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

: 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.: 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.: A total of 7 RCTs ( = 928) were included, comparing modified ultrafiltration ( = 473 patients) to controls ( = 455 patients) and 2 observational studies ( = 47,007), comparing conventional ultrafiltration ( = 21,748) to controls ( = 25,427). Overall, MUF was associated with transfusion of fewer intraoperative red cell units per patient ( = 7); MD -0.73 units; 95% CI -1.12 to -0.35 = 0.04; for heterogeneity = 0.0001, = 55%) compared to controls. CUF was no difference in intraoperative red cell transfusions compared to controls ( = 2); OR 3.09; 95% CI 0.26-36.59; = 0.37; for heterogeneity = 0.94, = 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).: 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.