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
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Drug
Class
Uses
Halothane
halogenated
alkane
General
Anesthesia (low
TI, steep doseresponse)
Isoflurane
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Desflurane
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Sevoflurane
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Methoxyflurane “
Nitrous Oxide
anesthetic gas
Side Effects/Toxicity
Miscellaneous
dose-dependent hypotension, CO,
hypoxia, sensitivity to NE/E
induced arrhytmias, autonomic fxn,
possible halothane hepatitis, possible
malignant hyperthermia w.
succinylcholine (trt. with dantrolene)
dose dependent hypotension, no
catecholamine induced arrhythmias,
ho hepatotoxicity, no ICP effects
similar to isoflurane, HR, initial
airway irritation
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 brain
lower potency, faster onset/recovery, minimal
metabolism, DOC for most neuroanesthesia,
better muscle relaxation
very rapid onset and recovery (monitor
patients), very low metabolism, outpatient
procedures
somewhat slower onset and recovery, 100X
higher hepatic metab. than desflurane
good analgesia at concentrations less than 1
MAC, significant muscle relaxation (except
uterus), rarely used
good analgesia at concentrations less than 1
MAC due to endorphin release (reversible with
naloxone), large inter-patient MAC variability,
no muscle relaxation
similar to desflurane, no tachycardia,
less airway irritation
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>50% metabolism, renal toxicity due
to high fluoride levels, sensitivity to
NE/E induced arrhytmias
combination with minimal CNS/CV toxicity,
inhalation/IV GA, diffusional anoxia
low potency
Intravenous Anesthetics and Adjunct Anesthetics
Drug
Class
Uses
Barbiturate (ultrashort), IV,
adjunct, GABA-A
agonist
ultra-short nonbarbiturate
rapid acting nonbarbiturate
rapid induction of
anesthesia
Ketamine
NMDA
antagonist, opiod
sigma agonist
(similar to PCP)
Midazolam
Benzodiazepine
Fentanyl
opiod analgesic
marked,
analgesia, trauma
and emergency
surgery,
radiologic proc.
preanesthetic
sedation, antianxiety
cardiac surgery,
epidural use
Succinylcholine
depolarizing
muscle relaxer
non-depolarizing
muscle relaxer
Thiopental
Etomidate
Propofol
d-Tubocurarine
adjunct for
regional anes.
Side Effects/Toxicity
tissue necrosis at site of
injection, hyperalgesia
muscle spasms (trt. with
diazepam), cortisol
vasodilation, stable
hypotension, resp.,
response to CO2, painful
upon injection
dissociative anesthesia,
hallucinations, delirium,
OD potential (trt. with
cranberry juice to acidify
urine)
amnesia
severe but predictable resp.
depression and pruritis
(rev. with naloxone), N/V
malignant hyperthermia,
hyperkalemia
Miscellaneous
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 recovery
sedative, unconsciousness lasting 5 min, DO NOT
USE for prolonged sedation in critically ill
no renal or hepatic impairment, ICP, beware of
allergies or bacterial contamination, REFRIGERATE,
rapid emergence from anesthesia
respiratory control not affected, CO, BP, HR,
reversible with flumenazil
often used in conjunction with NO
MAC of inhalational anesthetics, avoid in patients
on AChE inhibitors (Myasthenia Gravis)
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