A case of prolonged hypotension following intravenous guanethidine block.

A 25-year-old female developed causalgia following a nerve injury in the left hand, and this was treated successfully with a series of intravenous guanethidine blocks. However, after the 13th block, systolic arterial blood pressure decreased to 60 mmHg and remained low (80 mmHg) for one week. Accumulation of guanethidine at the sympathetic nerve ending, resulting in autonomic denervation, might be the underlying mechanism of the prolonged hypotension. Treatment was conservative; however, the use of tricyclic antidepressants and sympathomimetic amines to restore the blood pressure to a normal level can be considered with appropriate caution.