Transfusion Use and Hemoglobin Levels by Blood Conservation Method After Cardiopulmonary Bypass

Abstract

Guidelines recommend modified ultrafiltration (MUF) and cell washing for blood conservation after cardiopulmonary bypass (CPB), although information on outcomes is lacking. This research compared online MUF (ultrafiltration of the patient's entire circulating volume) with off-line MUF (ultrafiltration of the residual CPB volume) and centrifugation (cell washing of the residual CPB volume). This prospective cohort study enrolled 99 consecutive patients, grouped by method (group I, online MUF, n= 35; group II, off-line MUF, n= 30; group III, centrifugation, n= 34). Primary outcome was transfusion by 18 hours. Secondary outcomes were 18-hour hemoglobin levels, fluid balance (weight change), and biomarker levels indicating coagulation and organ function. By 18 hours, 22.9%, 6.7%, and 14.7% of group I, II, and III patients, respectively, had undergone transfusion (P= .19). Percentage weight gain differed by group (group I, 5.7%; group II, 1.3%; group III, 4.5%; P<.0001). Baseline to 18-hour hemoglobin change also differed by group, with the group I increase significantly exceeding that of group II (P= .002) but not differing from group III (P= .36). After adjustment for European System for Cardiac Operative Risk Evaluation II (EuroSCORE), weight gain, and transfusion, only the group II to III difference remained significant (P= .002). Online MUF does not appear to offer a reduction in blood transfusion over other methods. Although patients undergoing online MUF had greater improvement in baseline to 18-hour hemoglobin compared with patients undergoing off-line MUF, this benefit appeared attributable to fluid shifting. Off-line MUF was associated with the least frequent transfusions. Although online MUF does not appear to reduce blood transfusion, larger prospective randomized controlled studies are required for confirmation.