26 January 2000
Oxygen beats infections
by Kate Melville
After our recent story about disinfectants (Science A Go Go 24/01/2000) it seems appropriate that we delve further into the annals of infection.
Generally when people end up in hospital they hope that their operation goes well and that they can get home ASAP (penny pinching hospital administrators also want you out the door quick smart as they either save or make more money depending on your point of view). Anyway, when something does go wrong infection is one of the most likely problems and this can lead to prolonged (read expensive) hospital care and a much higher risk of fatality!
However, a new report from the University of California, claims that infection rates can be halved just by giving patients more oxygen during and after anaesthesia. This simple and inexpensive practice can save many lives, time and money. For example, with colorectal surgery, infection rates range run between nine to twenty seven percent and extend hospital stays by a week or more .
These dramatic findings were published in a recent edition of the New England Journal of Medicine and was based on a study of five hundred colon surgery patients done in three European hospitals.
By increasing inhaled oxygen during and after surgery seems to boost their immune system's ability to fight off infections. The most important immunological defense is where neutrophils cells kill bacteria by exposing them to a reactive form of oxygen. Research has shown that the number of bacteria killed is directly linked to the amount of oxygen in wound tissues and that by breathing extra oxygen the amount of oxygen available to facilitate neutrophils is greatly increased.
Dr. Daniel Sessler, Professor of anesthesia and perioperative care at UCSF said, "We now have evidence that increasing oxygen levels during and just after anaesthesia provides the immune army with more ammunition to kill bacteria at the wound site". The study was a joint venture between the University of California and European researchers who drew on the records the University of Vienna, Donauspital-SMZO in Vienna and the University Hospital Eppendorf in Hamburg, Germany. All five hundred patients were undergoing surgery for colon cancer or inflammatory bowel disease.
These various research groups form Outcomes Research Group whose goal is to examining accepted practices in anaesthesia and to look for simple, inexpensive ideas that can result in improved patient care.
Patients in the study were randomly assigned to breathe one of two oxygen concentrations during and for two hours after surgery. One group received the routine 30 percent oxygen and the other group received 80 percent. Aside from this each group received identical amounts of anaesthesia (even the surgeons were not aware which oxygen concentration their patients were receiving).
An analysis of the cost of an extra week of hospitalisation for infected patients ran to around US$12,500 whereas medical oxygen costs only a thousandth of a cent per quart! Sessler pointed out. "It (oxygen) is 40 times less expensive than tap water."
So if you are heading to hospital bribe the anesthetist to crank up the oxygen and you should be fine!