Infection Rate From Surgery Cut In Half If More Oxygen Given During Anesthesia

The safe, inexpensive practice can save lives, time and money, the researchers report, since wound infections are common, often prolong hospitalization and can cause fatal complications. In colorectal surgery, for example, wound infection rates range from nine to 27 percent and often extend hospital stays a week or more, the scientists noted.

The dramatic finding of reduced infections with increased oxygen is based on a study of 500 patients who underwent colon surgery in three European hospitals. The report on the study appears in the January 20 issue of the New England Journal of Medicine.

The increased oxygen inhaled by patients during and after surgery appears to improve their immune system's ability to fight infections, the scientists found. Immune cells called neutrophils normally kill invading bacteria by exposing them to a highly reactive form of oxygen. This is the most important immunologic defense against bacteria associated with surgery, and research has shown that the number of bacteria killed is directly linked to the amount of oxygen in wound tissues. In the new paper, the scientists report that breathing extra oxygen markedly increases the amount of oxygen available to neutrophils.

"We now have evidence that increasing oxygen levels during and just after anesthesia provides the immune army with more ammunition to kill bacteria at the wound site," said Daniel Sessler, MD, professor of anesthesia and perioperative care at UCSF, senior author on the NEJM paper and director of the international Outcomes Research™ Group that carried out the study.

The collaboration between UC San Francisco and European investigators drew on patients at the Donauspital-SMZO in Vienna, the University of Vienna and the University Hospital Eppendorf in Hamburg, Germany. It is the latest of several hundred studies by the Outcomes Research ? Group examining accepted practices in anesthesiology in search of simple, inexpensive ways to significantly improve anesthesia care.

Several years ago, the group determined that post-operative infection rates could be cut three-fold simply by keeping patients warmer during general surgery. The team also found this practice reduced blood loss and the need for transfusions. Maintaining patients' normal body temperatures during surgery has since been widely adopted.

Last year the group showed that increasing oxygen during and after anesthesia is safe and cuts the risk of postoperative nausea and vomiting in half.

In the current study, 500 patients undergoing surgery for colon cancer or inflammatory bowel disease were randomly assigned to breathe one of two oxygen concentrations during and for two hours after surgery. One group was given 30