Modification of the circulatory effects of extradural block combined with general anaesthesia by the addition of adrenaline to lignocaine solutions.

The cardiovascular changes associated with extradural block were measured in two groups of patients who were also receiving light general anaesthesia. In the first two group (five patients) 2% plain lignocaine 20 ml was used and decreases occurred in mean arterial pressure, cardiac output, stroke volume and peripheral resistance. In the second group (10 patients) 2% lignocaine 20 ml to which adrenaline 1:200,000 had been added was used. Decreases in arterial pressure and peripheral resistance occurred in all patients, but the responses of the cardiac output and heart rate were variable, decreasing in three patients and remaining stable or increasing in seven patients. A high segmental block was presumed to have occurred in those patients who developed bradycardia and a decreased cardiac output. The differences between these studies in anaesthetized patients and those previously reported in conscious volunteers are discussed.