Risk factors of massive introperative blood loss in posterior spinal fusion for adolescent idiopathic scoliosis

Objective: To investigate the risk factors and prognostic impact of massive introperative blood loss in posterior spinal fusion (PSF) surgery for adolescent idiopathic scoliosis (AIS). Methods: Clinical data were collected of 1 896 AIS patients who underwent PSF surgery under general anesthesia in Drum Tower Hospital Affiliated to Nanjing University Medical School from November 2010 to October 2019 and retrospectively analyzed. According to the volume of intraoperative blood loss, the patients were divided into the massive introperative blood loss group [estimated blood loss (EBL)/estimated blood volume (EBV)≥30%] and the non-massive introperative blood loss group (EBL/EBV<30%). The perioperative parameters between the two groups were compared, single factor analysis and multivariate logistic regression analysis was performed to identify independent risk factors related to massive introperative blood loss in PSF surgery. Results: A total of 1 896 AIS patients who underwent PSF surgery were included in the study. There were 298 males and 1 598 females, with an age of (14.5±1.7) years. Among them, 633 (33%) experienced massive intraoperative blood loss. The factors significantly related to the massive blood loss during PSF surgery in this study are: sex, body mass index(BMI), preoperative blood platelet count (PLT), prothrombin time, international normalized ratio(INR), preoperative Cobb angle, duration of operation, the number of fused levels, the number of screws, thoracoplasty, intraoperative use of tranexamic acid and dexmedetomidine; The independent factors included duration of operation longer than 4 hours(OR=4.311,P<0.001), the number of fused levels to be more than 10(OR=4.044,P<0.001), thoracoplasty (OR=2.174,P=0.019), BMI lower than 18.1 kg/m2(OR=2.094,P<0.001), preoperative PLT less than 186.5×109/L(OR=1.480,P=0.009), preoperative INR larger than 1 (OR=1.531,P=0.003) and preoperative Cobb angle larger than 53°(OR=1.306,P=0.036) ;Intraoperative use of tranexamic acid (OR=0.770, P=0.047) and dexmedetomidine (OR=0.653, P=0.008) are protective factors for massive intraoperative blood loss. In addition, in the massive intraoperative blood loss group, length of postoperative hospital stay (P<0.001), volume of postoperative incision drainage (P<0.001), postoperative allogeneic blood transfusion rate (22.7% vs 14.3%, P<0.001), incidence of postoperative hypoalbuminemia (90.3% vs 80.7%, P<0.001) and the number of rescue opioid analgesic requirements after surgery (P=0.006) were significantly higher than those in the non-massive introperative blood loss group. Conclusions: Longer operation duration, higher number of fusion levels, lower BMI, lower preoperative PLT, higher INR, larger preoperative Cobb angle and intraoperative thoraplasty are independent risk factors for massive intraoperative blood loss in AIS patients undergoing PSF surgery. Intraoperative use of tranexamic acid and dexmedetomidine can reduce the risk of massive blood loss in PSF surgery. Massive intraoperative blood loss significantly affects the patient's prognosis.