SVR and PVR Calculator — Systemic and Pulmonary Vascular Resistance

How it works

SVR = 80 × (MAP − CVP) / CO; PVR = 80 × (mPAP − PCWP) / CO (dyn·s·cm⁻⁵, CO in L/min). Wood units = mmHg·min/L = dyn·s·cm⁻⁵ ÷ 80. Indexed values use cardiac index (CO / BSA) in place of CO. Transpulmonary gradient = mPAP − PCWP.

Vascular resistance follows Ohm’s law: pressure drop across a circulation divided by the flow through it. The factor 80 converts mmHg·min/L (Wood units) to dyn·s·cm⁻⁵. A normal adult SVR is about 800–1,200 dyn·s·cm⁻⁵; it is low in vasodilatory (septic) shock and high in cardiogenic or hypovolaemic shock. The 2022 ESC/ERS pulmonary hypertension guideline defines pre-capillary pulmonary hypertension as mPAP above 20 mmHg with PCWP 15 mmHg or less and PVR above 2 Wood units.

Worked example

With MAP 85 mmHg, CVP 6 mmHg and CO 5.5 L/min: SVR = 80 × 79 / 5.5 = 1,149 dyn·s·cm⁻⁵ (14.4 WU, normal). With mPAP 20 and PCWP 10 mmHg: PVR = 10 / 5.5 = 1.82 WU (145 dyn·s·cm⁻⁵), normal; the transpulmonary gradient is 10 mmHg.

Sources: Humbert M et al. — 2022 ESC/ERS Pulmonary Hypertension Guidelines · StatPearls — Physiology, Systemic Vascular Resistance

Frequently asked questions