Association Between Use of Lung-Protective Ventilation With Lower Tidal Volumes and Clinical Outcomes Among Patients Without Acute Respiratory Distress Syndrome: A Meta-Analysis

Study Questions:

What is the association between the use of lower tidal volumes and outcomes, and among patients who are receiving mechanical ventilation and do not have acute respiratory distress syndrome (ARDS) or acute lung injury (ALI)?

Methods:

This was a meta-analysis of studies that evaluated use of lower versus higher tidal volumes in patients without ARDS or ALI at onset of mechanical ventilation. Reported outcomes of interest were development of lung injury, overall mortality, pulmonary infection, atelectasis, and biochemical alterations.

Results:

Fixed-effects modeling demonstrated a decrease in development of lung injury (risk ratio [RR], 0.33; 95% confidence interval [CI], 0.23-0.47; number needed to treat [NNT], 11) and mortality (RR, 0.64; 95% CI, 0.46-0.89; NNT, 23) among patients receiving protective, lower tidal volume, when compared to those managed with higher tidal volume ventilation. Protective ventilation was also associated with a lower incidence of pulmonary infection and mean hospital length of stay. Of note, the median time of per-protocol mechanical ventilation was 6.90 hours for protective and 6.56 for conservative ventilation.

Conclusions:

Among critically ill patients without ARDS or ALI receiving mechanical ventilation for relatively short duration, a lower tidal volume strategy is associated with better outcomes, including lower mortality and length of hospital stay.

Perspective:

While it is accepted that higher tidal volume ventilation is associated with adverse outcomes among critically ill patients with ARDS or ALI, there is less consensus about the preferred ventilation strategy among patients without pre-existing lung injury. The present meta-analysis, though not definitive, suggests that higher tidal volume ventilation may be detrimental, even among those without lung injury at the onset. Clinical trials are needed to compare the two ventilation strategies.

Keywords: Incidence, Risk, Pulmonary Atelectasis, Tidal Volume, Respiratory Distress Syndrome, Adult, Cardiology, Respiration, Acute Lung Injury, Lung Diseases


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