Anaesthesia for cardioversion: immediate haemodynamics in patients anaesthetized with thiopental or althesin.

Immediate haemodynamic changes during electrical cardioversion were compared in 30 patients anaesthetized either with thiopental or with Althesin. The systolic arterial pressure, heart rate, stroke and cardiac indices were measured before atropine premedication, after atropine, during anaesthesia, and 3 and 10 minutes after defibrillation. The stroke index was estimated by transthoracic impedance method. Both anaesthetics caused a significant but similar decrease in systolic arterial pressure. The cardiac index remained relatively stable in both groups during all stages of the procedure. Atropine induced an expected increase in heart rate and a decrease in stroke index. while both variables tended to approach the baseline values after cardioversion with no difference between thiopental and althesin groups. No significant difference in the haemodynamic response to cardioversion was seen in patients with heart volumes exceeding 650 ml/m2 BSA as compared to those with smaller hearts. It is concluded that both thiopental and althesin can be considered as safe anaesthetics for cardioversion.