Low Tidal Volume Strategy in Acute Respiratory Distress Syndrome

The use of low tidal volume (LTV) ventilation strategies in critically ill adult patients with acute respiratory distress syndrome (ARDS) is associated with improved mortality rates, according to a recent systematic review and meta-analysis of relevant clinical trials. Findings from 7 randomized controlled trials involving a total of 1481 patients who met eligibility criteria were published in Annals of the American Thoracic Society.

The objectives of the meta-analysis were to compare clinical outcomes of various mechanical ventilation strategies that limit tidal volumes and inspiratory pressures with strategies that use tidal volumes between 10 and 15 mL/kg in patients with ARDS. Random effects models were used to examine the effect of LTV on 28-day mortality, organ failure, ventilator-free days, barotrauma, oxygenation, and ventilation. The primary analysis excluded all trials in which the LTV strategy was combined with the additional strategy of higher positive end-expiratory pressure (PEEP).

Mortality was not significantly lower in patients with ARDS who received an LTV strategy compared with patients who received a control strategy (33.6% vs 40.4%, respectively; relative risk, 0.87; 95% CI, 0.70-1.08). Moreover, use of an LTV strategy did not significantly decrease barotrauma or ventilator-free days compared with use of a lower PEEP strategy.

Meta-regression of the mortality effect estimate and tidal volume gradient between the intervention (LTV) and control groups demonstrated a significant inverse association between larger tidal volume gradient and log odds ratios for mortality (95% CI, –0.222 to –0.095; P =.0022).

The investigators concluded that the trend toward lower mortality rates with LTV ventilation in the primary analysis, along with the significant association between the degree of tidal volume and the mortality effect, imply that LTV ventilation can lead to improved mortality in critically ill individuals with ARDS. In addition, fewer organ failures were reported in patients who received LTV ventilation.

Reference

Walkey AJ, Goligher E, Del Sorbo L, et al. Low tidal volume versus non-volume-limited strategies for patients with acute respiratory distress syndrome: a systematic review and meta-analysis [published online August 28, 2017]. Ann Am Thorac Soc. doi: 10.1513/AnnalsATS.201704-337OT