Abstract
We read the article by Surat et al. with great interest. 1 This randomized controlled trial shows no statistically significant difference between limited driving pressure ventilation and low tidal volume (LTV) strategies in preventing lung injury 7 days post-mechanical ventilation. It is noted that driving pressure is most strongly associated with survival. 2 These days, it is essential to avoid driving pressures exceeding 15 cmH2O. However, according to the ESICM guidelines, 3 LTV ventilation is recommended to avoid ventilator-induced lung injury. This study aimed to determine which strategy is more effective in protecting against acute respiratory distress syndrome (ARDS).
Upon reviewing this article, we noticed a contradiction. The baseline respiratory parameters after enrollment differ between the two groups, particularly in the percentage duration of tidal volume per predicted body weight over 8 mL/kg. The authors noted in the discussion that the “potential advantage of low driving pressure (LDP) over the LTV strategy is its allowance for variations and potentially higher tidal volumes.” However, this does not explain why the percentage duration of driving pressure over 15 cmH2O is similar in both groups. Statistically, the duration of driving pressure over 15 cmH2O should be shorter in the LDP group compared to the LTV group. A possible reason could be that physicians might not intervene until airway pressures increase, at which point they attempt to reduce the pressure. This factor might have influenced the result, showing no statistically significant difference between the two strategies. For example, if tidal volume is closely monitored to prevent increases in the LDP group, the duration of driving pressure over 15 cmH2O can be reduced, leading to a statistically different outcome.
Accordingly, we suggest that this study cannot exclude the effect of the duration of driving pressure over 15 cmH2O of the two groups. To try to avoid the circumstances, the outcome will be different.
