Double cycling with breath-stacking during partial support ventilation in ARDS: Just a feature of natural variability?

Summary

In 20 hypoxemic patients under NAVA, PAV+, and PSV, double cycling events were rare (median ≤0.6%) and correlated with variability in tidal volume and respiratory rate. DC/BS breaths had higher effort and stretch, yet subsequent cycles showed improved EELI and compliance, suggesting sigh-like, not inherently injurious, behavior during assisted ventilation.

Key Findings

• DC/BS incidence was low across NAVA (0.6%), PAV+ (0.0%), and PSV (0.1%) with no significant difference between modes (p=0.06).
• DC/BS correlated with variability in tidal volume (p=0.014) and respiratory rate (p=0.011).
• DC/BS breaths showed higher tidal volume, muscular pressure, and regional stretch; subsequent cycles often improved EELI and dynamic compliance, resembling sighs.

Clinical Implications

Clinicians may avoid overly suppressing respiratory drive or changing modes solely due to rare DC/BS during assisted ventilation; these events might be tolerated akin to spontaneous sighs while monitoring for excessive effort.

Limitations

• Secondary analysis with small sample size (N=20), not powered for clinical outcomes
• Short observation periods; single-center physiology-focused study

Future Directions

Prospective multicenter studies to link DC/BS patterns with clinical outcomes and thresholds of harmful effort; algorithmic detection within ventilators to distinguish harmless from injurious patterns.