Influence of Pre-operative Treatment with Phenoxybenzamine on the Incidence of Adverse Cardiovascular Reactions during Anaesthesia and Surgery for Phaeochromocytoma

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Abstract
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 preoperative 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 > 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 arrhythmica. On the basis of our experience, we recommend that all phaeochromocytoma patients be treated pre-operatively with .alpha.-adrenoceptor blocking agents.