Stroke Volume Calculator

Stroke volume (SV) represents the volume of blood ejected from the ventricles per heartbeat. The primary formula relates stroke volume directly to cardiac output (CO) and heart rate (HR): SV = (CO * 1000) / HR, where cardiac output is typically measured in liters per minute and heart rate in beats per minute. Additionally, clinicians frequently normalize this metric using the body surface area (BSA)—calculated via the Du Bois formula based on height and weight—to derive the stroke volume index (SVI), which accounts for differences in body size across diverse patient populations.

Consider a patient with a measured cardiac output of 6.0 liters per minute and a resting heart rate of 75 beats per minute. To find the stroke volume, first convert cardiac output to milliliters per minute by multiplying by 1000, giving 6,000 mL/min. Next, divide this value by the heart rate: SV = 6,000 / 75 = 80 milliliters per beat. If this same patient has a body surface area of 2.0 square meters, their stroke volume index would be calculated as 80 mL/beat divided by 2.0 m², yielding an SVI of 40 mL/beat/m², indicating healthy left ventricular performance.

Always ensure that input units are consistent before performing manual checks or verifying calculator outputs, particularly when converting liters to milliliters for cardiac output. When assessing stroke volume index, remember that body surface area formulas like Du Bois rely on accurate height and weight measurements; minor errors in scaling can alter indexed hemodynamic values. Furthermore, always evaluate stroke volume in the context of the patient's overall clinical presentation, including blood pressure, systemic vascular resistance, and fluid responsiveness.