Lec 10 Chemical Restraint

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  • Many tranquilizers produce some state of sedation.
  • Muir 4th Ed Handbook of Veterinary Anesthesia
  • Each practice will set its own protocols but they will most often include:Pre-medication drug (e.g., acepromazine) Induction drug (e.g., ketamine-diazepam mixture)Maintenance drug (e.g., sevoflurane gas)Analgesic (e.g., morphine)
  • A complete list of considerations is listed on page 927.
  • Vital signs are used to assess if a patient is safe while under anesthesia.They are loosely correlated to depth of anesthesia.Vital signs can be affected by specific agents used and preexisting illness.Many anesthetic agents are respiratory depressants.Hypothermia is experienced by most anesthetized patients and should be prevented.
  • Palpebral reflex: gently tapping the skin at the medial or lateral canthus causes animal to blink.Swallowing reflex: normal reflex to saliva or food in the pharynx; watch the throat for swallowing motions.Pedal reflex: vigorously pinch a toe; limb should withdraw.Corneal reflex: place a drop of sterile artificial tears on the cornea; eyeball will retract slightly within the orbit.Muscle tone: resistance to opening jaw or observing the anal opening.Eye position and pupil size: nystagmus indicates a light surgical plane.
  • Recovery should take place where the animal can be extubated and monitored.Monitor vital signs every 5 minutes.
  • Be prepared for excitement stage as animal recovers.Gently talk to the animal to calm it down.
  • Horse recoveries can be dangerous to the horse and to the anesthetist.Ruminant recoveries are less traumatic; they will stay in sternal recumbency for some time.
  • Most problems can be corrected by carefully watching the anesthetic machine, the patient, and monitoring devices.Make sure the animal is correctly hooked up to the anesthetic machine.Watch all gauges, the reservoir bag, and the carbon dioxide canister.
  • Chapter 34 explains CPCR (cardiopulmonary-cerebral resuscitation).If animal vomits during surgery, move its head lower than the body so vomitus flows into the oral cavity and away from the pharynx.Keep endotracheal tube cuff inflated during surgery to prevent aspiration of vomitus.
  • Anticholinergics prevent bradycardia and excessive salivation.BAG = butorphanol, acepromazine, and glycopyrrolateRAT = xylazine (Rompun), acepromazine, and butorphanol (Torbugesic)
  • CNS depression, analgesia, and muscle relaxation are the main therapeutic effects of α-adrenergic drugs.Xylazine can be used to induce vomiting in cats after toxin ingestion.
  • http://iacuc.uaa.alaska.edu/Training/module%202/2_legal.html
  • CNS depression, analgesia, and muscle relaxation are the main therapeutic effects of α-adrenergic drugs.Xylazine can be used to induce vomiting in cats after toxin ingestion.
  • Used with tranquilizers or sedatives in dogs and horses.Eyes remain open after administration, so use a corneal lubricant.
  • Opioids are among the analgesics available.May cause euphoria or dysphoria.Adverse effects: CNS and respiratory depression
  • Used with tranquilizers or sedatives in dogs and horses.Eyes remain open after administration, so use a corneal lubricant.
  • Anticholinergics prevent bradycardia and excessive salivation.BAG = butorphanol, acepromazine, and glycopyrrolateRAT = xylazine (Rompun), acepromazine, and butorphanol (Torbugesic)
  • Lec 10 Chemical Restraint

    1. 1. Chemical Restraint
    2. 2. Anesthesia The absence of sensation  General anesthesia • Unconsciousness and insensibility to feeling and pain • Used for general surgery and painful procedures  Local anesthesia • Loss of sensation in a localized body part or region • No loss of consciousness Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3
    3. 3. More Terminology Sedation  State of calm or drowsiness Tranquilization  State of relaxation and reduced anxiety Neuroleptanalgesia  State of profound sedation and analgesia  Produced by administration of an opioid and a tranquilizer  Used to perform minor procedures Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4
    4. 4. 5
    5. 5. Balanced Anesthesia Concurrent administration of two or more anesthetic drugs to achieve the desired anesthetic state  Loss of sensation  Muscle relaxation  Analgesia  Altered consciousness  Patient safety  Minimal adverse effects • Especially respiratory and cardiac functions Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6
    6. 6. Anesthetics Complete loss of sensation – often loss of consciousness. Provides depression of nervous tissue, local or general• Be prepared to intubate• Typically metabolized by hepatic or pulmonary systems
    7. 7. Extravasation is bad Drugs can cause tissue damage if given perivascular (around the vein)  Examples: Ketamine, Chemotherapeutics, 10% Dextrose If it happens:  Inform DVM  May infuse equal amount isotonic saline or may watch/wait (benign neglect) then treat PRN
    8. 8. Reasons for Chemical Restraint Reduce anxiety Reduce fear related aggression, so improved safety for handlers Immobilization Reduce stress Reduce struggling, so less potential for injury to patient or handler during procedure
    9. 9. Routes of Administration Oral Spray Pill/liquid Parenteral S.Q. Subcutaneous I.M. Intramuscular I.V. Intravenous Darts
    10. 10. Disadvantages Most are CNS depressants Many are CV and/or respiratory depressants Hypothermia is common If sedation for handling, may be unexpected  P may have eaten recently  > chance of V Injury can occur during induction or recovery Patient requires monitoring after procedure
    11. 11. Considerations Species  Emotional status Fearful? Physical factors   Aggressive? Age  Environment Sex  Noise Odors Physical condition   Other patients Pregnancy Anatomy Brachycephalic
    12. 12. What does the RVT do? Prepare supplies for sedation & procedure Controlled Substance Log Prepare area to maximize P comfort Position P appropriately Induce anesthesia or assist DVM in inducing Monitor P during & after procedure Keep DVM informed of any changes in P status
    13. 13. Controlled Substances Schedule Drugs  I – no accepted medical use (PCP, LSD)  II – high abuse potential, severe physical dependence (many opioids, pentobarbital)  III – moderate/low physical dependence, less abuse potential (ketamine, Telazol, buprenorphine, euthanasia - pentobarbital)  IV – low abuse potential, limited physical dependence (phenobarbital, benzodiazepines, butorphanol)  V – lowest abuse potential of controlled drugs
    14. 14. Patient Care During induction and maintenance of general anesthesia, the positioning, comfort, and safety of the patient must be considered  Prevent trauma by supporting patient’s body  Check endotracheal tube for proper placement  Make sure the tube cuff is inflated  Don’t hyperflex or hyperextend neck or limbs  Don’t compress chest  Make sure patient stays warm  Sterile lubricant in eyes every 90 minutes Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15
    15. 15. Vital Signs Used to evaluate cardiovascular and respiratory systems  Heart rate and rhythm  Respiratory rate and depth  Mucous membrane color  Capillary refill time  Blood pressure  Body temperature Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16
    16. 16. Reflexes and Other Indicators of Anesthetic Depth Reflex: Involuntary protective responses to stimuli that can be used to determine anesthetic depth  Palpebral reflex  Swallowing reflex  Pedal reflex  Corneal reflex Muscle tone Eye position and pupil size Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17
    17. 17. Anesthetic Recovery Time between discontinuation of anesthetic and time when patient is able to walk unaided Factors  Length of procedure  Anesthetic protocol used  Patient condition  Body temperature Patient must be watched continually during recovery Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18
    18. 18. Level of Consciousness Terms BAR – bright, alert, responsive Obtunded – slow, lethargic, dull Stuporous – aroused by strong stimuli Comatose – no cerebral response to stimuli 19
    19. 19. Anesthetic Recovery Rubbing, patting the chest, and turning the animal may hasten recovery Gentle movement of endotracheal tube will stimulate breathing Recovery involves reverse movement through the planes and stages of anesthesia Deflate the cuff and untie the tube before the animal shows signs of recovery to allow removal when animal swallows Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20
    20. 20. Anesthetic Recovery Horses must stand shortly after recovery Some horses will try to stand too early and have a rough recovery Ruminants will stay in sternal recumbency during recovery Try to prevent bloat in recovering ruminants Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21
    21. 21. Anesthetic Problems Adverse drug reactions Equipment malfunction Anesthetic overdose Complications of surgery  Blood loss Human error Apnea or hypoventilation Hypotension Cyanosis or low oxygen saturation Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22
    22. 22. Anesthetic Emergencies The animal won’t stay anesthetized  Check the machine and endotracheal tube Excessive anesthetic depth  Stop anesthetic delivery; give pure oxygen Cardiopulmonary arrest (CPA)  No heartbeat, pulse or respirations  Requires immediate CPCR Vomiting or regurgitation  Can result in aspiration into the lungs Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23
    23. 23. What if something goes wrong? Do not panic Breathe Inform DVM Take action Keep detailed records  Include drugs administered, times given, amount (mg, ml)
    24. 24. How can I convince my doctor to let me do more? Show DVM they can TRUST you  Attention to detail  Always be prepared  Knowledge of anesthesia  Patient care, monitoring  Procedure, medicine  Drugs used  Always clean up
    25. 25. Injectable Anesthetic Agents Phenothiazine tranquilizers  To calm and sedate patients before general anesthesia  Reduced anxiety during induction and recovery  Does not diminish P consciousness  Example: acepromazine alone or in combination with other drugs Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 27
    26. 26. Phenothiazine Tranquilizers• Often see hypotension, sometimes profound• Depresses CNS• No analgesia• Anti-emetic• Potent – long lasting• May not always work as anticipated • Cats, horses, some dogs• Avoid in P w/ seuizure hx, in stallions
    27. 27. Injectable Anesthetic Agents α2-adrenergic drugs  Sedatives used with other drugs to produce effects from sedation to general anesthesia  Examples: • Xylazine and medetomidine and dexmedetomidine in SA • xylazine, detomidine, and romifidine in LA Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 30
    28. 28. Alpha-2 agonists Xylazine, Detomidine, Meditomidine, Dexmeditomidine  Initial hypertension, then HYPOtension  Bradycardia Use for sedation and analgesia Ruminants VERY sensitive (small dose) IM on aggressive animals, IV if can handle animal IV-sedation in 3-5 min; IM -5 to 15 min Quiet, calm environment IMPORTANT
    29. 29. Alpha-2 antagonists Yohimbine, Atipamezole, Tolazoline  Used to reverse effects of alpha-2 agonists (anesthesia, analgesia)  Typically takes effect in 3-5 minutes after IM injection
    30. 30. Benzodiazepine + dissociative Telazol - Equal parts zolazepam (benzodiazepine) + tiletamine (dissociative, cyclohexanone) Acidic (can burn/sting) Provides analgesia & muscle relaxation Not okay as sole agent for major surgery  Can do TKX (telazol + ketamine + xylazine) Effect in 1-10 minutes following IM injection Mostly used IM, but Plumb lists an IV dose
    31. 31. Injectable Anesthetic Agents Benzodiazepine tranquilizers  Used with other drugs to produce effects from sedation to general anesthesia  Controlled substances  Examples: Diazepam, midazolam, zolazepam Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 37
    32. 32. Benzodiazepines Diazepam (valium)  Anti-convulsant  Muscle relaxant  Can cause excitement in some spp if given alone (Feline, equine) M99 (Etorphine) * Synthetic opiate * Highly analgesic
    33. 33. Injectable Anesthetic Agents Dissociatives  Used alone to immobilize patients for minor or brief procedures  Produce immobilization, not surgical anesthesia  Example: ketamine Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 40
    34. 34. Disassociatives, cyclohexanones Produces trance like state with some reflexes intact.  Ketamine, tiletamine Some analgesia (poor visceral analgesia) Rigidity of muscles (catalepsy) May cause seizures in dogs when used alone IV, IM, (SQ)
    35. 35. Injectable Anesthetic Agents Opioids  Narcotics related to morphine  Used as sedatives, analgesics and neuroleptanalgesics (with tranquilizers)  Cats and large animals: experience anxiety, excitement, hyperthermia, and mydriasis  Dogs and primates: experience sedation, hypothermia, and miosis  Examples: fentanyl, hydromorphone, oxymorphone, buprenorphin e, butorphanol, naloxone (reversal) Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 45
    36. 36. Narcotics (opiods) Provide sedative, hypnotic and analgesic properties Decrease respiration Emesis  (note: apomorphine – substance used to induce vomiting) Hypersensitivity to noise Can be given IV, IM, SC
    37. 37. Injectable Anesthetic Agents Propofol  Short-acting IV anesthetic  Used to induce general anesthesia  Has anticonvulsant and antiemetic properties  Rapid induction can cause apnea and hypotension Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 48
    38. 38. Propofol Non-barbiturate, non-dissociative IV anesthetic agent Used for sedation, induction and/or anesthetic maintenance by repeated bolus injection Transient apnea after rapid IV injection No analgesia Not controlled May cause myoclonus (some like to give w/ diazepam) Discard 6h after reconstituting (new 28d formula)
    39. 39. Injectable Anesthetic Agents Imidazole derivatives  Short-acting sedative/hypnotic  Used to induce anesthesia in dogs and cats  Example: etomidate  Minimal CV effects  Minimal respiratory effects  Good to pre-med w/ benzodiazepine • Minimize excitement, myoclonus Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 50
    40. 40. Injectable Anesthetic Agents Guaifenesin  AKA glyceryl guaiacolate or GG  A muscle relaxant and sedative  Used in combination with other drugs in large animals • Must give rapidly • Extravasation  tissue necrosis, sloughing  Also used as an expectorant Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 51
    41. 41. 52
    42. 42. Injectable Anesthetic Agents Barbiturates  Are used for induction of general anesthesia, treatment of seizures, and euthanasia  Are controlled substances  Thiopental sodium methohexital: ultrashort-acting for induction of general anesthesia  Pentobarbital sodium: intermediate acting used for euthanasia Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 53
    43. 43. Anticholinergics Not true anesthetic agents Counteract effects of the parasympathetic nervous system – work to prevent/counteract bradycardia and excessive salivation May be part of premedication for surgical procedures Examples: atropine and glycopyrrolate Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 55
    44. 44. Inhalant Anesthesia

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