Chapter 2: Cardiovascular System

Explanatory Notes

Circulation

The initial diagram shows a simplified circulation of the flow of blood through the heart and the remainder of the body. The heart, as is well known, is situated in the centre of the chest. Its two main neighbours are the lungs and consequently any upset to these organs can have impact on the others e.g. tension pneumothorax (see diagram 3) can significantly impair the heart action as can mediastinal emphysema. The important pulses to look for in the body are in the neck (carotids), the wrists (radials) and in the groins (femorals) and at the ankle during assessment of leg injuries. diagram 1(b)

Shock

This is where there is failure of the heart to maintain normal circulation. The features of it are:-

pale
cold
clammy
may have altered consciousness
low blood pressure
shallow and weak breathing
rapid thready pulse (rate >100)

On examination of the periphery it will be noted that the capillary return is lengthened, the peripheral pulses may disappear in the following order according to the severity of shock - radials and then femorals. The usual cause of shock in trauma is either external or internal bleeding. The significance of the latter is that it cannot be controlled without surgical help and, as such the subject having an injury like this requires rapid transfer to a hospital facility.