Oxygen limits infections from surgery

Of all the recent advances in surgery, some of the simplest are among the most valuable. For instance, scientists discovered 4 years ago that just keeping a patient warm during and after surgery reduces infections. A year later, other researchers found that this precaution also saves lives (SN: 4/12/97, p. 220).

Researchers now report that giving a patient extra oxygen during and after surgery halves the occurrence of postsurgical infection, a dangerous complication.

“We’re trying to evaluate simple, inexpensive, easy things that might make a big difference in how patients do [during and after surgery],” says Daniel I. Sessler, an anesthesiologist at the University of California, San Francisco.

Between 1996 and 1998, Sessler and his colleagues studied 500 patients, average age 57, in Vienna, Austria, and Hamburg, Germany. Each patient underwent colon or rectal surgery for cancer, inflammatory bowel disease, or another illness. Of these, 250 patients received a standard 30-per-cent-oxygen mixture while under anesthesia in surgery and for 2 hours afterward. The others received an 80-percent-oxygen mix. Normal air is about 21 percent oxygen, but anesthetized patients breathe easier with slightly more oxygen.

During the first week or so of recovery, 28 patients who had received the 30-percent-oxygen mix developed infections around their sutures, but only 13 of those with the higher oxygen dose had that problem. Patients in both groups received the same anesthesia and antibiotics during surgery, the scientists report in the Jan. 20 New England Journal of Medicine. The surgeons didn’t know which patients received the higher oxygen dose.

Close examination of tissue samples from some of the patients in each group indicated that blood in individuals getting the higher oxygen dose was delivering more oxygen to cells. This enables immune cells called neutrophils to capture and destroy bacteria more efficiently, thwarting infection, Sessler says. Last year, the researchers reported that extra oxygen during surgery reduces nausea and vomiting afterward.

The work “is very interesting,” says Michael E. Rogers, a medicinal chemist at the National Institute of General Medical Sciences in Bethesda, Md. It provides “a really nice, practical outcome that’s useful in the clinical setting,” he says.

In the new study, the researchers had planned to enroll 1,000 patients but ended the trial after data on the first 500 patients indicated a strong benefit from the increased oxygen.

“That’s not uncommon,” Rogers says. “If the effect is so significant, you don’t want to withhold that treatment from people who might benefit from it.” The extra oxygen, which costs pennies per patient, will translate well to other surgeries, Sessler says.

However, the effect may show up more in colorectal surgery, which has a high infection rate. Unless a patient has a specific condition that precludes it, Sessler says, “I can’t think of any reason why [physicians] wouldn’t provide supplemental oxygen” during surgery.

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