What is the estimated mean pulmonary arterial pressure if the systolic pressure is 33 mmHg?

Estimated Mean Pulmonary Arterial Pressure for Systolic Pressure of 33 mmHg

The estimated mean pulmonary arterial pressure (mPAP) for a systolic pulmonary arterial pressure of 33 mmHg is approximately 22 mmHg, calculated using the formula mPAP = 0.61 × sPAP + 2 mmHg.

Calculation Methods

Several formulas exist for estimating mPAP from systolic pulmonary arterial pressure (sPAP):

• The most accurate formula is mPAP = 0.61 × sPAP + 2 mmHg 1

  • Using this formula: mPAP = (0.61 × 33) + 2 = 22.13 mmHg

• Alternative formulas include:

  • mPAP = 2/3 × sPAP (parabolic shape) 1
  • Using this formula: mPAP = 2/3 × 33 = 22 mmHg

• The classic rule of thumb (2/3 × dPAP + 1/3 × sPAP) is considered the most precise but requires knowledge of diastolic pressure 1

Clinical Significance

• A mPAP of 22 mmHg falls within the borderline range (20-24 mmHg) that requires careful clinical consideration 2

• Normal mPAP at rest is 14-20 mmHg according to current guidelines 2

• mPAP > 20 mmHg is now considered the threshold for pulmonary hypertension according to the latest guidelines 2

• A systolic PAP of 33 mmHg is slightly above the upper limit of normal (approximately 30 mmHg) for healthy individuals 2

Diagnostic Implications

• A mPAP of 22 mmHg represents a borderline elevation that warrants close follow-up 2

• This level falls into what was previously called "borderline pulmonary hypertension" (mPAP 21-24 mmHg) 2

• Patients with mPAP in this range have been shown to have increased mortality risk compared to those with normal pressures 2

Assessment Considerations

• When measuring pulmonary pressures via echocardiography, careful attention to TR signal quality is essential for accurate estimation 3

• Right heart catheterization remains the gold standard for confirming pulmonary pressure measurements 2, 4

• In critically ill patients, echocardiographic estimation may have limitations with a mean difference of approximately 1.9 mmHg (SD 5.0) compared to catheterization 5

Clinical Approach

• For a patient with sPAP of 33 mmHg and calculated mPAP of 22 mmHg:

  • Further evaluation for underlying causes should be considered 2
  • Risk factors for pulmonary hypertension should be assessed 2
  • Regular follow-up is recommended as this represents a borderline elevation 2

• A systolic PAP > 36 mmHg has been shown to diagnose pulmonary hypertension (mPAP > 25 mmHg) with high sensitivity and specificity 1