Influenza A (H1N1) vs non-H1N1 ARDS: analysis of clinical course

The purpose of the study is to compare H1N1-induced acute respiratory distress syndrome (ARDS) with ARDS due to other causes of severe community-acquired pneumonia focusing on pulmonary function.

This is a retrospective data analysis of adult ARDS patients between January 2009 and December 2010 in an ARDS referral center. Patient characteristics, severity of illness scores, modalities, and duration of extracorporeal lung support were evaluated as well as intensive care unit stay and survival. Parameters of mechanical ventilation and pulmonary function were analyzed on day of admission and over the consecutive 10 days using a nonparametric analysis of longitudinal data in a 2-factorial design. In a logistic regression analysis, risk factors for extracorporeal lung support were investigated.

Twenty-one patients with H1N1-ARDS and 41 with non-H1N1-ARDS were identified. Gas exchange was more severely impaired in patients with H1N1-ARDS over course of time. Extracorporeal membrane oxygenation was more frequently needed in H1N1-ARDS. Despite significantly prolonged weaning off extracorporeal lung support and intensive care unit stay in H1N1 patients, the proportion of survivors did not differ significantly. Only Sepsis-Related Organ Failure Assessment score could be identified as an independent predictor of extracorporeal lung support.

Clinical course of H1N1-ARDS is substantially different from non-H1N1-ARDS. Affected patients may require extensive therapy including extracorporeal lung support in ARDS referral centers.