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10 Cards in this Set
- Front
- Back
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What are the inhaled anesthetic mechanisms of actions?
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UNKNOWN!! Promiscuous ligands ~1-2% of all proteins. Can act EVERYWHERE IN BRAIN. Small effects at a lot of different target organs. Suspected action on GABA!
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How are inhaled anesthetics metabolized/eliminated?
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VERY LITTLE METABOLISM...Eliminated via respiration (same way in as out)
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Steps in Anesthesia
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#1) Induction using short-acting IV anesthetic
#2) Narcotic (morphine, fentanyl) as analgesics #3) Muscle relaxant (NO ANESTHETIC QUALITIES) #4) Inhaled anesthetic to "maintain" anesthesia |
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What are the different inhaled anasthetics?
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Nitrous Oxide (low potency, good analgesia - endorphins?)
Halothane (liver toxicity!)-minimal use ISOFLURANE - most used halogenated anesthetic in US. Moderate solubility Tachycardia potential. DESFLURANE - Low blood solubility. Tachycardia. SEVOFLURANCE - Inhalational drug of choice for children. Less potent, low solubility. |
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How are anesthetics dosed?
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Anesthetics are "dosed" by concentraction, not actual dose. MAC = minimal alveolar concentration
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What is MAC?
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Minimal alveolar concentration = concentration of vapor needed to prevent movement response to surgical pain in 50% of patients. MAC needed to prevent movement is 2-4x higher than to ablate awareness of pain. MAC is varied based on procedure type (higher MAC for surgery than small incisions)
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What determines Anesthesia uptake and distribution.
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Cardiac output and drug solubility. Greater solubility means faster equilibrium, which means SLOWER INDUCTION. SLOWER INDUCTION is NOT GOOD because patient is not knocked out. Faster induction is the name of the game. Faster equilibrium in organs with high cardiac output (brain, heart) than to areas wiith lower blood flow (fat)
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Effects of anesthetics?
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Decreased blood pressure, decreased metabolism, respiration rate increases b/c hypoxic drive depressed, increased pCO2, variable heart rate (tachycardia potential with some meds). Decreased uterine blood flow (except nitrous).
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Correlation between ANESTHETIC POTENCY and OIL SOLUBILITY?
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INCREASED OIL SOLUBILITY = INCREASED POTENCY. ANESTHETICS ALTER CELL MEMBRANE PROPERTIES.
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Possible toxicity in inhaled anesthetics?
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Liver toxicity (halothane). Neurotoxicity (isoflurane) - Post-operative cognitive dysfunction in 20% patients over 60. Nitrous toxicity (inhibition of b12-related enzymes. megaloblastic bone marrow depression).
MALIGNANT HYPERPYREXIA - rapid temperature elevation. tachycardia, arrythmias |
