INTRAVENOUS NICARDIPINE IN THE TREATMENT OF POSTOPERATIVE ARTERIAL-HYPERTENSION

Background: Calcium entry blockers are commonly used in the management of postoperative hypertension. The hemodynamic and blood gas effects of nicardipine, a dihydropyridine derivative available intravenously, were studied in patients after abdominal aortic surgery. Methods: Sixt een patients (66 +/- 8 years) who developed arterial hypertension (mea n arterial pressure, >90 mmHg) after abdominal aortic aneurysm reconst ruction were studied. Fourteen patients had already been treated with a sodium nitroprusside infusion, the doses of which were maintained co nstant (mean dose: 1.42 +/- 1.04 mu g/kg/min). Hemodynamic and blood g as data were collected at baseline, 15 minutes, and 45 minutes after a slow bolus administration of 3 to 5 mg of nicardipine. Results: After the nicardipine administration, mean arterial pressure decreased from 101 +/- 11 to 83 +/- 11 mmHg (p < 0.001), and the cardiac index acute ly increased from 3.96 +/- 0.74 to 4.57 +/- 0.83 L/min/m(2) (p < 0.05) . Systemic vascular resistance significantly decreased, there were no significant changes in heart rate, stroke volume, cardiac filling pres sures, pulmonary artery pressures, pulmonary vascular resistance, left ventricular stroke work, or right ventricular stroke work. One patien t developed acute pulmonary edema, associated with a dramatic increase in cardiac filling pressures, and electrocardiographic signs of myoca rdial ischemia. Nicardipine administration was also associated with an acute reduction in Pao(2) from 85.0 +/- 12.1 mmHg to 70.3 +/- 9.2 mmH g (p < 0.001), associated with an increase in venous admixture from 21 .7% +/- 3.2% to 28.0% +/- 5.2% (p < 0.01). Oxygen delivery increased m oderately and oxygen extraction decreased, but oxygen consumption was unchanged. Conclusion: This study confirms the excellent efficacy of n icardipine in the management of postoperative hypertension, but underl ines the risk of poor cardiac tolerance in patients after major surger y. Although oxygen delivery to the cells is usually well preserved, ni cardipine can also significantly alter blood oxygenation by increasing ventilation/perfusion mismatch. Copyright (C) 1997 by W.B. Saunders C ompany.