Resident Physician NYU Langone Health, Department of Neurosurgery New York, NY, US
Introduction: Adult spinal deformity (ASD) surgery results in significant blood loss especially in the setting of high-grade osteotomies. Reports of estimated blood loss (EBL) vary widely and are proposed to range from 1-2 L. Visual assessments of EBL are often inaccurate and under-resuscitation places patients at risk of neurological injury, hypotension, multiorgan injury, and even death. Despite its importance, objective quantification of blood loss in ASD remains underexplored. We aimed to (1) define the actual magnitude of blood loss during ASD surgery using a standardized quantitative blood loss (QBL) protocol and (2) establish an optimal intraoperative resuscitation target for three-column osteotomy (3CO).
Methods: This is a prospective, observational, single-center study of patients undergoing open ASD surgery following implementation of a QBL protocol between 1/7/2022-5/1/2024. Patients with SVA >4.5cm and/or PI-LL mismatch >10 were included. QBL was calculated through volumetric/gravimetric analysis of blood in suction canisters, sponges, and irrigation. The cumulative incidence of postoperative pRBC transfusion for 3CO cases was recorded to determine an ideal intraoperative HGB target.
Results: This study included 107 patients with a mean age of 68.5 years and mean of 10.8 levels fused. Mean QBL was 2758.8 ml (range 277-11963 ml) or 59.3% (range 6.2-316%) of estimated total blood volume (TBV). Fifty-five (51.4%) patients underwent posterior column osteotomy (PCO), 37 (34.6%) underwent 3CO, and 66 (62.3%) underwent interbody fusion. 3CO was most frequently performed in the lumbar spine (64.8%). Mean QBL increased with number of levels fused: 1877.7 ml for 5-9 levels, 3569.4 ml for 10-14 levels, and 3899 ml for ≥15 levels (p=0.002). Mean QBL for 3CO was 4709.9 ml (range 2690.4-11963 ml) or 96.7% TBV (range 12.4-316%). PCO (p=0.034) and 3CO (p < 0.001) were associated with major blood loss. Eighty percent of transfusions in patients undergoing 3CO occurred when immediate postoperative HGB was < 10.8g/dl.
Conclusion : EBL significantly underestimates blood loss during ASD surgery. Here, mean QBL was 2.75 L for all ASD cases and 4.71 L (97% TBV) for 3CO cases. Hence adequate and rapid resuscitation with blood products is essential to mitigate intraoperative extremis and postoperative complications. Targeting HGB>10 may reduce postoperative transfusion requirements.