Cardiovascular effects of a chlormethiazole infusion in combination with extradural anaesthesia

The cardiovascular effects of an infusion of chlormethiazole 30-40 ml min-1 were studied in six patients following an extradural injection of 2% lignocaine. There were small but statistically significant decreases in mean arterial pressure and left ventricular ejection time during the infusion. Increases in the pre-ejection period were noted, but there were no significant changes in cardiac output, stroke volume or heart rate. Patient acceptance was high. It is concluded that sedation with an infusion of chlormethiazole, during surgery carried out under extradural anaesthesia, has no clinically adverse cardiovascular effects.