Efficacy Endpoints: 28-day mortality, hospital mortality, mortality at end of follow-up period
Harm Endpoints: None known
Narrative: Among ICU patients, acute respiratory distress syndrome (ARDS) is a common cause of increased morbidity and mortality, especially in patients requiring mechanical ventilation. This systemic review includes 6 trials involving 1297 intubated patients in an ICU setting who were randomized to receive either conventional mechanical ventilation or a “lung protective” ventilation strategy. Conventional treatment was defined as providing a tidal volume in the 10 to 15 ml/kg range with a plateau pressure of greater than 30 cm H2O. Lung protective ventilation was defined as providing a tidal volume of 7 ml/kg or less with plateau pressure of 30 cm H2O or less. There was a significant all cause mortality benefit (ARR 7%, NNT = 14) in favor of lung protective ventilation at the end of the follow-up period for each trial. The follow-up period varied from hospital discharge to 180 days in the largest trial included in the study. When looking at the more homogenous outcome of mortality at 28 days of hospitalization, the benefit was even more pronounced (ARR 10%, NNT = 10).
Caveats: The final analysis of this Cochrane Review is heavily weighted by the results of a single study (ARDS Network 2000) that included 861 patients, accounting for two-thirds of the total study population. This study, and one much smaller trial (Villar 2006) which enrolled only 95 patients, are the only trials to demonstrate a statistically significant mortality benefit. Additionally, while the aggregate data shows a significant overall mortality benefit, none of the studies examined the impact of hypercapnia and its resulting acidosis on patient quality of life and morbidity. Furthermore, there was a variable follow-up period for each trial, and data on long-term outcomes is notably lacking. There is also insufficient data on the independent contribution of lower tidal volumes vs. lower plateau pressures on morbidity and mortality.
Author: Daniel Runde, MD and Jarone Lee, MD, MPH
Published/Updated: November 7, 2010
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