CARDIAC OUTPUT

10.10.2011

Posted on 1:36 AM by know about heart

It is the amount of blood that is ejected by each ventricle into the aorta or systemic circulation in each minute.

NORMAL VALUE:

5 to 6 liter per minute (when heart rate is about 75 beats per minute and the stroke volume is 70 to 80 ml).

Average: 5 liter per minute.

FACTORS AFFECTING CARDIAC OUTPUT:

It is increased in some physiological condition_

1) It is increased with age.

2) During exercise, cardiac output is increased markedly.

3) During eating, cardiac output is increased.

4) If body surface area is, more cardiac output is more.

5) Cardiac output is greater in sitting and lying position than erect posture due to venous return.

6) In some normal condition such as emotion, excitement increased cardiac output.

In some pathological or clinical condition, cardiac output is increased:

1) Hyperthyroidism: Hyperthyroidism increase heart rate and body metabolism, that cause increase cardiac output.

2) Fever

3) Anaemia

4) Fibrillation

5) Anterior venous fistula.

Cardiac output is decreased in some condition:

1) Hemorrhage: if there is blood loss from the body, the amount of blood decreased. Thus cardiac output is decreased.

2) Heart disease: in certain heart disease such as myocardial infarction(heart attack), congestive cardiac failure etc.

3) Shock

MEASUREMENT:

It is measured by two ways:

1) Direct method

2) Indirect method: In human beings, it is measured by indirect method.It is done by following methods:

A) Oxygen Fick method

B) Indicator dilution method

FACTORS CONTROL CARDIAC OUTPUT:

Some factors that control cardiac output, such as stroke volume, total peripheral resistance, heart rate, venous return, frank starling low etc.