Recently, one of my university students questioned the need to learn bleeding control and bandaging techniques since most injury victims can be rapidly transported to a medical facility.

While this may be true to some degree, the ability of a first-aider to control external bleeding can significantly improve a victim's chances of survival and help the healing in lesser injuries.Information on bleeding

Most large blood vessels are located deep in the muscle and close to the long bones. These, then, are more likely to be injured in a fracture than in soft-tissue trauma. Lacerations near the joints are more likely to involve damage to blood vessels since they are closer to the body surface.

If a blood vessel is completely severed, it can draw back into the tissue, constrict its diameter and slow the bleeding dramatically. If it is only partially cut across its diameter, however, constriction is incomplete because the vessel may not contract and the loss of blood may not slow as dramatically.

Clotting serves as a protective covering for the wound until the tissues underneath can repair themselves. In the healthy individual, initial clot formation normally takes about 10 minutes. Clotting time lengthens in a person who has lost a great deal of blood over a prolonged period of time, is taking aspirin or anti-coagulants, is anemic, is a hemophiliac, or has severe liver disease.

Controlling bleeding

External blood loss is most effectively controlled by direct pressure. Maintain the pressure for at least 10 minutes. Should direct pressure fail to stop the bleeding, consider elevating the wound. This should decrease the blood pressure at the bleeding site and, subsequently, the flow of blood. It should be used only for an isolated limb that is otherwise uninjured. It should be used in conjunction with direct pressure.

If elevation is not possible or does not seem to help, find the arterial pulse point near the wound. Apply firm pressure on the point until the bleeding slows or stops. Applying pressure to the pulse point should be done while using direct pressure on the wound. The advantage of pressure points over tourniquets in bleeding control is that the entire blood flow to the limb is not affected. Other arteries supplying the limb and all veins should function normally.

The tourniquet is controversial. Since it is intended to stop all blood flow to the extremity, it should be applied only after all other methods of bleeding control have failed. One complication of tourniquet use is the accumulation of by-products of anaerobic metabolism. This results in the buildup of toxins such as lactic acid. When the tourniquet is later released, these toxins will flow into the victim's bloodstream. The entrance of these materials into the circulatory system may be life-threatening.

The dressing of a wound has a direct significance on controlling bleeding. A dressing should be just large enough to cover the bleeding site and small enough to ensure that the pressure is directed to the bleeding source. It should also be non-adherent.

A bandage should apply direct pressure yet not compromise blood circulation. After applying a bandage, check the circulation periodically by evaluating the pulses, skin temperature and capillary-refill times.

First aid for external bleeding is relatively straightforward. Proper techniques can have a significant impact on an injured victim.

- Alton Thygerson is a professor of health sciences at Brigham Young University.