One of the definitions of the word "periphery" is "outward bounds" or "border area." Peripheral circulation, in layman's terms, refers to blood flow that reaches the upper and lower extremities of the body and the surface of the skin. The upper and lower extremities and the surface of the skin can be thought of as the outward bounds or the border area of the body. This type of circulation also might be loosely described as blood flow to the arms, hands, legs, feet and the uppermost layer of the skin where blood vessels lie — the dermis. Although the epidermis is the uppermost layer of the skin, it does not contain blood vessels, so peripheral circulation refers to blood flow to the dermis and the extremities.
Peripheral circulation produces what are known as peripheral pulses, which serve as a confirmation, particularly to healthcare providers, that the extremities of the body and the dermis are receiving oxygenated blood and all of the nutrients they need that are carried in the blood. For example, the presence of a radial pulse or the pulse felt at the wrist confirms that there is blood flow to the hands. It is possible to have normal central pulses and one or more weak peripheral pulses if there is a health condition that affects a person's peripheral circulation. There are even situations in which central circulation is normal at the same time that peripheral circulation to an extremity or to part of the skin is totally absent.
When healthcare providers, especially emergency medical technicians (EMTs) and paramedics, splint fractured bones in the field, they should verify that there is adequate peripheral circulation. For example, if the patient's leg is broken and splinting takes place before the patient arrives at a medical facility, the medic assesses at least the dorsalis pedis pulse to ensure that blood flow is reaching the foot. He or she also should check the posterior tibial pulse. This verification of circulation to the periperhy of the body is performed before and after splinting.
Among the signs of poor peripheral circulation are cold hands and feet and a pale complexion. Any problems with the circulatory system, however, could produce the same signs as well as other symptoms. Circulation involves not only the pumping action of the heart but also the flow of blood through a vast network of blood vessels. Those blood vessels are the arteries, which branch into arterioles and finally into the tiniest vessels, the capillary bed. They also include the veins, which branch into venules and finally into the capillary bed as well.