A Cardiac Output device measures Cardiac output (Q) which is the volume of blood being pumped by the heart, in particular by a ventricle in a minute. This is measured in dm3 min-1 (1 dm3 equals 1000 cm3 or 1 litre). An average cardiac output would be 5L - 7L per min for a human male and 4.5L per min for a female.