Question (Referred to the Eustatian Tube by Dr. Stephen Barrett [http://www.quackwatch.com]):
I recently encountered a client receiving "topical" hyperbaric oxygen therapy. It is my understanding that the only way to increase blood oxygen to therapeutic levels is through the use of a hyperbaric chamber, with the oxygen being BREATHED under elevated pressure. This client wore a plastic boot four days a week and oxygen was delivered directly to the wound topically under some pressure. I believe the name of the company was GWR. I viewed their website, and I do not understand how topical oxygen therapy could possibly work. Do you have any information on this treatment? Do you know of any legitimate studies that have been done? Could you tell me if there is any validity to this treatment? This is the site for the company to which I am referring: http://www.thbo.com. The company has a representative in our area making presentations and claims to physicians in order to interest them in ordering the treatment for their patients. My first experience with this treatment was not favorable, and the client's condition actually worsened.

Answer:
First, let me address the question by categorically stating that the term "topical hyperbaric oxygen therapy" is a misnomer, because little of any aspect of the technique is actually hyperbaric. More appropriately, the technique (hereinafter known as topical oxygen therapy) involves the strict topical application of oxygen, which clearly does not meet the definition of hyperbaric oxygen therapy as outlined by the Undersea and Hyperbaric Medical Society (http://www.uhms.org). Specifically, hyperbaric oxygen therapy involves nothing less than the INHALATION of 100% oxygen at a minimal ambient pressure of 1.4 atmospheres absolute. By contrast, the pressures used in the topical application of oxygen perhaps range from perhaps only 1.004 to a meager 1.013 atmospheres absolute. Therefore, having appropriately divorced the technique in question from the discipline of hyperbaric oxygen therapy, we are really left with the issue of determining whether topical oxygen therapy is truly therapeutic.

Studies assessing the efficacy of topical oxygen therapy began in earnest during the 1980s, when the approach was considered as a possible adjunct to hyperbaric oxygen therapy. However, the studies actually suggested that the technique was detrimental to healing. Nonetheless, a number of staunch advocates (usually from fields of podiatry and physical therapy) persisted in their views that topically applied oxygen dissolves in affected tissues in quantities sufficient to suppress bacterial proliferation and to promote angiogenesis (i.e., the ingrowth of new capillaries), thereby aiding healing.

Has strong evidence subsequently emerged to support topical oxygen therapy? The answer seems simple and clear - NO! A few studies have been conducted and have even reported positive results (see Heng et al., Ostomy Wound Manage 2000 Sep;46(9):18-28, 30-2). Unfortunately, the studies were, as a rule, not well controlled and are thus difficult to interpret. Also, what one generally tends to find in any body of scientific literature is that studies failing to show positive results tend not to be published (and are thus comparatively invisible), whereas positive results, however achieved, tend to make the headlines. This point is particularly well driven home by the web site in question (i.e., http://www.thbo.com). In order to promote the view that the technique really is therapeutic, case studies and testimonials are used in lieu of citations of valid rigorous research.

My conclusions are as follows:

1) Topical hyperbaric oxygen therapy is scarcely hyperbaric and should not be considered by members of the public as hyperbaric oxygen therapy. By virtue of the lower pressure and topical route of application, my hunch is that topical oxygen therapy is essentially a homeopathic version of traditional hyperbaric oxygen therapy.

2) Studies suggesting a therapeutic role for topical oxygenation tend to be scarce and lacking in good control, making it difficult to conclude that there is indeed medical merit to the technique (e.g., reported benefits may reflect placebo effects, good luck, etc.).

3) The simplicity of the technique means that increasing numbers of centers will offer the therapy (particularly if the technique generates revenue). Hopefully, systematic evaluations of the technique will proliferate correspondingly. That way, we can judge the outcomes fairly, whatever they may happen to be. As in so many other controversial avenues of commercial medicine, however, our understanding of the virtues and inadequacies of topical oxygen therapy is limited by the fact that careful systematic rational painstaking investigation of any putitively therapeutic technique is likely to be less profitable than the slick marketing of a dud.

4) My best advice to practitioners is to listen to the company representatives rather than to avoid them. Depending on how aggressive the local marketing, there are likely to be increased numbers of patients and colleagues with questions about the technique, and it is wise to understand the marketing pressure that patients and their caregivers are under. Certainly you should prepare to hear numerous well-scripted responses to your questions about controlled experiments and mechanisms of therapeutic actions. Nonetheless, a healthy skepticism is paramount.