The cardiovascular effects of a single dose of two short-acting intravenous anaesthetics, methohexitone and propanidid, were studied in ten healthy male volunteers. The doses used were selected to produce clinical anaesthesia of similar depth and duration. Methohexitone increased heart rate initially without changing arterial or filling pressures. The C(a-v) 02 difference was decreased, suggesting an increased cardiac output. The heart rate increase was of the same order of magnitude, indicating no important negative inotropic effect. Propanidid initially decreased arterial pressure and increased heart rate. Fining pressures increased slightly. The C(a-v) 02 difference decreased to the same extent as after methohexitone. A relatively larger increase in heart rate and increases in filling pressures point to a more clearcut negative inotropic effect. However, it would seem that with both agents the effect is predominantly peripheral.

Patients undergoing heart surgery usually constitute a group of poor-risk patients who merit special precautions relative to the management of anaesthesia. As previously reported, it has been found that pre-operative arterial oxygen tension values in this group of patients are considerably lower than those encountered in other patients of the same age (THUNG and NORLANDER (1966)%, MARTINEZ and NORLANDER (1968)84). It is also well documented that many heart patients show impressive pathological changes in lung function, which increase the risks of postoperative pulmonary complications (DAMMA" From the Department of Anaesthesia (Head: 0. P. NORLANDER),

SUMMARY Propanidid (Epontol®), like methohexital (Brietal®), has a direct, cardio‐depressant action on the isolated heart. The negative chronotropic and inotropic actions of propanidid are about 0.6 times that of methohexital (whereas the anaesthetic potency of propanidid is about one third of that of methohexital). The Walton‐Brodie strain‐gauge arch technique for recording changes in the myocardial contractile force was compared with an intraventricular balloon technique. It was concluded that the two techniques give identical results, but that the balloon technique for the isolated heart has many practical advantages. ZUSAMMENFASSUNG Propanidid (Epontol®) und Methohexital (Brietal®) haben eine direkte cardiodepressive Wirkung auf das isolierte Herz. Die negativ chronotropen und inotropen Wirkungen des Propanidid sind etwa 0,6 mal so stark wie die des Methohexital (wobei zu beachten ist, dass Methohexital eine 3 mal starkere anaesthetische Wirkung hat als Propanidid). Die Walton‐Brodie Dehnstreifengebertechnik zur Registrierung von Ver‐anderungen der Kontraktionskraft des Herzmuskels wurde mit einer intraven‐tricularen Ballontechnik verglichen. Es zeigte sich, dass beide Methoden iden‐tische Resultate ergeben, die Ballontechnik jedoch am isolierten Herzen viele praktische Vorteile hat.