Influence of pre-operative treatment with phenoxybenzamine on the incidence of adverse cardiovascular reactions during anaesthesia and surgery for phaeochromocytoma.

The influence of pre-operative treatment with the alpha-adrenoceptor blocking agent, phenoxybenzamine, on the incidence of adverse cardiovascular reactions during anaesthesia and surgery for phaeochromocytoma was evaluated in a series of 62 patients. Fifty-one of them received pre-operative treatment with phenoxybenzamine and eight of these were also treated with beta-adrenoceptor blocking agents. The median final daily dose of phenoxybenzamine was 160 mg and the median period of treatment 23 days. The evening before surgery and in the early morning on the day of surgery, intravenous infusion of phenoxybenzamine was given to 42 of the patients. Eleven patients operated on between 1956 and 1963 received no specific pre-operative treatment and served as a reference group. The alpha-adrenoceptor blocking treatment resulted in a considerably smoother peroperative course, as evidenced by a statistically significant reduction in the incidence of excessive blood-pressure variations. The blockade was not complete since 69% of the patients had systolic peaks greater than 175 mmHg during surgery. Pre-operative blood transfusions did not significantly affect the incidence of hypotensive episodes. Pre-operative beta-adrenoceptor blockade did not reduce the incidence of peroperative arrhythmia. On the basis of our experience, we recommend that all phaeochromocytoma patients be treated pre-operatively with alpha-adrenoceptor blocking agents.