Establishing a Benchmark for Iatrogenic Hemodilution and Blood Transfusion in Long-Segment Spine Fusion Surgery.

Study design: Single-center retrospective cohort study.

Objective: To identify risk factors for transfusion during long-segment thoracolumbar fusion surgery and benchmark cutoffs that could be used by the operative team to guide the use of transfusion.

Summary of background data: Perioperative transfusion for patients undergoing long-segment thoracolumbar fusion surgery is common. To date, no standardized intraoperative and perioperative management of transfusion administration has been defined.

Methods: Patients who underwent thoracolumbar fusion surgeries of 8 or more levels between 2015 and 2020 were identified. Patient demographics, surgical details, anesthesia and critical care records, and laboratory data were compared between patients who received intraoperative and postoperative blood transfusions and those who did not. Univariate and multivariate propensity-matched analyses were performed to identify independent predictors for blood transfusion, and ordinal analysis was performed to identify possible benchmark cutoffs.

Results: Among 233 patients identified who underwent long-segment fusions, 133 (57.1%) received a blood transfusion. Multivariate propensity-matched logistic regression showed that intravenous (IV) fluid volume was an independent predictor for transfusion (transfusion group 8051 mL vs. non-transfusion group 5070 mL, P <0.01). Patients who received ≥4 L total IV fluids were more likely to undergo transfusion than those who received <4 L (93.2% vs. 50.7%, P <0.01). Those receiving total IV fluids at a rate ≥60 mL/kg (OR 10.45; 95% CI, 2.62-41.72; P <0.01) or intraoperative IV fluids at a rate ≥9 mL/kg/hr (OR 4.46; 95% CI, 1.39-14.32; P <0.01) were more likely to require transfusions.

Conclusions: IV fluid administration is an independent predictor for blood transfusion after long-segment fusion surgery. Limiting IV fluid administration may prevent iatrogenic hemodilution and decrease transfusion rates. These data can be used to create perioperative protocols with the goal of decreasing transfusion rates when not indicated and allowing earlier administration when indicated.