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Excess Conventional Ultrafiltration Volume Increases Risk for Postoperative Cardiac Surgery-Associated Acute Kidney
Han Zhang1, Jing Wang1, Tianlong Wang1
1Department of Cardiopulmonary Bypass, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, National Clinical Research Center for Cardiovascular Diseases, Fuwai Hospital, Beijing, China.
Insights
Higher volumes of conventional ultrafiltration (CUF) during cardiac surgery increase the risk of acute kidney injury. Excessive CUF also correlates with prolonged ventilation but does not reduce red blood cell transfusions, suggesting cautious use.
Area of Science:
- Cardiology
- Nephrology
- Critical Care Medicine
Background:
- Conventional ultrafiltration (CUF) is a standard procedure during cardiopulmonary bypass for fluid management and blood component concentration.
- Cardiac surgery-associated acute kidney injury (CSA-AKI) remains a significant complication, necessitating research into modifiable risk factors.
Purpose of the Study:
- To investigate the association between the volume of conventional ultrafiltration and the incidence of postoperative CSA-AKI.
- To evaluate the impact of CUF volume on other perioperative outcomes.
Main Methods:
- A retrospective analysis of 22,403 adult patients undergoing on-pump cardiac surgery from 2018-2023.
- Patients were stratified into groups based on weight-adjusted CUF volume tertiles.
- Multivariable logistic regression and restricted cubic splines were used to assess outcomes, including CSA-AKI (KDIGO criteria), transfusion needs, and ventilation duration.
Main Results:
- The incidence of CSA-AKI was 28.1%.
- Increased weight-adjusted CUF volume was independently associated with a higher risk of any-stage CSA-AKI (aOR 1.25) and stage 2/3 CSA-AKI (aOR 1.42).
- A nonlinear, J-shaped relationship was observed between CUF volume and CSA-AKI. Higher CUF volumes correlated with increased mechanical ventilation and RBC transfusion.
Conclusions:
- Excessive weight-adjusted conventional ultrafiltration volume is linked to a greater incidence of CSA-AKI and prolonged mechanical ventilation after cardiac surgery.
- CUF did not demonstrate a reduction in perioperative red blood cell transfusion requirements.
- Findings suggest a need for careful consideration and judicious application of CUF in fluid management strategies for cardiac surgery patients.
Introduction:
Conventional ultrafiltration (CUF) is employed during cardiopulmonary bypass to remove excess fluid and concentrate specific blood components. The study aimed to investigate the impact of CUF volume on postoperative cardiac surgery-associated acute kidney injury (CSA-AKI).
Methods:
This single-center, retrospective study included adult patients undergoing on-pump cardiac surgery between 2018 and 2023. Patients were classified into four categories for comparative analysis: the none-CUF group and three groups according to tertiles of the weight-adjusted CUF volume (tertile 1, 0.1-15.2 mL/kg; tertile 2, 15.3-25.0 mL/kg; tertile 3, >25.0 mL/kg). The primary outcome was postoperative CSA-AKI according to the Kidney Disease Improving Global Outcomes (KDIGO) criteria, and secondary outcomes included perioperative blood transfusion, pulmonary complications, chest drainage volume, urine output, hospital and ICU lengths of stay, and in-hospital mortality. The association between weight-adjusted CUF volume and patient outcomes was assessed by multivariable logistic regression model.
Results:
A total of 22,403 patients were included and the incidence of CSA-AKI was 28.1%. Weight-adjusted CUF volume (per 10 mL/kg increase) was independently associated with higher risk of any-stage CSA-AKI (adjusted odds ratio [aOR], 1.25; 95% confidence interval [CI], 1.14-1.38; p < 0.001) and stage 2/3 CSA-AKI (aOR, 1.42; 95% CI, 1.22-1.66; p < 0.001). The restricted cubic splines model illustrated a nonlinear relationship between weight-adjusted CUF volume and any-stage CSA-AKI (p for nonlinearity 0.025), while a J-shaped relationship for stage 2/3 CSA-AKI (p for nonlinearity < 0.001). A higher CUF volume was associated with increased odds of prolonged mechanical ventilation (aOR, 1.38; 95% CI, 1.18-1.64; p < 0.001) and perioperative red blood cell (RBC) transfusion (aOR, 1.13; 95% CI, 1.03-1.25; p = 0.011).
Conclusion:
Excess weight-adjusted CUF volume was significantly associated with increasing incidence of CSA-AKI and prolonged mechanical ventilation, but did not reduce the requirement for perioperative RBC transfusion. These findings highlight the cautious application of CUF in fluid management during cardiac surgery.
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