Effects of sevoflurane on cardiovascular dynamics, coronary circulation and myocardial metabolism in dogs.

The effects of 2.5% and 5% of sevoflurane anesthesia on hemodynamics and myocardial metabolism were studied in pentobarbital-pancuronium anesthetized dogs. The interaction between nicardipine and 2.5% sevoflurane was also examined. Sevoflurane produced dose-dependent ( P << 0.05 to P << 0.01) decreases in systolic arterial pressure (SAP), heart rate (HR), cardiac index (CI), left ventricular minute work index (LVMWI), maximum rate of rise of left ventricular pressure (LV dP/dt), the time constant of fall in isovolumic left ventricular pressure (T) and systemic vascular resistance (SVR), whereas stroke volume index (SVI) and left ventricular end-diastolic pressure (LVEDP) remained unchanged. Central venous pressure (CVP) was significantly ( P << 0.05) increased at 5%. Myocardial oxygen consumption (MV(O)(2)), and myocardial lactate extraction ratio (ML ext) were decreased in a dose-dependent manner ( P << 0.05). Myocardial oxygen extraction ratio (M(O)(2) ext) was significantly ( P << 0.01) decreased at 5%. The ratio of the left ventricular minute work index to myocardial oxygen consumption (LVMWI/MV(O)(2)), i.e., left ventricular efficiency was significantly decreased only at 5% ( P << 0.05). Coronary sinus blood flow (CSBF) was significantly ( P << 0.05) decreased only at 2.5% sevoflurane and coronary vascular resistance (CVR) was significantly ( P << 0.01) decreased only at 5% sevoflurane. The ratio of CSBF to CO (CSBF/CO) showed a tendency to increase as sevoflurane concentrations were increased. Nicardipine (0.01 mg.kg(-1)) administered intravenously under 2.5% sevoflurane caused significant ( P << 0.05 to P << 0.01) decreases in SAP, HR, LV dP/dt, SVR, and CVR, and increases in CVP, SVI, CI, and CSBF ( P << 0.05 to P << 0.01). CSBF/CO remained unchanged. MV(O)(2), M(O)(2) ext, and ML ext were significantly ( P << 0.05 to P << 0.01) decreased. LVMWI/MV(O)(2) showed a tendency to increase. It is concluded that sevoflurane causes a rapidly and easily controlled cardiovascular depression and may not have unfavorable effects on coronary circulation and myocardial metabolism. Nicardipine exerts a synergistic myocardial depressant effect on sevoflurane, in terms of both cardiovascular dynamics and myocardial metabolism.