Efficacy and Safety of Acute Normovolemic Hemodilution in Adult Cardiac Surgery: A Systematic Review and Meta-Analysis of Latest Evidence

Acute normovolemic hemodilution (ANH) is a blood-conservation technique used during cardiac surgery to reduce allogeneic blood transfusion requirements and perioperative blood loss.This systematic review and meta-analysis (SRMA) aimed to evaluate the efficacy and safety of ANH in adults undergoing cardiac surgery.PubMed/MEDLINE, Embase, Scopus, and the Cochrane Library were searched for randomized controlled trials (RCTs) and comparative observational studies published between January 2005 and August 2026.Meta-analyses were performed using Review Manager (RevMan) version 5.4 (The Cochrane Collaboration, London, United Kingdom) with random-effects models.Continuous outcomes were pooled as mean differences (MDs), whereas dichotomous outcomes were pooled as risk ratios (RRs); both were reported with 95% confidence intervals (CIs).Statistical significance was set at P < 0.05, and heterogeneity was assessed using the I² statistic and Cochran's Q test.Fourteen studies were included.ANH was associated with reduced postoperative chest tube drainage across eight studies (MD, -66.74 mL; 95% CI, -121.45 to -12.02; P = 0.02; I² = 93%).Across seven studies, ANH was associated with a shorter hospital stay (MD, -0.75 days; 95% CI, -1.00 to -0.51; P < 0.00001; I² = 92%).The pooled analysis of perioperative RBC utilization showed a reduction in the number of RBC units transfused across 10 studies (MD, -0.34 units; 95% CI, -0.61 to -0.07; P = 0.01; I² = 85%).ANH was not associated with a statistically significant reduction in cardiac surgery-associated acute kidney injury (CSA-AKI) (RR, 0.84; 95% CI, 0.67-1.06;P = 0.15; I² = 0%).No statistically significant differences were reported for platelet or fresh frozen plasma (FFP) transfusion.Substantial heterogeneity was observed for chest tube drainage, hospital length of stay, and RBC utilization.ANH may reduce postoperative chest tube drainage, hospital length of stay, and perioperative RBC requirements in adults undergoing cardiac surgery.However, substantial heterogeneity across several outcomes and the absence of statistically significant differences in CSA-AKI and other transfusion outcomes warrant cautious interpretation.Further well-designed studies are needed to clarify its benefits across different cardiac surgical populations.