Respiratory failure & ventilation
Diagnostic performance of the recruitment-to-inflation ratio to assess lung recruitability by positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS). a computed tomography study
Authors' conclusion
In a population of ARDS patients with low recruitment potential, the R/I ratio had a poor diagnostic performance to predict lung recruitability, but R/I ratio values below 0.57 reliably identified ARDS patients with low recruitability, provided they did not present focal ARDS.
Study context
- Population
- Adult ARDS patients under invasive mechanical ventilation8 excluded
- Participants
- Fifty participants
- Comparison
- R/I ratio vs computed tomography (CT) for lung recruitability by PEEP
- Outcome
- Diagnostic performance of the R/I ratio to identify high recruiters, CT as gold standard
Methodological detailssingle-centre, prospective observational, Misclassification mainly from ventilator overestimation of PEEP volume, confirmed by bench study for 2 of 3 ventilators
- Single-centre
- Prospective observational
- Misclassification mainly from ventilator overestimation of PEEP volume, confirmed by bench study for 2 of 3 ventilators
Performance
As reported in the abstract
Identification of high recruiters
| Test or model | AUC | Optimal threshold | Sensitivity | Specificity | False positive rate | False negative rate |
|---|---|---|---|---|---|---|
| R/I ratio | 0.70 (95% CI 0.52-0.89) | 0.57 | 78% (95% CI 44%-100%) | 67% (95% CI 52%-82%) | 11/33 [33%] | 2/9 [22%] |
R/I ratio
AUC0.70 (95% CI 0.52-0.89)
Optimal threshold0.57
Sensitivity78% (95% CI 44%-100%)
Specificity67% (95% CI 52%-82%)
False positive rate11/33 [33%]
False negative rate2/9 [22%]
Further findings
Recruiter classification by CT
Median
| Outcome | Low recruiters | High recruiters | P value |
|---|---|---|---|
| R/I ratio, high vs low recruitersNot significantly higher | 0.42 (IQR 0.24–0.64) | 0.67 (IQR 0.57–0.74) | P = 0.07 |
Correlation of R/I ratio with recruited lung weight on CT
- No significant correlation (R2)
- 0.065; p = 0.10
Original publication
Diagnostic performance of the recruitment-to-inflation ratio to assess lung recruitability by PEEP in ARDS. a computed tomography study. Crit Care. Published 3 June 2025. doi:10.
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