Respiratory failure & ventilation
Electrical impedance tomography (EIT)-assessed ventilation–perfusion responses to prone positioning and inhaled nitric oxide in mechanically ventilated COVID-19-related acute respiratory distress syndrome (ARDS): a prospective sequential study
Authors' conclusion
Both prone positioning and iNO improved oxygenation in moderate-to-severe COVID-19-related ARDS. Within the EIT-assessed thoracic slice, these improvements were accompanied by better regional V/Q matching, which was mainly perfusion-related rather than ventilation-related and suggests limited recruitability of the imaged region; the effect of iNO on regional V/Q matching was attenuated in the prone position.
Study context
- Population
- Mechanically ventilated patients with moderate-to-severe COVID-19-related ARDScompleted all study phases
- Participants
- 28 participants
- Exposure
- Supine vs prone ventilation, each with and without inhaled nitric oxide (iNO)
- Outcome
- Prespecified within-patient contrasts across the four sequential conditions (primary analyses)
Methodological detailswithin-patient contrasts, exploratory difference-in-differences analyses
- Within-patient contrasts
- Exploratory difference-in-differences analyses
Main finding
As reported in the abstract
- Supine position ventilation (SPV) + iNO vs SPV: change in global non-perfused fraction
- −7.28%
- SPV + iNO vs SPV: change in wasted ventilation
- −8.14%
- SPV + iNO vs SPV: change in wasted perfusion
- −5.89%
- PPV: change in global non-perfused fraction
- −8.76%
- PPV + iNO: change in dorsal low V/Q compartment
- + 4.01%
Observational data: associations, not effects.
Further findings
Oxygenation (PaO2, PaO2/FiO2, FiO2 requirement)
- SPV + iNO and PPV significantly increased PaO2 and PaO2/FiO2 vs SPV
- PPV + iNO further improved oxygenation and reduced FiO2 requirements
Position-dependent response to iNO (difference-in-differences)
- Body position did not significantly modify oxygenation response to iNO but significantly altered EIT-derived V/Q responses (attenuated in prone position)
- Exploratory
Safety
Hemodynamics and respiratory mechanics
- Remained stable across all four conditions
Original publication
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