Effect of Semisitting Versus Supine Positioning on Intraoperative Bleeding During Endoscopic Endonasal Pituitary Surgery: A Randomized Clinical Trial

BACKGROUND AND OBJECTIVES: In endoscopic endonasal trans-sphenoidal pituitary surgery, the semisitting position (SSP) may reduce intraoperative bleeding compared with the supine position (SP); however, supporting evidence is lacking. The aim of this study was to compare the SSP with the SP and assess its effect on intraoperative bleeding. METHODS: This randomized, controlled, single-blind superiority trial was conducted at a Swiss tertiary hospital from 2021 to 2024. Of 107 patients screened, 64 were randomized and 56 included in the final analysis. In the intervention group, patients were placed in the SSP, with the torso elevated 30° and the legs raised, and compared with those in the SP. All patients were monitored for venous air embolism using a precordial Doppler. The primary outcome was intraoperative blood loss. Secondary outcomes included, among others, the frequency of interruptions for suctioning or hemostatic maneuvers, as well as the incidence of air embolism. RESULTS: Twenty-eight patients were allocated to each group. Most patients had a pituitary neuroendocrine tumor (25 [89.3%] in the SSP group and 27 [96.4%] in the SP group). The mean (SD) intraoperative blood loss was lower in the SSP group than in the SP group (184.7 [130.3] mL vs 277.3 [181.0] mL), corresponding to a mean reduction of 92.6 mL (33.4%) (95% CI, −177.1 to −8.1 mL; P = .03). Similarly, the median (IQR) frequency of intraoperative interruptions was lower in the SSP group than in the SP group (85.5 [62.3-109.0] vs 104.0 [77.5-135.5]), with a rate ratio of 0.80 (95% CI, 0.66-0.98; P = .03). Venous air embolism occurred in 3 patients (10.7%) in the SSP group and none in the SP group ( P = .09); all events were hemodynamically insignificant and resolved spontaneously. CONCLUSION: The SSP in endoscopic endonasal pituitary surgery reduces intraoperative bleeding and may improve surgical workflow, without raising major safety concerns.