A Case of "Anaphylaxis" to NovoSeven in a Hemophiliac Patient

Anaphylaxis is a life-threatening emergency that may be confused with other less serious conditions. The onset of true anaphylaxis typically occurs within minutes following exposure to an offending agent, and it can variably include dyspnea/wheezing, hemodynamic compromise, rash, hives/pruritus, swelling, or gastrointestinal symptoms. The absence of an expected association between exposure(s) and classic symptoms should lead to the consideration of alternative diagnoses. Here, we describe the course of a patient with hemophilia B who developed stridor and wheezing after exposure to the recombinant factor VII, NovoSeven, and tranexamic acid (TXA) for the management of hematomas. Due to a reported prior history of anaphylaxis to multiple factor replacements, the patient's initial management included NovoSeven with steroid/antihistamine prophylaxes and close monitoring with epinephrine at the bedside. Despite the administration of prophylaxis, the patient developed significant stridor, was treated with epinephrine and nebulizers and additional steroids, and was transferred to the intensive care unit. There, a pattern of NovoSeven administration followed variably by wheezing and stridor continued for two days until the patient's respiratory condition was predictable and stable. The patient's subsequent clinical course following transfer to the general medical ward was not consistent with anaphylaxis. This case highlights the importance of evaluating for mimickers of anaphylaxis, especially where only select symptoms such as stridor and wheezing are present without other serious signs of anaphylaxis such as hypoxemia, hypotension, or significant tachycardia.