[Hemodynamic features of hypotension induced by nicardipine in dogs]

Hemodynamic features of hypotension induced by nicardipine were studied in 18 mongrel dogs under 0.87% halothane in oxygen (1MAC). They were randomly allocated to one of two groups. Group C received no vasodilator therapy and served as control and group N received infusion of nicardipine. Mean arterial pressure decreased and was maintained at 60 mmHg for 60 minutes in group N. No change was noted in hemodynamic variables measured in group C throughout the experiment. During and after induced hypotension in group N, cardiac index (CI), stroke volume index (SVI), central venous pressure (CVP), and right ventricular stroke work index (RVSWI) increased significantly compared with the control values. On the other hand, systemic vascular resistance (SVR) was significantly reduced, reaching 25% of the control value at the end of hypotension period. Heart rate showed a progressive increase but not significantly. Left ventricular maximum dp/dt showed a moderate increase during hypotension, but then decreased gradually to the control value after induced hypotension. Left ventricular stroke work index (LVSWI) and pulmonary vascular resistant (PVR) were unchanged from the control value during and after induced hypotension. The data indicate that nicardipine is a potent systemic vasodilator with hyperdynamic hemodynamic effects in addition to significant increase in right ventricular function.