Preoperative Acute Normovolemic Hemodilution for Minimizing Allogeneic Blood Transfusion: A Meta-Analysis.

Previous studies have evaluated the efficacy of preoperative acute normovolemic hemodilution (PANH) in reducing the need for allogeneic blood transfusion. However, the results to date have been controversial. In this study, we sought to reassess the efficacy and safety of PANH based on newly emerging evidence.Medline, EMBASE, ISI Web of Knowledge, and Cochrane Central Register of Controlled Trials databases were searched using the key words "hemodilution," "autotransfusion," or "hemorrhage" to retrieve all randomized controlled trials examining the benefits of PANH compared with control patients not undergoing PANH in any type of surgery.Sixty-three studies involving 3819 patients were identified. The risk of requiring an allogeneic blood transfusion and the overall volume of allogeneic red blood cell transfused during the perioperative period were reduced in the PANH group compared with the control group (relative risk, 0.74; 95% confidence interval, 0.63 to 0.88; P = 0.0006; weighted mean difference, -0.94 units; 95% confidence interval, -1.27 to -0.61 units; P < 0.0001). However, there was significant heterogeneity (I2 = 79.6%, χ2 = 151.95, P < 0.0001; I2 = 95.3%, χ2 = 574.28, P < 0.0001) and publication bias (P = 0.001; P = 0.009) for both outcomes, limiting conclusions regarding the efficacy of PANH for reducing allogeneic transfusion. Perioperative blood loss, adverse events, and the length of hospitalization were comparable between these groups.Although these results suggest that PANH is effective in reducing allogeneic blood transfusion, we identified significant heterogeneity and publication bias, which raises concerns about the true efficacy of PANH.