The Role of Duration in Cardiopulmonary Bypass on Thyroid Function in Cardiac Surgical Patients

Background: Cardiopulmonary bypass (CPB) is an essential technique in cardiac surgery, but it can induce physiological changes, including alterations in thyroid function. Prolonged CPB duration is associated with a stress response, hypothermia, and hemodilution, potentially leading to transient hypothyroidism or euthyroid sick syndrome. This study aimed to assess the role of duration in cardiopulmonary bypass on thyroid function in cardiac surgical patients. Methods: This comparative study at Bangabandhu Sheikh Mujib Medical University, (BSMMU), Bangladesh from September 2021 to August 2022. A total of 54 cardiopulmonary bypass patients grouped by CPB duration: A (<60 mins), B (60-90 mins), C (>90 mins) were included in this study. Data analysis was done using SPSS 29.0. Results: TSH and FT3 values decreased significantly across groups (C > B > A). Mean ±SD TSH values in samples I-IV were A: 2.93-2.60, B: 2.51-1.36, C: 2.76-1.06. FT3 values were A: 4.25-4.00, B: 4.29-3.03, C: 4.26-2.46. FT4 values (A: 15.14-14.39, B: 15.30–14.67, C: 15.03-13.94) showed no significant differences. Conclusion: TSH and FT3 levels show a greater reduction in patients with cardiopulmonary bypass (CPB) durations of 60-90 minutes compared to those with <60 minutes, with the most significant decline observed in patients with CPB durations >90 minutes. Conversely, no notable decrease in FT4 levels was observed across the groups in this study.