Cardiac output refers to the fraction of blood uptake of the heart, its normal value is more than 50%, some regulations are more than 55%, but generally as long as it is more than 50% heart function is considered normal. For the cardiac output it suggests the situation of heart function, if it can be greater than 50% uptake fraction is normal, less than 50% greater than 40% belongs to is a mild decline in heart function. If the cardiac uptake fraction is 30%-40%, it is a moderate cardiac insufficiency. If the cardiac output is also the blood uptake fraction is less than 30%, it is more serious cardiac insufficiency. So for the determination of cardiac uptake fraction, there is a very important reference value, the lower the number tends to suggest that the poorer the cardiac function, its normal value should be more than 50%.