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 (≃ 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. Conclusion: 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.