Post-heparinization autologous donation with autologous circuit priming versus acute normovolemic hemodilution in cardiac surgery: A retrospective cohort study

Objective: To compare postoperative chest-tube drainage and cumulative allogeneic red blood cell (RBC) exposure between two integrated autologous blood-conservation strategies: post-heparinization pre-bypass acute autologous donation (PAAD), which incorporated autologous circuit priming, and pre-heparinization acute normovolemic hemodilution (ANH).Methods: This single-center retrospective cohort included 220 adults undergoing first-time elective on-pump cardiac surgery with preoperative hemoglobin ≥12 g/dL; 117 received PAAD and 103 ANH as routine care. The primary outcome was cumulative chest-tube drainage during the first 24 hours after intensive care unit admission. The key secondary outcome was allogeneic RBC exposure from cardiopulmonary bypass-flow start through discharge or death. Crude and covariate-adjusted estimates were calculated.Results: Mean (standard deviation) 24-hour drainage was 876.2 (692.2) mL with PAAD and 855.0 (657.8) mL with ANH. The crude PAAD-minus-ANH mean difference was 21.2 mL (95% confidence interval [CI], -159.1 to 201.6), and the adjusted difference was 44.3 mL (95% CI, -146.3 to 234.9). Cumulative RBC exposure occurred in 38/117 (32.5%) PAAD and 29/103 (28.2%) ANH patients (risk difference, 4.3 percentage points; 95% CI, -7.9 to 16.2; risk ratio, 1.15; 95% CI, 0.77 to 1.73).Conclusion: In this selected elective cohort, neither outcome clearly differed between the integrated strategies, but the wide intervals were compatible with clinically relevant associations in either direction. These observational data do not establish equivalence, causation, or a preferred strategy.