Abstract
This multicenter prospective cohort study investigated whether breathing effort, estimated by esophageal pressure swing (ΔPes), is associated with survival in adults with acute hypoxemic respiratory failure (AHRF) receiving noninvasive respiratory support (NRS). Across 12 ICUs in Italy, 180 patients were enrolled. The study found that higher breathing effort—particularly ΔPes >10 cmH₂O—was independently associated with increased mortality, suggesting that monitoring and controlling excessive effort during NRS could be clinically important.
Key Points
- Background and rationale – In AHRF, spontaneous breathing can be beneficial by maintaining diaphragm activity and improving oxygenation, but excessive effort may worsen lung injury via patient self-inflicted lung injury (P-SILI). Quantifying breathing effort in clinical practice is challenging, and its prognostic value during NRS is uncertain.
- Objective – To assess the association between breathing effort, measured via ΔPes, and 30-day survival in AHRF patients managed with NRS (high-flow nasal oxygen [HFNO], continuous positive airway pressure [CPAP], or noninvasive ventilation [NIV]).
- Methods – A prospective observational cohort design across 12 ICUs in Italy. Eligible patients had AHRF (PaO₂/FiO₂ ≤200 mmHg) and were initiated on NRS. ΔPes was measured within 3 hours of starting NRS using an esophageal balloon catheter during tidal breathing.
- Exposure variable – Breathing effort quantified as ΔPes, with a threshold of >10 cmH₂O considered high effort, based on prior physiologic studies linking this level to injurious transpulmonary pressures.
- Primary outcome – All-cause 30-day mortality.
- Secondary outcomes – Intubation rates, ICU and hospital length of stay, ventilator-free days, and complications related to NRS.
- Results – effort distribution – Median ΔPes was 10 cmH₂O (IQR 7–14). Forty-eight percent of patients had ΔPes >10 cmH₂O. Higher ΔPes correlated with lower PaO₂/FiO₂, higher respiratory rate, and greater use of NIV.
- Results/outcomes – Mortality was significantly higher in the high-effort group (38%) compared with the low-effort group (15%). After adjusting for severity (SAPS II), PaO₂/FiO₂, and NRS type, high ΔPes remained independently associated with increased mortality (adjusted HR ~2.3).
- Physiologic interpretation – Excessive effort may exacerbate P-SILI through high transpulmonary pressures, regional overdistension, and increased negative intrathoracic swings, potentially worsening pulmonary edema.
- Clinical implications – Routine monitoring of breathing effort—using esophageal manometry or validated surrogates—could help tailor NRS settings to mitigate P-SILI risk. Strategies may include sedation, switching to invasive ventilation, or adjusting PEEP and flow to reduce inspiratory drive.
Conclusion
In AHRF patients receiving NRS, excessive spontaneous breathing effort (ΔPes >10 cmH₂O) is independently associated with higher mortality. These findings support integrating breathing effort monitoring into NRS management protocols to optimize outcomes and prevent P-SILI.
Discussion Questions
- How feasible is routine esophageal manometry in diverse ICU settings for monitoring effort during NRS?
- What alternative noninvasive surrogates for ΔPes could reliably predict high-risk breathing effort?
- Should high breathing effort during NRS be a formal criterion for early intubation to prevent P-SILI?
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