ANGIOTENSIN-CONVERTING ENZYME-INHIBITION HAS NO EFFECT ON BLOOD-PRESSURE AND SPLANCHNIC PERFUSION AFTER CARDIAC-SURGERY

Purpose: The purpose of this study was to study the effect of the angi otensin-converting enzyme inhibitor, enalaprilat, on blood pressure an d splanchnic perfusion after cardiac surgery. Materials and Methods: S ixteen patients were studied after coronary artery bypass grafting. Af ter admission to the intensive care unit, a 30-minute baseline measure ment of systemic hemodynamics, oxygen transport, and gastric tonometry was performed. In 6 of 10 patients receiving enalaprilat and in each of 6 control patients, regional (splanchnic and leg) blood flows were measured also. After the baseline measurement period, 10 patients rece ived a 0.5 mg bolus of enalaprilat and thereafter an incremental infus ion of enalaprilat up to a total dose of 10 mg (mean 8.3; range 4 to 1 0 mg) was continued to reduce the mean arterial pressure (MAP) to 70 t o 80 mm Hg. A 30-minute measurement period was repeated 2 to 3 hours a fter the first measurement period. In the control group, the second me asurement was performed at corresponding time points. Results: Though MAP decreased in the enalaprilat group (enalaprilat 99 +/- 14 mm Hg v 89 +/- 21 mm Hg, P <.05; control 95 +/- 13 mm Hg v 82 +/- 10 mm Hg, P = NS) in only 4 of 10 patients was the targeted MAP reduction achieved . No significant changes were observed either in systemic or regional blood flows. Systemic, pulmonary, and femoral vascular resistance indi ces decreased significantly in both groups. Gastric-arterial Pco(2) di fference did not change in either groups. Angiotensin-converting enzym e activity decreased in the enalaprilat group (10.0 +/- 2.3 v 1.3 +/- 0.3 U . l(-1) P <.01), but plasma renin and endothelin-1 concentration s did not change in either group. Conclusions: The effect of enalapril at on blood pressure was poor and it had no beneficial effects on spla nchnic circulation. Renin-angiotensin activation is not a major factor in hypertension and splanchnic perfusion after cardiac surgery. Copyr ight (C) 1998 by W.B. Saunders Company.