Hemodynamic effects of nicardipine-induced hypotension during enflurane/nitrous oxide anesthesia in man.

Hemodynamic effects of nicardipine-induced hypotension during enflurane/nitrous oxide were evaluated in 10 surgical patients. An infusion of nicardipine was titrated to maintain mean arterial pressure at 60 to 70 mmHg under enflurane 1.5 to 2.0 vol% and nitrous oxide 60 vol%. Mean arterial pressure was well controlled with the nicardipine infusion, whereas cardiac index increased with decreased systemic vascular resistance. Heart rate increased concomitantly with decreased blood pressure, which indicated that enflurane 1.5 to 2.0 vol% did not suppress baroreceptor reflex during nicardipine administration. However, rate-pressure-product was not increased by the nicardipine. Right and left ventricular systolic work indices were not increased by the nicardipine. Right ventricular ejection fraction was not also changed by the nicardipine. Although serum norepinephrine level increased during the nicardipine infusion, the values remained within physiological ranges. Our results suggest that nicardipine-induced hypotension may be safely performed during enflurane/nitrous oxide anesthesia because neither ventricular work nor myocardial oxygen demand was increased by nicardipine.