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48 Cards in this Set
- Front
- Back
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Who came up with stages of anesthesia?
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Guedel
-used ether |
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stage 1 of anesthesia
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stage 1: analgesia
-loss of consciousness -high response to stimulus |
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stage 2 of anesthesia
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stage 2: delerium/excitement
-increase sympathetic tone -struggling with eyes open -try to avoid this stage -vomiting, defecation, urination -wait to intubate |
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stage 3 of anesthesia (4 planes)
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plane 1: light anesthesia
plane 2: surgical anesthesia (slow palpebral reflex but strong corneal reflex, ventro-medial eyes, slow nystagmus in horses) plane 3: deep anesthesia (weak corneal reflex, flaccid jaw) place 4: resp failure, severe cardiac depression and hypotension) |
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stage 4 of anesthesia
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resp arrest, then cardiac arrest, then death
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nitrous oxide
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doesn't produce surgical anesthesia alone
-good analgesia, little muscle relaxation -minimal cardio-respiratory depression |
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diffusion hypoxia
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-occurs when N2O is discontinued
-gas leaves blood and dilutes other gases in alveoli (decreases stimulus to breathe) -prevent by giving 100% O2 |
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nitrous oxide in ruminants, horses?
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not used because it increases gas spaces (mainly in GIT)
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nitrous oxide congenital effects
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only occurs with prolonged use
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methoxyflurane (potency, cardiac effects, induction speed)
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most potent inhalation
-depresses myocardial contractility -slow induction/recovery |
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halothane
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-rapid induction/recovery
-keep CO2 levels low to prevent increase in intra-cranial pressure -sensitizes myocardium to catecholamines -decreases hepatic and renal blood flow |
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post-anesthetic halothane-induced hepatitis
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hepatic necrosis due to prolonged halothane anesthesia
-goats are most sensitive |
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malignant hyperthermia
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genetic mutation on calcium receptors
-all inhalation anesthetics can trigger -treat with dantrolene -pigs most susceptible |
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isoflurane
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-most popular
-CNS depression -better for high-risk CNS patients -respiratory depression -minimal effects on liver, kidney -better muscle relaxation -respiratory elimination |
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safest inhalation anesthetic for hypotensive patient
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halothane
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safest inhalation anesthetic for heart-compromised patient
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isoflurane
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enflurane
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not popular due to CNS stimulation
-muscle twitching at anesthetic depth -contraindicated in epileptic animals |
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desflurane
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-higher vapor pressure (needs special vaporizor)
-respiratory depression -bad odor, may irritate airways (not good for mask induction) |
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compare respiratory depression of inhalation anesthetics from highest to lowest
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des > iso > halo
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sevoflurane
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-least airway irritation
-similar to iso and halo -reacts with CO2 absorbant to form compound A (renally toxic) -use higher O2 flow rate and caution in patients with renal compromise |
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diethyl ether
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-highly flammable
-used mainly for lab animals -profound muscle relaxation |
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blood solubility ranking from highest to lowest (inhalation anesthetics)
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ether > methoxy > halothane > iso > des, sevo, N2O
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which anesthetic has most/least increase in heart rate?
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halothane - least
enflurane - most |
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which anesthetic has most/least decrease in cardiac output?
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halothane - most
iso - least |
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which inhalation anesthetic decreases peripheral resistance most?
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isoflurane
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factors that increase MAC (temp and salt)
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hyperthermia, hypernatremia,
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factors that lower MAC
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pregnancy, higher age
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trace levels of anesthetic should be below ___?
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2ppm
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E-tank
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holds 750L of O2 (1,600L of N2O)
-service pressure is 2200 psi (750 psi for N2O) |
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H-tank
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holds 7000L of O2 (16,000L of N2O)
-service pressure is 2,200 psi (750 psi for N2O) |
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Oxygen should be up/down stream from other gases?
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always down-stream
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non-precision vaporizer
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not agent-specific
-patient's exhaled air carries anesthetic (instead of O2) -no compensation for temp, flow or pressure -used with low vapor pressure anesthetics |
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precision vaporizer
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-agent specific
-compensation for flow, pressure and temp |
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which 2 anesthetics have preservative that doesn't vaporize?
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halothane and methoxyflurane
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rebreathing bag should be __x the patient's tidal volume?
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6x
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CO2 absorbant
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soda lime or barium hydroxide lime
-turns purple and hard when used |
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hypothermia more likely with closed (rebreathing) system or open?
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open (non-rebreathing) due to high O2 flow rate and loss of heat
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local anesthetic MOA
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-interferes with sodium channels
-slows rate of depolarization -action potential isn't propagated |
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local anesthetics (esters)
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procaine, chlorprocaine, tetracaine
-tetracaine is most potent, chlorprocaine has most rapid onset |
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most rapid onset local anesthetic (amides)
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lidocaine has most rapid onset
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metabolism of ester local anesthetics
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hydrolysis by cholinesterase in plamsa
-some by liver also |
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metabolism of amide local anesthetics
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hepatic metabolism (microsomal emzymes)
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why use vasoconstrictor (like epi) with local anesthetics?
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decreases systemic absorption, toxicity
-prolongs duration |
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local anesthetic toxicity of CNS vs cardiovascular
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CNS most sensitive
-signs: twitching, seizures, |
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what species is very sensitive to lidocaine?
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goat
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treatment for systemic toxicity of local anesthetic
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oxygen hyperventilation
-anti-seizure drug |
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cardiotoxicity of amide local anesthetics
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bupivicaine most cardiotoxic
-lidocaine least |
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CV signs of systemic lidocaine toxicity
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profound hypotension
-reflex tachycardia |
