A MECHANICAL MEDICINAL LEECH?

US researchers have developed a mechanical leech which they say can replace the flesh-and-blood variety used to prevent blood from clotting in plastic surgery.

Researchers at the University of Wisconsin–Madison and the William S. Middleton Memorial Veterans Administration Hospital have applied to patent a device they say promotes the flow of blood in tissues "without the unpleasantness of having a blood-sucking parasite attached to your body".

Medicinal leeches were used for everything from headaches to stomach-aches in the time of ancient Egypt and have re-emerged recently in modern medicine to treat venous congestion. This is a complication that can occur after reconstructive surgery in which blood flowing into the reconstructed tissue cannot flow back out because the veins clot up.

This condition, which can kill tissue by depriving it of oxygen and nutrients, most often arises in complicated procedures where tissue is moved from one place to another.

The treatment of choice in such dire situations is to place leeches strategically on the tissue to help draw the blood through and stop it from clotting.

According to researcher Michael Conforti, however, the mechanical leech has a number of distinct advantages over its flesh-and-blood counterpart: it's more sterile, does a better job at delivering the anticoagulant heparin to the affected tissue, has a rotating tip that further inhibits coagulation, and unlike the real leech, it is insatiable.

From the patient's point of view, say the researchers, the mechanical leech overcomes the squeamishness factor and doesn't slip off patients and re-attach itself to other parts of the body.

According to Randall Sach, a spokesperson of the Australian Society of Plastic Surgeons, most plastic surgery clinics would use leeches two or three times a year to save tissue that would otherwise die.

"Leeches are only employed when things are desperate. It's a short-term solution to get circulation through the tissue until it develops its own."

Mr Sach estimates that about one third of patients feel uncomfortable about having leeches on their body.

"But when faced with the alternative of losing the tissue, they generally accept it," he said.

The concept of the mechanical leech is "not unreasonable", he said, but whether it would be used would depend on factors such as cost, availability and versatility.

He said that when leeches are not available, another option is to shave off some skin and drip heparin onto the tissue, wiping it every half hour.

"Perhaps this mechanical leech is an extension of this kind of approach."

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