Cardiac Output and Hemodynamics Calculator
Calculate cardiac output, cardiac index, and systemic vascular resistance from heart rate, stroke volume, body surface area, and mean arterial pressure.
Cardiac output (CO) is the volume of blood pumped by the heart per minute. It is the product of heart rate and stroke volume:
CO (L/min) = HR (beats/min) x SV (mL/beat) / 1000
A resting adult has a CO of roughly 4-6 L/min. During maximal exercise, trained athletes can reach 30-40 L/min.
Cardiac index (CI) normalizes CO to body surface area, allowing comparison across patients of different sizes:
CI = CO / BSA (L/min/m^2)
Normal CI is 2.5-4.0 L/min/m^2. Values below 2.2 suggest cardiogenic shock. This calculator uses the DuBois formula for BSA:
BSA = 0.007184 x height^0.725 x weight^0.425 (m^2)
Systemic vascular resistance (SVR) measures the resistance the left ventricle must overcome to eject blood. It requires mean arterial pressure (MAP) and central venous pressure (CVP):
SVR = (MAP - CVP) / CO x 80 (dynes s/cm^5)
Normal SVR is 800-1200 dynes s/cm^5. The factor of 80 converts from mmHg/(L/min) to CGS units. Elevated SVR means the heart is working harder to push blood through constricted vessels.
Mean arterial pressure can be estimated as: MAP = diastolic + (systolic - diastolic)/3, though direct measurement is preferred in clinical settings.
Pulse pressure = systolic - diastolic. Narrow pulse pressure (less than 25 mmHg) can indicate low stroke volume. Wide pulse pressure may indicate aortic regurgitation or high stroke volume states.