KIDNEY STONES: 2 NEW TREATMENTS

West German doctors developed two new techniques, one using high-energy shock waves, to remove kidney stones much less painfully and without the customary major surgery.

The techniques also promise to reduce by several weeks the recovery period for tens of thousands of patients. In one of the new methods, the kidney stone is extracted directly through the skin, but the patient still must undergo general anesthesia. The other methods, generally painless, involves no surgery at all. It relies on the delivery of high-energy electric shock waves monitored by X-rays.

The overwhelming majority of kidney stones pass out of the body on their own, often accompanied by excruciating pain. Surgery is necessary in about 20 per cent of kidney stone cases. In the operation that has been used for decades, the surgeon cuts . through layers of tissue to reach the kidney in the lower back, then is able to reach into the organ to remove the stone by hand and with forcepts. Patients usually stay in the hospital for one or two weeks, and are limited in the amount of physical activity and work they can undertake for another four or five weeks.

In most cases the new techniques should do away with this major operation. But people who develop one kidney stone often develop another, and neither technique prevents the formation of new stones.

Doctors first inject a chemical dye to outline the kidneys in X-rays. Then they insert a wire, much like a needle, the kidney. This part of procedure requires no anesthesia. The next day, the surgeon uses the wire as a guide to insert a tube into the kidney. The tube, which contains instruments and fiberoptical devices, anables doctors to see the kidney both directly and on a television screen. Depending on the circumstances in each case, the doctors can then remove the stone under direct vision or they can pulverize it by sending ultrasound through the tube. The small pebbles are then removed with a suction device. This procedure usually takes no more than 90 minutes and patient's hospital stays have averaged only four days. The technique was successful in 104 of 109 cases.

The second technique was developed in Munich. After a local anesthetic is injected into his back, the patient sits in a tank filled with water in such a position that the kidney stone is at the focal point of a Shockwave generator. Then from 500 to 1,500 shocks are given to destroy the stone.

The timing of the shocks is coordinated with an electrocardiogram to prevent cardiac arrest. The number of shocks generally depends on the size of the stone. Within two days after the treatment, the patient passes the pulverized stones in his urine.

The stones were entirely removed in 90 percent of the patients. Pieces of stone were left in 9 percent and surgery had to be done in 1 percent.