anethesia test

  1. which injectables are barbiturates
    thiopental sodium, methohexal sodium
  2. which injectables are cyclohexamines
    ketamine, tiletamine
  3. Specifics about injectable anesthetics
    • route: always parenteral-usually IV
    • used to maintain anesthesia: drip for short procedures
    • -important to know which accumulate in the body tissues
  4. why is it important to pass through the first two stages quickly
    decreased chatacholamine production
  5. advantages injectable anesthetics vs gas
    • simple to give
    • little equipment needed
    • more economical
    • no chance of explosion or polution
    • no irritation to airway
  6. Disadvantages of injectable anesthetics
    • Possibe tissue irritation-barbituates
    • once given no removal or reversal agent
    • depth of anesthesia not easily altered
    • airway not often provided
    • drug may be cumulative
    • recovery-excitement/hallucinations
    • induction apnea possible
    • elimates throught the kidneys
  7. Iv admin
    • more immediate effect-drug is deposited directly into blood
    • easier to titrate to final effect-occurs almost immediatly after injection
    • used for drugs that are irritating to the tissues (barbituates)
    • requires more restraint
  8. Im Admin
    • does not require as much restraint
    • cant titrate to effect, can be extreamly variable between pts
  9. IP admin
    only on pts that you cant access a vein: rodents neonates
  10. Injectable anesthetics are used for:
    • induction agents
    • -allow intubation, allow maintenance w. an inhalent
    • maintain anesthesia for short proceedures
    • -short-acting, drugs w/ littel accumulation in body tissues
    • quickly re-establish anesthetic plane
    • -only if on inhalent
    • increased analgesia
    • -lidocaine
    • -supplement to inhalent anesthesia
  11. factors that affect IV anesthesia
    • blood flow to brain and other tissues of the body-lipid solubility
    • distribution to and absorption by other tissues of the body
    • metabolism-redistribution must happen
    • elimination
  12. barbituates specifics and uses
    • schedule III (some II)
    • induction
    • general anesthesia
    • sedatives/hypnotics-pentobarbitol
    • anticonvulsant-phenobarbitol
    • euthanasia-pentobarbitol
  13. 3 classes of barbiturates
    • Short acting
    • intermediate acting
    • long acting

    the shorter the drug action the more lipid soluble the drug
  14. Short acting barbiturates
    • thiopental-10 mins of true anesthesia, complete recovery w/in an hour
    • ultrashort-methohexital
  15. Intermediate acting barbiturates
    Pentobarbital 30mins/6hrs
  16. long acting barbiturates
    phenobarbital 4hrs/15hrs
  17. why is lipid solubility important
    high lipid content of the brain and blood allows for immediate effect
  18. barbituates vary in?
    • lipid solubility
    • distribution
    • onset of action
    • length of effect
  19. CNS effects of barbiturates
    • depression-degree depends on dose and drug
    • anticonvulsant
    • excitation during induction and recovery
  20. respiratory effects of barbiturates
    • Resp. depression-rate and tidal volume and response to rising CO2
    • Dose dependant relationship
    • apnea-w. rapid admin or high doses
  21. Cadiopulmonary effects of barbiturates
    • can significantly depress CVS if given rapidly or in high doses
    • directly depresses the myocardium resulting in decreased cardiac output
    • increase heart senstivity to the action of epinephrine-especially in excited or stressed animals can cause dangerous arrythmias
  22. classes of pts that are particularly sensitive  to barbiturates
    • hypoproteinemic
    • acidotic
    • lean animals-sight hounds
    • liver dysfunction
    • renal failure
    • cats
  23. 5 steps you must use if admin outside the vein
    • stop injection
    • keep (-) pressure on syringe while withdrawing it from pt
    • infiltrate/dilute w/ isotonic saline (+/- lidocaine)
    • notify veterinarian
    • watch for signs of irritation (1-2hrs) sloughing (2-5 days)
  24. 5 signs that occur after perivascular injection
    • local swelling
    • pain
    • necrosis
    • tissue sloughing
    • scaring
  25. side effects of barbiturates
    • stage II excitement-due to extravascular inj. or subanesthetic amoutns, may be dangerous due to injury, give 1/3 rapidly then titrate
    • hypothermia-slow metabolism & excretion
    • Cats-more sensitive due to enzymes
  26. common barbiturates used in vet med
    • thiopental-pentothal
    • methohexitol-brevital
  27. Thiopental specifics
    • supplied in a powdered form
    • reconstitute to 1-5% solution
    • unstable shelf life (2 weeks in fridge)
    • continuous admin with cause:
    •    body to become saturated
    •    recovery will be prolonged
    • 70%-80% is bound to plasma
  28. Thiopental effects
    • causes splenic engorgement
    • may not want to use for abdominal sx
  29. Thiopental use in large animal
    • horses-use following tranquilization given iv using 5% solution
    • Cattle-not used
    • pigs-same as dogs or cats
  30. Cyclohexamines/dissociatives
    • ketamine-kataset, ketalean, vetatar
    • tiletemine-always combine w/ zolazapam- telazol
  31. Mode of action of the cyclohexamines
    • disrupt nervous system pathways
    • -amneasia, analgesia (only to limbs) and catalepsy
    • protective reflexes may be exaggerated rather than depressed
    • -difficult to assess depth
    • marked sensitivity to sound and light
  32. General characteristics of cyclohexamines
    • provide analgesia to skin and limbs
    • poor visceral analgesia
    • metabolized by the liver
    • renal excretion
    • cannot reverse-will cause extream excitement
    • could help in speeding recovery and controlling extreme post anesthetic excitement
  33. System effects of cyclohexamines
    • tissue irritation-but no sloughing
    • ptyalism-drooling
    • increased csf pressure
    • eyes remain open, centrail and dialated
  34. cardiopulmonary effects of cyclohexamines
    • stimulates Cardiovascular system
    • -Increased HR, CO, mean arterial BP and venous pressure
    • -increased Oconsumption demand
  35. Respiratory effects of cyclohexamines
    • apneustic repiration pattern
    • -inspiratory followed by prolonged pause, exhalation short hard breath
    • can tap nose to encourage breathing
  36. Contradictions for cyclohexamines
    • Epileptogenic-seizure pt
    • emergence delirium
    • -vocalization, agitation, uncoordination, tranqs can help min. effects
    • caution for repeated admin.
    • -accumulation in tissues especially  in overweight pts increased risk of seizures PO
    • metabolized by the liver excreted by the kidneys
  37. Drugs commonly used in combo with ketamine
    • ace
    • diazepam-most commin in sm animal
    • guaifenesin-lg animal
    • xylazine-lg animal (cats)
    • medetomidine-fractious cats (cat magic)
  38. Tiletamine
    Schedule III used with zolazepam-Telazol
  39. advantages of tiletamine advantages
    • newer dissociative
    • onset of action is more rapid and longer than ketamine/diazepam IM
    • good muscle relaxation
    • good induction agent in health dogs and cats
    • less apneustic respiration
    • variety of species, wild life immobilization
  40. disadvantages of tiletamine
    • rough recovery
    • cats have prolonged recovery
  41. Propofol
    diprivan, rapinovet, propoflo
  42. Specifics of propofol
    • slighty water soluble-but needs to be mixed
    • contains soybean oil and egg lecithin
    • supports bacterial growth-once open discard w/in 6hrs
    • extended use version has benzyl alcohol good for 12hrs but contra indicated in cats
    • wide margin of safety
  43. advantages of propofol
    • short duration in dogs and cats
    • does not accumulate-can be used CRI
    • no reaction if given perivascularly
    • rapid onset caused by cns uptake
    • good induction agent for sight hounds
    • no need for anticholenergic (may want tranq pa)
    • brisk, smooth recovery
    • safe w/ pts with hepatic dz and renal dz pts
    • can be used to quickly reestablish anesthetic plane
  44. disadvantages of propofol
    • will cause dose dependant apnea and hypotension
    • caution should be used if animal has cardiac preload problem (blood loss or dehydration)
    • poor analgesic
    • expensive
    • poor storage
    • may exacerbate systemic infections
  45. metabolism and elimination of propofol
    • meabolized by conjugation w/ the liver playin an important role
    • plasma clearance exceeds hepatic blood flow suggesting other organs may also be involved
  46. effects of propofol
    • cns depression
    • can produce resp, depression and apnea
    • transient decrease in arterial BP and myocardial contractility
  47. routes of propofol
    • titrate to effect slowly over a period of 20-60 seconds
    • 1cc/5-10sec
    • onset of action <60 sec
    • duration 5-10 mins
  48. Etomidate
    • amidate
    • sedative hupnotic
  49. general characteristics Etomidate
    • not h2o soluble dissolved w. 35% propylene glycol
    • may cause pain and irritation w/ iv infusions
    • Rapid onset of action and rapid recovery
    • single dose w/ depress adrenal fx up to 3 hrs
    • may cause
    • -retchin
    • -apnea
    • -excitement stage
  50. Cardiopulmonary effects Etomidate
    • clinical dose does not effect cardiopulmonary fx
    • no change in HR or BP or myocardial activity
    • agent of choice for cardiac cases or animals in shock
    • mild-moderate dose dependant resp. depression
  51. metabolism and elimination of Etomidate
    • single dose 10-20 mins
    • rapid hepatic metabolism/urine excretion
    • no accumulation
  52. clinical uses for Etomidate
    • ideal for high risk pts
    • min. cardiopulmonary effects
    • rapid metabolism
    • rapid recovery
  53. disadvantages of Etomidate
    • propylene glycol causes
    • high osmolality of solution
    • may cause iv hemolysis
    • -always admin w/ fluids
  54. neuroleptanalgesia
    combo of analgesics w/ tranq
  55. genral characteritics of neuroleptanalgesia
    • induce profound sedation
    • used as an induction agent (not suitable for healthy pts)
    • safe alternative for comp pts
  56. Neuroleptanalgesia combos
    • Dissociatives oxymorephone+ ace
    • barbituates    oxymorephone+medetomidine
  57. Guaifenesin
    • Gecolate
    • centrally acting muscle relaxant:
    • -does not affect the diaphragm
    • -may cause transient hupotension
    • produces muscle relaxation w/o depression of resp. center
    • always admin iv cath w. dextrose to help prevent hemolysis
  58. Def of inhalation anesthesia
    tech of administrating anesthetic agents via the lungs
  59. inhalation agents
    • methoxyflurane-metofane, penthrane
    • halothane-fluothane
    • isoflurane-aerrane, isoflo, forane
    • sevoflurane-ultane sevoflo
    • desflurane-suprane
  60. intake of gas into the body
    • liquid anesthetic vaporized into o2
    • delivered to pt by mask or ET tube
    • conducted to air passege & into alveoli
    • anesthetic diffueses across resp. membrane into blood stream
    • rate of diffusion is contolled by:
    • -gradient between the aveoli and the blood
    • -tissue perfusion
  61. Distro of gas into the body
    • alveolar conc is high and clood conc so anesthetic moves down the gradient
    • perfusion and lipid solubility allow accumulation of anesthtic in brain causing loss of consciousness
  62. main of anesth gas
  63. depth maintained through sufficient amounts of gas being delievered to the alveoli regulated by:
    • % of anesthetic delivered
    • wentilation of the pt
  64. elimination of anesthetic gas
    • blood conc, of anesthetic is high soooo
    • -anesthtic moves down conc fradient from the brain and into alveoli
    • -elimnated by resp
    • removed by scavenge

    must leave pt on 100% o2 for 5 min to create steep gradient
  65. Vapor pressure
    amount of liquid anesthetic that will evaporate at 20 degrees C and determin the type of vaporizer required
  66. Vapor pressure properties
    • 1. agents w/ high VP evaporate and will reach a lethad conc. of 30% in o2 delivered to the pt
    • 2. anesthetics with a high vapor pressure require a precision vaporizer to limit vaporization to 5% which can still be fatal
    • 3.low vapor pressure ansethetics may be safely used in a non-precision vaporizer
  67. Specific vapor pressures
    • Halothane (red) 244mmHg
    • Isoflurane (purple) 241mmHg
    • Methoxuflurane 225mmHg
    • Sevoflurane (yellow) 160mmHg
  68. Solubility Coefficient
    measures the tendacy of the anesthetic agent to exist as a jas or dissolve in the blood
  69. low solubility Coefficient
    • tend to remain as a gas in the alveoli rather than dissolving in the blood and tissue, has rapid induction, depth change and recovery
    • Hal-2.4%
    • Iso-1.2%
    • Sevo-0.6%
  70. High solubility coefficient
    • dissolve readily in blood and tissues  so cause slow induction depth change and recovery
    • Methoxo 12%
  71. MAC
    • minimun alveolar concentration
    • lowest concentration whcih produces no response to pain in 50% of the pts exposed to painful stimuli

  72. MAC levels
    • Methoxy-0.23%
    • Halothane-0.87%
    • Iso-1.2-1.3%
    • Sevo-2.4%
  73. Halothane
    • MAC .87% (moderate analgesic)
    • induction dose 2.5%
    • maint dose 1.5%
    • solubility Coef 2.4% (low)
    • Vapor Press-243mmHg (precision)
  74. Halothane Cadiovascular effects
    • sensitized heart to catecholamine->dysrrythmia
    • most pronunced during first 30 minutes
  75. Contra indications for Halothane
    • associated w. malignant hyperthermia
    • pt w/ hepatitis or lvr dz
    • cardiac conditions
  76. Isoflurane
    • Iso-forane, isoflo
    • -S.C-1.4%
    • -MAC 1.2-1.3%
    • -Induction 2.5%
    • -Maint 1.5%
  77. Sevoflurane
    • Sevo-Ultane
    • -S.C 0.6%
    • -MAC 2.4%
    • -Induction 4.5%
    • -Maint 3.5%
  78. Characteristics of ISo and Sevo
    • Rapid induction due to low S.c's change in depth 1-2min
    • Rapid recovery w/in 1-2 min of turing of vap
    • low rubber solubility
    • high MAC so not as potent
  79. advantages of iso and sevo
    • inhalation drug of choice for
    • -cardiac pts, hepatic pts, renal pts, and neonates
    • Due to elimination through the lungs
    • Sevo allows cog and motor fx to return @ same time  (equine)
  80. Disadvantages of iso and sevo
    Sevo is expensive
  81. Elimination of inhalents from the body
    • hal-50-80% from norm respirations
    • iso-99% through respirations
    • sevo-97% through respirations
  82. Inhalent effects on the Respirations
    • Hal-dec resp and Tidal volume, dose dependant
    • Iso-Resp depression
    • Sevo resp depression
  83. Inhalent effects on the heart
    • Hal: sever cardiac depression, decreased myocardial contration, and dysrhythmias
    • Iso: min to mod effects
    • sevo: min to mod effects
  84. Effects of inhalents on BP
    • Halo: sever arterial hypotension due to myocardial depression
    • iso and sevo: decreases due to decrease in vascular resistance
Card Set
anethesia test