CANINE CORONARY BLOOD FLOW RESPONSES TO HYPOXAEMIA: THE INFLUENCE OF HALOTHANE

Abstract

Electromagnetic flow meters were used to measure blood flow in the coronary and pulmonary arteries of 6 anesthetized dogs following thoracotomy. Halothane 1% (vol/vol) decreased arterial pressure, coronary artery flow, cardiac output and myocardial and total body O2 consumption and increased coronary vascular resistance. Hypoxemia increased coronary artery flow during cardiac systole and diastole, but not until PaO2 [arterial O2 partial pressure] was less than 5.3 kPa [kilo-Pascals]. This response was not influenced by the presence of halothane. Although myocardial O2 availability and consumption were maintained during hypoxemia, total body O2 availability and consumption were markedly reduced.