Association of Intraoperative Mean Perfusion Pressure with Acute Kidney Injury in Valve Replacement Surgeries: A Single-Center Analytical Cross-Sectional Study

Abstract

Background: Acute kidney injury (AKI) is a frequent and serious complication following cardiac surgery involving cardiopulmonary bypass (CPB). Intraoperative perfusion pressure, particularly mean arterial pressure (MAP) during CPB, has been suggested as a potentially modifiable risk factor influencing postoperative renal outcomes. However, evidence regarding its association with AKI in valve replacement surgery remains limited.  Aim and Objectives: To evaluate the association between intraoperative mean perfusion pressure and postoperative acute kidney injury  in Valve Replacement patients.

To explore the changes in value of mean arterial pressure (ΔMAP) from preoperative to intraoperative phases.  To determine whether intraoperative MPP can serve as a predictor of postoperative acute kidney injury. Materials and Methodology: This Analytical Cross-Sectional Study included 56 adult patients who underwent valve replacement surgery with CPB between October 2025 and December 2025. Preoperative, intraoperative, and postoperative data were collected from medical records. Intraoperative perfusion variables, including mean and lowest MAP during CPB, were recorded. Postoperative AKI was defined and staged according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Descriptive statistics were used to summarize patient characteristics. A p-value <0.05 was considered statistically significant. Results: A total of 56 patients who underwent valve replacement surgery with cardiopulmonary bypass and met the eligibility criteria were included in the study. Postoperative AKI occurred in 29(51.8%). According to KDIGO staging, 24(42.9%) developed stage 1 AKI, 2(3.6%) developed stage 2 AKI, and 3(5.4%) developed stage 3 AKI. Lower intraoperative perfusion pressure was associated with an increased incidence of postoperative AKI. On univariate logistic regression analysis, lowest intraoperative MPP during CPB showed significant results as a predictor of AKI (odds ratio [OR] = 0.914; 95% CI: 0.841–0.992; p = 0.032), indicating a higher risk of AKI with decreasing MPP values. Delta  MAP did not show a statistically significant association with AKI.  Conclusion: Lower mean arterial pressure during cardiopulmonary bypass was associated with a higher incidence of postoperative acute kidney injury in patients undergoing valve replacement surgery. Duration of MAP below 60 mmHg during CPB demonstrated a borderline association. Although increasing age and reduced postoperative urine output are also independent predictors of AKI. These findings highlight the importance of maintaining adequate perfusion pressure during CPB and closely monitoring high-risk patients to potentially reduce the risk of postoperative renal dysfunction.

Keywords: Acute Kidney Injury, Cardiopulmonary Bypass, Central Venous Pressure, Delta MAP,  Mean Arterial Pressure , Mean Perfusion Pressure, Venous Congestion, Valve Replacement Surgeries.