Decrease in Effective Renal Perfusion Pressure is Associated with Increased Acute Kidney Injury In Patients Undergoing Cardiac Surgery

Abstract

Abstract Purpose: To evaluate the relationship between intraabdominal pressure (IAP) and renal perfusion indices and postoperative acute kidney injury (AKI) in cardiac patients. Methods: In a prospective cohort study conducted at a single academic institution, we collected data from adult patients undergoing open-heart operations with cardiopulmonary bypass (CPB) at our institution from February 2022 to April 2022 using the Accuryn SmartFoley system. Patients on mechanical support devices, pregnant patients, and patients on hemodialysis were excluded. Demographics, hemodynamics, and mean airway pressures (mAir) were measured at the beginning of the cardiac operations and during the first 4 hours of ICU. Renal perfusion indices were then calculated (Mean Perfusion Pressure (MPP) = MAP – CVP; Abdominal Perfusion Pressure (APP) = MAP – IAP; effective Renal Perfusion Pressure (eRPP) = MAP - (CVP + mAir + IAP)). Length of stay (LOS) were measured from the day of surgery to ICU discharge (ICU LOS) and hospital discharge (hospital LOS). Results: During the first 4 hours of ICU stay, the non-AKI group had lower IAP and higher renal perfusion indices (MPP, APP, and eRPP). Logistic regression showed high perfusion pressures correlated with lower postoperative AKI (all OR < 1, p<0.05). Postoperative AKI group also had significantly longer ICU LOS (7.33 vs. 4.57 days) and hospital LOS (17.0 vs. 10.2 days). Conclusion: Renal perfusion indices are a promising tool to predict postoperative AKI in cardiac surgery patients.