Haemodynamics and myocardial oxygen consumption during isoflurane (forane) anaesthesia in geriatric patients.

The influence of isoflurane on haemodynamics and myocardial oxygen consumption was examined in seven geriatric patients under conditions of controlled ventilation and a normal arterial carbon dioxide tension. During isoflurane/nitrous oxide in oxygen anaesthesia (0.75 and 1.5 vol% inspired isoflurane) no significant changes occurred in cardiac output, stroke volume, heart rate, central venous and pulmonary artery pressure. Arterial pressure decreased, as did total peripheral resistance. A reduction in left ventricular maximum dp/dt (18-39%) was, at least in part, a result of changes in loading conditions. Total body (CaO2--CVO2) and base excess values remained within the normal range. We consider that the oxygen supply was adequate to meet the metabolic demands of the body as a whole. Myocardial oxygen consumption decreased by 25% during 0.75 vol% inspired isoflurane and by 43.5% with deepening of anaesthesia (1.5 vol% isoflurane).