Effect of ultrafiltration during cardiopulmonary bypass on viscoelastic profiles in cardiac surgery: Retrospective analysis

Abstract

Background: In cardiac surgery patients, conventional and modified ultrafiltration reduces free water and concentrates all blood components during cardiopulmonary bypass (CPB). Concentrating plasma substrate would be beneficial in attenuating CPB-induced dilutional coagulopathy. This retrospective study determined whether ultrafiltration affects viscoelastic profiles during CPB for cardiac surgery.

Methods: We reviewed Electronic medical records (EMR) of patients who underwent cardiac valve surgery under moderate hypothermic CPB in a tertiary university hospital from 2019 to 2021. We analyzed the values of maximum clot firmness of EXTEM assay (MCF-EXTEM) of rotational thromboelastometry test (ROTEM™) in patients who underwent ultrafiltration before the weaning from CPB the EMR data.

Results: In the EMR data of 30 included patients, the mean volume of the removed fluid by MUF was 1692 ml, and the mean CPB duration was 206 min. Ultrafiltration increased hematocrit (Hct, mean±SD, 21.9±3.3 vs. 25.7±3.2%, p<0.001). As the primary measure, ultrafiltration significantly increased MCF-EXTEM (median[1Q-3Q], 48.0[38.8-54.0] vs 50.5[40.0-56.0]mm, p=0.015, Table 1). With the assumption that ultrafiltration would increase MCF-EXTEM, we applied the receiver operating characteristic (ROC) analysis to the MCF-EXTEM changes: the area under the ROC curve (AUC) was 0.89 (95%CI: 0.77‒1.00, P <0.001, Fig. 1); and the cut-off value of MCF-EXTEM was 50.5 mm (specificity of 81.8% and sensitivity of 84.2% in Youden’s J statistics). In the subgroup analyses employing the cutoff value (Fig. 2), in patients with MCF-EXTEM before-ultrafiltration of <50.5 mm (n=18/30), ultrafiltration significantly increased MCF-EXTEM (40.5[34.5-44.8] vs. 42.5[39.3-51.3] mm, p=0.001), but in patients with MCF-EXTEM before-ultrafiltration of ≥50.5 mm (n=12/30), it did not produce any change (57.5[52.8‒60.3] vs. 56.0[51.0‒60.3] mm, p=0.504).

Conclusion: Ultrafiltration at the end of CPB enhanced overall clot strength in cardiac surgery patients, especially patients with reduced coagulation performance. It would be beneficial in attenuating CPB-induced dilutional coagulopathy and enhancing overall coagulation performance in cardiac surgery.