Lec 10 Chemical Restraint
Transcript of Lec 10 Chemical Restraint
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Chemical Restraint
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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
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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
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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
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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
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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
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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
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Routes of Administration
Oral Spray Pill/liquid Parenteral S.Q. Subcutaneous I.M. Intramuscular I.V. Intravenous Darts
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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
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Considerations Species Physical factors Age Sex Physical condition
PregnancyAnatomy
Brachycephalic
Emotional status Fearful? Aggressive?
Environment Noise Odors Other patients
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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
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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
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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
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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
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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
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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
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Level of Consciousness Terms
BAR – bright, alert, responsive Obtunded – slow, lethargic, dull Stuporous – aroused by strong stimuli Comatose – no cerebral response to
stimuli
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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
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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
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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
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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
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What if something goes wrong?
Do not panic Breathe Inform DVM Take action Keep detailed records
Include drugs administered, times given, amount (mg, ml)
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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
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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
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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
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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
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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
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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
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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
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Injectable Anesthetic Agents
Benzodiazepine tranquilizers Used with other drugs to produce effects from
sedation to general anesthesia Controlled substances Examples: Diazepam, midazolam, zolazepam
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Benzodiazepines
Diazepam (valium) Anti-convulsant Muscle relaxant Can cause excitement in some spp if given
alone (Feline, equine)
M99 (Etorphine) * Synthetic opiate * Highly analgesic
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Injectable Anesthetic Agents
Dissociatives Used alone to immobilize patients for minor or
brief procedures Produce immobilization, not surgical anesthesia Example: ketamine
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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)
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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,
buprenorphine, butorphanol, naloxone (reversal)
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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
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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
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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)
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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
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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
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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
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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
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Inhalant Anesthesia