Brian M Fuller, Nicholas M Mohr, Anne M Drewry, Christopher R Carpenter Critical Care 2013, 17:R11 (18 January 2013)
Introduction: The most appropriate tidal volume in patients without acute respiratory distress syndrome (ARDS) is controversial, and has not been rigorously examined. The objective was to determine whether a mechanical ventilation strategy using lower tidal volume is associated with a decreased incidence of progression to ARDS when compared to a higher tidal volume strategy.
Methods: A systematic search of MEDLINE, EMBASE, CINAHL, the Cochrane Library, conference proceedings, and clinical trial registration using a comprehensive strategy was performed. Studies providing information on mechanically ventilated patients without ARDS at the time of initiation of mechanical ventilation, and in which tidal volume was independently studied as a predictor variable for outcome, were included. The primary outcome was progression to ARDS.
Results: The search yielded 1704 studies, of which thirteen were included in the final analysis. One randomized controlled trial was found; the remaining twelve studies were observational. The patient cohorts were significantly heterogeneous in composition and baseline risk for developing ARDS, therefore a meta-analysis of the data was not performed. The majority of the studies (n=8) showed a decrease in progression to ARDS with a lower tidal volume strategy. ARDS developed early in the course of illness (5 hours to 3.7 days). The development of ARDS was associated with increased mortality, lengths of stay, mechanical ventilation duration, and non-pulmonary organ failure.
Conclusions: In mechanically ventilated patients without ARDS at the time of endotracheal intubation, the majority of data favors lower tidal volume to reduce progression to ARDS. However, due to significant heterogeneity in the data, no definitive recommendations can be made. Further randomized controlled trials examining the role of lower tidal volumes in patients without ARDS, controlling for ARDS risk, are needed.
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