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Cardiac output

Areen Saied Halawa ID:1303

Definition: Cardiac output (CO) is the quantity of blood pumped into the aorta each minute by the heart.

This is also the quantity of blood that flows through the circulation.
Cardiac output is one of the most important factors to consider in relation to the circulation because it is the sum
of the blood flows to all the tissues of the body. [1]

When one states that cardiac output is controlled by venous
return, this means that it is not the heart itself that is normally

the primary controller of cardiac output. Instead, it is the
various factors of the peripheral circulation that affect flow of

blood into the heart from the veins, called venous return, that
are the primary controllers. [1]

Normal Value: Normal cardiac output in adults is 5-6 lit/min

(approximately 8% of the body weight).[1] Age Cardiac output is less in Figure 1
elderly. This occurs due to decrease in heart rate and stroke volume in aged

individuals. In children, though the heart rate is more, cardiac out- put is less due to less stroke volume.[2]

A. Conditions that increase cardiac output:
1. Exercise

2. Anxiety

3. Emotion and excitement
4. Increased environmental temperature
5. After eating

6. Pregnancy
B. Conditions that decrease cardiac output:

1. Standing from lying posture

2. Excessive sweating Figure 2
C. Conditions that do not change cardiac output:

1. Sleep

2. Mild to moderate change in environmental temperature [2]

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