MON-205 Effectiveness of Pre-Op α-Blockade on Intra-Op Blood Pressure Control in Patients with Pheochromocytoma

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Pheochromocytoma are rare tumors arising from catecholamine producing chromaffin tissue. Surgical manipulation of pheochromocytoma inevitably leads to supraphysiologic levels of circulating catecholamines. Such manipulation has the potential to lead to an intra-operative hypertensive crisis, cardiac arrhythmia, myocardial infarction, or pulmonary edema. When inadequately primed pre-operatively, a patient exposed to such surges may experience life-threatening consequences.Phenoxybenzamine is a non-competitive, non-selective α 1 and α 2 receptor antagonist that prevents blood pressure liability during surgical resection of pheochromocytoma. Previous literature has suggested that phenoxybenzamine affords more pronounced peri-operative systolic blood pressure control as compared to selective alpha-blockers. This superior control potentially is at the cost of postoperative hypotension owing to the irreversible nature of phenoxybenzamine.1Our study compares the effects of pre-operative phenoxybenzamine on perioperative outcomes at a single tertiary medical center from 2004 to 2019. The cumulative pre-operative phenoxybenzamine dose was compared to the maximum intra-operative blood pressure, need for IV blood pressure lowering medications, duration of vasopressor need, volume replacement need, duration of time in the OR, duration of hospital stay, and pre-operative catecholamine levels. We speculate that increased phenoxybenzamine exposure will result in reduced peak intra-operative blood pressure and need for IV blood pressure lowering medications but may increase the need for post-resection intra-operative vasopressors and post-resection volume replacement.After IRB approval, (ID #00031606), we performed a data warehouse query for the ICD 9 and 10 codes of “pheochromocytoma” and “paraganglioma”. Patients who did not have confirmed pheochromocytoma on pathology were excluded. Data was collected retrospectively on 30 patients who underwent adrenalectomy for pheochromocytoma. 14 charts were excluded due to incomplete intra-operative anesthetic documentation.Our results suggest that there is no significant correlation between peak intra-operative MAP and cumulative phenoxybenzamine exposure. The cumulative dose of pre-operative phenoxybenzamine did not correlate with the number of anti-hypertensive medications used intra-operatively. An increased cumulative dose of pre-operative phenoxybenzamine was not associated with an increased duration of intra-operative vasopressor medications. Intra-operative volume replacement needs were surprisingly reduced with increased cumulative pre-operative phenoxybenzamine exposure. 1 P.A. van der Zee, A. de Boer. Pheochromocytoma: A review on preoperative treatment with phenoxybenzamine or doxazosin. The Netherlands Journal of Medicine. May 2014; Vol. 72 No 4, 190-201.