe nausea may be left using catheter techniques with local anaesthetics or low untreated for more than 1 hour. dose mixtures of opiate and local anaesthetic for epidural Limitations of PCA therapy and spinal blocks • Selection of agent available for use. 3. Autonomic nervous blockade with local anaesthetic-for- • Pediatrics, older and debilitated patients may not be able to use it. example celiac and stellate ganglion blocks • Mechanical errors 4. Non-opiate analgesics-for example, non-steroidal anti- • Initial cost. inﬂammatory drugs such as diclofenac and ketrolac • Narcotic side effect. Functions of an acute pain service 1. Clinical 2. Teaching 3. Administration 4. Audit 5. Research

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Dr Azam’s Notes in Anesthesiology 2013 ASSESSMENT OF PAIN.Continuation: Dr Azam’s Notes in Anesthesiology 2013

Relative contraindications • Abusing illicit drugs • Sepsis. • Severe ﬂuid and electrolyte disturbance. • End stage hepatic or renal disease. • History of sleep apnoea. • Severe COPD. • Intravenous PCA for acute postoperative pain relief.

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Dr Azam’s Notes in Anesthesiology 2013 58. Preemptive Analgesia. Dr Azam’s Notes in Anesthesiology 2013

• Common definition of the term, “preemptive analgesia”. Clinical Pain • “The pre-injury administration of analgesics resulting in post- • It can be divided into inflammatory and neuropathic pain. Inflammatory injury pain relief longer than from post injury drugs”. pain is associated with peripheral tissue damage such as might occur • The past decade has seen significant progress in the after surgery or trauma, whereas neuropathic pain refers to direct neurophysiologic description of pain (nociceptive) pathways, damage to the nervous system. receptors, and mediators (endogenous and exogenous). • Both types of clinical pain are characterized by a reduction in the Wall, in an editorial “The Prevention of Postoperative pain” intensity of stimuli necessary to initiate pain when normally they could proposed the possibility that “preemptive preoperative not. (This is called allodynia). There is alos an exaggerated analgesia” has prolonged effects which outlast the presence responsiveness to noxious stimuli, (hyperalgesia). of drugs. He was cp,,emtomg pm a commenting on a clinical • There are two mechanisms that operate to produce this hypersensitivity report where the authors reported as series of 929 patients found in inflammatory pain: after orthopedic surgery. Whereas only 5% of the control 1. First is an increase in the sensitivity of the transduction mechanisms group required no analgesics, 12, 18, and 26% of patients of high threshold primary nociceptive neurons at their peripheral who received opiate premedication local anaesthesia and terminals when they are exposed to a number of inflammatory both required no additional analgesia. mediators liberated in response to tissue damage. This phenomenon is called “peripheral sensitization”. 2. The second mechanism of hypersensitivity is a change in the Pathophysiology of Post-Injury Pain Hypersensitivity excitability of some spinal cord neurons, triggered by the outlasting • An important concept to our understanding of pain is that the actual nociceptive afferent inputs. This phenomenon is called “physiologic pain” is something that we experience every day “central sensitization”. This is responsible for some of the changes at when exposed to noxious stimuli, whereas “clinical pain” is the site of injury and all the changes in the zone of secondary that resulting when frank tissues or nerve injury has hyperalgesia outside the site of injury. occurred. • The fundamental difference between peripheral and central sensitization is that the peripheral sensitization enable low intensity Physiologic Pain stimuli to produce pain by activating sensitized A-delta and C- It is localized and transient and has a stimulus response • nociceptors, whereas the central sensitization represents an input in relationship similar to other somatic sensations. Its normal low threshold A-beta sensory fibers producing pain as a result of fundamental role is to operate as a protective warming changes in sensory processing in the spinal cord. system. The highly specialized nature of our peripheral Clinical pain differs from physiologic pain by the presence of pathologic sensory receptors and pathways permits discrimination of • hypersensitivity. innocuous sensations which travel via A-beat fibers from true pain sensations that travel via A-delta and C-fiber pathways.

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

• In summary, the involvement of centrals sensitization in Chest Wall clinical pain has important implications for therapeutic • Intercostals nerve block intervention. Those states of analgesia that eliminate all physiologic and clinical pain need to be differentiated from Lower extremity blocks those in which only abnormal hypersensitivity is eliminated. • Femoral nerve Although complete analgesia is required intra-operatively, • Fascia iliacus compartment converting clinical pain to physiologic sensitivity may be • Lateral femoral cutaneous sufficient for the postoperative period. • Sciatic Nerve • Considering all of the analgesic drugs that can be employed • Ankle Block through multiple sites of administration throughout the entire • Digital nerve blocks. perioperative period, it seems little wonder that the definitive study is yet to be done. However, there seems to be a clean Upper limb Block clinical impression that there is benefit to be gained by earlier • Brachial Plexus block. (preoperative) and more prolonged sustained use of • Elbow blocks (radial, ulnar and median nerve) analgesic agents throughout the period of tissue injury and • Digital nerve blocks recovery. • Wrist blocks (radial, ulnar and median) • The various preemptive – Regional anaesthetic techniques and details are described elsewhere in this booklet. The range of local anaesthetics used with their dosages in given table. Choice and dosages of local anaesthetics Regional technique for pain relief in children Agent Maximum paediatric Maximum paediatric Central neuraxial blocks bolus dose (mg.kg-1) infusion dose (mg.kg-1 h-1) Caudal Lignocaine (pan) 5.0 4.0 Epidural Lignocaine (with adrenaline) 7.0 N/A Bupivacaine Peripheral nerve blocks Head and neck Neonates 2 0.2 – 0.25 • Supraorbital and supratrochlear Infants 2.5 0.4 – 0.5 • Greater occipital nerve block Toddlers and older children 3 • Greater auricular nerve block -1 • Infraorbital block Ropivacaine 0.2% solution 2mg.ML N/A (0.5-1.0 mL.kg-1) Abdominal and genitals • llioniguinal and iliohypogastric • Penile

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

• It is our responsibility to extend our pain services beyond the four walls of the theatre, more importantly the postoperative period. A rational combination of careful assessment of pain and judicious application of available techniques will greatly beneﬁt our patients and modify overall outcome and elevate our image as “perioperative physicians”

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Dr Azam’s Notes in Anesthesiology 2013 59. Chronic Pain Management. Dr Azam’s Notes in Anesthesiology 2013

• Developments in understanding the aetiology and II Non-Cancer pain management of chronic pain is being emphasized in post- graduate education. The advances in our understanding the 1. Sympathetically maintained pain : Complex Regional Pain Syndrome basic sciences with respect to pain, with the plethora of CRPS (Causal gai in 1800s, Reflex Sympathetic Dystrophy 1900s, effective pharmacologic and interventional treatments and CRPS 1999) with stress on psychological aspects of chronic pain 2. Neuropathic Pain management enhanced the knowledge of pain specialists A. Post herpetic neuralgia. and influence post-graduate students to pursue career in B. Post Surgical Pain syndromes. this field. C. Metabolic (diabetic) toxic neuropathy. • Pain is defined as ʻa sensory and emotional experience D. Central Pain associated with actual or potential tissue damage or E. Radiculopathy. described in terms of such damageʼ (International 3. Neuralgias Association for Study of Pain). The subjective experience of • Trigeminal neuralgia. pain varies from person to person and the clinicians need to 4. Musculoskeletal Pain be sensitive about these aspects. Low back pain. Inflammatory disorders – Rheumatoid arthritis. CLASSIFICATION OF CHRONIC PAIN 5. Chronic orofacial pain – Headaches. I Cancer pain 1. Pain associated with tumour progression, involvement of MANAGEMENT OF CANCER PAIN bone, nerves, viscera or soft tissues. • Pain is the most feared consequence of cancer next to death. More 2. Pain associated with cancer therapy, post Surgery, post than a million people in India suffer from cancer pain. 60-90% of Radiotherapy, post Chemotherapy patients with advanced cancer experience significant pain2 which further can lessen the patientʼs activity, function, appetite and sleep. It can also induce fear and increase suffering in patients with cancer. Cancer pain is characteristically different from other chronic pains in that the patients usually experience multiple pain syndromes which progressively increases as the disease progress. The world Health Organisation (WHO) has developed a three step analgesic ladder for effective pain management in cancer.

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

• The five essential components in the W.H.O. approach to STEP I – NON – OPIOIDS drug therapy are : • Includes acetaminophen and non steroidal anti-inflammatory drugs to 1. by the mouth. treat mild to moderate cancer pain. 2. by the clock. • Action : It produces analgesia by decreasing the levels inflammatory 3. by the ladder. mediators generated at the site of issue injury by inhibiting the enzyme 4. for the individual cyclooxygenase which catalyzes the conversion of arachidonic acid to 5. with attention to detailMANAGEMENT OF CHRONIC PAIN 61 prostaglandins and leukotrienes which sensitize nerves to painful stimuli. They do not activate opioid receptors. The concurrent use of the opioids and NSAIDs provide mor analgesia than either drug alone. It Non-steroidal anti- i n f l a m m a t o r y drugs Strong opioid does not develop tolerance or physical dependence. It has ceiling Non-steroidal anti-inflammatory drugs (NSAIDs) interfere with +/- adjuvant effect. Such that increasing the dose beyond a certain level does not +/- NSAID produce additive effects. the production of prostaglandins and prostacyclins by inhibiting Adverse effects the enzyme cyclooxygenase. They possess analgesic and anti-in- Minor : flammatory action and are used widely in the management of mild Dyspepsia, heart burn, nausea, vomiting, diarrhea, constipation, Weak opioid • to moderate pain, particularly of somatic origin. They may be very epigastric pain and abdominal pain. effective for painful bone metastases and useful in dysmenorrhoea, +/- adjuvant +/- NSAID Major: arthritis and musculoskeletal pain. They may be used orally or as a • renal failure, hepatic failure, bleeding and gastric ulceration. suppository. Side-effects may be a problem, especially in the elderly. • Newer generation of NSAIDs are cyclooxygenase 2 (COX-2) selective McQuay & Moore (1998) have assessed the efficacy of topical Non-opioid/NSAID inhibitors and are known to have less adverse effect profile and NSAIDs for chronic painful conditions using the concept of num- +/- adjuvant decrease G.I. injury. ber-needed-to treat (NNT). An NNT value of 1 describes an event that occurs in every patient given the treatment but in no patient Fig. 61.3 STEP II – WEAK OPIOIDS in the comparator group. NNTs of 2-4 indicate effective treat- The WHO analgesic ladder. Weak opioids are weak mu-agonists. ments. Published randomized control trials on chronic painful Name and action Dose Duration of action conditions (mainly knee osteoarthritis) have studied over 1000 Codeine 30-60mg 4-6 hrs subjects using either topical NSAIDs or placebo and found that, 65 mg with 6-8 hrs – economical and for analgesic effects from topical NSAIDs, the NNT was 3.1. Dextropropoxyphene and drowsiness. Tolerance does not appear to be a problem clinic- paracetamol commonly used ally. Many patients with static disease take the same dose of Tramadol hydrochloride weak mu- Opioid analgesics morphine for long periods of time. Disease progression may nece- agonist ssitate an increase in dose, but there is no upper limit to the dose 50-100 mg 4 – hrs, expensive Cancer pain with amine uptake inhibitory action of morphine and pain control is usually regained without diffi- Pentazocine – Not recommended for long-term usage as it has Approximately 70% of patients with advanced cancer develop sig- culty. Addiction (psychological dependence) does not occur in psychomimetic side effects nificant pain before death. Most cancer pain responds to pharma- patients with cancer pain, and if the pain is relieved by other cological measures and successful treatment is based on simple means, such as radiotherapy or a nerve block, many patients will 115 principles that have been promoted by the World Health Organi- stop their opioids. Nausea and vomiting may occur when mor- zation and are extensively validated. Analgesic drugs shouldDr b eAzam’sphin Notese is firs int Anesthesiologycommenced and 2013 an antiemetic can be prescribed for taken 'by mouth', 'by the clock' (i.e. regularly) and 'by the anal- the first week after commencing this medication, but often it may gesic ladder' (Fig. 61.3). Cancer pain is continuous and medica- then be stopped. Sedation and cognitive impairment may occur as tion must be taken regularly. It is given orally unless intractable the dose is increased but usually resolve. However, there is no nausea and vomiting occur or unless there is a physical impedi- tolerance to the constipating effect of morphine and laxatives need ment to swallowing. The first step on the 'analgesic ladder' is a to be taken regularly. non-opioid, such as paracetamol, aspirin or an NSAID. If this is Efforts should be made to reassure both patients and relatives of inadequate, a weak opioid such as codeine is added. The third step the efficacy and safety of morphine analgesia in both the short and is substitution of the weak opioid by a strong opioid. Inadequate the long term to ensure that medication is taken. pain control at one level requires progression to an drug on the Alternative opioids and alternative routes of administration. next level, rather than to an alternative of similar efficacy. Adjuvant Hydromorphone is an alternative opioid which has been recently analgesics, such as tricyclic antidepressants or anticonvulsants, may licensed for use in the UK, although it has been available for sev- be used at any stage. eral years in North America. It is used orally and is more potent Using these strategies, pain can be controlled successfully in than morphine, with 1.3 mg of hydromorphone being equivalent about 90% of patients with cancer pain without resorting to other to 10 mg of morphine. When administered orally, hydromor- interventions. phone reaches its peak effect more rapidly than morphine and has Morphine is the strong oral opioid of choice. Immediate-release a slightly shorter duration of action. Immediate-release and sus- oral morphine, either as a liquid or in tablet form, is given every 4 tained-release preparations are available. Hydromorphone is nor- h, if necessary in increasing dosage, until pain is controlled. When mally used if morphine is not tolerated. the required daily dose has been established, it is usual to convert Methadone is a potent opioid analgesic and also an N-methyl- to sustained-release morphine tablets, which need to be taken only D-aspartate (NMDA) receptor antagonist. Methadone is absorbed once or twice daily. In addition, immediate-release morphine elixir rapidly by the oral route and has a long half-life that may range or tablets should be prescribed for breakthrough pain. The dose of from 13 to 51 h. Initial dosing must be monitored carefully as r e l - morphine necessary to treat breakthrough pain is one-sixth of the atively small doses of methadone may be needed in comparison total daily morphine requirement. with the previous opioid dose. When repeated doses are given, the Education of the medical and nursing professions, and also the drug accumulates and after the first few days the frequency of patient and family, is still necessary to ensure that adequate doses administration may need to be reduced to twice or thrice daily. of opioids are prescribed and taken. Health care professionals Methadone should be considered a third-line drug indicated for often overestimate the side-effects of morphine. Respiratory cancer pain that appears poorly responsive to morphine, diamor- depression is uncommon when morphine is prescribed for cancer phine, fentanyl or hydromorphone in spite of dose escalation and pain. Surveys have shown that patients are concerned about side- the use of adjuvant drugs. Methadone is available as tablets, linctus effects of morphine, especially tolerance, addiction, constipation and injection.

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

• For 72 hours. The patch has to be changed every 72 hours PHANTOM LIMB PAIN and is expensive. Adverse effects are the same as other • It comprises of Phantom Limb pain, Phantom limb sensation and stump opioids but less severe in intensity. pain. The mechanisms of pain postulated are the peripheral and central contributions like pre-amputation pain. ADJUVANT ANALGESICS Weak opioids are extensively used in our country for the following An adjuvant analgesic is one whose primary indication is other reasons : than pain but is analgesic in some painful conditions. • Non-availability of strong opioids in all places. • Due to stringent narcotic regulations of our government. • Neuropathic pain • ʻMisconceptionsʼ4 about oral morphine amongst general public and also • Nerve compressionSteroids medical professionals that it causes addiction, respiratory depression • Nerve infiltration Antidepressants and hastens death. • Anticonvulsants • Antiarrhythmics STEP III – STRONG OPIOIDS • Oral morphine : Is the preferred strong opioid of choice for cancer pain • Muscle spasmDiazepam management the world over. • Baclofen • Dose : is that which relieves pain. It has no ceiling dose. • Bone pain NSAID, Steroids • Dose titration : 5 to 10 mg 4 hrly and the same dose for break through • Visceral painSteroids, Antispasmodics pain. Total daily dose of morphine should be reviewed after 24 hours • Raised IC tension Steroids intervals and regular 4 hrly dose can then be adjusted • Cellulitis Antibiotics ADVERSE EFFECTS CHRONIC POST SURGICAL PAIN SYNDROMES • Day time drowsiness, dizziness, which resolve within a few days of Pain after breast surgery initiation of therapy. • Mastectomy with or without axillary clearance, Usually • Nausea and vomiting occur in one third or half of the first few days, can caused by nerve injury during surgery or brachial plexopathy. be controlled by antiemetics. Symptoms occur within the first few weeks as pain around • Constipation is almost invariable and it should be anticipated and the scar, chest wall and arm, numbness, paraesthesia and treated with peristaltic stimulants and stool softeners. muscle weakness. • Pruritis – A few require antihistaminic. • Urinary retention is relatively rare. Pain after thoracic surgery • Cause : Mechanical stretching of intercostal nerves or resection of a part of rib. • A few patients experience symptoms of neuropathic pain with both spontaneous and evoked pain with sensory disturbances.

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

BUPRENORPHINE CRPS – II is associated with major nerve injury. It is characterised by The most commonly used sublingual opioid. It is a mu- • pain and dysfunction of the sympathetic nervous system usually opioid receptor agonist. manifested in the extremities and face. • Dose : 0.2 to 0.4 mg 8 hrly. It has a ceiling to its analgesic effect at a dose of 3 to 5 mg/day/which limits its use in Symptoms cancer pain. • Spontaneous burning and stinging pain. Extreme sensitivity to temperature changes. TRANSDERMAL FENTANYL PATCHES • Asymmetry of colour and temperature of the affected limb • It is now available in our country for the past 2 years. It • consists of a reservoir of the drug sealed in a chamber with (vasomotor autonomic disturbance) a rate controlling membrane, whose area determines the • Sweating asymmetry. rate at which the drug is delivered. Currently available • Tropical changes in the skin, nail or hair follicles. patches deliver 25, 50 and 100 micrograms per hour • Swelling and stiffness of the limbs. Jumping tremors in the affected part (occasional). • Post never cut neuroma formation, changes in the dorsal • root ganglia, spinal sensitiisation and anatomical Signs reorganization in lamina of the spinal cord and cerebral Sensory disturbances like allodynia, hyperalgesia, hyperpathia and reorganization. • autonomic disturbances like temperature allodynia are characteristic The other surgical procedures which produce neurogenic • of CRPS. pain syndromes are cholecystectomy, hernia repair, Vasctomy, orthopaedic procedures like Hip replacement, Management and lumbar spinal fusion, and cardiac surgery. • Focused primarily on function restoration by occupational therapy, • Treatment : Chronic post surgical pain syndromes are recreational therapy. physiotherapy and vocational rehabilitation and effectively treated in the lines of neuropathic management psychotherapy. • Medical Management : include tricyclic antidepressants, antiepileptics, preferably gabapentine and phenytoin. NSAIDs ate considered if inﬂammation exists. The other drugs used ate cloniding for pain. Nifedipine for ischaemic pain and lidocaine patches for local allodynia. Nerve blocks : The most frequently performed are : • Paravetebral sympathetic blocks, epidural blocks. • Intravenous phentolamine or I.V. regional sympathetic blockade using guanethidine or bretylium.

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

CHRONIC NON – CANCER PAIN The dose should be increased every few days and these can be used for • Most of the charonic pain syndromes are of neuropathic depression and insomnia complication chronic pain. origin. Neuropathic pain is defined as pain initiated or caused by a primary lesion or dysfunction in the nervous system. It Anticonvulsants : causes changes in the peripheral nerve or spinal cord after • Are the first line agents for neuropathic pain and acts by membrane peripheral nerve injury or alteration in the brain following stabilization peripheral nerve injury. • Carbamezepine 200-400 mg 8th hrly • Phenytoin Signs and symptoms of neuropathic pain include : • Sodium valproate 200-400mg daily upto 1200mg • Allodynia : experience of pain for innocuous stimuli. • Hyperalgesia : an exaggerated response for a prolonged Newer anticonvulsants time to a slightly painful stimulation. • Gabapentine150mg 8 hrly upto 2-4gms/day • Hyperpathia :increased pain threshold, but once exceeded • Lamotregene50mg HS upto 200-400mg pain reaches maximal intensity too rapidly, is more severe • Gabapentine and phenytoin have a particular role in CRPS and than expectd. gabapentine in postherpetic neuralgia. • Spontaneous, continuous and paroxysmal pain. • Abnormal evoked pain. Oral local anaesthetics and antiarrhythmic drugs: • Referred pain and abnormal pain sensation • Mexietine -150mg per day gradual dose escalation upto 900mg • It has severe cardiac adverse effects. Management of chronic non-cancer pain : 1. Treat the underlying cause. Steroids : 2. General W.H.O. analgesic regimen. • Coticosteroids provide a range of effects including mood elevation, 3. Treat the neuropathic pain. antinflammatory activity, antiemetic activity and appetite stimulation. It reduces perineural odema and pressure on nerves. The most preferred are Dexamethasone, Prednisolone and Methylprednisone. MANAGEMENT OF NEUROPATHIC PAIN Ketamine hydrochloride: • A wide range of drugs have been claimed to be effective in • It acts as an NMDA receptor antagonist, there by reduces the chronic neuropathic pain. development of spinal windup and used for the relief of intractable Tricyclic antidepressants neuropathic pain. The drugs act by enchancement of noradrenergic and • Oral dose : 0.5 mg/kg/six hours and gradually increased. serotonergic mechanisms. The analgesic effect occurs with much lower doses and in 4-7 days. • Amitriptyline • Desipramine 10mg-75mg at bed time.

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

Topical therapies : • Improvement of level of function in social, familial and household roles. • Topical application in certain conditions of hyperalgesia and • Improvement or restoration of strength and functional status. allodynia. • Topical capsaicin : 0..025% - 0.075%. INTERVENTIONAL CHRONIC PAIN MANAGEMENT • Topical local anaesthetics lidocaine – 5% ointment used in • Interventional procedures are performed when the oral pharmacologic postherpetic neuralgia and post mastectomy pain syndrome approach fails. Nerve blocks with local anaesthetics or neurolytic and painful diabetic neuropathy. agents are helpful in managing intractable pain. Commonly used nerve • EMLA cream can also be tried for refractory neuropathic blocks are: pain. • Chemical rhizolysis of trigeminal ganglion or its peripheral branches. MUSCULOSKELETAL PAIN • Stellate ganglion block for upper extremity CRPS. Low back pain : It is the most common painful condition • Neurolytic celiac plexus block for upper abdominal or pancreatic amongst non – cancer pains. It is only a symptom and in most malignancy. cases the pathoanatomic diagnosis is unattainable despite • Lumbar sympathetic block for neuropathic pain of lower extremity. regular sophisticated investigative procedures. • Superior hypogastric plexus block for pelvic visceral pain. The common causes are: • Continuous epidural analgesia. • Myofasial syndrome is a disease of soft tissue with a restricted range of motion in the back hips or legs or the PSYCHOLOGICAL MANAGEMENT: presence of muscle tenderness, trigger points or both. Chronic pain patients are often disabled and also suffer from sleep • This causes mechanical dysfunction, continued strain, difﬁculties and fatigue. The psychological measures of cognitive muscle fatigue, pain and depression. behaviour therapy by multidisciplinary team is an effective adjunct in • Radiculopathy. chronic pain management. Broadly this therapy is tailored to local • Facet joint degeneration. population. The key components of this therapy are as follow.: • Failed back syndrome – persistent back pain or sciatica • Direct positive reinforcement of pain behaviour. exists after surgery. • Indirect positive reinforcement of pain behaviour. Management. • Positive reinforcement of well behaviour Chronic low back pain management requires multidisciplinary • Physical ﬁtness and function. team involvement. Treatment goals of multidisciplinary team • Cognitive reframing. are as follow: • Education and empowerment • Reduction or elimination of pain. • Critical process factors. • Reduction or elimination of medication intake. • Correction of physical abnormalities, such as posture, gait and range of motion. • Reduction of psychiatric or psychological impairment. • Education of chronic pain patients in the roles that emotions, behaviour and attitudes play. • Improvement of activities of daily living. 119

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

CONCLUSION • Chronic pain decreases function status, causes constant fear in the patients that they can not live normal lives and take-up family roles and responsibilities. It is always a challenge to any individual clinician and warrants a multidisciplinary team approach to improve the quality of life.

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Dr Azam’s Notes in Anesthesiology 2013 60. Mixture of Local Anesthetics. Dr Azam’s Notes in Anesthesiology 2013

INTRODUCTION CHANGES IN PHYSIOCHEMICAL PROPERTIES WHEN MIXING OF LOCAL • In this modern anesthetic practice mixing of local anesthetics ANAESTHETICS practice mixing of local anesthetics for peripheral nerve block • Local anesthetics base is poorly water soluble and also unstable. So and epidural block has become indispensable to most of the commercial preparation of local anesthetics are in acidic in combination practicing anesthetist, but standard text books doesnʼt with hydrochloride salts for increasing the stability. strongly discuss the advantage of mixing the local • e.g. Lignocaine HCI pH 6.5, Bupivacaine pH 5.2. Ester local anesthetics. These are the common questions to every one anesthetics preparation are stable against chemical hydrollysis in in doing the mixture. aqueous solution of pH 3-4 e.g. chloroprocine pH 3.6. • What does it really mean? Why it was done? What is the proposed advantage? Is it really so? WHAT HAPPENS TO THE PH WHEN LOCAL ANAESTHETICS ARE COMBINED PURPOSE OF MIXING LOCAL ANAESTHETICS • Anibal Galindo et al says that of nerve block and their combination in • The aim of mixing the local anesthetics is to get a faster our department. onset of nerve blockage and prolong the duration. The long The results. acting local anesthetics usually have slow onset, so to get DrugpH the advantage of these two drugs a short acting and a long Lignocaine6.5 acting local anesthetics are commonly mixed to perform the Bupivacaine 5.2 nerve block. Lignocaine : Bupivacaine • In our country we are using only bupivacaine as long acting 2 : 16.5 and lignocaine as short acting drug. So the common ideal 1 : 16.5 mixture used in combination of these two drugs in different 1 : 16.5 proportion. The following discussion is mainly about this With adrenaline 1:2000006.5 combination. • So the pH of the lignocaine is not affected by various combination, at FACTORS AFFECTING THE ONSET AND DURATION OF NERVE the same time increasing the pH makes it favorable for the action BLOCK bupivacaine • pKa is the main factor affecting the onset drugs, having pKa close to body pH have fast onset of action due to more unionized drug that is available for diffusion across the membrane. pKa of lignocaine is 7.9, and Bupivacaine 8.1. Other factors include barriers like perineurium, presence or absence of myelin, size of axon, anatomical position of the axon and alkalinisation of the durg – inﬂuence the action. • Duration of nerve blocks depend on lipophilicity and protein binding of the drug. • Drug with high lipophilicity and protein binding have longer duration of action. 121

Dr Azam’s Notes in Anesthesiology 2013 Mixture of Local Anesthetics.Continuation: Dr Azam’s Notes in Anesthesiology 2013

WHAT HAPPENED TO THE CONCENTRATION? DOES IT HOLD GOOD FOR ALL TYPES OF BLOCK? • Mixing of two drugs will definitely reduce the concentration of • For peripheral nerve blocks mixing of local anesthetics have definite both drug to half if mixed in 1:1 ration. Does it affect the advantage in faster onset and prolonging the duration, but in case of onset, duration, quality of sensory block and degree of motor epidural the duration of motor blockade is not as much prolonged as block? peripheral nerve blockade. The degree of motor block is good but the • Martin R et says, in axillary block the mixture of drug have duration of motor blockage compared to sensory blockage is less, similar type of quality of sensory and motor blockage as probably due to the dilution effect of bupivacaine after the lignocaine lignocaine and bupivacaine. Mixture having faster onset than action wear off. bupivacaine alone, longer duration than lignocaine alone. DOES TOXICITY ENHANCED? • Kaukinen set al says, the mixture of bupivacaine and • Lignocaine bupivacaine mixture – its no more toxic than parent drug lignocaine produce a block with some what better properties • The mixing of lignocaine with bupivacaine increases the distance than bupivacaine alone, some what faster onset, similar between the convulsant dose and lethal dose. duration and markedly shorter motor block than bupivacaine • At the same time mixing the bupivacaine (amide) and chloroprocaine alone. Sensory block was not significantly prolonged. (ester) intensify the chloroprocaine intoxication. This is due to • Even though the concentration of individual drug is reduced hydrolysis of chloroprocaine by plasma choline sterase is being by dilution, since the diluent is also a local anesthetic, there inhibited by bupivacaine in vitro by 38% is no reduction in its properties of neural blockage. • Mixtures of local anesthetics administered under experimental WHAT HAPPENS TO THE PROTEIN BINDING? conditions approaching the dose used in peripheral nerve blocks in • When two amide drugs are mixed together, the drug having man, exhibit essentially additive toxicity, and thus are no more toxic high protein affinity displace the other drug from protein than if the agents were injected singly. Definitely there is now binding and increase the free fraction. The systemic toxicity synergism. directly correlates with the free fraction of drugs. FATE OF ADRENALINE IN LOCAL ANESTHETIC MIXTURE • C.T.Hartick et al says, addition of bupivacaine with • Premixed adrenaline with local anesthetics having lower pH than local mepivacaine increase the free fraction of mepivacaine this anesthetics alone, due to the presence of antioxidants. interaction increase the risk of toxicity Vasoconstrictive effect of adrenaline is also pH dependent. Below the • Bupivacaine is 95% protein bound Mepivacaine 78%. pH of 5.6 vasoconstriction effect is very minimal, so mixing lignocaine Lignocaine 64% with bupivacaine increase the bupivacaine pH to 6.5 may help in • Other studies says that bupivacaine displace the lignocaine adrenaline action. from its protein binding sites but the effect is insignificant. CONCLUSION • Mixing of local anesthetics is having definite advantage in peripheral nerve block by making the onset of block faster and prolonging the duration of block and with a better degree of motor blockage. But in case of epidural, mixture of local anesthetics may not have all the advantages as in peripheral nerve block. There is a lack of studies in this topic as the reason why the standard textbook are not discussing it in detail. So further studies are needed to show the presence or absence of advantage of mixture of local anesthetics. 122

Dr Azam’s Notes in Anesthesiology 2013 61. Spinal Anesthesia In Children Dr Azam’s Notes in Anesthesiology 2013

• Spinal anesthesia is increasing being used in children of all • SA is either administered in lateral or sitting position. But keep the neck age groups. The excellent block within a few minutes is extended in sitting position so as to prevent airway obstruction. A short compatible with light sedation levels which maintain beveled 22 or 25G spinal needle is advanced slowly until CSF flows defensive airway reflexes. back when drug is injected slowly. • Barbotage method is not recommended as this may result in Anatomical considerations: unacceptable high levels of motor blockade and potential for total spinal • The termination of spinal cord in neonates is at L3, hence the blockade. The child is placed horizontally immediately after the lumbar puncture is commonly carried out at L4-5/S1-2. injection. Neonates and infants have smaller pelvis than adults and • But the caudal end of patient is not elevated for positioning or sacrum is located, more cephaloidd relative to iliac crests. placement of electro cautery as a total spinal can result from spread of Therefore intercristal line crosses the midline of the vertebral LA solution to a higher level. Successful block occurs in 2-4 minute column at the L4-5 or L5-S1 interspace well below after injection and assessing the level of blockade is performed by termination of spinal cord making land mask applicable in all Bromage score. pediatric patients. • The CSF volume will be almost double in children when Local anesthetic choices and doses: compared to adults and also CSF hydrostatic pressure will • Hyperbaric bupivacaine 0.5% is most commonly used agent others are be reduced in children. tetracaine, lidocaine, amethecaine, levobupivacaine and ropivacaine. • CSF volume is larger on an ml/kg basis in infants and • Various adjuvants to spinal solution have been used in order to neonates 4ml/kg compared to adults (2ml/kg). This may in increase duration and quality of spinal block. part account for the higher LA dose requirements and shorter • Clonidine 1mg/kg prolonged the duration of sensory block achieved duration of action of SA in this population. with bupivacaine by 30 minutes and post operative analgesia by 120 • Children with anticipated difficult airway require special care minutes without severe adverse events. as airway management is a priority in these patients even • Clonidine 2mg/kg prolonged the anesthesia action of bupivacaine but though spinal anesthesia is a reasonable choice. may be associated with hypotension. Techniques: • The puncture site is prepared with EMLA cream (eutectic Clinical uses: mixture of LA cream) or LMX (4% lidocaine cream) when • Preterm infants at high risk of apnea following GA from the commonest spinal is planned under sedation. indication of SA in pediatric patients. • Standard monitoring devices (BP cuff, pubeoximetry, ECG • Various other surgeries like cardiac surgery in combination with GA. leads) applied prior to performing the block. • Preterm infants at high risk of post operative apnea and Brady cardia are usually managed without supplemental iv or General Anesthesia while undergoing lower abdominal procedures of <90 minutes duration.

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Dr Azam’s Notes in Anesthesiology 2013 Spinal Anesthesia In Children. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Indications of SA: Contra indications: • Herniorrhaphy colostomy • Major malformation of sacrum • I & D of rectal abscess gastrostomy bowel resection • Meningomyelocoele • Append icectonomy • Meningitis • Rectal biopsy • Spinal deformity • Orchidectomy / orchiodopexry • Infection at the site of injections • Hydrocoelectomy • Coagulopathies. • Cystoscopy • Increase ICP, VP shunts. • Vasicostomy • Ureteral reimplant Dosage regimen of 0.5% bupivacaine in children • Torsion of testis 0 – 5kg 5 – 10kg 15kg • Circumcision • PUV ablation Dose (mg/kg) 0.5 0.4 0.3 • Orthopedic lower limb surgeries amputation of lower Volume (ml.kg) 0.1 0.08 0.06 extremely Duration (minutes) • Club foot repair excision of tumor 65 – 75 70 – 80 75 – 85

Miscellaneous: • Meningomyelocoele repair • PDA ligation • ASD/VSD closure Glenn shunt etc. • Radiation Oncology • Chronic pain management

Complications: • Hemodynamic changes are less frequent sympathetic block is profound in 5 year old child to cause hypotension and Brady cardia • Respiratory failure and apnea if level is above T1 • Total spinal anesthesia if proper positioning not done. • Infections • PDPH

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Dr Azam’s Notes in Anesthesiology 2013 62. Bromage score Dr Azam’s Notes in Anesthesiology 2013

Description of the Bromage score. Grade Criteria Degree of Block Grade Criteria Degree of Block I Free movement of legs and feet Nil (0%) II Just able to ﬂex knees with free Partial (33%) movement of feet III Unable to ﬂex knees, but with free Almost Complete movement of feet (66%) IV Unable to move legs or feet Complete (100%)

Modified Bromage score as used by Breen et al. Score Criteria 1 Complete block (unable to move feet or knees) 2 Almost complete block (able to move feet only) 3 Partial block (just able to move knees) 4 Detectable weakness of hip flexion while supine (full flexion of knees) 5 No detectable weakness of hip flexion while supine 6 Able to perform partial knee bend

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Dr Azam’s Notes in Anesthesiology 2013 63. Blocks of Eye. Dr Azam’s Notes in Anesthesiology 2013

! Signs of successful block: 1. Ptosis 2. Either no movement or minimal movement in all directions. 3. Inability to fully close the eye once opened. Advantages: 1. Single injection 2. Needs only a small amount of the drug. 3. Quick onset – 3-5 mts, as the LA is placed directly onto the nerves within the cone. 4. Reliable. It requires supplementary facial nerve block to produce akinesia of the lid and orbicularis oculi.

INTRODUCTION: Complications: May be due to technique or the LA used. 1. Intravenous injection and anaphylaxis. 1. Patient is either sitting or lying in a supine position. 2. Retrobulbar haemorrhage 2. 25 Gauge, 2.5 cm, needle is selected. 3. Chemosis 3. Patient is asked to look upwards and inwards to move 4. Preforation of globe internal oblique and fascia between lateral rectus and 5. Central spread of LA-convulsions, respiratory depression, cardiac inferior rectus out of path of advancing needle. arrest 4. Skin wheal is made at the junction of lateral and middle 6. Oculocardiac reﬂex one third of the inferior orbital margin. 7. Optic nerve atrophy 5. Once the needle passes through 1 cm, the needle is directed upwards and nasally towards the apex of the orbit. Contra Indications: 6. Pop is felt as the needle enters the inner space. 1. Bleeding disorders. 7. After negative aspiration, 2-3 ml is injected. The eye ball 2. Extreme myopia (increase risk of perforation) should be given gentle massage for 5-10 mts. Intermittent 3. Open eye injuries. ﬁrm digital pressure is applied for 20-30 seconds and off for 5-10 sec. to prevent occlusion of retinal artery. Massage to produce hypotony of the eye and diffusion of LA.

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Dr Azam’s Notes in Anesthesiology 2013 63. Blocks of Eye. Dr Azam’s Notes in Anesthesiology 2013

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Dr Azam’s Notes in Anesthesiology 2013 63. Blocks of Eye. Dr Azam’s Notes in Anesthesiology 2013

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Dr Azam’s Notes in Anesthesiology 2013 Blocks of Eye. Continuation: Dr Azam’s Notes in Anesthesiology 2013

FACIAL NERVE BLOCK COMPLICATIONS: AIM: • To paralyse orbicularis oculi muscle to prevent blephrospasm 1. Laryngospasm which causes a rise in IOP 2. Dysphagia Different Techniques: 1. Brien technique-commonly used 2. Van lint technique Inferior temporal site: 3. Atkinson method Peribulbar Block Superior nasal site: 4. Nadbaths technique

Procedure – O brien technique: AIM: LA in injected around rather than behind the globe. 1. Patient in sitting or lying position 2. Locate the position of the condyle and temperomandibular PROCEDURE :- Diagram shows superior & inferior sites of deposition of joint. LA 3. Ask the patient to open the mouth. 4. 25 G. needle is inserted anterior to the tragus over the condyle. 5. 4ml 0f 2% lignocaine is given after negative aspiration and after closing the mouth. 6. Firm pressure and local massage to the skin.

1. Inferior temporal site: • Patient is aksed to look straight ahead. • Enter the inferior lid at the junction of lateral and middle third with bevel towards the globe. 1ml is injected posterior to orbicularis oculi. • The needle is angled laterally and advanced anterior to the equator and inject 1 ml. • The needle is advanced just past the equator remaining outside the cone – 2 ml solution is injectd.

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Dr Azam’s Notes in Anesthesiology 2013 Blocks of Eye. Continuation: Dr Azam’s Notes in Anesthesiology 2013

2. Superior nasal site: SUBTENON ANAESTHESIA • The upper eye lid is entered between superior orbital 1. Solution is injected into subtenon space under the effect of topical notch and trochlea – 1 ml is injected. anaesthesia using 27 G needle. • The needle is advance parallel with roof of the orbit – 1 2. Alternatively LA is delivered using ﬂexible cannula after incising the ml is injected in the superior nasal quantum. conjunctiva and tenon capsule following topical anaesthesia in the • Mild proptosis and bulging of superior nasal lid fold are inferotemporal or inferonasal quadrant. indications of good block. • Ocular compression for 10-15 mts. ADVANTAGES: 1. Lack of elevation of BP and transitory cardiac arrthythmia. ADVANTAGES: 2. No post operative rise of IOP. 1. No need for supplementary facial nerve block 2. Easy to learn. CONCLUSION: 3. The incidence of serious complications is less-because the Careful attention to technique and knowledge of orbital anatomy are needle is placed further away from the optic nerve. crucial to perform a safe and reliable block.

DISADVANTAGE: 1. At least two intra ocular injections. 2. Requires large volume of LA 3. Longer time to work – 8 – 12 mts.

COMPLICATIONS: 1. Peribulbar haemorrhage 2. Ocular muscle pain 3. Ocular perforation 4. Blindness.

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Dr Azam’s Notes in Anesthesiology 2013 Blocks of Eye. Continuation: Dr Azam’s Notes in Anesthesiology 2013

Procedure: • • Apply topical anesthesia to the conjunctiva and retract the lower lid using speculum. • In the inferonasal quadrant, the conjunctiva is lifted with moor ﬁelds forceps at a point 5 to 7mm from the limbus. • A small incision is made in the conjunctiva with round tippet scissors, dissect inferomedially in a plane between the sclera and Tenonʼs capsule. • Once in this plane a blunt curved Southampton cannula is passed back wards beyond the equator and 3.5 ml of LA is deposited. • Sub - Tenons block can be used safety in patient with axial length 2-6mtn. • It is the block of choice in anticoagulated patients since any bleeding point can be cauterized directly.

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