Predictors of prolonged ICU stay after bimaxillary orthognathic surgery: the role of blood loss and intraoperative fluid management. A retrospective study

BACKGROUND: Bimaxillary orthognathic surgery carries substantial perioperative risks, but clear criteria for identifying patients who require postoperative intensive care unit (ICU) monitoring are lacking. METHODS: We retrospectively analyzed 94 patients who underwent bimaxillary surgery between 2014 and 2019 and were routinely admitted to the ICU postoperatively. Primary outcomes were duration of intubation and postoperative course, classified according to the Clavien-Dindo system. Demographic, surgical, and laboratory variables were assessed as predictors of prolonged ICU stay, with particular emphasis on hemoglobin (Hb) changes corrected for hemodilution. RESULTS: Of the 94 patients, 29 required prolonged intubation or extended ICU care, 19 showed early postoperative concerns but recovered without complications, and 46 had an uncomplicated course. Multivariate analysis identified Hb reduction on postoperative day one and mandibular advancement as strong independent predictors of prolonged intubation and complicated postoperative outcomes (both p < 0.001). Operative duration showed only marginal significance (p = 0.046). Corrected blood loss was significantly associated with adverse outcomes, whereas estimated intraoperative blood loss and Hb reduction at the end of surgery were not. Receiver operating characteristic analysis indicated thresholds of 1300 mL blood loss or a 3.9 g/dL Hb decrease in a 70-kg adult, predicting increased risk with 86% sensitivity and 63% specificity. CONCLUSIONS: Postoperative day-one Hb reduction corrected for hemodilution and the extent of mandibular advancement are reliable predictors of complicated recovery following bimaxillary orthognathic surgery and may support more targeted ICU utilization.