A Randomized Comparison of Two Doses of Tranexamic Acid in Open-Heart Surgery

Perioperative bleeding during cardiac surgery is associated with a higher incidence of reoperation and blood transfusion leading to an increase in morbidity and mortality. Coagulopathy is a major cause of excessive bleeding. It is associated with use of cardiopulmonary bypass which activates the intrinsic and extrinsic coagulation pathway, platelet dysfunction and systemic inflammatory response. Increase in duration of cardiopulmonary bypass correlates directly with increase bleeding during cardiac surgery. Antifibrinolytic agents like tranexamic acid has shown promising result in major surgeries and in trauma patients. Current clinical practice guidelines recommended use of tranexamic acid in cardiac surgery. There are wide variations in dose of tranexamic acid ranging from 10mg/Kg to 100mg/kg. The higher dose of this drug is associated with seizures and thromboembolic events including stroke. The objective is to find out the minimal effective dose of tranexamic acid in open-heart surgery.

This is a prospective comparative study among the patients undergoing open heart surgery in Shahid Gangalal National Heart Center, Kathmandu Nepal. The inclusion criteria include patients with age more than 18years, surgery with total cross clamp time more than 60 min. The exclusion criteria are the patients with allergy to tranexamic acid or any of the lysine analogues, history of seizure, chronic homeostasis abnormality, on anticoagulants, severe chronic kidney disease with creatinine clearance less than 30ml/hr, deranged liver function test, total cross clamp time less than 60 min. The sample size was calculated to be 100 including 10% dropout cases. Patients will be randomized into two groups Group H (High dose group) and Group L (Low dose group) with a sealed envelope technique. Low-dose TEA consists of 10 mg/kg bolus administration before incision, followed by1 mg/kg/hr infusion; High-dose TEA consists of a 30 mg/kg bolus followed by a 1mg/kg/hr infusion till the end of surgery. Blood sampling and transfusion will be done as per protocol of Shahid Gangalal National Heart Center. The primary study endpoint was the amount of blood loss during the first 24 hours after surgery. The secondary endpoint was the incidence of overall blood transfusion and hemoglobin concentration on the first postoperative day after surgery. All adverse effects of the drug were noted and were treated as per hospital protocol. Data will be collected using the data collection form (proforma). Collected data will be analyzed by means of spss version 20 for windows. The result will be presented as mean ± SD. The continuous variable will be compared between the two groups by student t test and categorical variables with the chi-square test. A minimum level of significance is maintained at the p-value of \<0.05.

Perioperative bleeding is a common complication during cardiac surgery. This is associated with higher incidence of reoperation and blood transfusion increasing morbidity and mortality. \[1,2\] Coagulopathy is a major cause of excessive bleeding. It is associated with use of cardiopulmonary bypass which activates the intrinsic and extrinsic coagulation pathway, platelet dysfunction and systemic inflammatory response. \[3,4\] Increase in duration of cardiopulmonary bypass correlates directly with increase bleeding during cardiac surgery. Antifibrinolytic agents like tranexamic acid has shown promising result in major surgeries and in trauma patients. Tranexamic acid blocks reversibly the lysine binding sites of plasminogen. It prevents the activation of plasmin and thus stops lysis of polymerized fibrin.\[5\] Current clinical practice guidelines recommended use of tranexamic acid in cardiac surgery.\[6\] The significance for use of this drug is more for the cardiac surgery with higher risk of bleeding like Aortic valve surgery, Coronary artery bypass grafting, redo surgeries and surgery with prolong cardiopulmonary bypass time.\[7\] However, there is wide variation in dose of tranexamic acid ranging from 10mg/Kg to 100mg/kg.\[8\] The tranexamic acid use is not free from adverse events. The higher dose of this drug is associated with seizures and thromboembolic events including stroke. \[9,10\] The objective of this study is to find out the minimal effective dose of tranexamic acid in high-risk open-heart surgeries.

Eligibility Criteria:
Inclusion Criteria:

* Age more than 18years scheduled for cardiac surgery and requiring CPB
* Surgery with total cross clamp time more than 60 min (Aortic valve surgery, double valve, CABG)

Exclusion Criteria:

* Allergy to tranexamic acid or any of the lysine analogues
* History of seizure
* Chronic homeostasis abnormality, platelet \<100000/cumm PT\>20sec INR\>2
* On anticoagulant
* Severe chronic kidney disease with creatinine clearance less than 30ml/hr
* Deranged liver function test
* Total cross clamp time less than 60 min