89b - Intravenous and Inhalational Anesthetics

Question 1

Benzodiazepine general function

Answer 1

used for antianxiety and amnestic effects prior to surgery

Question 2

IV anesthetic (propofol, etomidate, ketamine, barbituates) general function

Answer 2

used for induction of anesthesia (to rapidly render unconsciousness)

Question 3

Inhalation agent general function

Answer 3

used typically to maintain anesthetic state until the conclusion of surgery

Question 4

Neuromuscular blocking agent general function

Answer 4

used to paralyze skeletal muscle and facilitate surgical exposure

Question 5

Opoid general function

Answer 5

used to provide analgesia during and after surgery

Question 6

What two features determine onset and duration of action of drugs

Answer 6

lipid solubility and redistribution of drug

Question 7

Barbituate (Thiopental) mechanism of action

Answer 7

activates GABA A receptors and increases duration of Cl- conductance leading to neuronal hyperpolarization

IV anesthetic

Question 8

Barbituate (Thiopental) pharmacokinetics/dynamics

Answer 8

hypnotic action has a short duration (only a few minutes) - due to redistribution of drug from the brain to more slowly equibrilating tissues (muscle, splanchnic tissue, etc)

metabolism occurs slowly in the liver - can accumulate to toxic levels in tissue after repetitive administration or continuous infusion (half-life depends on duration of infusion)

thus Thiopental is not used for the whole duration of anesthesia

Question 9

Barbituate (Thiopental) side effects

Answer 9

most likely IV anesthetic to cause myocardial depression leading to hypotension

induces central medullary respiratory depression

decreases cerebral metabolic rate of O2 consumption and decreases cerebral blood flow

contraindicated in patients with a history of acute intermittent porphyria

Question 10

Propofol mechanism of action

Answer 10

activates GABA A receptors and increases duration of Cl- conductance leading to neuronal hyperpolarization

Question 11

Propofol pharmacokinetics/dynamics

Answer 11

rapid induction of anesthesia and short duration of action - identical to thiopental but with three advantages:

rapidly metabolized by the liver and excreted in urine, so can be used for long duration anesthesia in a continuous infusion

the only anesthetic with antiemetic effects, so provides an easy recovery

very mild bronchodilating effect

Question 12

Propofol side effects

Answer 12

can cause severe hypotension (resulting from a loss of systemic vascular resistance and peripheral vasodilation)

induces central medullary respiratory depression

decreases cerebral metabolic rate of O2 consumption and decreases cerebral blood flow

Question 13

Fospropofol

Answer 13

a water-soluble prodrug hydrolyzed to produce propofol (approved in 2008)

Question 14

Etomidate mechanism of action

Answer 14

activates GABA A receptors and increases duration of Cl- conductance leading to neuronal hyperpolarization

Question 15

Etomidate pharmacokinetics/dynamics

Answer 15

rapid induction of anesthesia and short duration of action

Question 16

Etomidate side effects

Answer 16

involuntary movements during induction, high incidence of nausea and vomiting during recovery, adrenocortical suppression

offers cardiovascular stability during use, allowing blood pressure to remain in normal range

induces central medullary respiratory depression

decreases cerebral metabolic rate of O2 consumption and decreases cerebral blood flow

Question 17

Benzodiazepine (Midazolam) mechanism of action

Answer 17

activates GABA A receptor by increasing the frequency of the Cl- channel opening

relatively safer than barbituates - unconsciousness curve levels off