A Single-Center Randomized Trial of Intraoperative Zero-Balanced Ultrafiltration During Cardiopulmonary Bypass for Patients With Impaired Kidney Function Undergoing Cardiac Surgery

ObjectivesThe authors investigated whether zero-balance ultrafiltration (Z-BUF) during bypass significantly improves clinical and cost outcomes or biomarkers of kidney injury for patients with preoperative kidney impairment (estimated glomerular filtration rate [eGFR]<60 mL/minute) undergoing cardiac surgery.DesignA single-center randomized controlled trial recruited, patients between 2010 and 2013, with a 12-months follow-up.SettingHospital.ParticipantsOne hundred ninety-nine patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).InterventionsPatients were assigned randomly to receive zero-balance ultrafiltration (Z-BUF) or not, with stratification for degree of kidney dysfunction and diabetes.Measurements and Main ResultsThe authors assessed clinical efficacy and kidney function biomarkers. Cumulative probability of discharge from the intensive care unit (ICU) was assessed by Kaplan-Meier plots and was found not to be significantly different between the two trial arms (p = 0.61). After adjusting for EuroSCORE, diabetes, eGFR, cardioplegia types and type of surgery in a Cox proportional hazard model, hazard ratios (HR) for ICU length of stay between the Z-BUF and no-Z-BUF groups was not significantly different: HR (95% CI): 0.89 (0.66, 1.20; p = 0.44). In contrast, significant reductions in postoperative chest infections and the composite of clinical endpoints (death, strokes, and myocardial infarctions) in the Z-BUF group were observed. In addition, Z-BUF significantly abrogated the rise in the kidney damage markers urinary NGAL/creatinine ratio, urea, creatinine and eGFR during CPB and adverse events risks.ConclusionsZ-BUF during bypass surgery is associated with significant reductions in morbidity and biomarkers of CPB-induced acute kidney injury soon after CPB, which are indicative of clearance of inflammatory/immune mediators from the circulation.