The Effects of Tranexamic Acid or Placebo on Perioperative Bleeding in Adults Undergoing Liver Transplantation.

In this study, only adult ASA III to IV patients (18 to 70 years old), scheduled for orthotopic liver transplantation at the Hospital de Clínicas de Porto Alegre, Santa Casa de Porto Alegre and at the Hospital das Clínicas of the Faculty of Medicine, will be included. Medicine at the University of São Paulo. All hospitals involved will be of equal importance, varying participation according to the number of liver transplant surgeries performed at the institutions. Patients with a history of acute arterial thrombosis or venous thromboembolism (<1 month), patients with a history of known thrombophilia, Budd-Chiari syndrome, primary biliary cholangitis, primary sclerosing cholangitis, patients with reduced left ventricular function ( ejection fraction <40%), pulmonary hypertension, preoperative pulmonary edema, or severe preoperative hemodynamic changes requiring the use of vasoactive drugs, planned use of tranexamic acid systemically during surgery, hypersensitivity or known allergy to acid tranexamic, history of seizure disorder, patients who have recently suffered a stroke or myocardial infarction (<1 month), patients with subarachnoid hemorrhage in the last 30 days and patients previously undergoing cranial neurosurgery. Patients with chronic dialysis kidney disease or patients in need of a liver-kidney transplant will also be excluded from the study.

To calculate the sample size, considering a 95% confidence interval and an 80% power and aiming to detect a statistical difference in the incidence of major bleeding of approximately 24% in patients in the placebo group and 14% among patients exposed to tranexamic acid, a sample of 128 patients was estimated, approximately 64 patients for each study group. The main outcome considered for the calculation of the sample size was the presence of major bleeding requiring transfusion in the perioperative period (intraoperative and in the first 24 hours postoperatively). In order to overcome possible losses during the treatment protocol, the estimated sample will be increased by approximately 10% in its final number, totaling an estimated sample of 140 patients divided into two treatment groups or arms (70 patients for each study group) .

Major bleeding in this study will be defined as bleeding that results in hemoglobin ≤ 8.0 g / dL and the patient receiving a transfusion of ≥ 1 unit of red blood cells; results in a drop in hemoglobin ≥ 4.0 g / dL and the patient receives a transfusion of ≥ 1 unit of red blood cells; results in the patient receiving a transfusion of ≥ 4 units of red blood cells over a 24-hour period; or bleeding leading to surgical reintervention.

Bleeding in the postoperative period during the hospitalization of the patient in the intensive care unit (ICU) will be assessed by the nursing staff through the flow of abdominal drains routinely used in liver transplant surgery and recorded in medical records every six hours or before bleeding. increased. In addition to bleeding, clinical, hemodynamic and laboratory / gasometric parameters will be considered for clinical or surgical intervention in the patient.

The sample calculation for this study was based on two recent previous studies. An observational study demonstrated the need for transfusion of at least one unit of packed red blood cells in approximately 24% of liver transplants and a recent systematic review demonstrated a reduction of approximately 41% in the transfusion rate of blood components related to intraoperative administration of tranexamic acid when compared to placebo in patients undergoing major non-cardiac and non-orthopedic surgeries.