Association between Cardiopulmonary Bypass Time and Postoperative Renal Dysfunction following Cardiac Surgery

Abstract

Background: Renal dysfunction is a significant postoperative complication in patients undergoing cardiopulmonary bypass, contributing to increased morbidity and mortality. Identifying the factors that influence postoperative renal function is crucial for improving patient outcomes. Objective: Our study aims to examine the prevalence of renal dysfunction in cardiac surgery patients after cardiopulmonary bypass and investigate the correlation between cardiopulmonary bypass duration and renal function markers. Methods: This observational study was retrospective conducted at Bahawal Victoria Hospital, Bahawalpur, on 184 patients who underwent ON-pump cardio-pulmonary bypass surgery. The demographics, intraoperative, and postoperative data of 184 patients were collected from the patients' medical records after obtaining institution ethical approval. Preoperative and postoperative creatinine levels were recorded. Pearson’s correlation was used to determine the  association between post-bypass creatinine and cardiopulmonary bypass duration. The test of Chi-square  was used to find the  association between cardiopulmonary bypass time and renal dysfunction. Results: The prevalence of postoperative renal dysfunction was 7.07% among the study population. A paired t-test confirmed a statistically significant increase in creatinine (t = -6.81, p < 0.001)  and BUN levels (t = -4.47, p <0.001) postoperatively. A weak negative correlation (r = -0.025, 95% CI: -0.159 to 0.101, p = 0.73) was observed between post-bypass creatinine levels and bypass time, indicating no statistically significant association. The Chi-Square test (p = 0.942) further confirmed that cardiopulmonary bypass duration alone was not associated with renal dysfunction. However, pre- and post-bypass creatinine (r=0.398, p <0.001) and BUN levels (r=0.797, p <0.001) showed a significant relationship, suggesting that factors beyond bypass time influence post-operative renal function. Conclusion: Despite the traditional assumption that prolonged bypass time increases the risk of renal dysfunction, this study found no significant association between cardiopulmonary bypass duration and postoperative renal impairment.