Elisa Estenssoro1*, Fernando G Ríos2, Carlos Apezteguía2, et al. Published ahead of print on March 4, 2010. Am. J. Respir. Crit. Care Med. 2010
Rationale: The rapid spread of the 2009 Influenza A(H1N1) around the world underscores the need for a better knowledge of epidemiology, clinical features, outcomes, and mortality predictors, especially in the most severe presentations.
Objectives: To describe these characteristics in patients with confirmed, probable, and suspected viral pneumonia caused by 2009 influenza A(H1N1) admitted to 35 intensive care units with acute respiratory failure requiring mechanical ventilation in Argentina, between June 3 and September 7.
Methods: Inception-cohort study including 337 consecutive adult patients. Data were collected in a form posted on the Argentinian Society of Intensive Care website.
Measurements and main results: Proportions of confirmed, probable, or suspected cases were 39%, 8%, and 53% and had similar outcomes. APACHE II was 18±7; age 47±17 years; 56% were male; and 64% had underlying conditions, with obesity (24%), chronic obstructive respiratory disease (18%), and immunosupression (15%) being the commonest. Seven percent were pregnant. On admission, patients had severe hypoxemia (PaO2/FIO2140[87-200]), extensive lung radiologic infiltrates (2.87±1.03 quadrants) and bacterial coinfection, (25%; mostly with S.pneumoniae). Use of adjuvants such as recruitment maneuvers (40%) and prone positioning (13%); and shock (72%) and acute kidney injury requiring hemodialysis (17%), were frequent. Mortality was 46%, and was similar across all ages. APACHE II, lowest PaO2/FIO2, shock, hemodialysis, prone positioning, and S.pneumoniae coinfection independently predicted death.
Conclusions: Patients with 2009 influenza A(H1N1) requiring mechanical ventilation were mostly middle-aged adults, often with comorbidities, and frequently developed severe ARDS and multiorgan failure requiring advanced organ support. Case-fatality rate was accordingly high.
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