UK London ambulance service prehospital TXA protocol. UK London ambulance service prehospital TXA protocol. Patients with time critical injury where significant internal/external hemorrhage is suspected and/or injured patients >12 years of age, fulfilling local Step 1 or Step 2 on the major trauma decision tree. Lena M Napolitano Trauma Surg Acute Care Open 2017;2:e000056 Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/