The 2009 novel swine-origin influenza A (H1N1) virus was identified in April 2009 in Mexico, and the World Health Organization declared the first phase 6 global influenza pandemic of the century on June 11, 2009. The pandemic spread worldwide in just a few weeks. Most patients diagnosed with H1N1-2009 virus had a self-limited respiratory illness. However, among patients admitted to hospitals, 20 to 33% were hospitalized in intensive care units (ICUs) because of influenza-associated pneumonia and acute respiratory distress syndrome (ARDS). Mortality in patients admitted to the ICU with respiratory failure varied between 17 and 28% and was associated with greater illness severity scores and the need for mechanical ventilation on admission as well as the presence of comorbid conditions and older age. Despite attempts to optimize ventilator settings, some patients developed refractory hypoxemia or hypercapnia and received extracorporeal membrane oxygenation (ECMO) as a rescue therapy. In most of these cases, patients were retrieved from outside major cities and safely transported under ECMO to experienced tertiary centers through semiformal referral networks. However, whether the 25 to 50% mortality observed in the reported ECMO series was affected by the recourse to this technique could not be established.

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