Pulmonary Vascular Resistance (PVR) Calculator

PVR in Wood units and in dyn·s·cm⁻⁵, with the transpulmonary gradient, the diastolic gradient the 2022 guideline dropped, and the 2 Wood unit threshold the definition of pulmonary hypertension now turns on.

Last updated 8 Oct 2026

Pulmonary vascular resistance and the pressure gradients

(mPAP − PAWP) ÷ CO

Mean pulmonary arterial pressure (mmHg)From right heart catheterisation. The 2022 ESC/ERS guidelines define pulmonary hypertension as a resting mPAP above 20 mmHg; a systematic review put the normal supine value at 14 ± 3.3 mmHg with an upper limit of 20.6.

Diastolic pulmonary arterial pressure (mmHg)Used only for the diastolic pressure gradient below. The 2022 ESC/ERS guidelines stopped using that gradient to separate isolated from combined post-capillary pulmonary hypertension, “because of conflicting data”. It is printed here so a reader meeting it on an older report knows what it is and what happened to it.

Pulmonary arterial wedge pressure (mmHg)The downstream pressure, standing in for left atrial pressure. The 15 mmHg line divides pre-capillary from post-capillary disease in the 2022 definitions, and a wedge trace that is over-wedged, under-wedged or read at the wrong point in the respiratory cycle moves this whole calculation. Published range on both reference cards is 6 to 12 mmHg.

Cardiac output (L/min)Thermodilution or Fick. In the pulmonary circulation the choice matters more than elsewhere: thermodilution is unreliable in tricuspid regurgitation and in low-output states, which are exactly the patients being catheterised. See the Fick cardiac output calculator.

Body surface area (m²)For the indexed figure only. As with the systemic index, the pulmonary index divides by the cardiac INDEX, so PVRI is larger than PVR by exactly the surface area.

4.89Wood unitsExample

mPAP 32 mmHg, dPAP 20 mmHg, PAWP 10 mmHg, cardiac output 4.5 L/min, BSA 1.9 m²

The formula, the 80, and the gradient that was dropped

PVR (Wood units) = (mPAP − PAWP) ÷ CO
PVR (dyn·s·cm⁻⁵) = 80 × (mPAP − PAWP) ÷ CO
Transpulmonary gradient = mPAP − PAWP
Diastolic pressure gradient = dPAP − PAWP

why Wood units here: pulmonary resistance is conventionally quoted in Wood units (mmHg·min/L) and systemic resistance in dyn·s·cm⁻⁵, and the two differ by exactly 80. The 2022 ESC/ERS guidelines are written in Wood units, so that is the headline figure here, with the dyn·s·cm⁻⁵ equivalent beside it
the 80: a unit conversion only: 1 mmHg is 1333.22 dyn/cm² and 1 L/min is 16.667 cm³/s, so 1 mmHg·min/L is 79.99 dyn·s·cm⁻⁵. The 2 Wood unit threshold is 160 dyn·s·cm⁻⁵ and the 5 Wood unit one is 400. See the systemic vascular resistance calculator for the same conversion worked the other way
2 Wood units: the 2022 ESC/ERS guidelines: “the upper limit of normal PVR and the lowest prognostically relevant threshold of PVR is 2 Wood units”. Pulmonary arterial hypertension requires mPAP above 20 mmHg, PAWP at or below 15 mmHg and PVR above 2 Wood units
5 Wood units: the same guidelines define severe pulmonary hypertension in lung disease as mPAP above 20 mmHg with PVR above 5 Wood units
transpulmonary gradient: mPAP − PAWP. A gradient above 12 mmHg was the conventional marker of disproportionate pulmonary hypertension. Naeije and colleagues showed why it fails: it is “sensitive to changes in cardiac output and both recruitment and distension of the pulmonary vessels”, so it moves with flow rather than with vascular disease
diastolic pressure gradient: dPAP − PAWP, proposed as the flow-independent replacement for the transpulmonary gradient. The 2022 ESC/ERS guidelines dropped it: it is “no longer used to distinguish between isolated postcapillary PH and combined post- and precapillary PH because of conflicting data”. A negative value is common and is usually a measurement artefact rather than a finding
indexed PVR: PVRI divides by the cardiac index, so PVRI = PVR × BSA and is larger than PVR. The reference cards print a PVRI range of 255 to 285 dyn·s·cm⁻⁵·m² beside a PVR range of 100 to 250, and those two cannot both be right at a normal body size — see the table below. The indexed figure is given here in Wood units·m² and no range is quoted for it

Worked example

mPAP 32 mmHg, dPAP 20 mmHg, PAWP 10 mmHg, cardiac output 4.5 L/min, BSA 1.9 m²
Transpulmonary gradient = 32 − 10 = 22 mmHg
PVR = 22 ÷ 4.5 = 4.89 Wood units — above the ESC/ERS upper limit of normal of 2, and at or below the 5 used for severe PH in lung disease
In dyn·s·cm⁻⁵: 80 × 4.89 = 391 dyn·s·cm⁻⁵. The same resistance, and a number a reader trained on systemic resistances of 800 to 1200 would read as reassuringly low
Indexed: 4.89 × 1.9 = 9.29 Wood units·m², which is 743 dyn·s·cm⁻⁵·m²
Diastolic pressure gradient = 20 − 10 = 10 mmHg
Classify it on the 2022 criteria: mPAP 32 is above 20, the wedge of 10 is at or below 15, and the PVR is above 2 — the guideline's pre-capillary pattern. Raise the wedge to 22 with everything else unchanged and the gradient falls to 10, the PVR to 2.22 Wood units, and the pattern becomes combined post- and pre-capillary
Raise the wedge to 26 instead and the PVR falls to 1.33 Wood units, at or below 2: isolated post-capillary. The pulmonary vasculature has not changed in any of these three — only the wedge pressure, which is the single most error-prone number in the whole study
Now change the output instead. Hold the pressures and drop the cardiac output to 2.5 L/min: PVR becomes 8.80 Wood units, above 5. Resistance rises when flow falls, with no change in the vessels

The 2022 ESC/ERS haemodynamic definitions

From the 2022 ESC/ERS pulmonary hypertension guidelines. Two things worth noticing: the resistance never defines pulmonary hypertension on its own — the mean pressure does that — and the same resistance puts a patient in a different category depending on the wedge, which is the least reproducible measurement in the study.
Pattern	mPAP	PAWP	PVR
No pulmonary hypertension	20 mmHg or below	—	—
Pre-capillary PH	Above 20 mmHg	15 mmHg or below	Above 2 Wood units
Isolated post-capillary PH	Above 20 mmHg	Above 15 mmHg	2 Wood units or below
Combined post- and pre-capillary PH	Above 20 mmHg	Above 15 mmHg	Above 2 Wood units
Unclassified PH	Above 20 mmHg	15 mmHg or below	2 Wood units or below
Severe PH in lung disease	Above 20 mmHg	—	Above 5 Wood units
Exercise PH	mPAP/CO slope above 3 mmHg/L/min between rest and exercise	—	—

Published normal ranges for pulmonary resistance, which do not agree

A resistance of 2.5 Wood units is above normal on the guideline, inside the Edwards range and far above the general reference’s. The guideline figure is the one a pulmonary hypertension service works to and is the only one here with a stated prognostic basis. The last row is printed as a caution: an indexed range of 255 to 285 cannot be consistent with a non-indexed range of 100 to 250 at any adult body size, since indexing multiplies by the surface area, so at least one of the two is not what it claims. This page therefore quotes no range for the indexed figure.
Source	PVR	In Wood units
2022 ESC/ERS guidelines, upper limit of normal	160 dyn·s·cm⁻⁵	2.0
Edwards Lifesciences reference card	100 to 250 dyn·s·cm⁻⁵	1.25 to 3.13
WVU SICU reference card	Under 250 dyn·s·cm⁻⁵	Under 3.13
The widest-circulating general reference	20 to 130 dyn·s·cm⁻⁵	0.25 to 1.63
Edwards card, indexed (PVRI)	255 to 285 dyn·s·cm⁻⁵·m²	3.19 to 3.56 ·m²

Wood units, the 2 that defines the disease, and the gradient that was dropped

Pulmonary vascular resistance is the same quotient as systemic resistance — a pressure difference divided by a flow — and it is quoted in different units, which is the most reliable way to be eightyfold wrong in haemodynamics. The pulmonary literature uses Wood units, mmHg·min/L, where normal is a single digit. The systemic literature uses dyn·s·cm⁻⁵, where normal is four figures. This page leads with Wood units because the 2022 ESC/ERS guidelines are written in them, and prints the dyn·s·cm⁻⁵ equivalent beside it every time. The conversion is a factor of 80 and contains no physiology: 2 Wood units is 160 dyn·s·cm⁻⁵, and 5 Wood units is 400.

The 2 matters more than it used to. The 2022 guidelines lowered the definition of pulmonary hypertension to a resting mean pulmonary arterial pressure above 20 mmHg, and stated that the upper limit of normal resistance and the lowest prognostically relevant threshold are both 2 Wood units. Resistance does not define the disease — the mean pressure does — but it classifies it together with the wedge: above 20 mmHg with a wedge at or below 15 and a resistance above 2 is pre-capillary; above 20 with a wedge over 15 is post-capillary, isolated if the resistance is at or below 2 and combined if it is above. A raised mean pressure with a normal wedge and a resistance below 2 the guideline simply calls unclassified.

The gradients are the part most likely to be new to a reader who learned the subject a decade ago. The transpulmonary gradient, mean pulmonary pressure minus wedge, used to decide whether a pulmonary pressure was disproportionate to the left heart disease behind it, with 12 mmHg as the line. Naeije and colleagues showed it is sensitive to cardiac output and to the recruitment and distension of pulmonary vessels, so it tracks flow rather than disease. The diastolic pressure gradient was proposed as the flow-independent replacement — and the 2022 guidelines dropped that too, because of conflicting data. Both are printed here so a reader meeting them on a report knows what happened to them.

Everything on this page rests on the wedge, and the wedge is the least reproducible number in a right heart catheter study. Over-wedging, under-wedging, reading at the wrong point in the respiratory cycle and a balloon in an incompletely occluded vessel all shift it by several mmHg, and in the example here a sixteen mmHg change in the wedge alone moves a patient from pre-capillary to combined to isolated post-capillary disease with the pulmonary vasculature untouched. The cardiac output does the same work from the denominator: hold the pressures and halve the output and the resistance doubles. Every figure here is derived from other measurements, so it carries their errors as well as its own. A derived index is never more reliable than the least reliable number that went into it. A derived haemodynamic number is read alongside the patient — the history, the perfusion, the lactate, the trend across serial measurements — and never instead of them. It supports a clinician’s judgement rather than replacing it.

Frequently asked questions

What is the formula for pulmonary vascular resistance?

In Wood units it is (mean pulmonary arterial pressure − pulmonary arterial wedge pressure) ÷ cardiac output, with pressures in mmHg and output in L/min. Multiply by 80 for dyn·s·cm⁻⁵. At an mPAP of 32, a wedge of 10 and an output of 4.5 L/min that is 4.89 Wood units, or 391 dyn·s·cm⁻⁵.

What is a normal pulmonary vascular resistance?

The 2022 ESC/ERS guidelines state that the upper limit of normal, and the lowest prognostically relevant threshold, is 2 Wood units — 160 dyn·s·cm⁻⁵. Reference cards print wider figures that do not agree with the guideline or with each other: 100 to 250 dyn·s·cm⁻⁵ on one, 20 to 130 on another. The guideline figure is the one with a stated prognostic basis.

Why is pulmonary resistance in Wood units and systemic in dyn·s·cm⁻⁵?

Convention, and nothing more. The two unit systems differ by exactly 80 — a pure unit conversion between mmHg·min/L and dyn·s·cm⁻⁵. The practical consequence is that a reader carrying systemic instincts into a pulmonary report, or the reverse, is eighty-fold out: a PVR of 400 dyn·s·cm⁻⁵ sounds trivially small next to a systemic 1000 and is in fact 5 Wood units, the guideline’s threshold for severe pulmonary hypertension in lung disease.

What happened to the diastolic pressure gradient?

The 2022 ESC/ERS guidelines stopped using it. It was proposed as a flow-independent replacement for the transpulmonary gradient in separating isolated from combined post-capillary pulmonary hypertension, and the guideline states it is no longer used for that purpose because of conflicting data. The transpulmonary gradient it was meant to replace had itself been shown to move with cardiac output and with pulmonary vascular recruitment rather than with vascular disease.

Does a normal PVR rule out pulmonary hypertension?

No. Pulmonary hypertension is defined by a mean pulmonary arterial pressure above 20 mmHg at rest, not by the resistance. A raised mean pressure with a wedge above 15 mmHg and a resistance at or below 2 Wood units is the guideline’s isolated post-capillary pattern — pressure transmitted from the left heart. A raised mean pressure with a normal wedge and a resistance below 2 is what the guideline calls unclassified pulmonary hypertension.

Related calculators

References

Humbert M, Kovacs G, Hoeper MM, et al. 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. Eur Heart J. 2022;43(38):3618–3731. PH “is defined by a mean pulmonary arterial pressure (mPAP) >20 mmHg at rest”; “the upper limit of normal PVR and the lowest prognostically relevant threshold of PVR is 2 Wood units”; the diastolic pressure gradient is “no longer used” to separate the two post-capillary patterns “because of conflicting data”.
Comments on the 2022 ESC/ERS guidelines for pulmonary hypertension. Rev Esp Cardiol. 2022. Sets out the haemodynamic table used here: pre-capillary “mPAP > 20 mmHg, PAWP ≤ 15 mmHg, PVR > 2 WU”, isolated post-capillary “PAWP > 15, PVR ≤ 2 WU”, combined “PAWP > 15, PVR > 2 WU”, and exercise PH as an “mPAP/cardiac output slope between rest and exercise > 3 mmHg/L/min”.
Impact of the new classification of pulmonary hypertension. Arch Bronconeumol. 2023 (S0300289623000042). The source of the 5 Wood unit figure: severe group 3 PH is “mPAP >20 mmHg and PVR >5 Wood units”, against group 3 PH as “mPAP >20 mmHg … with a pulmonary vascular resistance (PVR) >2 Wood units”.
Naeije R, Vachiery J-L, Yerly P, Vanderpool R. The transpulmonary pressure gradient for the diagnosis of pulmonary vascular disease. Eur Respir J. 2013;41(1):217–23. Defines the gradient as mean pulmonary arterial pressure minus wedge and shows why it fails: it “is sensitive to changes in cardiac output and both recruitment and distension of the pulmonary vessels”. A TPG above 12 mmHg was the conventional marker of disproportionate pulmonary hypertension.
Editorial on the normal pulmonary circulation at rest and on exercise. Eur Respir J. 2012;39(2):231. Restates the systematic review figure adopted by the 4th World Symposium on Pulmonary Hypertension: “a normal resting P̄pa of 14 ± 3.3 mmHg with an upper limit of normal of 20.6 mmHg in the supine position”.
Edwards Lifesciences. Normal Hemodynamic Parameters and Lab Values (EU master reference card). Cardiac output 4–8 L/min, cardiac index 2.5–4 L/min/m², stroke volume 60–100 mL/beat, stroke volume index 33–47 mL/m²/beat, SVR 800–1200 and SVRI 1970–2390 dyn·s·cm⁻⁵ (·m²), PVR 100–250 dyn·s·cm⁻⁵, MAP 70–105 mmHg, CVP 2–6 mmHg, PAWP 6–12 mmHg; prints MAP as “[SBP + (2 x DBP)]/3” and SVR as “MAP-RAP x 80/CO”.

Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/