CHAPTER 19 | IV Anesthetics Flashcards
This is defined as the time to achieve a 50% reduction in concentration after stopping a continuous infusion:
A. Context-sensitive halftime
B. Elimination half-life
C. Bioavailability
A. Context-sensitive halftime
Reduction in concentration AFTER stopping the CONTINUOUS infusion
The following are pharmoco-properties IDEAL for IV anesthetics EXCEPT:
A. It should be water-soluble and stable
B. No tissue damage with extravasation
C. Low incidence of histamine release or hypersensitivity
D. Slow onset and predictable duration
E. Rapid metabolism to inactive metabolites
D. Slow onset and predictable duration - False statement
ideally it must be fast onset!
Which of the following is MOST accurate regarding the IV anesthetic and its effect on the CNS?
A. GABA is the primary excitatory neurotransmitter in CNS
B. Activation of GABA causes increase in chloride conductance, and therefore hyperpolarization of neuron
C. Benzodiazepines decreases the frequency of chloride channel openings
D. glutamate, glycine, and D-serine are major inhibitory neurotransmitter
B. Activation of GABA causes increase in chloride conductance, and therefore hyperpolarization of neuron
Which of the following is MOST accurate regarding the clinical effects of Propofol:
A. It can produce bronchodilation in patients with
COPD
B. Propofol inhibits pulmonary vasoconstriction
C. It does not exhibit myoclonus like that of thiopental
D. Fospropofol is a prodrug of Propofol which has a faster onset and longer duration
A. It can produce bronchodilation in patients with
COPD
This is the time it takes for the plasma concentration of a drug to decrease to 50% of its
original concentration:
A. Context-sensitive halftime
B. Elimination half-life
C. Bioavailability
D. Volume of distribution
B. Elimination half-life
This concept works well to describe a one compartment model for a drug distributed only to the blood, or if the drug is administered only once.
In contrast, pharmacokinetic modeling that describes intravenous anesthetics administered by infusion needs to account for multiple compartments, phases of distribution, and elimination.
TRUE or FALSE
Thiopental has a LOWER context-sensitive half-time compared to Propofol.
FALSE
In comparison to thiopental, propofol has a much lower context-sensitive half-time. Although,
the elimination of propofol is prolonged with longer infusions, it is not to the same magnitude as with thiopental.
It is the low context-sensitive half-time that allows for propofol to be used as a continuous infusion.
Which of the following is MOST accurate regarding the pharmacodynamic of Propofol?
A. a state of paradoxical excitation is expected at the start of low dose
B. it acts primarily via inhibition of gamma-aminobutyric acid-A (GABA-A) pathways
C. Propofol binds post-synaptically and enhances GABA-nergic inhibition
D. Burst suppression is not expected even with low dose
C. Propofol binds post-synaptically and enhances GABA-nergic inhibition
TRUE or FALSE
The rapid onset of ETOMIDATE is due to high lipid solubility and large non-ionized fraction at physiologic pH
TRUE
Non-ionized = RAPID onset
High lipid solubility = RAPID onset
TRUE or FALSE
Propofol shortens seizure duration
TRUE
It has also been used successfully to treat status epilepticus, thus it is rarely the anesthetic of choice during induction of anesthesia for electroconvulsive therapy (ECT) because it SHORTENS seizure duration.
TRUE or FALSE
The loss of consciousness attributed to propofol can be partially reversed physostigmine.
TRUE
The effects of ketamine related to pain can be best described as:
A. antihyperalgesic, antiallodynic, or tolerance protective
B. antihyperalgesic only
C. antiallodynic but NOT tolerance protective
A. antihyperalgesic, antiallodynic, or tolerance protective
Which form of KETAMINE is more potent?
A. S(+) enantiomer
B. R(+) enantiomer
A. S(+) enantiomer
MORE potent, SHORTER duration, cleared RAPIDLY
The S(+) enantiomer of ketamine is three to four times more potent than the R enantiomer. The S enantiomer has a shorter duration of action and is cleared more rapidly.
Why is it needed to decrease the DOSE of ketamine in patients with severe critical illness?
Ketamine has INTRINSIC myocardial depressant hence, in severely ill patients with DEPLETED catecholamine reserves, it is crucial to lower the dose to minimize the myocardial depressant effect!
Which is MOST accurate regarding KETAMINE:
A. Ketamine is a racemic mixture and the R(-) enantiomer is considered more potent than S(+)
B. Norketamine is eliminated primarily by hepatobiliary excretion
C. Ketamine has poor protein binding
D. Norketamine is the metabolite of ketamine and has no clinical effect
C. Ketamine has poor protein binding
The high lipid solubility and low protein binding (20%) allow for a rapid uptake of ketamine in the brain, as well as a fairly rapid redistribution.
ONSET: 15 - 30 seconds
DURATION: 10 - 15 minutes
