Oral and Intravenous Tranexamic Acid in Lumbar Spine Surgery

The purpose of this project is to compare the effectiveness of two different but well accepted routes of administration of tranexamic acid in order to reduce blood loss and need for transfusion in patients undergoing lumbar spine surgery. Specifically, this study seeks to identify if intravenous tranexamic acid is superior to oral tranexamic acid in reducing blood loss and need for transfusion.

Spine surgery is associated with large amount of perioperative blood loss. Factors influencing blood loss include surgical technique, operative time, number of vertebral levels arthrodesed, and others. Significant blood loss is associated with complications such as hypotension, end organ damage, or coagulopathy. Blood transfusions can increase risks of infection, blood incompatibility, and allergic reactions. Due to the significant risks and complications associated with blood loss and allogenic transfusions, efforts to identify safe and effective ways of lowering blood loss during spine surgery are crucial. Many methods have been utilized to reduce allogenic blood transfusions, such as autologous blood predonation, antifibrinolytic drugs, acute normovolemic hemodilution, intraoperative blood salvage, and others. Furthermore, the administration of antifibrinolytics, such as tranexamic acid (TXA) and epsilon-aminocaproic acid (EACA), has been shown to reduce bleeding in cardiac, gynecological, urologic and total joint replacement surgeries. There have been many published studies investigating various antifibrinolytic agents such as TXA, EACA, and aprotinin. While aprotinin was shown to increase mortality rate in patients following cardiac surgery, TXA and EACA have not been shown to cause any substantial morbidity or to increase rate of thromboembolic events. Although IV TXA has been shown to be effective in reducing blood loss and transfusions in patients undergoing spine surgery, no studies in the literature have investigated the efficacy of PO TXA in decreasing blood loss and transfusions. The investigators believe that PO TXA will be just as efficacious and more cost-effective in reducing blood loss and transfusion needs in patients undergoing lumbar spine surgery. The ultimate goal is identifying the most cost-effective protocol to decrease blood loss and need for transfusion. If oral TXA is found to be as efficacious as IV TXA in reducing blood loss and need for transfusion, significant cost savings can be achieved for the patient and the health care system in general.

The IV TXA group will receive the standard dosing for our institution of 1 g TXA (diluted in 100 mL normal saline) given as an IV bolus immediately before incision and another 1 g TXA given before closure.

The oral TXA group will receive 1950 mg TXA (3 tablets of 650 mg) approximately 2 hours before incision.

To identify if intravenous tranexamic acid is superior to oral tranexamic acid in reducing blood loss and need for transfusion in lumbar spine surgery.

For males: BV = 0.3669*(Height in meters)^3 + 0.03219*(Weight in kilograms) + 0.6041 For females: BV = 0.3561*(Height in meters)^3 + 0.03308*(Weight in kilograms) + 0.1833 Hbloss = BV*(Hbi-Hbe )*0.001 + Hbt Blood loss = 1000*(Hbloss/Hbi) Hbloss = Hemoglobin loss; BV = Blood Volume; Hbi = initial Hgb; Hbe = ending Hgb; Hbt = transfused Hgb = about 52g (SD 5.4g) per 1u pRBC (320mL)

1 day after surgery until patient returns for first postoperative visit (through study completion, an average of 4 weeks after surgery)

Inclusion Criteria: Adult patients over age 18 and scheduled for open lumbar spine surgery (primary or revision) Must be able to swallow tablets Exclusion Criteria Known allergy to TXA History of renal failure or kidney transplant History of arterial thromboembolic event (eg. myocardial infarction, stroke) within the past year Placement of an arterial stent within the past year History of blood clots (DVT, PE) within the past year Refusal to receive blood products

Nadler SB, Hidalgo JH, Bloch T. Prediction of blood volume in normal human adults. Surgery. 1962 Feb;51(2):224-32. No abstract available.

Good L, Peterson E, Lisander B. Tranexamic acid decreases external blood loss but not hidden blood loss in total knee replacement. Br J Anaesth. 2003 May;90(5):596-9. doi: 10.1093/bja/aeg111.