The effects of dihydroergotamine (DHE) on the circulation of the leg during combined epidural and general anaesthesia were studied to determine if DHE would enhance leg blood flow and prevent postoperative deep vein thrombosis in a double-blind trial of 40 elderly female patients subjected to cholecystectomy. Central and big toe temperature, arterial blood pressure, heart rate, calf volume and arterial inflow of the leg by electrical impedance plethysmography and the venous outflow by Doppler method were measured. DHE 0.5 mg subcutaneously reduced the volume of the leg, i.e. increased the electrical impedance, probably due to venous vasoconstriction. Simultaneously the need for etilefrine hydrochloride was reduced. No significant changes in the pulsatile inflow of the leg or the outflow were detected. Deep vein thrombosis (DVT) was detected by fibrinogen uptake test in five patients (three in DHEH and two in the control group) and verified by ascending phlebography in four patients. Intraoperative characteristics in patients with postoperative DVT were tachycardia (P < 0.001), enhanced need for etilefrine (P < 0.01) and a more rapid increase in big toe temperature (P < 0.05) after induction of epidural analgesia, compared with patients without DVT. Femoral vein flow velocity remained at the preinduction level, whereas pulsatile arterial inflow slightly increased. Together with a low basal impendance of the leg, the changes were indicative of a more intense vasodilatation, probably leading to stagnant flow and development of postoperative deep vein thrombosis.

The efficacy of a single dose of dihydroergotamine (DHE) 0.5 mg i.v. in preventing the decrease in arterial pressure resulting from extradural anaesthesia was studied in 47 patients; 24 received DHE and 23 a placebo, in a randomized double-blind manner. Although the decrease in systolic arterial pressure was more pronounced in the placebo group than in the DHE group, the difference was not significant. Diastolic and mean arterial pressures were both significantly lower in the placebo group than in the DHE group during the initial phase of extradural anaesthesia. Administration of DHE did not cause any significant changes in heart rate. In both groups the heart rate decreased significantly during the 5-h period following the induction of extradural anaesthesia. The patients in the placebo group needed additional medication to increase unacceptably low arterial pressures or heart rate more frequently than the patients in the DHE group.