I.V. LABETALOL IN THE TREATMENT OF HYPERTENSION FOLLOWING CORONARY-ARTERY SURGERY

Abstract

The cardiovascular effects of incremental fixed i.v. doses of labetalol were evaluated in 10 normovolaemic sedated patients presenting with hypertension and tachycardia in the early period after myocardial revas-cularizaoon. A first dose of 20 mg was sufficient to provoke a (P < 0.01) mean decrease in systolic (−9.3%), diastolic (−8.2%) and mean arterial (−7.9%) pressure (AP) and in the rate-pressure product (RPP) (−13.1%). The mean heart rate (HR) did not change significantly, but a linear correlation could be established between the change at 2 min and the value before injection (r = 0.73). A second dose of labetalol 40 mg given S min later did not decrease AP further, but a significant decrease in HR was noted. A marked difference in the individual response among patients was found as the range of effective total doses per kg body weight was 0.6–4.1 mg kg⁻¹ (mean 2.2). Apart from one patient, no patient needed vagolytic or sympathomimetic drugs to oppose the alpha or beta actions of labetalol during the 24-h follow-up period.