How this calculator works
PVR divides the pressure drop across the pulmonary circulation by cardiac output. Use mean pulmonary artery pressure and mean pulmonary artery wedge pressure from appropriately obtained haemodynamic measurements. Wedge pressure estimates left atrial pressure under suitable conditions. No diagnostic category is assigned from PVR alone. The result is an estimate for information only and is not medical advice.
Formula
PVR(WU) = [mPAP - PAWP](mmHg) / CO(L/min). PVR(dyn·s/cm⁵) = 80 × PVR(WU).
Worked example
Mean pulmonary pressure 25, wedge pressure 10 mmHg and cardiac output 5 L/min give 3 WU, or 240 dyn·s/cm⁵. A 20 mmHg gradient at 4 L/min gives 5 WU.
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Frequently asked questions
Is wedge pressure always left atrial pressure?
No. Measurement technique and clinical conditions affect that approximation.
Can I enter zero flow?
No. Resistance cannot be calculated by division by zero flow.
Does PVR alone diagnose pulmonary hypertension?
No. Diagnosis requires the full haemodynamic definition and clinical context.