Inhalation Anesthetics Flashcards
T/F: Soluble drugs take longer to reach steady state then insoluble drugs
True:
A soluble drug has a longer induction and recovery, large Vd, and is more potent, while insoluble anesthetics have a fast induction and recovery (if completely insoluble they will not get into the brain)
Two important physiologic factors for inhalation anesthetics
Ventilation and cardiac output
T/F: All inhalation anesthetics are fat soluble, penetrate most tissues, but do not cross the placenta
False:
They do cross the placenta
What is MAC?
Minimum Alveolar Concentration - at steady state it will prevent purposeful movement in response to supra maximal noxious stimulus in 50% of individuals (ED50)
~1.3 MAC for maintenance
Second gas effect
Large proportion of gas volume moves from higher to lower tension (alveolus –> blood) to equilibrium
Nitrous oxide = more fresh gas to alveolus
Fink effect
Nitrous oxide from blood to alveolus displaces alveolar gas (including O2)
Give 100% O2 on recovery
Which inhalation anesthetics are considered vapors?
Halothane
Isoflurane
Desflurane
Sevoflurane
Which inhalation anesthetics are considered gases?
Nitrous oxide
Halothane effects on the liver
Decreased hepatic blood flow
60-80% eliminated in air
Isoflurane effects on the liver
Decreased hepatic blood flow but less than with Halothane
NOT metabolized in the liver (0.2%)
Desflurane effects on the liver
Decreased hepatic blood flow
NOT metabolized in the liver (0.2%)
Sevoflurane effects on the liver
Decreased hepatic blood flow
NOT metabolized
Nitrous oxide effects on the liver
Minimal effects
Respiratory/Cardiac effects of Halothane
Depression
MOST arrhythmogenic, sensitizes heart to Epinephrine
Respiratory/Cardiac effects of Isoflurane
LESS cardiac depression than Halothane
SAME respiratory depression as Halothane
Respiratory/Cardiac effects of Desflurane
MORE respiratory depression than Isoflurane
SAME cardiac depression as Isoflurane
Respiratory/Cardiac effects of Sevoflurane
SAME CV and respiratory depression as Isoflurane
Respiratory/Cardiac effects of Nitrous oxide
Low respiratory and cardiac depression
CNS effects of Halothane
MOST potent cerebral vasodilator
CNS effects of Isoflurane
LESS cerebral vasodilation than Halothane
Anticonvulsant
Cerebral circulation autoregulation
CNS effects of Desflurane
Similar to Isoflurane
LESS cerebral vasodilation than Halothane, Anticonvulsant, Cerebral circulation autoregulation
CNS effects of Sevoflurane
LESS cerebral vasodilation than Isoflurane and Desflurane
CNS effects of Nitrous oxide
Increased cerebral blood flow, cerebral metabolic rate, and intracranial pressure
Good analgesic
Other factors of Halothane
Decreased renal blood flow
Thymol build up in vaporizers
Other factors of Isoflurane
Decreased renal blood flow
MORE potent than Halothane to enhance competitive NMBs
Blood/gas coefficient = 1.4
Other factors of Desflurane
HIGH vapor pressure = special vaporizer
Enhance competitive NMBs
LOWEST blood/gas coefficient (0.45)
SAME muscle relaxation as Isoflurane
Other factors of Sevoflurane
Reacts with soda lime
No renal or hepatic injury
Low blood/gas coefficient (0.65)
SAME as Isoflurane to enhance competitive NMBs
Other factors of Nitrous oxide
Low blood/gas coefficient (0.47)
NOT potent anesthetic (MAC = 200-250%)
2nd gas effect (Fink effect)
Poor muscle relaxation, diffuses into air-filled space
