title: Predictors of intra-operative blood loss and blood transfusion in orthognathic surgery: a retrospective cohort study in 92 patients.
abstract: BACKGROUND
  Patients undergoing orthognathic procedures can require blood transfusions. The objectives of this study were to evaluate the predictors of intra-operative blood loss in patients undergoing orthognathic procedures and the transfusion rates and practices of our institution.
  
  
  METHODS
  This retrospective study included 92 patients who underwent the following four types of orthognathic procedures: Group 1, bimaxillary; Group 2, bimaxillary with bone grafts; Group 3, LeFort I osteotomies; and Group 4, LeFort I osteotomies with bone grafts. The intra-operative blood loss, operative time, age, gender and pre- and post-operative HGB and HCT were assessed.
  
  
  RESULTS
  The mean blood loss for all groups was 650 ± 397.8 mL, and there were differences in blood loss between the four groups (p = 0.211). The mean operative time was 5 hours and 32 minutes. There were no differences in intra-operative blood loss between the genders or the BMI categories. The operative time was moderately correlated with the intra-operative blood loss (p < 0.001, r =0.332). Eighteen of the 92 patients (19.5%) received blood transfusions. The mean intra-operative blood loss was higher among the patients who received transfusions (p < 0.001).
  
  
  CONCLUSIONS
  The only predictor of intra-operative blood loss was operative time. The observed transfusion rate was higher than those that have been reported for similar procedures; thus, our institution needs to revisit our transfusion policy and use more time-efficient techniques in the operating room.
authors.affiliation: Department of Oral and Maxillofacial Surgery, King AbdulAziz University, Faculty of Dentistry, PO Box 80209, Jeddah, 21589 Kingdom of Saudi Arabia.
authors.forename: Maisa O
authors.initials: MO
authors.lastname: Al-Sebaei
keywords: Bimaxillary surgery; Blood loss; Blood transfusion; Hemoglobin; Hypotensive anesthesia; Orthognathic surgery