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Calcimator

CPAP Pressure Calculator

Predict starting CPAP pressure based on BMI, AHI, neck circumference, and positional data using the Hoffstein prediction model.

Inputs

Results

Predicted CPAP Pressure

7 cmH₂O

Pressure Range (low)5 cmH₂O
Pressure Range (high)9 cmH₂O
Titration Recommendation1
OSA Severity2
How to Use This Calculator
  1. Enter the patient's BMI in kg/m².
  2. Input the Apnea-Hypopnea Index (AHI) from the diagnostic polysomnography report.
  3. Enter neck circumference in cm and supine AHI if available.
  4. Review the estimated starting CPAP pressure range.
  5. Titrate final CPAP pressure through an attended titration study or auto-CPAP data.

How the result changes with BMI (kg/m²)

BMI (kg/m²)Predicted CPAP Pressure
205 cmH₂O
316.8 cmH₂O
448.9 cmH₂O
5610.8 cmH₂O

What each input means

BMI (kg/m²)
Body Mass Index. Higher BMI generally requires higher CPAP pressure.
AHI (events/hour)
Apnea-Hypopnea Index from sleep study. Mild: 5-15, Moderate: 15-30, Severe: 30+.
Neck Circumference (cm)
Measured at the level of the cricothyroid membrane.
Supine AHI (events/hour)
AHI when sleeping on the back. Higher than overall suggests positional apnea.
Gender
1 = male, 2 = female.

What each result means

Titration Recommendation
1 = auto-CPAP acceptable, 2 = lab titration recommended.
OSA Severity
0 = normal, 1 = mild, 2 = moderate, 3 = severe.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    BMI (kg/m²) = 32, AHI (events/hour) = 25, Neck Circumference (cm) = 42, Supine AHI (events/hour) = 35 = 5 input(s) provided
  2. Calculate Predicted CPAP Pressure
    7 = 7
  3. Calculate Pressure Range
    5 = 5
  4. Calculate Pressure Range
    Pressure Range
    9 = 9

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