Haemodynamic Effects of Thiopentone, Midazolam, Etomidate and Propofol During Induction of Anaesthesia

The commonly used anaesthetics have a direct effect on myocardial performance and both arterial and venous peripheral vasculature, with secondary effects on the circulatory system mediated via the sympathetic nerves and catecholamine release. The purpose of this study was to investigate the cardiovascular effects of 4 intravenous anaesthetic agents commonly used for induction of anaesthesia. 100 patients were randomly allocated to 5 groups: (1) thiopentone 4 to 5 mg/kg + fentanyl 0.1 mg; (2) midazolam 0.1 mg/kg + alfentanil 40 µg/kg; (3) midazolam 0.1 mg/kg + fentanyl 4 µg/kg; (4) etomidate 0.3 mg/kg + fentanyl 0.1 mg; (5) propofol 1.5 mg/kg + fentanyl 0.1 mg. Cardiodynamic parameters were assessed by thoracic electrical bioimpedance at baseline, after induction of anaesthesia, during intubation and 1 and 5 min after intubation.