Compare and contrast the cardiovascular effects of an induction dose of propofol and ketamine.

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College Answer

The key words in this question were "compare and contrast", "cardiovascular effects" and
"induction dose". Some candidates described aspects of both drugs other than the
cardiovascular effects but gained no marks for this. Better answers used a combination of a
table plus some explanation to contrast the cardiovascular effects of the two drugs
concentrating on aspects such as heart rate, cardiac output, vascular resistance and blood
pressure.

Many candidates were confused by the direct versus the indirect cardiovascular effects of
both drugs.

Propofol probably has no direct negative inotropic effect. Ketamine has a direct myocardial
depressant action but this effect is overridden by the centrally mediated sympathetic action of
the drug. The effect of both drugs on the baroreceptor receptor response alone is a difficult
area as there is significant interplay between the direct cardiovascular effects of the drugs and their effect on the baroreceptor reflex. Allowance was made for this in the marking. Propofol
resets the baroceptor reflex producing a slower heart rate for a given level of blood pressure.
Overall both drugs depress the baroreceptor reflex.


Comparison of the effects on cerebral, coronary, renal and hepatic blood flow earned extra
marks.