Estimated Mean Pulmonary Artery Pressure (Chemla): Clinical Guide

Overview

Estimates mean pulmonary artery pressure from systolic pulmonary artery pressure using the Chemla equation.

Clinical Significance

Provides an estimate of mean pulmonary artery pressure when direct measurement is unavailable. It does not replace right-heart catheterisation.

When to Use

• Use when the required measurements are available, reliable and clinically relevant.

How It Is Calculated

• Mean PAP ≈ 0.61 × PASP + 2.

Interpretation

• Provides an estimate of mean pulmonary artery pressure when direct measurement is unavailable. It does not replace right-heart catheterisation.

Worked Example

Enter valid values in the displayed units. MedicalC then applies: Mean PAP ≈ 0.61 × PASP + 2.

Limitations

• The result does not establish a diagnosis or mandate treatment.
• Measurement error may be more important than arithmetic precision.
• Published thresholds may differ between populations and settings.

Clinical Pearls

• Document the source values and units with the final result.
• Review trends rather than isolated values where appropriate.

Common Mistakes

• Using the wrong unit.
• Combining values from different time points.
• Applying the result outside the intended measurement or clinical context.

References

1. Chemla D et al. New formula for predicting mean pulmonary artery pressure using systolic pulmonary artery pressure. Chest. 2004. — Primary, supporting or authoritative reference for the implemented relationship.