Respiratory failure & ventilation
Approaches to Converting Spo 2/Fio 2 Ratio to Pao 2/Fio 2 Ratio for Assessment of Respiratory Failure in Critically Ill Patients: A Systematic Review
Authors' conclusion
SF and PF ratios demonstrate good correlation, and may have similar prognostic value. Although there is no clear optimal method to convert SF to PF ratios, linear equations show acceptable correlation and are most easily applied at the bedside.
Study context
- Population
- Critically ill patients assessed for respiratory failure45 observational studies
- Comparison
- SpO2/FiO2 ratio vs PaO2/FiO2 ratio
- Outcome
- Best ways to convert SF and PF ratios: diagnostic/prognostic accuracy and clinical utility
Methodological detailsQUADAS II risk of bias assessment, Studies ranged from 61 to 141,000 measurements
- QUADAS II risk of bias assessment
- Studies ranged from 61 to 141,000 measurements
Pooled result
As reported in the abstract
Conversion of SF to PF ratio
- Strong correlation between SF and PF ratios in all studies, but no clear best equation
- SF to PF imputation less accurate when SpO2 ≥97%
- 4 equations prioritised (1 linear, 1 logarithmic linear, 2 nonlinear), all with strong correlation; linear easiest to apply
Further pooled results
Correlation with clinical outcomes
- SF ratio correlated well with clinical outcomes vs PF ratio, alone and within a comprehensive score, with more discriminating performance in some cases
Original publication
Approaches to Converting Spo 2/Fio 2 Ratio to Pao 2/Fio 2 Ratio for Assessment of Respiratory Failure in Critically Ill Patients: A Systematic Review. Crit Care Med. Published 2 January 2026. doi:10.
Composed by AI from the published abstract and checked against it. How Briefs are made →