Stroke Volume Variation (SVV) and PPV Calculator

The respiratory swing in pulse pressure or stroke volume, as a percentage — and the list of conditions that invalidate it, which is longer than the formula and is the real content of the measurement.

Last updated 8 Oct 2026

Pulse pressure variation and stroke volume variation

Normalised respiratory swing

Largest value in the respiratory cycleEnter pulse pressures in mmHg for PPV, or stroke volumes in mL for SVV. The arithmetic is the same either way, because the result is a normalised ratio and the units cancel. Read both values over one mechanical breath, not over a minute.

Smallest value in the same respiratory cycleThe trough of the same cycle. Before entering anything, check the prerequisites in the table below: in a patient breathing spontaneously, in atrial fibrillation, on a tidal volume under 7 to 8 mL/kg or with an open chest, this number has a published direction of failure and no useful threshold.

12.0%Example

Largest pulse pressure 44 mmHg, smallest 39 mmHg, over one mechanical breath in a passively ventilated patient

The formula, and the prerequisites that decide whether it means anything

PPV (%) = 100 × 2 × (PP_max − PP_min) ÷ (PP_max + PP_min)
SVV (%) = 100 × (SV_max − SV_min) ÷ mean SV
Both reduce to: the swing over one respiratory cycle, divided by the mean of that cycle

the two denominators: Biais and colleagues print PPV with the mean written out as (PPmax + PPmin)/2, which is what this page computes. Monitors computing SVV use the mean stroke volume over the whole respiratory cycle instead. Over a single sinusoidal cycle the two are nearly identical; where the swing is asymmetric they differ slightly, and the difference is far smaller than the grey zone
what it is measuring: a positive-pressure breath transiently reduces venous return and so reduces left ventricular stroke volume a couple of beats later. The size of that dip depends on where both ventricles sit on their function curves, which is why the swing carries information about preload reserve that a static filling pressure does not
the published threshold: a meta-analysis of 22 studies and 807 patients found a pooled sensitivity of 88% and specificity of 89%, with a median threshold of 12% and an interquartile range of 10 to 13%. The threshold itself varies between studies by as much as the grey zone is wide
the grey zone, 9 to 13%: Cannesson and colleagues’ operating-theatre cohort: the band in which neither sensitivity nor specificity reaches 90%, containing an estimated 24% of values met in practice. Their patients were ventilated at a mean tidal volume of 7.9 mL/kg, with 51% above 8
the grey zone in intensive care, 4 to 17%: Biais and colleagues, 556 ventilated ICU patients who met the validity prerequisites: “PPV values between 4 and 17%, encountered in 62% patients exhibiting validity prerequisites, did not predict fluid responsiveness”. The ICU zone is four times as wide as the theatre one and covers nearly two thirds of patients
the prerequisites, and the direction each failure takes: the measurement assumes a passive patient in sinus rhythm, a tidal volume big enough to load the right ventricle, a closed chest, a normal abdominal pressure, enough cardiac cycles inside each breath and a right ventricle that is not failing. Spontaneous breathing effort, arrhythmia, raised intra-abdominal pressure and right ventricular failure give FALSE POSITIVES — a real swing with no preload reserve behind it. Low tidal volume, low lung compliance, an open chest and a heart-rate-to-respiratory-rate ratio below 3.6 give false negatives. The table below gives the mechanism for each
right ventricular failure in particular: the one worth singling out. A failing right ventricle is afterload-sensitive and every mechanical breath raises pulmonary vascular resistance, so its output drops with each inflation. The swing is large, genuine, and points the wrong way
the tidal volume challenge: the published route round a protective tidal volume: raise it transiently to 8 mL/kg and read the CHANGE rather than the level. A rise in absolute PPV of 3.5% or more, or in SVV of 2.5% or more, makes fluid responsiveness very likely

Worked example

Largest pulse pressure 44 mmHg, smallest 39 mmHg, over one mechanical breath in a passively ventilated patient
Swing = 44 − 39 = 5 mmHg
Mean of the two = (44 + 39) ÷ 2 = 41.5 mmHg
PPV = 100 × 5 ÷ 41.5 = 12.0%, which is also 100 × 2 × 5 ÷ 83
That lands inside the 9 to 13% grey zone — and on the median threshold of 12% from the 22-study meta-analysis, which is to say the published cut-off and the published zone of uncertainty are the same number
Widen the swing to 48 and 36: PPV = 28.6%, above the grey zone
Narrow it to 42 and 40: PPV = 4.9%, below the grey zone
Boundary check, because a threshold written with the wrong inequality moves one patient in a hundred: 53.25 and 46.75 give exactly 13.0%, which this page places INSIDE the grey zone because Cannesson's zone is stated inclusively — while 53.3 and 46.7 give 13.2% and fall above it
The same two stroke volumes instead of pulse pressures — 44 and 39 mL — give the identical 12.0%, because the result is a ratio and the units cancel. What does not carry across is the cut-off: the grey-zone work was done on PPV
Now the part that matters. If that patient was taking breaths of their own, or in atrial fibrillation, or ventilated at 6 mL/kg, or had an open chest, this 12.0% has a published direction of failure and no threshold at all — see the table

The conditions that invalidate PPV and SVV, and which way each fails

Directions of failure as tabulated by Monnet, Marik and Teboul (Annals of Intensive Care 2016), with the heart-rate-to-respiratory-rate threshold of 3.6 as published there. The distinction between the two columns is the useful part: a false negative wastes the measurement, while a false positive produces a confident high number in a patient who has no preload reserve — which is why right ventricular failure is at the bottom of this list and not at the top of the formula.
Condition	Direction of failure	Mechanism
Spontaneous breathing effort	False positive	The patient’s own inspiratory efforts create swings the formula attributes to the ventilator
Cardiac arrhythmia, especially atrial fibrillation	False positive	Beat-to-beat stroke volume varies with diastolic filling time rather than with the breath
Low tidal volume or low lung compliance	False negative	Too little airway pressure reaches the pleural space to load the right ventricle. The floor is about 7 to 8 mL/kg
Open chest or open sternum	False negative	Airway pressure is not transmitted to the heart at all
Raised intra-abdominal pressure, pneumoperitoneum	False positive	More pressure is transmitted to the thorax per breath, exaggerating the swing without extra preload reserve
Very high respiratory rate, HR/RR below 3.6	False negative	Fewer than about four cardiac cycles per breath, so the dip cannot develop
Right ventricular failure	False positive	The afterload-sensitive right ventricle drops its output with every breath. A real swing with no preload reserve behind it

Published thresholds and grey zones, with their cohorts

The grey zone in intensive care is four times as wide as the one in theatre and covers nearly two thirds of patients, and the difference is largely tidal volume. Note the fourth row: the commonly quoted SVV figure of 10 to 15% comes from a manufacturer’s reference card with no derivation cohort stated, which is a weaker provenance than anything else in this table — the grey-zone work was all done on pulse pressure variation.
Figure	Value	Cohort	Source
PPV pooled threshold	12% (IQR 10 to 13%)	22 studies, 807 patients; pooled sensitivity 88%, specificity 89%	Monnet, Marik and Teboul 2016
PPV grey zone, operating theatre	9 to 13%, about 24% of values	413 theatre patients, mean tidal volume 7.9 mL/kg	Cannesson et al. 2011, as reported in Monnet 2016 and Biais 2014
PPV grey zone, intensive care	4 to 17%, 62% of patients	556 ventilated ICU patients meeting the validity prerequisites	Biais et al. 2014
SVV, quoted normal	Under 10 to 15%	Not stated as a derivation cohort — a manufacturer’s reference figure	Edwards Lifesciences reference card
Tidal volume challenge	Absolute rise in PPV of 3.5% or SVV of 2.5%	Patients with ARDS ventilated at low tidal volume, transiently raised to 8 mL/kg	Monnet, Marik and Teboul 2016

The formula is one line; the prerequisites are the measurement

A positive-pressure breath squeezes the thorax, venous return falls, and a couple of beats later left ventricular stroke volume dips. How far it dips depends on where both ventricles are sitting on their function curves: a ventricle with preload reserve loses a lot of stroke volume when its filling is cut, and one already on the flat part of the curve loses very little. That is why the respiratory swing carries information a static filling pressure cannot. The arithmetic is the swing divided by the mean, and it is identical whether the quantity swung is the pulse pressure from an arterial line or the stroke volume from a pulse-contour monitor.

The threshold is less settled than the formula. A meta-analysis of 22 studies and 807 patients found a pooled sensitivity of 88% and specificity of 89% with a median cut-off of 12%, and an interquartile range of 10 to 13%. Cannesson and colleagues then asked a sharper question: over what range does the number fail to discriminate at all? In theatre patients the answer was 9 to 13%, containing roughly a quarter of the values met in practice. Biais and colleagues repeated it in 556 intensive care patients who met every validity prerequisite and found a grey zone of 4 to 17%, covering 62% of them. The difference is mostly tidal volume, and the honest reading is that in a protectively ventilated ICU population the measurement is uninformative in most patients.

Which brings us to the list, and the list is the content of this page. The measurement assumes a passive patient in sinus rhythm, on a tidal volume big enough to load the right ventricle, with a closed chest, a normal abdominal pressure, enough cardiac cycles inside each breath, and a right ventricle that is not failing. Each assumption fails in a known direction. Spontaneous breathing effort, arrhythmia, raised intra-abdominal pressure and right ventricular failure all give false positives — a big swing with no preload reserve behind it. Low tidal volume, low compliance, an open chest and a respiratory rate too high relative to the heart rate all give false negatives. The asymmetry matters: a false negative wastes a measurement, while a false positive hands a clinician a confident number pointing the wrong way.

Right ventricular failure deserves singling out. A failing right ventricle is exquisitely afterload-sensitive, and every mechanical breath raises pulmonary vascular resistance, so its output drops with each inflation and the arterial swing is large and genuine. Nothing in the number distinguishes that from preload responsiveness. Where the tidal volume is the obstacle rather than the physiology there is a published way forward: raise the tidal volume transiently to 8 mL/kg and watch the change rather than the level — a rise in absolute pulse pressure variation of 3.5% or in stroke volume variation of 2.5% makes a fluid response very likely. This page computes a number and gives the published ranges with their sources. It renders no management decision: it does not say whether the figure is adequate for this patient, and nothing on it is a treatment or dosing recommendation. 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 pulse pressure variation?

PPV as a percentage is 100 × 2 × (PPmax − PPmin) ÷ (PPmax + PPmin), both read over one mechanical breath — which is the swing divided by the mean of the two. At 44 and 39 mmHg that is 12.0%. Stroke volume variation is the same calculation on stroke volumes, with the mean taken over the respiratory cycle.

What is the grey zone for pulse pressure variation?

It depends on the population, and this is the figure to quote rather than a single cut-off. In 413 operating-theatre patients ventilated at a mean tidal volume of 7.9 mL/kg, Cannesson and colleagues found a grey zone of 9 to 13%, containing about 24% of values. In 556 ventilated intensive care patients who met every validity prerequisite, Biais and colleagues found 4 to 17%, containing 62% of patients. The pooled threshold from 22 studies is 12% with an interquartile range of 10 to 13%.

When is PPV or SVV unreliable?

In spontaneous breathing effort, cardiac arrhythmia, tidal volumes below about 7 to 8 mL/kg, low lung compliance, an open chest or sternum, raised intra-abdominal pressure, a heart-rate-to-respiratory-rate ratio below 3.6, and right ventricular failure. Each of those fails in a published direction: the first two, raised abdominal pressure and right ventricular failure give false positives; low tidal volume, low compliance, an open chest and a very high respiratory rate give false negatives.

Can I use PPV during protective ventilation at 6 mL/kg?

Not at its usual threshold — a tidal volume that low does not load the right ventricle enough, and the failure is towards a false negative. The published route round it is the tidal volume challenge: raise the tidal volume transiently to 8 mL/kg and read the change rather than the level. A rise in absolute PPV of 3.5% or more, or in SVV of 2.5% or more, makes fluid responsiveness very likely.

Are the cut-offs for SVV and PPV the same?

The arithmetic is the same and the published evidence is not. The grey-zone and meta-analysis work cited here was done on pulse pressure variation. The commonly quoted stroke volume variation figure of under 10 to 15% comes from a manufacturer’s reference card with no derivation cohort stated, which is a weaker provenance. This page bands on the PPV grey zone and prints the SVV figure in the table with its source rather than treating the two as interchangeable.

Related calculators

References

Monnet X, Marik PE, Teboul J-L. Prediction of fluid responsiveness: an update. Ann Intensive Care. 2016;6:111. Source of the pooled figures (22 studies, 807 patients; sensitivity 88%, specificity 89%; “median threshold of the PPV was 12% (interquartile range 10–13%)”), of the 9 to 13% grey zone covering about 24% of values, of the tidal volume challenge, and of Table 2 — the direction in which each prerequisite fails, including “very high respiratory rate (HR/RR < 3.6)”.
Biais M, Ehrmann S, Mari A, et al. Clinical relevance of pulse pressure variations for predicting fluid responsiveness in mechanically ventilated intensive care unit patients: the grey zone approach. Crit Care. 2014;18:587. 556 ICU patients. Prints the formula as “PPV (%) = 100 x 2 [(PPmax − PPmin)/(PPmax + PPmin)]” and concludes: “PPV values between 4 and 17%, encountered in 62% patients exhibiting validity prerequisites, did not predict fluid responsiveness.”
Michard F, Chemla D, Teboul J-L. Meta-analysis of pulse pressure variation (PPV) and stroke volume variation (SVV) studies: a few rotten apples can spoil the whole barrel. Crit Care. 2023;27:460. Argues that pooled accuracy figures are inflated by studies that ignored the prerequisites, naming “atrial fibrillation, spontaneous breathing activity, low tidal volume”, the open chest and pneumoperitoneum, and treats tidal volumes below 7 mL/kg as outside the measurement’s validity.
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/