anesthetic-related drugs

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  1. anesthetic adjuncts
    not true anestheic drugs, used during anesthesia to produce desired effect--muscle relaxation, sedation, analgesia, or reversal
  2. goals of preanesthetic medication
    • decrease anxiety and fear
    • aid in restraint during IV catheterization and induction
    • provide pre-emptive analgesia
    • decrease amount of drugs needed for anesthetic induction and maintenance
    • decrease airway secretion and salivation (not necessary)
    • make induction and recovery phases smoother
  3. administration routes of premedication
    • trans-mucosal: cats, ketamine, buprenorphine, dexdomitor
    • PO, SQ, IM leads to unpredictable absorption and peak onset of action (stimulation can overcome)
  4. considerations in choosing premed
    • age
    • physical status
    • species
    • disposition
    • surgical procedure/duration
    • inpatient vs outpatient
    • elective vs emergency
    • DVM's/anesthetist's experience
  5. anticholinergic agents
    • glycopyrrolate, atropine
    • no longer routinely recommended as preanesthetics
    • fix bradycardia from vagal stim
    • reduce salivary and respiratory tract secretions
    • mydriasis, reduced tear secretion
    • reduce GI motility
  6. atropine
    • anticholinergic agent
    • extreme caution in horses (ileus leading to colic)
    • Not recommended in ruminants (cross blood-brain barrier, causes restlessness, disorientation, inappetance, rumen stasis)
    • may potentiate effects CNS depressants
    • Not for use in C-sections
    • First choice in small animal emergencies
  7. glycopyrrolate
    • generally considered anticholiergic of choice, except in CPCR
    • compared to atropine, glyco has less tachyarrhytmias, longer duratin (2-3h instead of 45 minutes)
  8. sedative hypnotic agents, definition
    • tranquilizers
    • agents that act on CNS to calm and quiet the patient, making it unconcerned with its surroundings (and sleepy)
  9. sedative
    decreases motor activity, moderates excitement and instills calm
  10. hypnotic
    causes drowsiness and facilitates sleep
  11. major tranquilizers
    • phenothiazine derivatives, ex. acepromazine
    • sedative effect
    • cause mental calming, stimuli can reverse, so use cautiously in aggressive animals
    • decrease motor activity
  12. acepromazine breed characteristics
    • major tranquilizer, phenothiazine derivative.
    • giant breeds and greyhounds are sensitive
    • dogs with MDR1 may need reduced doses
    • terriers resistant
    • more effective in dogs than cats
    • if not sedated at lower dose, higher dose won't be effective
  13. acepromazine cardio effects
    • peripheral vasodilation leads to hypotension, which leads to heat loss and hypothermia (can't shiver)
    • contraindicated in dehydration, hypovolemia and shock (where vasodilation would be bad)
    • AVMA against routine use in travel
  14. effects of acepromazine
    • antiemetic effect (blocks dopamine receptors)
    • mild antihistamine effect (not for allergy testing)
    • May have increased potency/prolonged duration in neonates, geriatrics and animals with liver dysfunction (reduce dosage)
    • no longer contraindicated in seizure history
  15. acepromazine contraindications
    • not for use in C-sections
    • paraphimosis in horses (usually resolves in 30 minutes-2 hours, can be permanent in stallions)
    • prolapse of nictitans in horses, dogs, cats
  16. minor tranquilizers
    • benzodiazepines: diazepam, midazolam
    • schedule IV
    • VERY safe for healthy, but hepatic biotransformation, reversible
    • antianxiety and hypnosis (paradoxical excitement, agitation, vocalization, careful with aggressive)
    • skeletal muscle relaxation
    • anticonvulsant (drug of choice for seizure risk)
    • appetite stimulant in cats and ruminants, maybe dogs
  17. diazepam
    • benzodiazepine
    • propylene glycol vehicle (hemolysis, thrombophlebitis, arrhythmias, hypotension, apnea, pain in small veins or IM)
    • don't mix in syringe
    • IV only, inject slowly
  18. midazolam
    • benzodiazepine
    • water-soluble (IV, IM, SQ), mixed in syringe okay, no propylene glycol problems
    • faster onset, shorter duration, crisper wake-up than diazepam
    • can cause behavioral changes, esp given alone
  19. flumazenil
    • reversal for benzodiazepines (antagonist at receptors)
    • contraindicated where BZD treating seizures
    • IV only (extravasation causes local tissue irritation)
  20. alpha-2 adrenoreceptor agonists
    • xylazine, medetomidine, dexmedetomidine
    • CNS effects (sedation & analgesia, dose-dependant), muscle relaxation
    • Higher doses increase sedation duration but don't increase analgesia (ceiling effect). Sedation lasts longer than analgesia
    • excitement/stress may negate sedation (keep dark and quiet), sudden stimuli can cause aggression
  21. effects of alpha2 agonists
    • sedation and analgesia, sedation lasts longer
    • muscle relaxation
    • cardio effects: INITIAL VASOCONSTRICTION (=hypertension, 1 hour), bradycardia and A-V block (decreases CO even at low doses), followed by significant vasodilation and hypotension.  HEALTHY ANIMALS ONLY
    • GI effects: xylazine=vomiting (90% cats 50% dogs).  Medetomidine=vomiting (lower %), bloating in ruminants and dogs
  22. anticholinergics and alpha 2 agonists
    anticholinergics at least 10 minutes before but not during or after alpha2s (dogs)
  23. dexmedetomidine administration
    • best to administer in conjunction with other agents (balanced regimen) due to cardiac effects
    • like kitty magic (ketamine, dexdormitor and butorphanol or buprenorphine)
  24. absorption of alpha 2 agonists
    can be absorbed through abraded skin and mucous membranes.  WASH HANDS
  25. reversals of alpha 2 agonists
    • xylazine: yohimbine or tolazoline
    • medetomidine: atipamezole (IM only, rapid reversal can cause severe hypotension)
  26. narcotic
    drug that produces insensibility or stupor; term reserved for opioids that are illegally used (illegal non-opioids also described this way)
  27. opiate
    any agent containing opium or its derivatives (naturally derived)
  28. opioid
    • any compound with opiate-like actiity that is legally used for accepted medical purposes
    • Ideal Term
  29. opioid analgesic agents
    • most effective analgesic agents
    • provide safe and reversible analgesic effects
    • act at mu, kappa and/or delta receptors
    • Full (strong) mu or mixed agonist/antagonist (partial)
    • CNS - analgesia, sedation, euphoria/dysphoria, respiratory, cardiovascular, GI, ophthalmic, body temp
  30. mu full or strong opioid agonists
    • morphine, hydromorphine, fentanyl, methadone, oxymorphone
    • for moderate to severe pain
  31. mixed agonist-antagonists (partial agonists)
    • buprenorphine, butorphanol
    • mild-to-moderate pain
    • don't fully stimulate opioid receptor causing plateau effect
    • bupe used for more severe pain in cats because tolerated so well
  32. basic effects of opioids
    • analgesia
    • sedation - excitement/agitation may indicate excessively high dose or too-rapid absorption (better with sedative/hypnotic, hydromorphone best with dogs)
    • euphoria/dysphoria
    • body temp - dogs hypothermic (thermoregulatory center), cats hyperthermic (4-6h post-op)
    • Give slowly to minimize effects
  33. respiratory and cardio effects of opioids
    • respiratory despression rare with appropriate doses and for awake animals in pain
    • usually minimal cardio at recommended doses.  Bradycardia only if predisposed
  34. GI and ophthalmic effects of opioids
    • nausea/vomiting often occurs in non-painful, healthy animals (pre-med), less in recumbant than ambulatory
    • intenstinal cramping and constipation
    • miosis in dogs
    • mydriasis in cats and horses may indicate need for dose reduction.  
    • Mu agonists not used in intraocular surgery due to risk of synechia (lens stick to iris or other things).  Use kappa instead
  35. Recuvyra
    • concentrated fentanyl topical on dorsal scapular on dogs
    • dries in 5 minutes, lasts 4 days
    • wear gloves (absorbable)
    • administer 2-4h prior to sx, meant for post-op pain
  36. Remifentanil (Ultiva)
    • Ultrashort duration
    • used with propofol CRI for total anesthesia in dogs
    • very rapid recovery, dog awake within 5 minutes, recovered within 5-10 minutes
    • NO RESIDUAL ANALGESIA, need additional prior to recovery
  37. butorphanol
    • opioid primarily partial kappa agonists (very weak partial mu agonist)
    • good sedation at low doses
    • short anti-nocioception (d=30m-1h, c=2-3h), not great analgesia
    • PARTIALLY REVERSE strong mu opioids
    • schedule IV
  38. buprenorphine
    • cat well absorbed through buccal and sublingual mucous membranes (tolerate very well)
    • primarily partial mu agonist
    • duration analgesia = 4-8h (long-lasting)
    • schedule III
  39. opioid reversals
    • pure opioid receptor antagonist (no other effect, at mu, kappa and delta).  
    • naloxone (Narcan): 2-4h duration, may need to redose (bup lasts longer)
    • Naltrexone: last 2x as long as naloxone
    • also reverses ENDOGENOUS opioids, so increases pain if not reversing.  
    • partially reverses butorphanol, keeps some analgesia.
  40. tramadol
    • opioid metabolites in some species like cat but NOT IN DOG
    • inappropriate for use as sole analgesic unless pain is very mild, good as part of multimodal analgesia
    • variable bioavailability, lasts 4-6h
  41. neuroleptanalgesia
    profound state of sedation and analgesia produced by opioid combined with sedative/hypnotic
  42. drug classes for induction
    • cyclohexamines
    • neuroleptanalgesics
    • propofol
    • alpha2 agonists
  43. induction administration
    • administer to effect to given minimum dose needed to achieve desired level of anesthesia
    • administer slowly to reduce risk of excessive CNS depression
  44. cyclohexamines
    • dissociative agents, NMDA receptor antagonists
    • ketamine, tiletamine
    • selectively depress/stimulate portions of CNS (depress thalamus, stimulate limbic)
    • schedule III
    • telazol (tiletamine + zolazepam)
  45. effects of ketamine
    • apneustic breathing pattern (long inspiration, short expriation, still ok ventilation, looks like holding breath)
    • increased salivation
    • can cause SEIZURES (give with diazepam)
    • eyes stay open, no blink reflex, use eye lube
  46. ketamine
    • produces dissociative anesthesia with: skeletal muscle rigidity (use with tranquilizer) (stretched out limbs, extended neck)
    • sedation with marked stimuli sensitivity
    • oral, ocular, pharyngeal and laryngeal reflexes remain intact (weakened swallowing reflex)
  47. dissociative agents side effects
    • emergence phenomena during recovery
    • hallucinations in humans, suspected in cats
    • animals get vocalizing, anxiousness, thrashing
    • administer with sedatives
  48. recovery from ketamine
    • excited, violent recovery
    • bizarre behavior including tremors and seizures
    • monitor to prevent self-injury
    • cats may have hyperthermia 1-4 hours later
  49. propofol
    • IV rapid-acting sedative hypnotic, not a barbituate but similar. No damage if gets outside vein
    • Give slowly (60 sec) or apnea
    • causes hypotension/bradycardia (no cardiac Ps) and respiratory depression (pre-oxygenate)
    • anticonvulsant but causes seizure-like signs in dogs, hyperthermia in cats
    • ASEPTIC TECHNIQUE (sterile syringe, 6h, away from light, in fridge)
    • recovery in 10-20 minutes (alone)
    • subanesthetic = sedation and unaware of surroundings
    • anesthetic = unconscious, muscle relax
    • 4x more likely to get infections (microbial growth)
  50. etomidate
    • ultra short-acting, non-barbituate hypnotic
    • minimal cardio or respiratory depression (inductin in cardio disease, C-sections in debilitated animals)
    • NO analgesia
  51. adverse effects of etomidate
    • nausea, vomiting
    • myoclonus (repetitive, rhythmic contraction of skeletal muscles = rough waking up)
    • give with preanesthetic sedation
    • painful injection (propylene glycol)
    • duration is dose-related, redistributed in fat and biotransformed.
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anesthetic-related drugs
2014-04-21 17:49:13
vet tech 247
vet tech 247
anesthetic related drugs in surgical nursing
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