The hemodynamic effects of intravenous labetalol for postoperative hypertension.

Hemodynamic data were analyzed from 25 courses of intravenous pulse labetalol therapy for postoperative hypertension in 12 patients after major vascular surgeries. The hemodynamic determinations were obtained an average of 15 minutes after a therapeutic total dose of 10-120 mg of labetalol (mean, 37.5 mg). The mean arterial pressure (MAP) decreased an average of 27 mmHg or 20% after intravenous labetalol. This normalization of the postoperative hypertension was associated with a 19% increase in cardiac output (CO) and cardiac index (CI) (CO mean increase of 0.58 L/min and CI increase of 0.31 L/min/m2). Commensurate with this decrease in MAP and increase in CO was an average decrease in systemic vascular resistance (SVR) of 625 dyne/sec/cm-5 or 25%. The pulmonary vascular resistance decreased 15 dyne/sec/cm-5 or 4%. The heart rate decreased 9 beats per minute or 10% and the left ventricular stroke work improved by 9% or 1.6 g/m2/beat while the right ventricular stroke work increased by 33% or 2.8 g/m2/beat. The hemodynamic responses to intravenous labetalol in these patients were all beneficial, and there were no adverse effects secondary to the pulse doses of labetalol. Labetalol appears to be safe and efficacious for the treatment of postoperative hypertension in patients undergoing major vascular surgery.