Cardiovascular effects of meperidine-N2O anesthesia before and after pancuronium

The cardiovascular effects of 2 and 3 mg/kg of meperidine plus 60 to 67% N2O in O2 on cardiovascular dynamics in man were measured before and after the administration of 0.08 mg/kg of IV pancuronium. N2O and 2 mg/kg of meperidine did not change heart rate (HR) but produced a marked reduction (-49%) in cardiac output (QT) plus significant decreases in stroke volume (SV) and blood pressure (BP) and an increase in peripheral arterial resistance (PVR). Additional meperidine did not further alter any of the variables; however, surgical stimulation caused significant increases in HR, BP, and PVR. SV and QT were not significantly changed by surgical stimulation and were still markedly depressed when compared to control values. Pancuronium produced marked increases in HR, SV, QT, and BP and a reduction in PVR. These changes were maximal 4 to 8 minutes after pancuronium and returned toward pre-pancuronium values thereafter. These data demonstrate that N2O-meperidine anesthesia results in a moderate reduction in BP but a marked depression in QT. The findings also indicate that pancuronium reverses the cardiovascular depression produced by N2O-meperidine and is therefore, a desirable muscle relaxant when the above technic is employed.