Clinical trials suggest hyperbaric oxygen is an effective wound-healing therapy for lower extremity wounds connected with diabetes and wound healing problems related to radiation exposure.
"Now, there is more compelling evidence, at least from the basic science side, that hyperbaric oxygen therapy offers benefit in wound repair," says David Margolis, M.D., Ph.D., professor of dermatology and epidemiology, University of Pennsylvania, Philadelphia.
"On occasion, we will treat patients that have had a skin graft that is tenuous or looks like it might fail, as well as patients that have bad rheumatoid disease and may have an ulcer that is not ready for a grafting.
"In that case, we treat those patients in order to get a wound ready - to improve the granulating tissue base before grafting," Dr. Thom tells Dermatology Times.
Dr. Margolis says he has used hyperbaric oxygen therapy in the past for patients who failed other therapies and did not have other therapeutic options.
"The biggest problem from the patients' point of view is the time commitment that they have to make toward using it," he says.
Mechanisms of action
The thinking behind why hyperbaric oxygen therapy works has shifted in recent years, thanks to emerging basic science, Dr. Margolis says.
"I think initially that people were sort of mesmerized by that notion that somehow you were delivering oxygen to tissue and that the oxygen, by itself, was responsible for improved healing.
"Over the last half a dozen years or so, there has been much better information that additional oxygen probably affects the presence of reactive oxygen species - the ability of bone marrow-derived cells to become involved in angiogenesis," Dr. Margolis says.
The theory that hyperbaric oxygen mobilizes vasculogenic stem cells from the bone marrow, which then migrate to the wound and generate new blood vessels, makes the most sense at this time, according to Dr. Thom.
He adds that there is also data indicating that hyperbaric oxygen stimulates production of growth factors and causes cells to go to the wound to make new blood vessels, or granulation tissue.
The third mechanism has to do with the fact that wounds have poor vascularity, and putting patients in the hyperbaric chamber appears to result in the recruitment of macrophages, which go to the wound and generate growth factors to stimulate healing.
Dr. Thom says the data are pretty good for using hyperbaric oxygen therapy to treat wounds. There are animal studies, Cochrane evaluations and a few new third-party efficacy studies by Canadian researchers that suggest hyperbaric oxygen is an effective wound-healing approach.
Who's a candidate?
Dermatologists and others would prescribe hyperbaric oxygen in patients who were also getting aggressive local woundcare, Dr. Thom says.
One factor that might rule out some patients is prior cancer treatment with bleomycin, which increases the risk of oxygen toxicity. Dr. Thom says he also evaluates patients who have severe emphysema to make sure they do not have areas of the lungs that are being under-ventilated, but says that he treats patients with emphysema often.
Complications from the therapy are rare, according to Dr. Thom.
"One thing that we cannot predict and worry about is seizure, which is in evidence of central nervous system oxygen toxicity. That happens in approximately one in 10,000 patients," he says.
Seizure from the therapy is easy to control, he says. "We know how to treat these patients, and there is no permanent injury related to a convulsion from oxygen."
The only other recognized complication, Dr. Thom says, is a temporary change in vision. Patients can get nearsightedness if they get more than approximately 20 treatments, which is the protocol for most dermatologic indications. Nearsightedness occurs in about one in three patients, but is reversible.
Disclosure: Drs. Margolis and Thom report no relevant financial disclosures.