Left ventricular function during anaesthesia induction and sternotomy in patients with ischaemic heart disease. A comparison of six anaesthetic techniques.

A comparison between five anaesthetic procedures, fentanyl (FE), morphine (MO), halothane (HAL), fentanyl/droperidol (NLA) and thiopenthone (two dose levels: PE 3 and PE 6), all supplemented with nitrous oxide, was performed with respect to the left ventricular function (LVF) during anaesthesia induction and sternotomy in 47 patients with good preoperative LVF and maintained beta-blockers. Peroperative LVF was characterized by left ventricular stroke volume (stroke index) and external pressure volume stroke work (left ventricular stroke work index) in relation to filling pressure (pulmonary capillary wedge pressure) and outflow resistance (systemic vascular resistance). The individual patient patterns in each group indicated normal LVF in the awake state. Anaesthesia induction was followed by a moderate depression of LVF in the HAL, MO, PE 3 and PE 6 groups at full dose of anaesthetic agent. After addition of nitrous oxide, there was also a decrease of preload in all groups, masking any additional depressions of LVF. The response to external stimuli, endotracheal intubation and sternotomy was that of mildly depressed LVF in the majority of the patients. The haemodynamic reactions in the FE and NLA groups were more varied. In all groups some patients (approximately 30%) showed signs of left ventricular failing in response to external stimuli. With the exception of the more variable haemodynamic reactions in the FE and NLA groups, the differences between the anaesthesia groups with respect to LVF depended mainly on extracardiac factors.