Halothane-relaxant anaesthesia in elderly patients.

Twenty-three elderly patients, scheduled for elective cholecystectomy, were studied during halothane-relaxant anaesthesia. Anaesthesia was induced with thiopentone and maintained with halothane in 12 patients, six of whom had also received premedication. Eleven patients were anaesthetized with halothane, without thiopentone induction and with no premedication. Measurements of central haemodynamics were performed awake and during anaesthesia at end-tidal halothane concentrations of 0.5 and 1.0%; at the lower concentration, measurements were also made after addition of nitrous oxide. Premedication and thiopentone had no influence on the subsequent halothane anaesthesia. Halothane caused reductions of cardiac index, mean arterial blood pressure and oxygen uptake. However, neither right atrial nor pulmonary capillary venous pressure increased and the arterio-venous oxygen content difference decreased. These findings differ from those made by others in younger subjects and are probably attributable to a dose-dependent reduction in systemic vascular resistance. The addition of nitrous oxide had only minor effects on central circulation. The results suggest that the age of the patients influences their reaction to halothane anaesthesia.