PVR Calculator - Pulmonary Vascular Resistance

Pulmonary vascular resistance measures the resistance to blood flow through the pulmonary vascular bed, typically expressed in Wood Units (WU) or converted into standard dyn·s·cm⁻⁵. The fundamental mathematical relationship relies on the pressure gradient across the pulmonary circuit divided by the total blood flow. The formula is expressed as:

PVR = ((Mean MPAP - Left Atrial Pressure) * 80) / Cardiac Output

Where Mean MPAP represents the mean pulmonary arterial pressure in mmHg, Left Atrial Pressure (or pulmonary capillary wedge pressure) is measured in mmHg, Cardiac Output is measured in L/min, and multiplying by 80 converts the result from Wood Units to dyn·s·cm⁻⁵.

Consider a clinical scenario where a patient undergoes a right heart catheterization with the following recorded hemodynamic values: Mean Pulmonary Arterial Pressure (Mean MPAP) is 38 mmHg, Left Atrial Pressure (or pulmonary capillary wedge pressure) is 10 mmHg, and Cardiac Output is 4.0 L/min.

Step 1: Subtract the left atrial pressure from the mean MPAP: 38 - 10 = 28 mmHg.

Step 2: Multiply the pressure gradient by the conversion factor of 80: 28 * 80 = 2240.

Step 3: Divide the product by the cardiac output: 2240 / 4.0 = 560 dyn·s·cm⁻⁵ (or 7.0 Wood Units when omitting the 80 multiplier). This elevated value indicates significant pulmonary vascular resistance.

Ensure that all input pressure values are consistently measured in mmHg and cardiac output in L/min to prevent calculation distortions. Always verify whether your clinical context requires results in Wood Units or dyn·s·cm⁻⁵, as interpreting the wrong unit scale can lead to severe diagnostic miscalculations. Finally, correlate PVR findings alongside a comprehensive clinical evaluation of right ventricular function and patient symptoms.