What Is Tranexamic Acid?
Tranexamic acid (TXA) is an antifibrinolytic medication that prevents blood clots from breaking down. In the setting of major trauma with significant hemorrhage, TXA helps the body maintain the clots it has already formed, reducing ongoing blood loss and improving survival. It has become a standard component of trauma resuscitation in many EMS systems worldwide.
Mechanism of Action
When the body is injured and bleeding, the coagulation cascade forms blood clots to stop hemorrhage. Simultaneously, the fibrinolytic system works to break down these clots to prevent excessive clotting. In severe trauma, the fibrinolytic system can become overactive (hyperfibrinolysis), causing clots to dissolve faster than they form. This contributes to the lethal triad of coagulopathy, acidosis, and hypothermia.
TXA works by blocking the conversion of plasminogen to plasmin, the enzyme responsible for breaking down fibrin clots. By inhibiting fibrinolysis, TXA helps stabilize clots and reduce ongoing hemorrhage without causing new clot formation.
Evidence and Guidelines
The landmark CRASH-2 trial demonstrated that TXA reduces mortality from bleeding when administered within 3 hours of injury. The benefit was greatest when given within the first hour. Administration after 3 hours showed no benefit and potentially increased mortality. Based on this evidence, many EMS systems have incorporated TXA into their trauma protocols.
Prehospital TXA Protocol
The typical prehospital TXA dosing is:
- 1 gram IV infused over 10 minutes for adult trauma patients with suspected significant hemorrhage
- Administered within 3 hours of injury (ideally within the first hour)
- Contraindicated in patients with known allergy to TXA
- Use caution in patients with known thromboembolic disease
- Pediatric dosing is typically 15 mg/kg IV over 10 minutes
Expanding Applications
Beyond trauma, TXA is being studied for use in postpartum hemorrhage, gastrointestinal bleeding, and epistaxis. Some EMS systems now carry TXA for obstetric hemorrhage, and topical TXA application to wound surfaces is being investigated as an adjunct to direct pressure and hemostatic dressings. Follow your local protocols for approved TXA indications and dosing.