By Zencalcy Editorial TeamLast reviewed About us
Pulmonary vascular resistance estimates the resistance across the pulmonary circulation. It uses the gradient between mean pulmonary artery pressure and pulmonary capillary wedge pressure, divided by cardiac output. This calculator reports the result in Wood units and in dynes·s·cm⁻⁵.
Right-heart afterload in Wood units and dynes.
PVR = (mPAP − PCWP) ÷ CO Wood units = PVR; dynes·s·cm⁻⁵ = Wood units × 80
A pulmonary vascular resistance below 3 Wood units, equivalent to below 240 dynes·s·cm⁻⁵, is commonly described as normal. Higher values suggest increased resistance across the pulmonary bed. The wedge pressure is used as an estimate of left atrial pressure, so an inaccurate wedge value shifts the result.
| Symbol | Meaning |
|---|---|
| mPAP | Mean pulmonary artery pressure in mmHg. |
| PCWP | Pulmonary capillary wedge pressure in mmHg. |
| CO | Cardiac output in litres per minute. |
| PVR | Pulmonary vascular resistance in Wood units. |
The gradient is 25 − 10 = 15 mmHg. PVR = 15 ÷ 5 = 3.0 Wood units, which equals 3.0 × 80 = 240 dynes·s·cm⁻⁵, at the upper edge of normal. With mPAP 16, PCWP 8 and CO 4, PVR = 8 ÷ 4 = 2.0 Wood units and 160 dynes·s·cm⁻⁵.
The pulmonary circulation is a low-pressure, high-flow system, so small changes in resistance can have large effects on right ventricular workload. The formula separates the driving gradient from the flow, which is why a normal cardiac output can coexist with a high resistance when the pressure gradient is wide. Wedge pressure acts as the downstream pressure in the equation, and errors in that value propagate directly into the result. The measurement also assumes steady flow, while pulmonary flow varies with breathing and with the cardiac cycle. Clinicians therefore interpret PVR alongside mean pulmonary artery pressure, right atrial pressure, cardiac output and the clinical context. A single value is less informative than a full haemodynamic profile, and treatment decisions in pulmonary hypertension require specialist assessment rather than a calculator result.
Continue with the Mean Arterial Pressure Calculator, Pulse Pressure Calculator, or the QTc Calculator — or browse more cardiology tools and all health calculators.
A Wood unit is a unit of vascular resistance equal to one mmHg per litre per minute. It is numerically equal to the pressure gradient divided by cardiac output, which is why the first part of the PVR formula gives Wood units directly.
Blood pressure, ECG and risk scores are screening aids, not diagnoses. A single reading can be misleading; trends and proper technique matter. Scores estimate population risk and do not replace clinical assessment, anticoagulation decisions or emergency care.
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Last reviewed: September 2026. See how we build and check every tool on the about page.
Content updated: September 2026