Clinical use of etomidate.

Etomidate and methohexital were administered for induction of anesthesia in 45 patients who had to undergo open heart surgery. The anesthesia technique was otherwise standardised. Measurements of blood pressure and heart rate were obtained during a period of ten minutes after injection of the induction agent, and in a selected group of 16 patients cardiac index and stroke volume index were obtained by impedance cardiography. In the group of 45 patients, blood pressure one minute after induction was unchanged with Etomidate, but decreased (-6%) with methohexital. During intubation, important variations of systolic blood pressure occurred, specially with Etomidate (+ 36%) and less with methohexital (+ 21%). Heart rate increased in both groups during intubation (+ 41%) and returned towards starting value after ten minutes. In the group of 16 patients, cardiac index varied with Etomidate, decreasing during intubation (- 21%), increasing to + 32% and then returning to starting value afterwards. Heart rate increased with intubation (+ 39%) and was still somewhat elevated at ten minutes. Stroke volume index decreased with intubation (- 36%) and was still lower than the initial value at ten minutes (- 14%). With methohexital, cardiac index variations were less pronounced (+ 11%). Cardiac index was lower than the initial value at ten minutes (- 14%). Stroke volume index decreased with intubation (- 36%) and was still lower than the initial value at ten minutes (- 14%). This was compensated by an increase in heart rate. These measurements made during induction reflect the complex interaction of drug administration and technical manipulations. Blood pressure lowering one minute after the injection of methohexital can be ascribed to vasodilatation and myocardial depression. The important blood pressure and cardiac index variations observed with Etomidate are probably due to the short action and the lack of analgesic properties of this agent.