Wilderness First Aid Basics

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Shock

Shock may be present with almost any injury or illness, and is usually present in any serious one. Shock is what occurs when there is inadequate organ perfusion; that is, decreased oxygen passes through the organs. To understand this, we need to know how the circulatory system works.

The heart is a pump. The veins and arteries work like flexible hoses, carrying blood to and from every part of the body. Near the heart, the arteries carrying blood from the heart are large. They branch often, and get smaller and smaller. Finally, at the outer ends of the branches, they become so fine that parts of the blood pass through their walls. This blood reaches each cell of the body, bringing oxygen and food to it. The food and oxygen are used or "burned" in the cells, keeping the cells healthy and producing the heat needed to live.

When the blood leaves the cells, it carries their waste products back into tiny veins, which pour into larger ones and finally into the largest veins which feed directly into the heart.

Now the blood has almost made a round trip-but there is one more stop before circulating once again. The heart pumps the blood to the lungs and back to the heart. In the lungs, the blood loses the waste gases (mostly carbon dioxide) it has picked up in the cells, and each red blood cell picks up a new load of oxygen. Then it returns to the heart and the heart pumps it again through the arteries to the cells.

The most important point of this whole process is the provision of oxygen and food to the cells. If this is interrupted for only a few minutes, cells start to die. If the cells that die are in the vital organs especially the brain, heart, or kidneys-the whole body will also quickly die. When organs are not getting enough oxygen to work properly, the signs of shock start to show. But what causes shock? In order for the blood to get oxygen to the cells, the blood has to be under some pressure. This pressure is provided by the pump-the heart-and maintained by the veins and arteries, which are able to get slightly larger or smaller to control the pressure.

Several things might cause this pressure to drop. If there is a "leak" in the system, from a bad cut, blood flows out and the pressure drops. The body tries to deal with this automatically.

BODILY RESPONSES

Several types of illnesses can bring on shock by causing the large blood vessels in the trunk to loosen and expand. The vessels become bigger and can hold more, but the amount of blood in them remains the same, so the blood pressure drops. Sometimes a severe emotional shock can cause this to happen. (Fainting is not the same as shock, but it is caused by a shortage of blood to the brain.)

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