Systemic vascular responses to atracurium during enflurane-nitrous-oxide anesthesia in humans

Systemic circulatory responses to atracurium (0.2 and 0.4 mg/kg) were studied in 15 healthy (ASA I or II) adult patients during enflurane (1.0 to 1.25% inspired) and nitrous oxide (70% inspired) anesthesia. All patients were premedicated with intramuscular morphine (10-15 mg) and glycopyrrolate (0.2 mg). Compared with control measurements during enflurane-nitrous oxide anesthesia, heart rate, cardiac and stroke index, central venous pressure, and systemic mean arterial pressure remained unchanged at 2, 5, and 10 min after administration of both doses of atracurium. Systemic vascular resistance was minimally decreased (7% compared to control) (0.01 less than P less than 0.05) at 10 min following both doses of atracurium. No patient demonstrated a decrease in systemic mean arterial pressure greater than 6 mmHg. The authors conclude that atracurium in doses which produce adequate skeletal muscle relaxation during steady-state enflurane anesthesia produces no clinically significant alteration in hemodynamic variables.