Inhalation Anesthetics
MAC (minimum alveolar concentration) is reduced by CNS depressants, pregnancy, and age but increased in infants and children
MAC = 50% of population is anesthetized, 1.3 MAC = 99% anesthetized
Recovery and onset are inversely determined by solubility (solubility = onset and recovery)
High solubility agents = slow equilibrium (blood) increased by depth of respiration, slow onset and recovery
Low solubility agents = rapid equilibrium (blood) increased by heart rate, rapid onset and recovery
Elimination primarily by expiration (caution for Diffusional anoxia)
MOA = disruption of cell membranes or potentiation of GABA-A receptors
Drug / Class / Uses / Side Effects/Toxicity / MiscellaneousHalothane
/ halogenated alkane / General Anesthesia (low TI, steep dose-response) / dose-dependent hypotension, CO, hypoxia, sensitivity to NE/E induced arrhytmias, autonomic fxn, possible halothane hepatitis, possible malignant hyperthermia w. succinylcholine (trt. with dantrolene) / high potency, depth of anesthesia modifiable, 10-20% liver metabolism, non-flammable, NOT for head trauma, reduced vent response to CO2, blood flow to kidneys/liver, intracranial pressure, GFR, limited muscle relaxation, O2 consumption in brainIsoflurane
/ “ / “ / dose dependent hypotension, no catecholamine induced arrhythmias, ho hepatotoxicity, no ICP effects / lower potency, faster onset/recovery, minimal metabolism, DOC for most neuroanesthesia, better muscle relaxationDesflurane
/ “ / “ / similar to isoflurane, HR, initial airway irritation / very rapid onset and recovery (monitor patients), very low metabolism, outpatient proceduresSevoflurane
/ “ / “ / similar to desflurane, no tachycardia, less airway irritation / somewhat slower onset and recovery, 100X higher hepatic metab. than desfluraneMethoxyflurane
/ “ / “ / >50% metabolism, renal toxicity due to high fluoride levels, sensitivity to NE/E induced arrhytmias / good analgesia at concentrations less than 1 MAC, significant muscle relaxation (except uterus), rarely usedNitrous Oxide
/ anesthetic gas / combination with inhalation/IV GA, low potency / minimal CNS/CV toxicity, diffusional anoxia / good analgesia at concentrations less than 1 MAC due to endorphin release (reversible with naloxone), large inter-patient MAC variability, no muscle relaxationIntravenous Anesthetics and Adjunct Anesthetics
Drug / Class / Uses / Side Effects/Toxicity / MiscellaneousThiopental
/ Barbiturate (ultra-short), IV, adjunct, GABA-A agonist / rapid induction of anesthesia / tissue necrosis at site of injection, hyperalgesia / extremely rapid sleep induction (10-20 sec), slow hepatic metabolism, short duration due to redistribution, increase opening time of Cl channels, good in children, fat = more rapid recoveryEtomidate
/ ultra-short non-barbiturate / muscle spasms (trt. with diazepam), cortisol / sedative, unconsciousness lasting 5 min, DO NOT USE for prolonged sedation in critically illPropofol
/ rapid acting non-barbiturate / adjunct for regional anes. / vasodilation, stable hypotension, resp., response to CO2, painful upon injection / no renal or hepatic impairment, ICP, beware of allergies or bacterial contamination, REFRIGERATE, rapid emergence from anesthesiaKetamine
/ NMDA antagonist, opiod sigma agonist (similar to PCP) / marked, analgesia, trauma and emergency surgery, radiologic proc. / dissociative anesthesia, hallucinations, delirium, OD potential (trt. with cranberry juice to acidify urine) / respiratory control not affected, CO, BP, HR,Midazolam
/ Benzodiazepine / preanesthetic sedation, anti-anxiety / amnesia / reversible with flumenazilFentanyl
/ opiod analgesic / cardiac surgery, epidural use / severe but predictable resp. depression and pruritis (rev. with naloxone), N/V / often used in conjunction with NOSuccinylcholine
/ depolarizing muscle relaxer / malignant hyperthermia, hyperkalemia / MAC of inhalational anesthetics, avoid in patients on AChE inhibitors (Myasthenia Gravis)d-Tubocurarine / non-depolarizing muscle relaxer / “