INTRODUCTION: H1N1 influenza can cause severe acute lung injury (ALI). 
Extracorporeal membrane oxygenation (ECMO) can support gas exchange in patients 
failing conventional mechanical ventilation, but its role is still 
controversial. We conducted a systematic review and meta-analysis on ECMO for 
H1N1-associated ALI.
METHODS: CENTRAL, Google Scholar, MEDLINE/PubMed and Scopus (updated 2 January 
2012) were systematically searched. Studies reporting on 10 or more patients 
with H1N1 infection treated with ECMO were included. Baseline, procedural, 
outcome and validity data were systematically appraised and pooled, when 
appropriate, with random-effect methods.
RESULTS: From 1,196 initial citations, 8 studies were selected, including 1,357 
patients with confirmed/suspected H1N1 infection requiring intensive care unit 
admission, 266 (20%) of whom were treated with ECMO. Patients had a median 
Sequential Organ Failure Assessment (SOFA) score of 9, and had received 
mechanical ventilation before ECMO implementation for a median of two days. ECMO 
was implanted before inter-hospital patient transfer in 72% of cases and in most 
patients (94%) the veno-venous configuration was used. ECMO was maintained for a 
median of 10 days. Outcomes were highly variable among the included studies, 
with in-hospital or short-term mortality ranging between 8% and 65%, mainly 
depending on baseline patient features. Random-effect pooled estimates suggested 
an overall in-hospital mortality of 28% (95% confidence interval 18% to 37%; I² 
= 64%).
CONCLUSIONS: ECMO is feasible and effective in patients with ALI due to H1N1 
infection. Despite this, prolonged support (more than one week) is required in 
most cases, and subjects with severe comorbidities or multiorgan failure remain 
at high risk of in-hospital death.