Introduction: Cardiac Surgery involving Cardiopulmonary Bypass may leads to alterations in renal function, potentially affecting patient outcome. The primary objective is to evaluate the relationship between intraoperative urine output and postoperative renal function in patients undergoing single valve replacement surgery. considering various factors such as duration of bypass, ischemic time, temperature and hematocrit level. 

Materials and methods: A descriptive and cross-sectional study design with non-probability sampling technique of convenience sampling was carried out from January 1 to June 15 2025 in department of Cardiothoracic and Vascular Surgery at Manmohan Cardiothoracic Vascular and Transplant Center. Pre-op and Post-op Serum Creatinine was measured and medical records were reviewed.

Results: In this cohort of 87 patients, the incidence of postoperative acute kidney injury (AKI) was 20.7%. Preoperative diabetes mellitus and hypertension were identified as independent predictors of AKI in both the overall group and the subgroup with urine output less than 13.2 mL/kg/hr. Intraoperative urine output was significantly lower in patients who developed AKI and was associated with AKI in univariate analysis; however, it was not an independent predictor after adjusting for comorbidities. A clear inverse relationship was observed between urine output and AKI risk. 

Conclusion: This study highlights that reduced intraoperative urine output is closely linked to an elevated risk of postoperative kidney dysfunction following single valve replacement surgery. Patients with underlying hypertension and diabetes were particularly susceptible. These findings suggest that maintaining effective renal perfusion during cardiopulmonary bypass and identifying high-risk comorbid individuals preoperatively may play a critical role in preventing acute kidney injury.

Ishan Joshi is a Perfusionist at the Kathmandu Institute of Child Health (KIOCH), Nepal, working under Prof. Dr. Bhagawan Koirala, pioneer cardiac surgeon of Nepal and a recent Gold Medalist graduate in Perfusion Technology from the Institute of Medicine, Tribhuvan University. His research interests focus on intraoperative physiology, renal function, and hematological changes during cardiopulmonary bypass. He authored a published paper titled “Platelet Count Dynamics During Cardiopulmonary Bypass and Its Clinical Implications” in the Journal of College of Medical Sciences–Nepal. His undergraduate thesis, “Intraoperative Urine Output and Its Relation to Post-Operative Renal Function in Patients Undergoing Single Valve Replacement Surgery,” explored the renal effects of cardiac surgery under CPB. He also successfully completed a University Grants Commission–funded research project on “Left Atrial Myxoma: Histopathological and Clinical Correlation,” further broadening his investigative scope in cardiovascular pathology. Ishan received advanced training in cardiac perfusion at FTGM Hospital, Italy, under Dr. Bruno Murzi and Michele Guarino. Passionate about clinical innovation and academic collaboration, he aims to contribute to advancing perfusion research and cardiac care in Nepal.