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62 Cards in this Set
- Front
- Back
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What are the four stages of anesthesia?
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1. analgesia
2. excitement/disinhibition 3. surgical anesthesia 4. respiratory collapse/medullary depression |
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The depth of anesthesia of inhalational agents is directly proportional to what value? What about intravenous anesthetics?
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partial pressure
drug concentration |
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The partial pressure of an inhalational agent rises when the agent is ____ (more/less) soluble. This attribute ______ (increases/decreases) the rate of induction of anesthesia.
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less; increases
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How are inhalational anesthetics eliminated?
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exhalation, some in part by the liver (esp. methoxyflurane 70%, halothane 15-20%)
*some may be sequestered in the fat, prolonging recovery |
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The potency of inhalational anesthetics is inversely proportional to the ________ _______ concentration. Increased potency correlates with _____ (inc/dec) lipid solubility.
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minimum alveolar
increased |
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When you combine agents, how do you know the MAC?
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you add the individual MACs together
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What is the least potent inhalational anesthetic?
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nitrous oxide
*this is a more insoluble drug, so the induction of anesthesia is rapid but not potent; also it is not really metabolized by the liver (.004%), so it's safe |
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How do general anesthetics work?
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unknown for sure, but probably disrupt neuronal transmission by intercalating into the lipid bilayer, leading to ion channel dysfunction
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Analgesia produced by some general anesthetics is due to a decrease in activity of what neurons? (where are they located?)
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substantia gelatinosa in dorsal horn of SC
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What are the side effects of halothane? (wow)
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myocardial depression with reduced cardiac output, myocardium sensitization to catecholamines, respiratory depression, increased cerebral blood flow, minimal relaxation of skeletal muscle, sensitization of skeletal muscle to neuromuscular blockers, decreased GFR and renal blood flow, decreased splanchnic and hepatic blood flow
*someone tell me what decreased splanchnic blood flow even means, because i have no idea |
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What toxicities can be extrapolated from the side effects? Also there is one that can't really be.
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tachyarrhythmias, increase in intracranial pressure, postoperative HEPATITIS (tissue necrosis, abnormal LFTs, eosinophilia); malignant hyperthermia (rise in body temperature with massive increases in O2 consumption and metabolic acidosis)
*tx mal hyperthermia with dantrolene (reduces calcium release from the SR, blocking thermogenic activity) |
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How does enflurane differ from halothane?
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it causes less cardiovascular side effects, but it may cause seizures; it also causes more respiratory depression and more skeletal muscle relaxation
*it can cause hepatitis and malignant hyperthermia |
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How much enflurane is metabolized in the liver?
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~2%
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Who should not be given enflurane?
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any patient with a seizure disorder or renal dysfunction
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Isoflurane is preferred for which type of surgery? Why?
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neurosurgery; it decreases ICP
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Which agent is desflurane most similar to and what is the difference between the two?
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isoflurane; desflurane has a more rapid rate of induction
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What is different about methoxyflurane?
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it's not used due to nephrotoxicity; it is highly soluble, so has a slow induction and recovery
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Which organ might sevoflurane be toxic to? Are induction and recovery rapid or slow?
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kidneys; rapid induction/recovery
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What are the side effects of nitrous oxide?
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decreased myocardial contractility and increased circulating catecholamines and increased myocardial response to said catecholamines, leading to increased cardiac output and mean arterial pressure; mild respiratory depression; no increase in ICP, no muscle relaxation
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When is nitrous oxide used alone? What is a dangerous side effect of nitrous oxide?
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dental and obstetric procedures; diffusional hypoxia
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Name three barbiturates used for anesthesia.
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thiopental, thiamylal, methohexital
*bonus! how do barbiturates work? *A: they bind to GABAa receptors and increase the duration of the opening of Cl- channels |
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What are some effects of barbiturates?
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suppression of brain stem reticular activating system, hyperalgesia, decreased cerebral blood flow and metabolism, myocardial and respiratory depression, increased venous compliance
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How is the action of thiopental terminated?
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by redistribution from the brain to adipose and lean tissues; metabolized in liver
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What are some negative side effects of barbiturates?
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cough, respiratory depression, laryngospasm, bronchospasm, precipitation of porphyria
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When would you use a benzodiazepine for anesthesia?
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short dental and medical procedures
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Name two opioids used for anesthesia
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morphine and fentanyl
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What drugs would you combine with an opioid to achieve neuroleptic anesthesia?
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nitrous oxide and droperidol
*fentanyl and droperidol -> dissociated, but conscious *fentanyl, droperidol, and nitrous oxide -> unconsciousness |
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In which type of surgery are opioids preferred? Why?
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cardiac because cardiac output is maintained
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What is ketamine? How does it work?
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a dissociative anesthetic; it blocks NMDA glutamate receptors in the cortex and limbic system
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What are the effects of ketamine?
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sedation, analgesia, amnesia, immobility, increased CNS blood flow, increased ICP, sympathetic stimulation, may increase IOP
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Why does ketamine distribute rapidly to vascular organs?
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it's lipophilic
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What are the negative side effects of ketamine?
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postoperative behavioral phenomena (delirium)
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When is ketamine contraindicated?
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patients with hypertension, psychiatric disorders, or glaucoma
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To which drug is propofol similar?
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thiopental
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When is propofol used?
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outpatient surgery
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What side effects might propofol cause?
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marked hypotension during induction, apnea, bradycardia
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When is etomidate used? What are the side effects?
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rapid induction
nausea, vomiting, myoclonus, pain on injection |
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Local anesthetics consist of an aromatic ring (lipophilic), a hydrophilic group (usually a tertiary amine), and a linking chain, which can be one of two groups. What are they?
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ester, amide
*amides have an i before the "caine" |
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If a drug is more lipophilic, how does that affects its duration of action, potency, and toxicity?
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all are increased
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Local anesthetics are _____ (weak/strong) _____ (acids/bases). They penetrate nerve cell membranes in ________ (charged/uncharged) form and then become ___________ (protonated/deprotonated).
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weak bases
uncharged protonated |
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What channel do local anesthetics block?
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voltage-gated Na+ channel, especially those that are open or have been recently inactivated (just used)
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What might be added to a local anesthetic? Why?
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Vasoconstrictor (epinephrine)
to decrease systemic absorption of the drug |
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How are ester-type anesthetics degraded? (where and what enzymes?)
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plasma cholinesterases
liver esterases |
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How are amide-type anesthetics degraded? Caution should be used in patients with _____ failure
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liver amidases
renal (trick question!) |
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Which neurons are blocked first?
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small, unmyelinated fibers
autonomic, then sensory, then motor pain, cold, warmth, touch, then deep pressure |
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What are the side effects of local anesthetics?
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cardiovascular depression, CNS excitability then depression, hypersensitivity reactions
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Which agents more commonly cause an allergic reaction?
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ester-type
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When is cocaine used as a local anesthetic? How is it administered?
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topically in the nose and throat
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What happens when cocaine is used topically in the eye?
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corneal ulcerations
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What other effect does cocaine have that makes it a good local anesthetic?
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vasoconstriction (blocks reuptake of catecholamines)
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When is procaine used as a local anesthetic? How is it administered?
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local injection, nerve blocks, spinal anesthesia
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What is procaine hydrolyzed to and what problem might this cause?
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PABA (para-aminobenzoic acid)
it competitively inhibits sulfonamides |
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How does chloroprocaine relate to procaine (potency and toxicity)?
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it's more potent but less toxic
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When is chloroprocaine used?
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infiltration, nerve blocks, epidural anesthesia
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How is tetracaine related to procaine (potency and duration of action)?
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10x potent
longer duration |
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When is tetracaine used?
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spinal anesthesia and topical in eye and nasopharynx
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What is benzocaine?
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OTC topical anesthetic
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How is lidocaine related to procaine (potency and toxicity)?
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2x potent
2x toxic |
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How does lidocaine affect blood vessels?
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local vasodilation
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When is lidocaine used? How is it administered?
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topical and local injection, spinal anesthesia; iv for tachyarrhythmias
*Bonus! What antiarrhythmic class is lidocaine in? *A: class IB |
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What is different about bupivacaine? When is it used?
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prolonged duration of action
local infiltration, nerve blocks, spinal anesthesia |
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Mepivacaine produces ____ (more/less) vasodilation than procaine.
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less
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