Pulmonary Vascular Resistance
Enter mean pulmonary artery pressure, pulmonary capillary wedge pressure (or left atrial pressure), and cardiac output from right heart catheterization.
Use left atrial pressure if wedge is unavailable.
Thermodilution or Fick method.
How to Use This Calculator
Acquire catheterization data
Use accurate mean pressures averaged over several respiratory cycles and confirm wedge waveforms.
Enter the gradient and flow
Subtract wedge pressure from mean PAP, then divide by cardiac output to derive Wood units.
Interpret and act
Differentiate pre- versus post-capillary pulmonary hypertension and tailor therapy accordingly.
Formula
PVR (Wood units) = (Mean PAP − PCWP) ÷ Cardiac output
PVR (dynes·s·cm⁻⁵) = PVR (Wood units) × 80
Mean PAP and PCWP in mmHg; cardiac output in L/min.
Full Description
Pulmonary vascular resistance differentiates pre-capillary pulmonary hypertension (PVR ≥3 WU with normal wedge pressure) from post-capillary causes. It integrates pulmonary pressure gradients and cardiac output to quantify right ventricular afterload. Serial measurements track treatment response to vasodilator therapy, left heart unloading, or transplant evaluation.
Frequently Asked Questions
What if the wedge pressure is inaccurate?
Use left atrial pressure or LVEDP if wedge tracing is unreliable. Ensure balloon position and waveform confirmation.
How do I calculate transpulmonary gradient?
TPG = Mean PAP − PCWP. Elevated TPG with high PVR suggests significant pre-capillary involvement.
Should I index PVR to body surface area?
PVR index (PVRi) = PVR × BSA. It may aid pediatric assessments but is less commonly used in adults.
Can thermodilution and Fick cardiac outputs be used interchangeably?
Thermodilution may be inaccurate in low output or severe tricuspid regurgitation. Cross-check with Fick when available.