Ultrafiltration During Cardiac Surgery Requiring Cardiopulmonary Bypass and Its Effect on Acute Kidney Injury

Area of Science:

• Nephrology
• Cardiology
• Critical Care Medicine

Background:

• Cardiopulmonary bypass (CPB) is associated with a risk of acute kidney injury (AKI).
• Ultrafiltration (UF) is a common fluid management strategy during CPB.
• The impact of weight-adjusted UF volume on AKI risk requires further investigation.

Purpose of the Study:

• To determine if weight-adjusted UF volume is associated with an increased risk of AKI in cardiac surgery patients undergoing CPB.
• To explore the relationship between UF volume, nadir hemoglobin levels, and red blood cell transfusion in AKI development.

Main Methods:

• Retrospective cohort study of 2369 adult patients undergoing cardiac surgery with CPB.
• Patients were stratified into four groups based on weight-adjusted UF volume (0, 0.1-17.9, 18-29.9, >30 mL/kg).
• AKI was defined by KDIGO criteria; associations with UF volume, nadir hemoglobin, and transfusion volume were analyzed.

Main Results:

• Postoperative AKI occurred in 35.4% of patients.
• A higher incidence of AKI was observed in patients with UF volume >30 mL/kg (42.7%, p=0.019).
• Each 10 mL/kg increase in UF was associated with increased AKI odds (OR 1.14), though this association diminished after adjusting for intraoperative factors (OR 1.07). Higher UF was linked to AKI in patients with lower nadir hemoglobin.

Conclusions:

• Conventional UF volume adjusted for weight may be a risk factor for AKI post-CPB.
• Higher weight-adjusted UF volumes are associated with increased AKI incidence, particularly in specific patient subgroups.
• Further prospective, multicenter studies are needed to validate findings and explore optimized UF strategies.