Increased Cell Saver to Blood Loss Ratio is Associated with a Higher Risk of Pulmonary Embolism After Adult Spinal Deformity Surgery

Introduction: Reports have shown that cell saver salvage(CS) processing introduces fragile RBCs with sub-lethal injuries to its recipients. Mohanty et al discerned that a CS:EBL≥0.33 is associated with higher rates of 30D readmissions. We aim to analyze the effect of this ratio on cardiopulmonary(CP) and renal complications.

Methods: This study is an analysis of a prospective, multicenter cohort of ASD patients with ≥1 procedural and/or radiographic criteria: PI-LL≥25°, TPA≥30°, SVA≥15cm, thoracic scoliosis≥70°, thoracolumbar scoliosis ≥50°, global coronal malalignment≥7cm, ≥ 12 instrumented levels, and/or undergoing 3CO. Patients were dichotomized based on whether they received a CS:EBL ratio≥0.33 or < 0.33. Patients were excluded if they had no CS transfused. Patient characteristics, labs, operative data, and radiographic parameters were analyzed.

Results: 406 patients were included with 10.6%(N=43) and 89.4%(N=363) patients having CS:EBL ≥0.33 and < 0.33, respectively. The CS:EBL≥0.33 patients were older (66.2±12.2yrs vs 58.9±16.4,p=0.0007), experienced less EBL(1048.3±852.2cc vs 1695.6±1295.3cc,p < 0.0001), less TIL(12.2±3.3 vs 14.1±3.6,p=0.0001), less PCOs performed (72.1% vs 86.8%,p=0.0103) and less major coronal cobb correction(-17.0±14.6 vs -22.7±16.7,p=0.0373). Despite comparable transfusion rates, CS:EBL≥0.33 patients has lesser pRBC, FFP, 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, CS:EBL≥0.33 patients experienced a greater rate of pulmonary embolisms(PE)(9.3% vs 1.4%,p=0.0093) within 30D postop. A multivariable logistic regression model adjusting for age, EBL, PCOs performed, TIL, change in the max coronal cobb angle, and colloids, pRBC, FFP, and platelet units transfused discerned CS:EBL≥0.33 to be an independent risk factor for the development of PE [OR=6.57 (1.75-24.66)] with excellent model diagnostics (p=0.0031, AUC=0.92, Goodness-of-Fit Test p-value = 0.7264).

Conclusion : Patients with a CS:EBL≥0.33 have a 6.57x greater risk of developing a pulmonary embolisms early postop independent of EBL and transfusions administered. The findings support the re-evaluation of CS use in this patient population based on perceived benefits.