P/F Ratio Calculator (PaO2/FiO2)

Calculate the P/F Ratio to evaluate a patient's lung oxygenation. Discover its normal values and importance in cases of hypoxemia and ARDS.

Enter valid values.

P/F Ratio:

Severity:

*With PEEP ≥ 5. Formula used: (PaO2/FiO2)*100

What is the P/F Ratio and its function?

Also known as the PaO2/FiO2 ratio, it is a measure used in medicine to assess the efficiency of oxygen exchange in the lungs and the respiratory system's ability to deliver oxygen to the blood. This index is calculated by dividing the arterial partial pressure of oxygen (PaO2) by the fraction of inspired oxygen (FiO2).

The P/F Ratio is crucial for determining the severity of hypoxemia (low oxygen levels in the blood) in patients with respiratory problems, especially in contexts such as acute respiratory distress syndrome (ARDS) or other acute lung conditions.

Normal Values and Severity Ranges of the P/F Ratio

Normal values of the P/F Ratio vary depending on clinical conditions and oxygenation levels, but typically the following ranges are considered:

  • Normal: ≥ 300. Indicates good oxygenation with normal lung function.
  • Mild: < 300 and ≥ 200. May indicate mild dysfunction in oxygenation.
  • Moderate: < 200 and ≥ 100. Suggests moderate dysfunction in oxygenation, usually associated with conditions like moderate ARDS.
  • Severe: < 100. Indicates severe dysfunction in oxygenation, usually associated with severe hypoxemia and ARDS.

Importance of the P/F Ratio in Clinical Practice

The P/F Ratio is crucial in the assessment and management of patients with acute respiratory distress, helping clinicians determine the severity of hypoxemia and the response to treatment. It is widely used in intensive care units (ICUs) and emergency respiratory contexts to guide therapeutic decisions and monitor disease progression.