Treating Anesthesia-Induced Hypotension by Angiotensin II in Patients Chronically Treated with Angiotensin-Converting Enzyme Inhibitors

Abstract

Although angiotensin II bolus administration may be used to increase blood pressure in patients chronically treated with angiotensin-converting enzyme inhibitors (ACEI) who have severe hypotension on anesthetic induction, no data are available describing its time course and its effects on the left ventricular function. Fourteen patients chronically treated with ACEI for hypertension and scheduled for vascular surgery were prospectively studied. Patients with cardiac insufficiency were excluded. A transesophageal echocardiography probe was inserted to assess systolic left ventricular function. When hypotension was observed (systolic arterial pressure [SAP] <85 mm Hg), an IV bolus of 2.5 micro g of angiotensin II (AII) was given, and hemodynamic variables were recorded each 30 s over 5.5 min. Results are expressed as mean +/- SEM. Sixty seconds after the AII bolus injection, the SAP increased from 78 +/- 3 to 152 +/- 6 mm Hg. SAP remained higher than control until the 5th min. This was associated with significant increases in end-diastolic area (from 15.1 +/- 0.6 to 19.3 +/- 1.0 cm2, P <or=to 0.001), end-systolic area (from 6.6 +/- 0.4 to 10.7 +/- 0.7 cm2, P <or=to0.001), end-systolic wall stress (from 32 +/- 0.05 to 82 +/- 7 kdynes/cm2, P <or=to 0.001). In addition, a decrease in fiber-shortening velocity (from 1.1 +/- 0.05 to 0.76 +/- 0.04 circ/s, P <or=to 0.05) and in fractional area change (from 0.57 +/- 0.02 to 0.44 +/- 0.02, P <or=to 0.05) was observed. Heart rate did not significantly change during the study. Increases in preload and afterload were observed. However, the administration of AII causes a transient impairment in left ventricular function. We conclude that AII, given as an IV bolus of 2.5 micro g, is effective in restoring arterial blood pressure within 60 s in patients chronically treated with ACEI. Implications: Severe hypotension on anesthetic induction in patients chronically treated with angiotensin-converting enzyme inhibitors for hypertension could be treated with an IV bolus of 2.5 micro g of angiotensin II. (Anesth Analg 1998;86:259-63)