Use of Inhaled Epoprostenol in Patients with H1N1 Influenza–Associated Acute Respiratory Distress Syndrome: A Case Series

OBJECTIVE: To report a series of patients with confirmed novel influenza A (H1N1) and refractory hypoxemia secondary to acute respiratory distress syndrome (ARDS) treated with inhaled epoprostenol. CASE SUMMARY: Four patients admitted to our institution with confirmed H1N1 and refractory hypoxemia were treated with inhaled epoprostenol as potential salvage therapy. All patients were treated initially with antimicrobial agents, followed by oral oseltamivir at the time of suspicion or confirmation of H1N1. None of the patients received intravenous peramivir or extracorporeal membrane oxygenation. Clinically significant improvement in oxygenation was seen in only 1 of the patients receiving inhaled epoprostenol. Mortality was significant, with only 1 patient discharged from the hospital. DISCUSSION: Use of inhaled epoprostenol for the treatment of hypoxemia secondary to ARDS has been reported, with conflicting results. Deliveries via the inhalational route compared to the intravenous route theoretically preferentially vasodilate well-ventilated areas of the pulmonary vasculature, improving arterial oxygenation and pulmonary gas exchange. Increase in the ratio of arterial oxygen tension to fraction of inhaled oxygen is greatest upon initiation of inhaled epoprostenol, but this benefit has not been conclusively demonstrated to persist throughout therapy. Serious H1N1 presents a unique challenge for clinicians, often requiring the use of salvage therapies to treat critically ill patients. CONCLUSIONS: Given the variable response to treatment, it remains unclear whether inhaled epoprostenol is beneficial in H1N1-associated ARDS. Identification of patients for whom this therapy is most appropriate remains a clinical challenge.