We have a young (15) female patient in that has been diagnosed with Hereditary Angioedema. This Pt has had some severe episodes in the past and has required intubation and admittance into the ICU multiple times. I have completed interfacility transports with this patient from one hospital to another. Upon acquiring information  from the sending Physician and his treatment in the ER  was Epinephrine and Benadryl which he admitted does little to no help for the condition. He then told me that he was also treating with TXA because it inhibits bradykinin formation. My question is since we carry TXA and this is a known condition  (HAE) for this Patient could the crew patch and ask for an order for TXA in the pre-hospital environment since the Patient does not fit into our moderate or severe allergic reaction protocol ? Since this is not an allergen based reaction and yet is still a life  threatening. 

Hereditary Angioedema (HAE) consists of specialized (very expensive) treatments such as plasma derived or recombinant c1-INH concentrate, Ecallantide, or Icatibant. You are correct in recognizing that standard angioedema treatments (epinephrine, corticosteroids and antihistamines) are not effective, although you will still see them being provided by some practitioners despite lack of efficacy in HAE. 

TXA has no role in the treatment of acute attacks.  The American Academy of Allergy, Asthma and Immunology states that “antifibinolytic agents are not effective for acute angioedema attacks” (Zuraw et al 2013) . The US HAEA 2020 guidelines are even more direct “Anabolic androgens and antifibrinolytic agents have no role in on demand treatment” (Busse et al. 2021)  TXA is rather used as a second line treatment in long term prophylaxis of specific types of HAE and geared towards prophylaxis in cases of HAE with normal C1 INH levels. 

allergy, Angioedema, BHP Patch, Bradykinin, Hereditary Angioedema, TXA

A Focused Parameter Update: Hereditary Angioedema, Acquired C1 Inhibitor Deficiency and Angiotensin-Converting Enzyme Inhibitor-Associated Angioedema.  The Journal of Allergy and Clinical Immunology, 2013. Zuraw BL, Bernstein JA, Lang DM et al. 

USHAEA Medical Advisory Board 2020 Guidelines for the Management of Hereditary Angioedema.  The Journal of Allergy and Clinical Immunology. In Practice. 2021. Busse PJ, Christiansen SC, Riedl MA et al.