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Clinical Utility of Positive End-expiratory Pressure-incorporated PaO₂/FiO₂ Ratio in Prognosticating Mortality and

Vignesh Prabhu¹, Souvik Chaudhuri², Shwethapriya Rao²

¹Department of Respiratory Therapy, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, Karnataka, India.

Indian Journal of Critical Care Medicine : Peer-Reviewed, Official Publication of Indian Society of Critical Care Medicine

|July 8, 2026

Abstract

Introduction:

PaO₂/FiO₂ (PF) ratio is globally used for defining and classifying acute respiratory distress syndrome (ARDS), yet it does not take ventilatory support into consideration, which is crucial in achieving oxygenation. Incorporating the positive end-expiratory pressure (PEEP) into the PF ratio (PaO₂/FiO₂*PEEP; PFP ratio) may provide a more physiologically meaningful index of disease diagnosis, severity, and prognosis.

Objectives:

To evaluate the clinical utility of the PFP ratio in prognosticating mortality and its impact on reclassification of ARDS severity as compared to the traditional PF ratio.

Materials And Methods:

This systematic review and meta-analysis (SRMA) was performed following PRISMA guidelines and registered in PROSPERO (CRD420251110685). A search for relevant studies from inception to July 2025 was performed, and the studies on adults with ARDS receiving invasive mechanical ventilation (IMV) and those that reported PFP ratio and mortality outcomes were included. Summary receiver operating characteristic (sROC) model was used to evaluate the prognostic accuracy, while the reclassification of ARDS severity using PFP vs PF ratio was descriptively analyzed.

Results:

A total of five studies with 4,454 patients were included for meta-analysis. The pooled sensitivity and specificity of the PFP ratio for prognosticating mortality were 0.55 [95% confidence interval (CI): 0.41-0.67] and 0.90 (95% CI: 0.80-0.96), respectively. The area under the sROC was 0.84 (95% CI: 0.80-0.85), inferring good discriminant ability. For reclassification of ARDS severity based on PFP ratio, a total of four studies were included, and 30-71.9% of patients were reclassified, showing significant bidirectional shifts.

Conclusion:

Positive end-expiratory pressure incorporation to the PF ratio improves the prognostic ability and leads to meaningful reclassification of ARDS severity.

How To Cite This Article:

Prabhu V, Chaudhuri S, Rao S, Todur P. Clinical Utility of Positive End-expiratory Pressure-incorporated PaO₂/FiO₂ Ratio in Prognosticating Mortality and Severity Reclassification in Acute Respiratory Distress Syndrome: A Systematic Review and Meta-analysis. Indian J Crit Care Med 2026;30(5):420-429.

Keywords:

Acute respiratory distress syndrome Acute respiratory distress syndrome reclassification Mortality PaO2/FiO2 ratio Positive end-expiratory pressure incorporation to the PF ratio

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