Cardiac output is defined as the amount of blood that is pumped to the heart within one minute.
The formula for calculating cardiac output is:
DC = FC x VS
To know the value of cardiac output (CO) it is necessary to multiply the heart rate (HR) by the stroke volume (SV), which is the amount of blood pumped in one minute.
For example, if a person's heart beats 60 times a minute and pumps 70 ml of blood, the cardiac output will be 4200 ml/minute (4.2 liters of blood per minute).
The amount of blood that reaches the heart per minute is called venous return. Under normal conditions, the venous return value should be the same as the cardiac output.
Cardiac output should not be confused with blood volume. Volemia is the volume of blood that circulates and debt is the speed of blood circulation.
Decreased and increased cardiac output
cardiac output diminished it happens when there is a reduction in the amount of blood that is pumped to the heart. A decreased cardiac output is hypothesized when the volume falls below 4 liters of blood per minute.
Decreased output can be a symptom of hypertension, cardiogenic shock, arrhythmia, or heart failure.
cardiac output increased (or elevated) happens when there is an increase in the flow of blood pumped to the heart. It is considered that there is an increased flow when the blood volume is greater than 8 liters per minute.
Tachycardia can be a symptom of increased cardiac output.
Increased debt is a rare health condition. It is related to the difficulty of cardiac output to meet demand, as it requires more than the heart can offer. In medicine this condition is called high-output heart failure.
Cardiac output and exercise
During physical exercise, cardiac output may increase. This is because the output is a result of the heart rate (which increases during exercise) multiplied by the volume of blood pumped to the heart.
During exercise there is a redistribution of debt, that is, more blood is sent to the areas of the body that are more active during the practice.