Idiopathic acute eosinophilic pneumonia: A rare cause of hypoxic respiratory failure.

Idiopathic Acute Eosinophilic Pneumonia (IAEP) is a life-threatening cause of hypoxic respiratory failure. IAEP is challenging to diagnose as it may mimic infectious pneumonia or acute respiratory distress syndrome. Distinguishing IAEP from these alternatives is important; the mainstay of treatment for IAEP is corticosteroids, a therapy which might not otherwise be indicated. Patients treated appropriately usually experience a full recovery. In this case report we describe the presentation, evaluation, and management of a 19-year old male who presented to the emergency department (ED) in respiratory failure from IAEP. The patient was a military trainee who recently moved to the United States from Saudi Arabia. He also recently began smoking cigarettes for the first time, a known risk factor for IAEP. Upon initial presentation, the patient was in respiratory distress and had an oxygen saturation of 82% on room air. His ED diagnostic workup included chest X-ray showing diffuse interstitial thickening and chest computed tomography that demonstrated diffuse nodular opacification of pulmonary parenchyma. The patient was admitted to the intensive care unit (ICU) where bronchoscopy yielded cytology with 30% eosinophilia. The patient ultimately required 3 days of extra corporeal membrane oxygenation (ECMO) due to worsening hypoxic respiratory failure. After both intravenous and outpatient oral steroid treatments, the patient went on to have a full recovery with no ongoing respiratory issues. To our knowledge, this is the first case of IAEP requiring ECMO reported in the emergency medicine literature.