Respiratory failure & ventilation
Effects of CPAP and FiO2 on respiratory effort and lung stress in early COVID-19 pneumonia: a randomized, crossover study
Authors' conclusion
In early COVID-19 pneumonia, Helmet-CPAP increases respiratory effort without altering dynamic stress, while the effects upon static and total stress are variable, requiring individual assessment. Oxygen masks with higher FiO2 provide better oxygenation with lower respiratory effort.
Study context
- Population
- Patients receiving Helmet-CPAP for early (< 48 h) COVID-19 pneumonia without additional cardiac or respiratory disease; healthy subjects as controls28 COVID-19 patients · 7 healthy controls
- Comparison
- Helmet-CPAP vs non-rebreather mask vs Venturi mask
- Primary endpoint
- Changes in respiratory effort (esophageal swing), total lung stress (dynamic + static transpulmonary pressure), gas-exchange and hemodynamics
- Follow-up
- 20 min per interface
Methodological detailssingle-centre
- Single-centre
Primary result
As reported in the abstract
Respiratory effort (esophageal swing)
P < 0.01
- Helmet pressure decrease during inspiration
- - 3.1 ± 1.0 cmH2O, p = 0.16
- Dynamic stress remained stable
- P = 0.97
- Change in static lung stress NRB to Helmet-CPAP not significant (range - 4.5 to + 6.1 cmH2O)
- P = 0.07
- Change in total lung stress NRB to Helmet-CPAP not significant (range - 5.8 to + 5.7 cmH2O)
- P = 0.09
Further findings
Mean, mmHg
| Outcome | NRB | Helmet-CPAP | P value |
|---|---|---|---|
| PaO2, NRB vs Helmet-CPAP with FiO2 0.5 | 107 (SD 55) | 86 (SD 30) | P < 0.01 |
- PaO2, NRB vs Helmet-CPAP with FiO2 0.5: decreased, irrespective of positive pressure levels (p = 0.64)
Healthy subjects
- All findings confirmed, except increase in dynamic stress
- P < 0.01
Helmet-CPAP with FiO2 0.9
- PaO2 increased
- P < 0.01
- Oxygen delivery remained stable
- P = 0.48
- CO decreased
- P = 0.02
Respiratory effort when PaO2 < 60 mmHg with VM
- Respiratory effort increased proportionally
- P < 0.01, r = 0.81
Original publication
Effects of CPAP and FiO2 on respiratory effort and lung stress in early COVID-19 pneumonia: a randomized, crossover study. Ann Intensive Care. Published 17 October 2023. doi:10.
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