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Home , Monitoring (medicine), Thiofentanyl

8/5/2012

Workshop Objectives:

 Understand the concepts of general and Monitoring of Anesthesia and the effects of on different body systems  Understand monitoring equipment, its limits and proper NOHA ABOU- MADI , D V M , MSC , DIPL ACZM use A A Z A K CONFERENCE SEPTEMBER 2012  Critically assess, identify and correct external factors that SYRACUSE, NY may affect the success of a procedure at induction, during the procedure and recovery  Monitor vital parameters, recognize normal changes and problems that need corrections  Identify life-threatening emergencies for the animal and the staff  Provide excellent care for the anesthetized patient

Concepts of general anesthesia, Terminology … sedation and the effects of drugs on different body systems Anesthesia vs. chemical “immobilization”

Sedation and general anesthesia Most commonly used anesthetic agents

 Immobilization: old terminology, still misused  Route of absorption:  Tranquilization  Intravenous (intraosseous), intramuscular, subcutaneous, oral, transmucosal, transdermal, and inhalation (gas)  Sedation  Some drugs can only be given by one route (propofol: IV)  General anesthesia  (pain killers)  delivery  level  Restraint: none, operative conditioning, manual restraint, chutes  Administration: oral, hand-injection, stick-pole, remote delivery systems, inhalation

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Chute Squeeze cages

Remote Administration Devices

 Use of helicopter and land crew

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Tranquilizers and Tranquilizers and sedatives

 Depress the central nervous system  Tranquilizers: phenothiazines (acepromazine), butyrophenones (azaperone, haloperidol): produce  Alleviate fear and anxiety of indifference  Fear  increased cathecolamines  irregular beats  Increased dose tend to increase side effects but no loss of when exposed some drugs consciousness  Usually not pain killers (except for xylazine,  Sedatives: benzodiazepines (, zolazepam), medetomidine) thiazine (medetomidine, xylazine), barbiturates:  Increased stimulation reverse calming effects produce state of (a.k.a. hypnotics)   Keep environment quiet Increased dose produce more profound CNS (~ anesthesia)  Allow for sufficient time to have peak effect  Reversals (antagonists): thiazines, benzodiazepines,  Additive / synergetic effect with other anesthetics butyrophenones (antipyramydal effects)

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Analgesics also used in anesthetic protocols Induction and maintenance of general anesthesia

:  Injectable drugs:  , (1-2 x morphine), (4-50 x  , tiletamine (telazol) morphine, dose dependent), (75-100 x morphine)  Propofol  Super - Opioids:   (10,000 x morphine), (1000-3000 x Barbiturates morphine), thiofentanyl  Single injection or constant rate infusion (CRI)  Variable effect on receptors (agonist, antagonist, mixed  WARNING: the combination of butorphanol, agonist-antagonists) medetomidine, and midazolam causes heavy  In combination can cause neuroleptanalgesia or sedation neuroleptanesthesia  Reversals:  (short acting), ,

Induction and maintenance of general anesthesia Other drugs

Inhalant anesthetic agents  Muscle relaxants  Isoflurane  Guaifenesin (glyceryl guaiacolate)  Sevoflurane  Neuromuscular blocking agents  Succinylcholine  Desflurane  Gallamine, atracurium, vecuronium  Reversable or not

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Effects of drugs on the animal’s system Effects of drugs on the animal’s system

:  Gastro-intestinal effects:  Depression: decreased effort, slowed rate, increased secretions (obstruction)  Vomiting, regurgitation, defecation, diarrhea, constipation, ileus  Apnea (respiratory arrest)  Kidney function:  Decreased swallowing and potential for aspiration pneumonia  Decreased flow to kidneys  decreased excretion of wastes,  Cardiovascular system: decreased excretion of drugs (incl. anesthesia), injury from lack of  Depression: decreased heart performance and rate, dilation of blood to cells vessels  May cause permanent damage if renal function is already  Stimulation: increased heart performance and rate, constriction of blood vessels compromised  Decreased blood flow to any and every organ  injury to cells and  Liver function: compromised function (reversible or not)  Decreased blood flow: decreased ability to detoxify (incl. drugs),  Musculo-skeletal system: metabolize and excrete drugs  Muscle relaxation (excitement from lack of coordination, respiratory depression)  Increased enzymatic action: increased metabolism of certain drugs

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Effects of drugs on the animal’s system Species specific anatomy and physiology

 Acid-base balance and electrolytes disturbances  Mammals: 4 070 species  Secondary to effects on other systems (muscle, GI, kidney)  Aves: 10 000 species  Nervous system:  Reptiles: 6 000 species  Depression: ataxia, decreased alertness (decreased ability to prevent drowning, erratic running and impact; inability to  Amphibians: 4 000 species evade cage mates and engage in appropriate social response)  Fish: 20 000 species  Stimulation: , increased muscle activity (ketamine, tiletamine)  Invertebrates: > 10 millions species  Eyes:  Increased pressure inside eye  Decreased function of eye lids and potential of exposure and trauma to cornea and retina

The best piece of equipment

Understand monitoring equipment Limitations and proper use

Intmath.com

Be prepared for the unexpected OXYGENATION

 Close monitoring of the  To ensure adequate oxygen animal concentration in the inspired  Equipment and drugs ready gas and the blood during all to use anesthetics  Antagonist  Inspired gas: concentration of  Emergency drug dosages oxygen in the patient breathing calculated (drawn up?) system shall be measured by an  Water / ice oxygen analyzer  Oxygen  Endotracheal tubes  Blood oxygenation  Emergency drugs and material  : calibrated for  Fluids humans; many mechanical challenges  Bandage material  Arterial blood gases: temperature dependent  Surgical pack

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VENTILATION VENTILATION

 To ensure adequate ventilation  To ensure adequate ventilation of the patient of the patient  Qualitative clinical signs:  Qualitative clinical signs:  Chest excursion, observation of the reservoir breathing bag and  Chest excursion, observation of the auscultation of breath sounds reservoir breathing bag and  Continual monitoring for the auscultation of breath sounds presence of expired when patient is intubated:  Its correct positioning must be verified by clinical assessment  Identification of carbon dioxide in the expired gas: continual end-tidal carbon dioxide analysis: (can depend on and lung perfusion)

CIRCULATION BODY TEMPERATURE

 To ensure the adequacy of the  To aid in the maintenance of appropriate body patient’s circulatory function temperature during all anesthetics during all anesthetics.   Electrocardiogram continuously Rectal temperature probe displayed (only indicates electrical  Esophageal temperature probe activity of the heart)  Infrared temperature probe  Arterial blood pressure  Indirect (cuff and doppler) – variation in diameter of legs  Direct (intra-arterial ) - invasive  Palpation of a pulse, auscultation of heart sounds

DEPTH OF ANESTHESIA Avoid Unexpected Awareness

 Loss of righting reflex  Jaw tone  Position of the eye  Ear twitch  Loss of palpebral reflex  Loss of pedal withdrawal reflex  and circulation  Corneal reflex

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ASA Physical Status Classification

 ASA Physical Status 1 - A normal healthy patient  ASA Physical Status 2 - A patient with mild systemic disease  ASA Physical Status 3 - A patient with severe systemic Critically assess, identify and disease correct external factors that may  ASA Physical Status 4 - A patient with severe systemic disease that is a constant threat to life affect the success of a procedure at  ASA Physical Status 5 - A moribund patient who is induction, during the procedure not expected to survive without the operation  ASA Physical Status 6 - A declared brain-dead patient and recovery whose organs are being removed for donor purposes

Planning Physical restraint or general anesthesia?

 What is the procedure?  Is this an emergency?  Is the animal tractable?  Will the immobilization allow for the procedure?  Is the animal trained?  Address all safety issues (animal and staff)  Make sure the equipment is working (maintenance  Do you have access to an animal trained in a squeeze and testing prior to procedure) cage?  Training of staff (on going and review)  Is the animal small enough to capture (net/hand)?  How large is the enclosure or the cage?

Planning Planning

 Determine  Pay special attention to animals  environmental conditions  recently transported or never  Temperature  immobilized before now  Humidity  Discuss the behavior of the  Time of the day  animal and its exhibit mates  Intensity of the wind  Assess location of immobilization, procedure,  if applicable recovery  Decide whether it is best to keep the animal with its  Determine if method of confinement is safe exhibit mates or isolating it for induction  Can the animal be observed post-capture?  At all time, decrease sensory stimuli to animal

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Planning Pre – Anesthetic Preparation …

 Meeting before procedure  Assignment of tasks  Complete the procedure  Debriefing post-procedure

Pre-anesthetic considerations

 Which species is involved?  Determine the psychological status of the individual  What is the present condition of the animal?  Review past medical history, available blood work, previous anesthesia and radiographs  Fasting status  *** Keep excellent records ***

Pre-anesthetic considerations

 Might you be able to perform a pre-immobilization:  Physical examination, CBC and chemistry panel?  Estimated or accurate body weight?  Does the staff require additional training?  What will be the method of restraint? Monitor vital parameters,  If chemical immobilization is chosen, which drugs and method of delivery will you use? recognize normal changes and problems that need corrections

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Calculation of dosages: Effect of size Metabolic Scaling

 Estimation of physiological parameters  Calculation of drug dosages, and treatment frequency  Minimum energy cost:  MEC= K(BWkg0.75)  K=10 (reptiles)  K=70 (placental mammals)  K=125 (passerine birds)

Record keeping Look for trends

Every 5 minutes, or more often:  Double check machine results with your own senses  Record vital parameters  Intervene before it is too late  Look at anesthesia machine  Assess response to intervention and record results  Assess position of the animal  Touch the animal

Life-threatening problems

 Animal too light – depth of anesthesia  Animal too deep – loss of reflexes, depressed respiration and cardiovascular system  Animal not breathing well – obstruction (regurgitation, obstruction because of secretions, kinked endotracheal Identify life-threatening tube, depression from anesthetic drugs) emergencies for the animal and the  Circulatory collapse (, anesthetic drugs, positioning, hemorrhage) staff  Hypothermia or hyperthermia  Pressure on muscle mass or nerves  Exposure of eyes  Bloating

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Monitoring Fish

Provide excellent care for the anesthetized patient

Fish - Induction Maintenance

 Injectable agents  Baths  Tricaine methanesulfonate (MS222)  Clove oil  Isoflurane bubbled in water

Monitoring

 Monitoring water quality  Dissolved oxygen  pH  Concentration of drugs  Temperature   Respiration  Blood gases  Depth of anesthesia

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Recovery

Monitoring Amphibians

Assisted breathing

Amphibian - Induction Monitoring

 Tricaine methanesulfonate  Light plane of anesthesia:  First sign of induction with MS222: transient erythema of light-skinned  Loss of righting reflex and corneal reflex areas (ventrum)  Presence of withdrawal reflex, spontaneous  “Emotional” erythema (also associated with movements, gular respiration, visible heart restraint) beat  Initial excitement and attempts to escape  If apnea or :  Importance of soft-sided walls to minimize  Hypoxia, hypercarbia, acidosis trauma  100% oxygen bubbled through anesthetic  Respiratory efforts (incl. ventilation of solution will correct hypoxia, though gills) will slow down acidosis and hypercarbia will persist  Heart rate unchanged (or slight increase)

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Monitoring Monitoring

 Duration of anesthesia is variable  Overdose - Tricaine methanesulfonate  Move the patient to fresh water once anesthetic level is  Heart rate slows or becomes difficult to detect achieved – 30 min of anesthesia  If HR < 20%, remove patient from anesthetic bath and rinse  If longer anesthesia is required, patient can be returned to with clean water anesthetic bath at 50% of initial concentration

Anesthetic monitoring Recovery

 Heart rate  Recovery or emergency situation: rinse patient with  Visualize heat beats copious amounts of well-oxygenated, toxin free clean  Doppler probes water  ECG  Buccopharyngeal or pulmonic  Both hypoxic and hypercarbic respiratory drives  Respiratory movements usually cease if amphibian is maintained under hyperoxic conditions (return to room air to stimulate breathing)  Blood ()  Reflexes (righting, withdrawal, etc.)

Recovery

 Assess level of consciousness and reaction to stimuli Monitoring Reptiles  Do not replace in water until the animal is awake  Assess return of normal breathing  Provide analgesia

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Assess patient Stabilize

Anesthetic Management Induction - Propofol

 Do not use hypothermia in reptiles !!!  Muscle relaxant – animal still conscious  Premedication  Midazolam  Butorphanol ?  Medetomidine  Induction:  Medetomidine  Ketamine

Induction – Mask Intubation

Dr Schumacher

Dr Schumacher

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IV catheterization

Monitoring

 Best monitoring: Doppler flow  Alternate monitoring devices: ECG and pulse oximetry

Monitoring Monitoring

Cardiovascular system Depth of anesthesia  Heart rate  Righting reflex  Doppler (blood flow)  Uncoordinated muscle  ECG movements  Mucous membranes  Response to painful  Pulse oximetry stimuli

Respiratory system:  Tail movement  Respiratory rate:  Tongue flicking  Often masked by controlled ventilation (2-6 breaths/min)  Blood gases

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Recovery

 Assist ventilation until full return of spontaneous Monitoring Birds breathing  Monitor muscle tone  Assess tongue flicking  Provide POTZ, privacy  Keep dry until recovered  Analgesia

Birds are always high-risk patients Specialized Anatomy and Physiology

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Key Points: High metabolic rate

 Attentive monitoring during anesthesia  Rapid intervention in case of complication

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Species differences Induction

 Ratites – use injectable drugs  High metabolic rate

 High O2 consumption  Effect of drugs varies with species (ratites)

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Induction with mask for most species Intubation

 Anticipate difficult intubation in a few species  Controlled ventilation:  Maintains level of anesthesia  Prevents hypercarbia  Note: damage to trachea if tip of ET tube rotates or dry air is applied to same spot  Wean slowly during recovery to spontaneous breathing

Instrumentation Monitoring

 Warming devices  Monitoring equipment  Doppler  Blood pressure cuff  ECG  Temperature probe

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Monitoring:

Monitoring  Depth of anesthesia: reflexes (palpebral, cere, toe pinch, movement to pain e.g. feather plucking)  Circulation: volume (veins), amount of blood loss, blood pressure  Heart rate (Doppler flow, ECG)  Ventilation: respiratory rate, blood gases, end-tidal CO2, oxygen saturation  Temperature: esophageal probe for core temperature measurements

Fluids IV , IO catheter – Fluid administration via pump

 Venous access  IV or IO  Crystalloid  Dextrose PRN  10ml/kg/hour  Slow bolus PRN  Hetastarch 15ml/kg  Syringe pump

Care during procedure Extubation:

 Eye lubrication and eye ring  Examine glottis prior to extubation, remove  Keep head in line with body secretion or regurgitation  Avoid moving endotracheal tube  Slowly extubate the birds to avoid trauma to tracheal  Monitor for tracheal secretions and blockage of mucosa endotracheal tube  Re-examine oropharynx and remove secretions  Monitor for regurgitation  Examine endotracheal tube for evidence of secretion  Manage bradycardia and bradyarrhythmias / blood  Ventilation  Maintain body temperature  Change level of anesthesia and fluid rate

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Recovery Complications during recovery

 Attentive monitoring  Keep in warm, padded, and dark cage  Avoid rapid changes in  Supplemental oxygen if needed position (orthostatic  Hypothermia )  Excitement, hyperthermia  Restraint until in full  Hypercarbia, hypoxia control of equilibrium  Regurgitation  In hand  Wrapped in towel  Death

Care of the animal once it is immobilized Monitoring Mammals Field Situation  Approach dangerous animals from the rear  Position body so nothing impairs breathing  Cover eyes, plug ears

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Care of the anesthetized animal Care of the anesthetized animal

 Check : Respiratory and  Check for dart heart rates, wound and temperature, other injuries oxygen saturation  Collect data (red froth)

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Reversal

 Control recovery  Use of reversals  Monitor for renarcotization  Release or transport

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Anticipate Possible Difficult Intubation Monitoring Captive Large Mammals

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Large carnivores Large carnivores: Safety

 Protocols for escape  Assign one person to oversee entire procedure  Review procedure before start and assign tasks  Assign one / two (vet, curator) leaders of procedure  Keep doors closed during procedure  Keep dangerous animals enclosed  Limit number of staff near animal during procedure  Debrief after procedure, discuss good and bad events  Vaccination of staff and animals against rabies

Fasting Once the animal is unconscious

 12-24 hours for most species  Approach with caution (usually  Less than 4 hours if metabolic one veterinarian and a senior rate is high animal staff)  Keep water but remove a few  Assess depth of anesthesia hours before induction  Secure airway  Obtain baseline respiratory and heart rates and temperature  Adjust animal in safe position (may have to be done earlier if airway is compromised)

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Care of the animal

 Positioning – consider human safety (2 exits)  Nares should not be covered  Supplemental oxygen  Endotracheal intubation

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Care of the animal Care of the animal

 Place and secure 1 or 2  Lubricate and protect the eyes against light, wind, intravenous trauma  Install monitoring equipment  Monitor, monitor, monitor!!  Administer fluids and drugs  Heart rate (stethoscope / Doppler  ECG / oxygen saturation  Blood pressure  Respiratory rate  Blood gas  Temperature  Depth of anesthesia

Complications of Anesthesia Emergence and Recovery

 Failure of  Active monitoring  Improper dosage  Reversal – How much? When?  Trauma during induction and recovery  Intervention  Unexpected movement or  Must keep recovery area awareness  Dark  Cardiovascular collapse  Quiet  Respiratory compromise and  Ventilated arrest  Small  Regurgitation and aspiration  Easy to transport  / excitement  Flexible size  Vomiting

Hoofstock Positioning of the animal

 Most species: lateral  In ruminants: sternal, head above stomach, nose pointed down (ruminant)  Monitor for bloat  Positioning of the legs to avoid pressure points

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Care of the animal Care of the animal

 Nares should not be  Lubricate and protect the eyes against light, wind, covered trauma  Supplemental oxygen  Monitor, monitor, monitor!!  Install monitoring equipment  Administer fluids and drugs  Procedure

Complications

 Trauma Monitoring Smaller Mammals  Capture myopathy  Heat prostration  Shock  Death

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Monitoring / Instrumentation

 Eye ointment  ECG  IV / IO catheter  Stethoscope  Fluid pump  Pulse oxymeter  Doppler  Thermometer  Warmth

Fluid therapy

 10ml/kg/hour IV or IO  pre-anesthesia administration:  30ml/kg SQ

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Monitoring: Monitoring:

 Respiratory function  Temperature  mucous membranes  Depth of anesthesia  respiratory rate & rhythm  Muscle relaxation  tidal volume  Withdrawal (ear pinch and  airway obstruction pedal) and palpebral  Cardiovascular function reflexes  Response to  heart rate & rhythm  Cardiovascular and  blood pressure respiratory parameters  blood loss

Complications Recovery and post-operative care:

 Anesthetic overdose  Laryngeal trauma  Recovery area warm (27-  Cardiovascular collapse  Excitement 30ºC), quiet and padded  Respiratory depression  Hypothermia  Oxygen supplementation or obstruction  Hypoglycemia  Attentive monitoring

 Analgesia  Keep separate from cage mates

What problems can occur Complications of Anesthesia in this situation?

 Failure of drug delivery  Improper dosage  Trauma during induction and recovery  Cardiovascular collapse  Respiratory compromise and arrest  Regurgitation and aspiration

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Complications of Anesthesia Capture myopathy

 Bloat  4 clinical syndromes:  Hyper / hypothermia  Capture shock syndrome  Corneal erosion / retinal  Ataxic myoglobinuric syndrome damage  Ruptured muscle  Nerve damage  Delayed peracute syndrome  Capture myopathy  Drug exposure to personnel  Death

Questions?

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Benzodiazepines Alpha-2 adrenergic drugs

 Diazepam  producing CNS depression, stimulating  Midazolam (water soluble) central and peripheral alpha2 adrenoreceptors  Zolazepam (water soluble)  Agonists: Xylazine, detomidine, medetomidine  Minor tranquilizers, centrally acting muscle  Decrease in sympathetic outflow and circulating relaxants, anticonvulsive properties, minimal CNS cathecolamines – produces sleep-like state and and cardiorespiratory depression analgesia  May cause disorientation / agitation in some sp.  Cardiovascular and respiratory depression  Antagonist: Flumazenil  Antagonists: Yohimbine, atipamezole

Ketamine Tiletamine and zolazepam

 Produces dissociative anesthetia characterized by  Combination of dissociative anesthesic agent and a poor muscle relaxation and catalepsy tranquilizer  Safe and used in a broad range of species  Telazol  Can cause seizures, muscle rigidity and excitement  More potent than ketamine and diazepam (psychosomatic effects)  Longer duration of action  Animals are hyperresponsive and ataxic during  Small volume required recovery  Can cause seizure and excitement  Usually used in combination with an anticholinergic,  Do not use in tigers a muscle relaxant and or a sedative

Opioids Propofol

 Act by reversibly binding to one or more specific  Rapid acting, ultra-short, non-barbiturate and receptors in brain and spinal cord relatively noncumulative IV anesthetic  Produces sedation and analgesia  Dose-dependent respiratory depression and initial  Synergetic effects when combined with other drugs periods of apnea  Referred to as agonist, partial agonist,  Dose-dependent cardiovascular depression agonist-antagonist and antagonist  Rapid clearing from body be hepatic an dextra-  Agonists: Etorphine, Carfentanil, Fentanyl, Butorphanol (agonist and antagonist activity) hepatic metabolism  Antagonists: Diprenorphine, Naltrexone, , Naloxone

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Human safety: Human safety

 Site of use (zoo, in field, www.mongoliatrekking.com  Carfentanil, Etorphine, Thiofentanil: abroad)  Potent opioids: severe respiratory depression, death  On site human exposure  Transmucosal (ocular, nasal, oral) or percutaneous absorption protocol (drills)  Other anesthetics: do not underestimate danger  Notification and training of  Accidents if negligence during loading or cleaning of staff, local hospital and darts or careless handling of equipment emergency room personnel (incl. paramedics) Emerg Med J 2005; 22:524-525 © 2005 BMJ Publishing Group Ltd, and British Association for Accident and Emergency Accidental human poisoning with a veterinary tranquilliser . F H Cummins

Human Safety: Prevention Human Safety: Prevention

 First aid kit: CPR equipment, drug labels and inserts,  Wear protective glasses/shield, antidotes gloves (double?), long-sleeve jacket  Never work alone when preparing, using or cleaning  Avoid spraying, spilling, squirting darts drugs  Train staff to recognize clinical signs post-exposure  Treat darts, syringes and gun with utmost care  Locate and retrieve darts immediately after use  Loading of darts in helicopters is hazardous

In case of human exposure:

 Seek medical help immediately – communication cascade  Wash area immediately  If injected use pressure bandage to reduce absorption (?)  Monitor consciousness and breathing  Place an IV catheter  Decide if antidote is needed (naloxone, naltrexone)  CPR if warranted  Transport to medical unit - bring first aid kit with patient

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