Acute Respiratory Distress Syndrome Following Biphasic Anaphylaxis: A Comparative Analysis of Two Young Adults with Divergent Outcomes

Most anaphylaxis cases due to insect stings or bites result from Hymenoptera venom.In this presentation, two patients with surprisingly similar presentations and radiographic findings but different prognoses with biphasic anaphylaxis complicated by ARDS are compared.This comparison is important in determining key prognostic factors in biphasic anaphylaxis complicated by ARDS and the need for early diagnosis and management of such patients.It also draws attention IntroductIonBiphasic anaphylaxis is described as a challenging clinical phenomenon in which an anaphylactic attack recurs after an initial brief interval during which the symptoms appear to have resolved, usually within 1-72 hours after the index episode.The reported incidence ranges from 1 to 20% for biphasic anaphylactic reactions, with mostly less severe reactions in the second phase compared to the index episode.1 Notably, biphasic anaphylactic reactions can, in some cases, be severe and even fatal.Acute respiratory distress syndrome (ARDS) secondary to anaphylaxis has been reported very rarely in the medical literature, and only a few cases have been reported to date.The pathophysiology includes alveolar damage from inflammation, increased pulmonary vascular permeability, and inflammatory cell infiltrates, in this case, neutrophil infiltrates.When ARDS occurs after an episode of anaphylaxis, mortality increases to 40-60%.2,3 Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most common causes of hypersensitivity reactions due to medications and contribute to about 20-30% of cases that present to emergency departments because of hypersensitivity reactions.4 Another common cause of anaphylaxis is an insect bite or sting.