Ultrafiltration in cardiac surgery: Results of a systematic review and meta-analysis

Background: Ultrafiltration is used with cardiopulmonary bypass to reduce the effects of hemodilution and restore electrolyte balance. We performed a systematic review and meta-analysis to analyze the effect of conventional and modified ultrafiltration on intraoperative blood transfusion. Methods: Utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement, we systematically searched MEDLINE, EMBASE, Web of Science, and Cochrane Library to perform a meta-analysis of studies of randomized controlled trials (RCTs) and observational studies evaluating conventional ultrafiltration (CUF) and modified ultrafiltration (MUF) on the primary outcome of intraoperative red cell transfusions. Results: A total of 7 RCTs (n = 928) were included, comparing modified ultrafiltration (n = 473 patients) to controls (n = 455 patients) and 2 observational studies (n = 47,007), comparing conventional ultrafiltration (n = 21,748) to controls (n = 25,427). Overall, MUF was associated with transfusion of fewer intraoperative red cell units per patient (n = 7); MD −0.73 units; 95% CI −1.12 to −0.35 p = 0.04; p for heterogeneity = 0.0001, I ² = 55%) compared to controls. CUF was no difference in intraoperative red cell transfusions compared to controls (n = 2); OR 3.09; 95% CI 0.26–36.59; p = 0.37; p for heterogeneity = 0.94, I ² = 0%. Review of the included observational studies revealed an association between larger volumes (>2.2 L in a 70 kg patient) of CUF and risk of acute kidney injury (AKI). Conclusion: The results of this systematic review and meta-analysis suggest that MUF is associated with fewer intraoperative red cell transfusions. Based on limited studies, CUF does not appear to be associated with a difference in intraoperative red cell transfusion.