The incidence of nausea -- a frequent side effect of general anesthesia -- can be dramatically reduced simply by giving patients more oxygen during and after surgery, according to a new study led by University of California, San Francisco scientists.

The study, reported in the November issue of the journal Anesthesiology, found that the use of increased oxygen provides a simple, effective way to cut in half the number of patients who experience nausea.

A companion study led by UCSF researchers and reported in the October issue of the journal confirmed the safety of the procedure. Both studies involved researchers at UCSF and in Vienna.

As many as seven people out of ten experience nausea or vomiting after general anesthesia, said Daniel Sessler, MD, professor of anesthesia and perioperative care at UCSF and senior author of both studies.

The most effective anti-nausea drugs cost $30 per dose, he said, and are not given routinely but only after patients become sick to their stomachs. The drugs have only a fifty-fifty chance of working, he added.

In contrast, the use of additional oxygen costs almost nothing, causes no known problems, and can be given to all patients from the outset of surgery.

"The take-home message from the new studies is that extra oxygen is cheap, risk-free and reduces the incidence of nausea as well as any known drug," Sessler said.

In the new study, the researchers examined the effect of using 80 percent oxygen in the gas mixture administered during anesthesia compared with the standard 30 percent oxygen. In both cases, the designated oxygen level was maintained for two hours after surgery.

The study focused on 231 patients undergoing colon surgery at two hospitals in Vienna -- Donauspital-SMZO and the Vienna General Hospital. About half received the conventional 30 percent oxygen in their anesthesia gas and for two hours during recovery, and the other half received the elevated, experimental, oxygen levels
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Contact: Wallace Ravven
wravven@pubaff.ucsf.edu
415-476-2557
University of California - San Francisco
26-Oct-1999