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ASSOCIATED PRESS, JANUARY 20, 2000

More oxygen reduces risk of surgical infections

Researchers may have found a true ounce of prevention, reporting today that a few pennies' worth of oxygen can cut the risk of surgical infections in half — meaning thousands could be saved in medical bills.

Air is about 21 percent oxygen. But patients routinely get 30 percent oxygen during and after surgery, because lungs don't work well under anesthesia. The study tested whether a richer mixture would improve the outcome.

Boosting the oxygen level to 80 percent made a big difference. Twenty-eight of 250 patients on the standard mix developed infections, compared with only 13 out of 250 who got extra oxygen.

The study was published in today's New England Journal of Medicine and was led by Dr. Daniel Sessler of the University of California at San Francisco.

The study is significant because it shows an easy, inexpensive way to make a big cut in medical bills, said Dr. Avery Tung, an assistant professor of anesthesia at the University of Chicago's medical school.

According to another study, postoperative infections add an average of $12,500 to the cost of cancer surgery. The only cost to the richer-oxygen treatment is about three cents' worth of oxygen.

"It's just a matter of setting two knobs in different positions. Both knobs need to be set anyway, and you just turn them a little more to get more oxygen," Sessler said.

Doctors have worried that extra oxygen might make the lungs more likely to collapse. However, he said, a study of his last year in the journal Anesthesiology found no difference in the percentage of such collapses on high and normal doses of oxygen.

There was also an unexpected benefit — patients who got extra oxygen were half as likely to be nauseated after surgery.

The study was conducted at the Donauspital in Vienna, Vienna General Hospital and University Hospital Eppendorf in Hamburg, Germany.

Scientists already knew that the white blood cells known as neutophils use oxygen to kill germs. And they knew that high levels of oxygen in body tissues help prevent infection and that breathing higher levels of oxygen put more oxygen into the tissues. What they did not know was whether it made a difference in patients' healing.

"This shows it's not just a theoretical benefit but a real benefit, and that it's much greater than you might have expected," Sessler said. "It's an enormous benefit for no cost and effort and risk."

The study looked at bowel surgery patients because they have the highest risk of infection. The findings might have even greater implications for burn units, since infections cause most deaths there, said Tung, head of his hospital's burn unit.

"If I had a wish list of another study I'd like to see, I'd like to see the effect of this on preventing infections other than wound infections," he said. "Or whether oxygen therapy might be used to speed healing" of other infections.

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