SEVERAL PROCEDURES STOP BLOOD LOSS DURING SURGERY

Question: When I watch operations being performed on some of the cable television channels, there is almost no bleeding even though a lot of cutting is being done. When I get even a small cut, it bleeds quite a bit before stopping. How do surgeons operate without causing a lot of bleeding?

Answer: The body, itself, has two very effective mechanisms to prevent blood loss after an injury.

Blood vessels, especially arteries, have muscular walls. When they are cut, these muscles contract, causing the cut end of the vessel to close, stopping the blood loss.

There is also the clotting mechanism, a very complex cascade of steps that are set in motion when a blood vessel is injured. Factors are released into the blood from the injured area, and they cause a sequence of events to occur to cause a plug made up of blood cells and small structures in the blood called platelets. The plug seals the cut end, and if left undisturbed, the end of the vessel eventually will seal itself permanently.

Nearly every operation entails some blood loss, even if it is only a little. However, a number of procedures can reduce bleeding. Before cutting skin, some surgeons inject a little bit of epinephrine or adrenaline around the area of the incision. This causes the blood vessels in the skin to constrict, so that when the incision is made, blood loss is minimal or absent.

The effect lasts about an hour or two. The use of a sharp scalpel also reduces blood loss. Because the blood vessels are cut so cleanly, they can retract and close down more readily. Cuts made by less sharp objects, where some ripping and tearing occur, will bleed more.

In situations where the vessels cannot retract normally, more bleeding will occur. This happens often when incisions are made through a scar. The scar tissue serves to hold the blood vessel open so that retraction cannot occur, and the result may be a lot of bleeding.

A partially cut vessel will bleed more, too. The vessel tries to retract and, in doing so, makes the partial cut gape more, which increases the bleeding.

An electrocautery pencil is a small hand-held device connected to a current generator. The tip has a flat blade with no sharp edge. Electric current passing through this tip cuts tissue very cleanly by generating very high temperatures at the point of tissue contact.

Cutting cautery seals small blood vessels as it goes through tissue and produces an almost bloodless surgical field. A laser does much the same.

Several types of lasers will do this, but the most common is the carbon dioxide laser, which targets water in tissues. Laser incisions, however, are slower than cutting cautery. Neither technique is good for the skin, and skin incisions made with cautery or a laser are slower to heal.

Some blood vessels are too large to be affected by epinephrine injections, cautery or a laser. These need to be carefully identified before they are cut. Usually, they are clamped in two places with instruments called hemostats, then the vessel is cut between the hemostats and the ends are tied with one of several types of suture material.

Sometimes it is necessary to work in an area supplied by a blood vessel which cannot be cut and tied, or on the blood vessels, themselves, such as in vascular surgery. There are clamps available which can temporarily be applied and which will not damage the vessel. When the procedure is completed, the clamp is released, and the blood flow through the vessel is restored.

In some operations – particularly those that are lengthy or involve major vessels – blood loss is inevitable. You can expect to lose as many as several units of blood.

Of course, transfusions can be given when necessary, but a device called a cell saver may recover a lot of the blood. As bleeding occurs, the blood is suctioned from the operating field and into a machine that washes it and prepares it to be returned back to the patient. In effect, it recycles blood that would be lost otherwise. It can greatly reduce the need for transfusions in some of these cases. Cell savers cannot generally be used in cases of infection or cancer, however.

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