MON-194 Phaeochromocytoma-Paraganglioma (PPGL): Post-Operative Hypotension Is a Vanishing Phenomenon

Background: Treatment of hemodynamic instability in patients with PPGL in the intra-and postoperative periods is challenging. Persistent postoperative hypotension is a common and serious complication, reportedly occurring in 30-60% of PPGL patients. This phenomenon reflects 1) high doses of pre-operative antihypertensive drugs; 2) low intravascular volume secondary to chronic catecholamine-induced vasoconstriction with pressure natriuresis; 3) the sudden drop in circulating catecholamines after surgery. It has been shown that tumor size and preoperative levels of catecholamines are directly related to the need for treatment with vasopressor agents in the early period after tumor removal. The aim of this study was to evaluate the efficacy and safety of the current perioperative treatment protocol for PPGL used in our Institute. Methods: We retrospectively reviewed the rate of hemodynamic instability and postoperative hypotension in relation to catecholamine levels, and the efficiency of preoperative pharmacological preparation in consecutive patients with PPGL treated between 2000-2019. Results: There were 39 patients (F/M 19/20; mean age 50.4 ±16.5 years) 33 of which had adrenal lesions and 6 had extra-adrenal tumors. Mean tumor size was 3.9 ±2.2 cm. Median metanephrine and normetanephrine levels were 5 and 10 fold the upper limit of the normal range respectively. All patients were treated with α-blockade (phenoxybenzamine-17, mean dose 60±38 mg/day; doxazosin-22; mean dose 9.6±6.1mg/day) along with β- blockade, and high sodium diet and IV saline 24 hours before the operation. The length of the preoperative preparation period was 3.4±2 weeks. Within the first 24-48 hours from surgery, no episodes of hypotension (<90 mmHg systolic pressure) were recorded. Mean systolic BP was 121 ±14 (range 95-150) with a mean diastolic BP of 70 ±11 (range 89-46). In contrast, intraoperative hypotension occurred in 22% of the patients; and BP surge occurred in 36% of patients, mostly during tumor manipulation. There were no differences between subjects with and without such BP rises/falls in terms of pre/post- surgical BP, catecholamine levels or type of medical treatment. Conclusion: In contrast with older literature and previous reports, the patients in our cohort did not experience postoperative hypotension. This is most likely due to tight BP control while avoiding pre-operative hypotension, and adequate volume control. We propose that proper preoperative management in the modern era can drastically minimize intraoperative hemodynamic instability and post-operative hypotension.