Prone ventilation in H1N1 virus-associated severe acute respiratory distress syndrome: A case series

BACKGROUND: Management of H1N1 viral infection-associated acute respiratory distress syndrome (ARDS) has primarily been focused on lung protective ventilation strategies, despite that mortality remains high (up to 45%). Other measures to improve survival are prone position ventilation (PPV) and extracorporeal membrane oxygenation. There is scarcity of literature on the use of prone ventilation in H1N1-associated ARDS patients. METHODS: In this retrospective study, all adult patients admitted to medical intensive care unit (ICU) with H1N1 viral pneumonia having severe ARDS and requiring prone ventilation as a rescue therapy for severe hypoxemia were reviewed. The patients were considered to turn prone if PaO(2)/FiO(2) ratio was <100 cmH(2)O and PaCO(2) was >45 cmH(2)O; if no progressive improvement was seen in PaO(2)/FiO(2) over a period of 4 h, then patients were considered to turn back to supine. Measurements were obtained in supine (baseline) and PPV, after 30–60 min and then 4–6 hourly. RESULTS: Eleven adult patients with severe ARDS were ventilated in prone position. Their age range was 26–59 years. The worst PaO(2)/FiO(2) ratio range on the day of invasive ventilation was 48–100 (median 79). A total of 39 PPV sessions were done, with a range of 1–8 prone sessions per patient (median three sessions). Out of the 39 PPV sessions, PaO(2)/FiO(2) ratio and PaCO(2) responder were 38 (97.4%) and 27 (69.2%) sessions, respectively. The median ICU stay and mechanical ventilation days were 15 (range: 3–26) and 12 (range: 2–22) days, respectively. The common complication observed due to PPV was pressure ulcer. At ICU discharge, all except two patients survived. CONCLUSION: PPV improves oxygenation when started early with adequate duration and should be considered in all severe ARDS cases secondary to H1N1 viral infection.