P44. OPERATIVE TIME IS AN INDEPENDENT PREDICTOR OF ADVERSE POSTOPERATIVE OUTCOMES IN DIEP FLAP BREAST RECONSTRUCTION: A MULTIVARIATE ANALYSIS OF 1000 BILATERAL FLAPS

Abstract

PURPOSE: Operative Time (OT) as a risk factor for adverse postoperative outcomes in microvascular breast reconstruction has not been thoroughly investigated. This study evaluates the impact of OT on length of stay (LOS), overall morbidity, individual complications, and unplanned reoperation (UR) in Deep Inferior Epigastric Artery Perforator (DIEP) flaps, with a primary objective of identifying a clinically relevant time of decreased risk. METHODS: Patients who underwent bilateral DIEP flaps from 2010-2021 by two senior surgeons with standardized surgical and postoperative protocols were retrospectively reviewed. 1000 flaps (500 patients) were analyzed with multivariate regressions to adjust for potential confounders, including microsurgeon experience. To identify a cutoff, beyond which risk for postoperative complications, extended LOS (eLOS, defined as ≥5 days), and UR significantly increases, adverse outcomes were compared amongst OT intervals. RESULTS: With risk-adjustment, each hour of OT increased morbidity by 22% (p<0.001) and LOS by 4.8 hours (p<0.001).Procedures >5 hours had 3.9, 4.8, and 3-fold increased risk of UR (p=0.029), eLOS (p=0.007), and overall complications (p<0.001), respectively. Breast fat necrosis, donor-site, and medical complications had significantly higher risk after 5 hours. Lastly, a risk-adjusted linear regression showed that LOS can be calculated from OT: LOS (days) =1.702 + 0.201 x OT (hours) (p<0.001, R2=0.369). CONCLUSION: Operative time is an independent predictor of morbidity, LOS, and UR in DIEP flaps, with significantly greater risk >5 hours. The findings emphasize the importance of decreasing OT through efficiency models, such as process analysis, team-based intraoperative protocols, and co-surgery.