INTRODUCTION: Acute eosinophilic pneumonia (AEP) is an uncommon cause of acute hypoxemic respiratory failure in otherwise healthy young adults and is exceedingly rare in children. While it can be life-threatening, the need for extracorporeal membrane oxygenation (ECMO) support in this setting has not been previously described. We, therefore, are presenting a case of severe AEP in an adolescent who was successfully managed with ECMO support.
CASE PRESENTATION: A 17 year old, 116 kg, otherwise healthy white male presented with 2 days of high fevers, myalgias, headache, and dry cough. Risk factors for lung disease included recent initiation of smoking and occupational exposure to pigeon droppings. On admission to a referring hospital, he was hypoxic with bilateral pulmonary infiltrates on chest radiograph. He was started empirically on vancomycin, ceftriaxone, doxycycline, azithromycin, and caspofungin as well as BiPap support. On hospital day 3 he was transferred to our PICU due to progressive respiratory distress. On PICU arrival, his respiratory rate was 40 on BiPap 20/14, with a PaO2/FiO2 (P/F) ratio of 100, and x-ray findings consistent with ARDS. He was intubated and underwent rapid escalation in support, including inhaled nitric oxide and high frequency oscillatory ventilation. His P/F ratios remained around 100 with oxygenation index values around 40. Within 24 hours of PICU admission he was placed on veno-venous ECMO. The next day, bronchoscopy was performed with analysis of BAL fluid revealing 4543 WBC/mm3 of which 51% were eosinophils. A diagnosis of idiopathic acute eosinophilic pneumonia was made, with immediate institution of methylprednisolone 125mg IV q6 hr x 14 days followed by a taper. Extensive testing for infectious agents was negative. The BAL WBC count dropped to 314/mm3 (with no eosinophils) by day 5 of steroid treatment and his lung compliance improved. He required serial bronchoscopy to remove tenacious mucous plugs during his 14 day ECMO course. The patient’s ICU course was complicated by ventilator-associated pneumonia and severe myoneuropathy of critical illness necessitating tracheostomy, chronic mechanical ventilation, and inpatient rehabilitation. He was, however, ultimately discharged home 114 days after his initial presentation, ambulatory, decannulated, and without an oxygen requirement.
DISCUSSIONS: While uncommon in children, AEP is rapidly reversible with prompt treatment. Lack of recognition of the disease can result in a more severe, life-threatening course. The diagnostic criteria of AEP include BAL fluid with >25% eosinophils (or compatible lung biopsy) plus clinical criteria including acute febrile respiratory illness of <1 week, bilateral diffuse infiltrates on chest radiograph, and hypoxemia. Other causes of pulmonary eosinophilia must be excluded. Our patient had severe hypoxemic respiratory failure with ARDS and clinical instability that delayed bronchoscopy. Stabilization with ECMO support allowed for successful bronchoscopy, and BAL results led to a diagnosis of AEP. As expected, high dose corticosteroid therapy led to improvement, although our patient experienced many of the complications associated with high-dose glucocorticoid therapy. To our knowledge, this is the first described case of AEP requiring ECMO rescue.
CONCLUSION: Acute eosinophilic pneumonia remains an uncommon cause of acute respiratory failure, particularly in children, but should remain a consideration in children and adults with rapid onset, refractory respiratory failure of unknown etiology. Successful management requires early bronchoscopy for diagnosis, and high-dose corticosteroid therapy. ECMO represents a therapeutic option to provide respiratory support while diagnosis is sought in AEP or other causes of respiratory failure. However, early consideration of AEP in previously healthy children presenting with fever and rapidly progressive, diffuse hypoxemic lung disease may allow for more timely diagnosis and treatment of this disorder - before ECMO therapy is needed.
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