ARDS Severity Calculator

Calculator Form

Patient Label

Optional internal label for export and recordkeeping.

Assessment Date

Use the date of blood gas and support setting review.

Support Mode

Berlin severity assignment still depends on PEEP or CPAP meeting the threshold.

PaO₂ (mm Hg)

Enter arterial oxygen partial pressure from the blood gas.

FiO₂ (%)

Enter FiO₂ as a percent. The calculator converts it to decimal form.

PEEP / CPAP (cm H₂O)

Berlin oxygenation severity requires at least 5 cm H₂O.

SpO₂ (%)

Optional. Included only for added monitoring context.

Respiratory Rate (breaths/min)

Optional. Helpful for export notes and bedside review.

Bilateral Opacities Present?

Chest imaging should support bilateral pulmonary opacities.

Onset Within 1 Week?

Use yes when symptoms followed a known insult or recent worsening.

Edema Not Fully Cardiac or Fluid Related?

This is a key supportive criterion for the Berlin screen.

Clinical Notes

Optional notes are included in the export output.

Reset Form

Example Data Table

Case	PaO₂	FiO₂	PEEP	PF Ratio	Berlin Band	Supportive Criteria
A	92 mm Hg	30%	5 cm H₂O	306.7	No oxygenation band	Yes
B	88 mm Hg	40%	8 cm H₂O	220.0	Mild ARDS	Yes
C	72 mm Hg	50%	10 cm H₂O	144.0	Moderate ARDS	Yes
D	60 mm Hg	80%	12 cm H₂O	75.0	Severe ARDS	Yes

These rows are examples for demonstration only and are not patient-specific guidance.

Formula Used

Primary calculation:

PF Ratio = PaO₂ / (FiO₂ ÷ 100)

Example: if PaO₂ is 72 mm Hg and FiO₂ is 50%, then FiO₂ decimal is 0.50.

PF Ratio = 72 / 0.50 = 144

Severity logic used in this calculator:

No Berlin oxygenation band: PF ratio above 300, or support below threshold.
Mild ARDS: PF ratio above 200 and up to 300 with PEEP/CPAP at least 5.
Moderate ARDS: PF ratio above 100 and up to 200 with PEEP at least 5.
Severe ARDS: PF ratio 100 or below with PEEP at least 5.

The calculator also checks bedside support items for imaging, timing, and likely non-cardiogenic origin to build a fuller screen summary.

How to Use This Calculator

Enter the patient label and assessment date if you want them on exports.
Select the support mode and enter the measured PEEP or CPAP value.
Enter PaO₂ from the arterial blood gas and FiO₂ as a percent.
Optionally add SpO₂, respiratory rate, and clinical notes.
Mark whether bilateral opacities, recent onset, and non-cardiac origin are supported.
Click the calculate button to show the result above the form.
Review the PF ratio, severity band, support checks, and graph.
Use the CSV or PDF buttons to save the summary.

Frequently Asked Questions

1. What does this calculator measure?

It calculates the PaO₂/FiO₂ ratio, checks the minimum support threshold, and groups the result into a Berlin oxygenation severity band.

2. Why is FiO₂ entered as a percent?

Clinicians often chart FiO₂ as a percent. The calculator converts that value into decimal form before computing the PF ratio.

3. Why does PEEP or CPAP matter here?

Berlin oxygenation severity assignment is tied to a minimum support level. If PEEP or CPAP is below 5 cm H₂O, the tool flags that limitation.

4. Can this tool diagnose ARDS by itself?

No. It is an educational screening calculator. Final interpretation should always consider the full clinical picture, imaging, hemodynamics, and specialist review.

5. What if the PF ratio is above 300?

The entered oxygenation values do not fall into a Berlin ARDS severity band. The page will display that clearly in the result summary.

6. Why are there supportive criteria fields?

ARDS severity is not only a number. Timing, imaging, and likely non-cardiogenic origin help decide whether the broader Berlin screen is complete.

7. What do the CSV and PDF exports include?

They include inputs, calculated ratios, severity label, support checks, date, patient label, and any optional notes entered into the form.

8. Is SpO₂ required for the result?

No. SpO₂ is optional in this page. The main severity band is assigned from PaO₂, FiO₂, and the support threshold.