By Andrew M. Seaman
NEW YORK (Reuters Health) - Despite past clinical trials demonstrating that exposure to pure oxygen can help stubborn wounds heal, a large new study of diabetes patients with severe foot ulcers finds no benefit from oxygen treatments and possibly some harm.
Researchers following more than 6,000 diabetes patients receiving treatment for deep foot wounds found that patients who got oxygen-chamber treatments along with standard wound care were no more likely to heal and more than twice as likely to undergo amputations as those getting standard care alone.
The results, published in the journal Diabetes Care, surprised the study team from the University of Pennsylvania, not least because they defy so much previous research.
"We really thought we would see a replication of what occurred in the randomized trials. The data demonstrates that didn't come to pass," said Dr. Stephen Thom, a professor at the Perelman School of Medicine in Philadelphia who worked on the study.
For more than 20 years, people with serious open wounds or burns have been put into pressurized chambers or rooms that expose them to pure oxygen, in the belief that it helps to promote tissue growth and speed healing.
Because of nerve and blood vessel damage, people with diabetes are at risk of persistent ulcers forming on their toes and heels - wounds that can become infected and even lead to gangrene and amputation. Oxygen treatments are sometimes added to standard care of diabetic foot wounds to enhance healing.
For the new study, researchers wanted to see whether the oxygen therapy was making a difference in real-world settings.
They analyzed data on 6,259 diabetes patients treated for foot ulcers at wound care centers around the U.S. between November 2005 and May 2011.
Of those patients, only 793 ended up having the oxygen therapy on top of standard care. Their sessions lasted from 45 minutes to two hours in the pressurized chambers, and were done once or twice per day over four to five times per week.
Thom told Reuters Health that such treatments typically cost between $300 and $600 per session.
After 16 weeks, about 43 percent of oxygen therapy patients had fully healed wounds, compared to about 50 percent of patients who did not use oxygen therapy. And about 7 percent of oxygen therapy patients had an amputation, compared to just 2 percent of those who did not get oxygen treatments.
"It does not only say it's not equal, it says it may be worse. You're seeing a higher amputation rate and a longer healing of a foot wound," said Dr. Nicholas Morrissey, a vascular surgeon at New York-Presbyterian Hospital.
But Morrissey, who was not involved in the new research, also noted that all the previous studies and trials to have looked at oxygen therapy have had limitations, as did this one.
The authors point out in their report as well that further study is needed to better understand the current results and the effects of oxygen treatments.
For example, the team attempted to adjust for issues that might have influenced the outcomes, such as whether patients with worse wounds or additional illnesses might have been more likely to get oxygen treatments. But the nature of the study makes it impossible to know for sure, they write.
"It certainly could be that they're picking people who are more severe (for oxygen treatment), but we tried to compensate for that," the study's lead author Dr. David Margolis, also from the Perelman School of Medicine, told Reuters Health.
"It's like many things in medicine, it's just one other study and you have to look at the totality of the information available," Margolis cautioned.
Morrissey said that until a definitive study is done, patients shouldn't be afraid or concerned that they're going to have an amputation after oxygen therapy.
"As a physician who takes care of these wounds all the time, I wouldn't tell patients to be concerned… I would not take that home from this paper," he said.
SOURCE: http://bit.ly/W7ZXTZ Diabetes Care, online February 19, 2013.