Stroke Volume Variation Calculator

About this calculator

Stroke volume variation (SVV) measures how much a patient's stroke volume swings with each breath of positive-pressure mechanical ventilation, calculated as (SVmax − SVmin) ÷ SVmean over a respiratory cycle, typically expressed as a percentage. It works because in a fluid-responsive patient, the swings in intrathoracic pressure from ventilation cause larger cyclic changes in venous return and stroke volume — an SVV above roughly 10-13% suggests the heart is on the steep part of the Frank-Starling curve and would likely benefit from a fluid bolus, while a low SVV suggests the patient is already adequately filled.

This calculator takes the maximum and minimum stroke volumes recorded over a ventilator cycle — typically from an arterial pulse contour monitor — and returns the SVV percentage. Anesthesiologists managing goal-directed fluid therapy in the OR, and intensivists titrating fluids in mechanically ventilated ICU patients use it as a dynamic, load-independent predictor of fluid responsiveness, generally more reliable in this setting than static measures like central venous pressure.