Cardiopulmonary Bypass Copolymer Surface Modification Reduces Neither Blood Loss Nor Transfusions in Coronary Artery Surgery

Abstract OBJECTIVE: Surface-modifying additives (SMA) have been suggested for improving cardiopulmonary bypass (CPB) circuit biocompatibility, potentially minimizing inflammatory complications and bleeding associated with CPB. The purpose of this prospective, randomized clinical study was to compare a novel copolymer surface-modified CPB circuit (SMARXT™; COBE® Cardiovascular) against the unmodified circuit. METHODS: We randomized 122 patients with isolated coronary artery disease subjected to first-time surgery on CPB into either the SMA (n = 62) or the control group (n = 60). Exclusion criteria included renal insufficiency, liver disease, coagulopathy, anticoagulation therapy < 6 days preop, carotid artery stenosis > 70 %, and a history of stroke. We collected perioperative clinical data including drainage blood loss, transfusion requirements, duration of mechanical ventilation, and ICU stay. Platelet function was determined pre- and post-CPB. RESULTS: SMA patients received 3.2 ± 0.9 (SD) grafts during 48 ± 16 min of aortic cross clamp and 91 ± 30 min CPB (Control: 3.0 ± 0.9 grafts; p = 0.33, 46 ± 14 min AXC; p = 0.36, and 84 ± 23 min CPB ; p = 0.14). In the SMA group, 23 patients (37 %) received red blood-cell transfusions, 9 patients (15 %) fresh frozen plasma, and 3 patients (5 %) received platelets (control: n = 27 [46 %], p = 0.44; n = 10 [17 %], p = 0.91; and n=4 [7 %], p = 0.71, respectively). Platelet count on CPB fell to the same level in both groups. In SMA patients, platelet function decreased from 94.2 ± 24.9 % pre-CPB to 79.5 ± 32.8 % post-CPB (p = 0.043) (control: from 87.7 ± 25.6 % to 69.4 ± 34.7 %; p = 0.001). Postoperative drainage blood loss, mechanical ventilation duration, and ICU stay were similar in both groups (p > 0.3). One patient of the control group was excluded due to surgical bleeding, and one SMA patient died. CONCLUSIONS: Our results show that the surface-modified CPB circuit decreased neither blood loss nor transfusions despite slightly better platelet function preservation compared to the unmodified circuit. This type of CPB circuit surface modification does not appear to improve clinical outcome in low-risk coronary artery surgery patients.