Time-varying intensity of ventilatory inefficiency and mortality in patients with acute respiratory distress syndrome.

Summary

Pooling four ARDS Network trials (N=2,851), the authors modeled time-varying ventilatory inefficiency and found that higher ventilatory ratio (VR) over time and cumulative exposure to high VR were associated with increased 28-day mortality. These results support close bedside monitoring of VR during invasive mechanical ventilation.

Key Findings

• Secondary analysis of four ARDS Network RCTs included 2,851 intubated, mechanically ventilated patients; 28-day mortality was 21.3% and median ventilation duration was 9 days.
• Time-varying increases in ventilatory inefficiency, summarized by ventilatory ratio (VR), were associated with higher 28-day mortality in Bayesian joint models.
• Cumulative exposure to high VR intensity was linked to increased mortality, suggesting VR as a dynamic risk marker.

Clinical Implications

Track ventilatory ratio longitudinally in ARDS and consider strategies that reduce dead-space loading and PaCO2 retention; prospective interventional studies are needed to test whether VR-guided ventilation improves outcomes.

Limitations

• Secondary observational analysis; causal inference is limited
• Generalizability beyond ARDS Network trial populations is uncertain

Future Directions

Prospectively test VR-guided ventilatory strategies, integrate dead-space monitoring into protocols, and evaluate whether reducing cumulative VR exposure improves clinical outcomes.