Bolus administration of eltanolone, thiopental, or etomidate does not affect systemic vascular resistance during cardiopulmonary bypass.

OBJECTIVE

To discover possible effects on systemic vascular resistance of the anesthetic induction agent eltanolone in comparison with thiopental and etomidate. The measurements were performed during cardiopulmonary bypass to maintain a constant cardiac output (approximately pump flow).

DESIGN

The patients were prospectively randomized in three groups to receive either eltanolone, thiopental, or etomidate.

SETTING

University hospital as a single center.

PARTICIPANTS

Seventy-five patients scheduled for elective coronary artery bypass grafting.

INTERVENTIONS

The anesthetic induction agents were repeated at the same dosage when cardiopulmonary bypass was instituted. The respective mean dosages were eltanolone, 0.41 +/- 0.1 mg/kg; thiopental, 2.88 +/- 0.62 mg/kg; etomidate, 0.26 +/- 0.06 mg/kg.

MEASUREMENTS AND MAIN RESULTS

Systemic vascular resistance was calculated from the mean of a triple measurement (normal pump flow and +/- 20%). Points of measurement were before, and 2 and 5 minutes after injection of the hypnotic agent. None of the injected drugs made a significant change in the systemic vascular resistance. A small (not significant) decrease from 1,295 +/- 296 dyne/s/cm-5 to 1,196 +/- 323 dyne/s/cm-5 (mean +/- SD) was seen in the eltanolone group, whereas the other patients did not show any change during the study period.

CONCLUSIONS

The reason for the significant reduction of the arterial pressure attributed to anesthetic induction by eltanolone may be more a cardiodepressive effect than a direct vasodilation.