Inhalation Agents: MAC Flashcards
the ideal inhaled anesthetic
- nonflammable
- easily vaporized at ambient temperature
- potent
- low blood solubility to assure rapid induction and recovery from anesthesia
- minimal metabolism
- compatible with epinephrine
- skeletal muscle relaxation
- suppresses excessive sympathetic nervous system activity
- not irritating to airways
- bronchodilation
- absence of excessive myocardial depression
- absence of cerebral vasodilation
- absence of hepatic and renal toxicity
effects of increased fluorination
- nonflammable
- decreased solubility ***
- decreased potency
- less toxic due to resistance to degradation
- decreased percentage metabolized
MAC is
minimum alveolar concentration (partial pressure) of an inhaled agent at 1 atmosphere that prevents skeletal muscle movement in response to a noxious stimulus in 50 percent of patients (ED50, potency)
____ greater concentration than MAC produces immobility in ___ of patients
10-30%
90-95%
what portion of the central nervous system determines MAC
spinal cord
____ is decreased resulting in immobility
spinal cord
perfusion of the brain alone with ordinary concentration does not produce ____
immobility (took up to 3-6X MAC)
use minimal alveolar concentration because alveolar reflects
the concentration at the cord or the brain most accurately
with alveolar concentration you must allow
for equilibration (generally about 10-15 min)
alveolar concentration is dependent on
agent (3-4 time constants)
as age increase, MAC
decreases 6% per decade
___ decreases MAC in all ages, but more so in the elderly
nitrous oxide
MAC is greatest in patients
less than a year of age
MAC decreases in nearly
50% in the elderly years
MAC from greatest to least
infants > children > neonates > adults
60% nitrous oxide causes about a ____ reduction in MAC normally
60%
more so in elderly
____ reduction causes MAC reduction
body temperature
MAC of desflurane is decreased almost in half by
a 10 degree C decrease in temp
MAC of ___ is not affected by body temperature
nitrous oxide
pregnancy decrease MAC due to
increased concentrations of progesterone
MAC decreases ___ through early postpartum and normalizes within ___
30%
12-72 hours