Effect of dihydroergotamine on perpheral circulation during epidural anaesthesia in man

The effect of intravenous administration of dihydroergotamine (DHE) on regional blood flow in the forearm and calf after pharmacological nerve blockade of the lower body induced by epidural anaesthesia has been studied in 13 subjects. After anaesthesia, DHE induced a significant increase in blood flow in the forearm with intact innervation and a significant decrease in blood flow in the nerve-blocked calf. On the average, the arterial blood pressure increased slightly. The calculated local vascular resistance increased in the nerve-blocked calf, probably due to a direct myogenic constrictive effect of DHE. In the intact forearm, local vascular resistance decreased. The results indicate that DHE exerts a complex effect on resistance vessels in addition to its well-known effect on the capacitance vessels.