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PaO₂/FiO₂ ratio and ARDS (Berlin)

Measures oxygenation efficiency and grades acute respiratory distress syndrome severity by Berlin criteria.

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Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

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Method · Limits of application

Berlin ARDS 2012: P/F 100/200/300 plus PEEP/context; S/F component of Global Definition 2024, SpO₂≤97

The P/F ratio is only one component of the ARDS definition. Berlin classification requires the other conditions of the final definition as well as oxygenation limits; the ratio alone does not confirm ARDS. S/F classification belongs to the later global definition and requires its own criteria, without mixing in auxiliary variables removed from the Berlin draft.

Conditions of use

Check the population, units, inclusion and exclusion criteria, and version in the original source. A result alone does not establish a diagnosis, discharge decision or prescription.

Documented parameters

PaO₂ · mmHg
FiO₂ · %
PEEP or CPAP · cmH₂O
SpO₂ (for the SpO₂/FiO₂ ratio) · %

4/4 reference cases checked. Numerical tests are not clinical validation.

Sources and documentation

Documented formula

Transcribed from the source or a recorded revision; this is not a clinical recommendation.

P/F ratio = PaO₂ (mmHg) ÷ FiO₂ (fraction: 40% = 0.40).

SpO₂/FiO₂ = SpO₂ (%) ÷ FiO₂ (fraction), interpretable with SpO₂ ≤ 97%.

References

Identifier: relacao-pao2-fio2

Original clinical content: Brazilian Portuguese.

Method version

Berlin ARDS 2012: P/F 100/200/300 plus PEEP/context; S/F component of Global Definition 2024, SpO₂≤97

relacao-pao2-fio2@native-2026-10-05+3145990aaf43

Source for the active edition

The bibliographic edition identifies the source. By itself, it proves neither full conformity of the formula nor clinical approval.

Synthetic cases checked (4)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

PaO₂: 95 mmHg
FiO₂: 21 %

{
  "pao2": 95,
  "fio2": 21
}

Expected result

{
  "pf": 452.38
}

Actual result

{
  "pf": 452.3809523809524
}

Case 2

reference-002

Inputs

PaO₂: 90 mmHg
FiO₂: 40 %
PEEP or CPAP: 8 cmH₂O

{
  "pao2": 90,
  "fio2": 40,
  "peep": 8
}

Expected result

{
  "pf": 225
}

Actual result

{
  "pf": 225
}

Case 3

reference-003

Inputs

PaO₂: 80 mmHg
FiO₂: 40 %
PEEP or CPAP: 10 cmH₂O

{
  "pao2": 80,
  "fio2": 40,
  "peep": 10
}

Expected result

{
  "pf": 200
}

Actual result

{
  "pf": 200
}

Case 4

reference-004

Inputs

PaO₂: 60 mmHg
FiO₂: 80 %
PEEP or CPAP: 14 cmH₂O
SpO₂ (for the SpO₂/FiO₂ ratio): 90 %

{
  "pao2": 60,
  "fio2": 80,
  "peep": 14,
  "spo2": 90
}

Expected result

{
  "pf": 75,
  "sf": 112.5
}

Actual result

{
  "pf": 75,
  "sf": 112.5
}

Code and reproducibility

This tool’s code on GitHub

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Sources, version and reproduction instructions

README

Local installation

Code license: Apache-2.0

Guidelines and conditions

This repository’s license applies to the code. Third-party instruments, questionnaires, data and models remain subject to their owners’ conditions.

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.