Tranexamic acid does not have a dose-dependent effect on postoperative delirium after cardiac surgery – a retrospective cohort study

Background: Postoperative delirium, regularly seen after cardiac surgery, is challenging. It has significant implications for healthcare resources and significant implications for individual patients and their families. Although the exact mechanisms are not understood, there is emerging evidence that blood-brain-barrier disruption and neuroinflammation may play a role in developing postoperative delirium. Tranexamic acid, frequently used in cardiac surgery for its transfusion-sparing effect, has recently been shown to ameliorate neuroinflammation and stabilise the blood-brain barrier. This study investigates if there is a dose-dependent effect of tranexamic acid on developing postoperative delirium after cardiac surgery on cardiopulmonary bypass. Methods: 5525 patients were included in this retrospective, observational database study. Patients were divided into three groups, depending on the dose of tranexamic acid they had received before heparinisation (Group A (n = 1780) up to 22 mg/kg, Group B (n = 2130) 22.01 – 27 mg/kg, and Group C (n = 1615) 27.01 mg/kg or more). All three doses are clinically relevant and seen regularly. The presence of postoperative delirium was defined by at least one “CAM-ICU positive” entry in the patient’s medical record. Results: There was no statistically significant difference between the three groups in the incidence of postoperative delirium. The percentage of CAM-ICU-positive patients in each group was in keeping with the overall cohort (Overall = 18%, Group A = 18%, Group B = 17%, Group C = 20%, p = 0.25). Conclusion: The results do not support the theory that tranexamic acid given in the higher clinically acceptable dose range decreases the incidence of postoperative delirium after cardiac surgery.