Association between cell saver transfusion to estimated blood loss ratio and risk of pulmonary embolism after adult spinal deformity surgery.

Abstract

OBJECTIVE: The objective of this study was to determine whether increased cell saver (CS) salvage transfusion to estimated blood loss (EBL) ratio (CS:EBL) is a driver in the development of cardiopulmonary (CP) and/or renal complications. METHODS: Patients with adult spinal deformity (ASD) enrolled in a multicenter, observational prospective study from 13 spinal deformity centers in North America were queried. Eligible participants met at least one of the following radiographic and/or procedural inclusion criteria: pelvic incidence-lumbar lordosis mismatch ≥ 25°, T1 pelvic angle ≥ 30°, sagittal vertical axis ≥ 15 cm, thoracic scoliosis ≥ 70°, thoracolumbar/lumbar scoliosis ≥ 50°, global coronal malalignment ≥ 7 cm, having undergone a 3-column osteotomy, spinal fusion ≥ 12 levels, and/or age ≥ 65 years with ≥ 7 levels of instrumentation. Patients were dichotomized based on whether their CS:EBL was ≥ or < 0.33. Patients who did not have CS transfused intraoperatively were excluded. Key outcomes included renal and CP-related medical complications. Patient characteristics, preoperative laboratory results, operative data, and radiographic parameters were compared using appropriate statistical tests. A conceptual multivariable logistic regression model was built to assess risk factors associated with the primary outcome. RESULTS: Four hundred six patients were included in this analysis, including 10.6% (n = 43) with a CS:EBL ≥ 0.33 and 89.4% (n = 363) with a CS:EBL < 0.33. The patients with a CS:EBL ≥ 0.33 were significantly older (mean 66.2 [SD 12.2] vs 58.9 [SD 16.4] years, p = 0.0007), experienced less EBL intraoperatively (mean 1048.3 [SD 852.2] vs 1695.6 [SD 1295.3] ml, p < 0.0001), had fewer total instrumented levels (mean 12.2 [SD 3.3] vs 14.1 [SD 3.6] levels, p = 0.0001), had fewer posterior column osteotomies performed (72.1% vs 86.8%, p = 0.0103), and had less major coronal Cobb angle correction (mean -17.0° [SD 14.6°] vs -22.7° [SD 16.7°], p = 0.0373). Despite comparable transfusion rates, patients with a CS:EBL ≥ 0.33 had fewer packed red blood cell (RBC), fresh frozen plasma, and platelet units transfused intraoperatively (p < 0.05). No significant differences were observed among overall CP and renal complications. However, when stratifying CP complications by type, patients with a CS:EBL ≥ 0.33 experienced a significantly greater rate of pulmonary embolisms (PEs; 9.3% vs 1.4%, p = 0.0093) within 30 days of surgery. A multivariable logistic regression model adjusted for the significant differences between the two groups found a CS:EBL ≥ 0.33 to be an independent risk factor for the development of a PE, conferring an odds ratio of 6.57 (95% CI 1.75-24.66) with excellent model diagnostics (model p value = 0.0031, area under the receiver operating characteristic curve = 0.92). CONCLUSIONS: Patients with a high CS:EBL were at a significantly greater risk of developing a PE within the early postoperative period independent of blood loss and operative complexity. The findings support the re-evaluation of salvaged RBC use in this patient population based on perceived benefits.