Hemodynamic and hepatic effects of methohexital infusion during nitrous oxide anesthesia in humans.

The hemodynamic effects of methohexital, at infusion rates of 60-65 and 120 micrograms/kg/min with concomitant inhalation of 67% nitrous oxide in oxygen, have been studied during spontaneous and controlled ventilation in 8 patients. Under most of the conditions studied methohexital infusion anesthesia was associated with lower arterial pressure (-13% to -33%) than in the awake state, decreased cardiac output (-26% to -38%), and increased systemic vascular resistance (+5% to +37%) during surgery, but also with decreased cardiac output (-25%) and decreased systemic vascular resistance (-13%) during anesthesia without surgery. The higher infusion rate was not associated with decreases in arterial pressure or cardiac output during either spontaneous or controlled ventilation. The hemodynamic response to laryngoscopy and intubation was poorly suppressed by methohexital in that peak arterial pressures exceeded the preanesthetic values by 33%. No evidence of impaired hepatocellular function was found after infusions of methohexital lasting up to 4 h.