Determination of Stroke Volume (SV) and Cardiac Output (CARO)

The amount of blood pumped out of each ventricle per beat, the stroke volume is about 70 mL in resting man of average size in the supine position which 70mL from left ventricle and 70 mL from right ventricle.

 The output of the heart per unit time is the cardiac output.

In resting supine man, it averages about 5.0 L/min (70x72 beats/min).

There is a correlation between resting cardiac output and body surface which the output per minute per square metre of body surface (cardiac index) averages is 3.2

Variations in cardiac output can be produced by changes in cardiac rate or stroke volume.

• The cardiac rate is controlled primarily by cardiac innervation, sympathetic stimulation increasing the rate and parasympathetic stimulation decreasing it.
• The stroke volume also determined in part by neural input, sympathetic stimuli making the myocardial muscle fibers contract with greater strength at any given length and parasympathetic stimuli having the opposite effect

Calculating stroke volume (SV)

SV (mL)= 100 + 0.5 PAP - 0.6 DAP - 0.6 ag

PAP - pulse arterial pressure

DAP - Diastolic arterial pressure

Ag - age surveyed (complete years)

Calculating Cardiac Output (CarO)

CarO (L) = HR (bpm) x SV (ml) / 1000

HR- Heart Rate