# PVR Calculator

Calculate Pulmonary Vascular Resistance (PVR) in Wood units and dyn·s·cm⁻⁵ from mPAP, PCWP, and cardiac output. Includes clinical interpretation.

## What this calculates

Pulmonary Vascular Resistance (PVR) measures how much the pulmonary vasculature resists blood flow. It is a key hemodynamic parameter used to diagnose and classify pulmonary hypertension. Enter your right heart catheterization values to calculate PVR in both Wood units and CGS units.

## Inputs

- **Mean Pulmonary Artery Pressure (mPAP)** (mmHg) — min 0, max 120 — Average pressure in the pulmonary artery measured by right heart catheterization.
- **Pulmonary Capillary Wedge Pressure (PCWP)** (mmHg) — min 0, max 60 — Also called pulmonary artery wedge pressure (PAWP) or left atrial pressure estimate.
- **Cardiac Output (CO)** (L/min) — min 0.1, max 20 — Volume of blood pumped by the heart per minute.

## Outputs

- **PVR** — Pulmonary Vascular Resistance in Wood units
- **PVR (dyn·s·cm⁻⁵)** — PVR in CGS units (Wood units x 80)
- **Transpulmonary Gradient (TPG)** — Difference between mPAP and PCWP
- **Interpretation** — formatted as text — Clinical significance of the PVR value

## Details

PVR is calculated with the formula: PVR = (mPAP - PCWP) / CO, where mPAP is mean pulmonary artery pressure, PCWP is pulmonary capillary wedge pressure, and CO is cardiac output in liters per minute. The result is expressed in Wood units (mmHg/L/min). Multiply by 80 to convert to dyn·s·cm⁻⁵.

A normal PVR is below 2 Wood units (160 dyn·s·cm⁻⁵). The 2022 ESC/ERS guidelines define pulmonary hypertension as mPAP > 20 mmHg, and pre-capillary pulmonary hypertension requires both mPAP > 20 mmHg and PVR > 2 Wood units. The transpulmonary gradient (mPAP minus PCWP) helps distinguish pre-capillary from post-capillary causes.

PVR is measured during right heart catheterization, the gold standard for diagnosing pulmonary hypertension. Cardiac output is typically determined by thermodilution or the Fick method. This calculator is intended as a quick reference for healthcare professionals reviewing catheterization data.

## Frequently Asked Questions

**Q: What are Wood units?**

A: Wood units (also called hybrid resistance units or HRU) express PVR in mmHg per liter per minute. They are named after cardiologist Paul Wood. Normal PVR is less than 2 Wood units. To convert to CGS units (dyn·s·cm⁻⁵), multiply by 80. Both units are widely used in cardiology literature.

**Q: When is PVR measured?**

A: PVR is measured during right heart catheterization, which is performed when pulmonary hypertension is suspected based on echocardiography, symptoms (shortness of breath, exercise intolerance), or other testing. It is essential for confirming the diagnosis, classifying the type of pulmonary hypertension, and assessing treatment response.

**Q: What is the transpulmonary gradient?**

A: The transpulmonary gradient (TPG) is the difference between mean pulmonary artery pressure and pulmonary capillary wedge pressure (mPAP minus PCWP). A TPG above 12 mmHg suggests a pre-capillary component to pulmonary hypertension. It is a simpler measure than PVR but does not account for cardiac output.

**Q: Can PVR change over time?**

A: Yes. PVR can change with treatment (pulmonary vasodilators), disease progression, fluid status, and other factors. Serial right heart catheterizations are often performed to assess response to therapy. PVR can also decrease with supplemental oxygen in patients with hypoxic pulmonary vasoconstriction.

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Source: https://vastcalc.com/calculators/health/pvr
Category: Health & Fitness
Last updated: 2026-04-08