Impact of Cardiopulmonary Bypass on Prothrombin Time: Pre- and Post-Operative Variation
Keywords:
Cardiopulmonary bypass; Prothrombin time; International normalized ratio; Activated partial thromboplastin time; Cardiac surgery; Coagulation; Haemodilution.Abstract
Background: Cardiopulmonary bypass (CPB) is an essential component of modern cardiac surgery that temporarily replaces the function of the heart and lungs during complex surgical procedures. Despite its clinical benefits, CPB is associated with haemodilution, systemic inflammatory activation, platelet dysfunction, and coagulation abnormalities that may increase postoperative bleeding risk. Monitoring perioperative coagulation parameters is therefore important for optimizing patient management. Objective: To evaluate the effect of cardiopulmonary bypass on prothrombin time and other coagulation-related laboratory parameters by comparing pre-operative and post-operative measurements in patients undergoing cardiac surgery. Methods: A hospital-based observational study was conducted over four months at Gulab Devi Hospital and the Punjab Institute of Cardiology, Lahore. Seventy-three patients aged 35–55 years undergoing elective coronary artery bypass grafting or valve surgery requiring CPB were enrolled using consecutive sampling. Venous blood samples were obtained before surgery and after completion of CPB for determination of prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (APTT), hemoglobin, red blood cell count, platelet count, total leukocyte count, neutrophils, and lymphocytes. Statistical analysis was performed using paired-sample t-tests in IBM SPSS Statistics version 26.0, with p < 0.05 considered statistically significant. Results: Among the 73 participants, 58.9% were male and 41.1% were female. Significant postoperative increases were observed in PT (p=0.001), INR (p=0.003), and APTT (p<0.001), indicating impaired coagulation following CPB. Total leukocyte count increased significantly (p=0.008), whereas lymphocyte count decreased significantly (p=0.032). Hemoglobin levels also declined significantly (p<0.001), consistent with haemodilution. Platelet count showed no statistically significant difference (p=0.290). Conclusion: Cardiopulmonary bypass was associated with significant alterations in coagulation parameters, particularly prolonged PT, INR, and APTT, together with perioperative hematological changes. These findings underscore the importance of careful perioperative coagulation monitoring and individualized hemostatic management in patients undergoing cardiac surgery with CPB. Keywords: Cardiopulmonary bypass; Prothrombin time; International normalized ratio; Activated partial thromboplastin time; Cardiac surgery; Coagulation; Haemodilution.
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