Historical Basis for HBO

Hyperbaric Oxygen Therapy (HBO) is a non-invasive therapy in which patients are placed in a specially designed chamber and pressurized for therapeutic purposes. In clinical applications patients breathe 100% oxygen in the chamber at pressures up to three time’s normal atmospheric pressure. Normal physiological function and healing are oxygen-dependent and rate limited by its availability at tissue level. HBO is used to promote oxygen transport to tissues in conditions where the normal oxygen delivery pathway is compromised by traumatic injury, tissue poisoning, infection, inflammation or edema. In certain cases the only way sufficient levels of oxygen can be delivered to compromised tissue is by using pressure to substantially elevate blood oxygen levels and create the gradient necessary for oxygen to diffuse from the blood into tissue to a degree not possible at normal atmospheric pressure.

The FDA considers oxygen delivered for therapeutic purposes to be a drug. Even when patients are breathing 100% oxygen the only way to significantly increase oxygen availability to tissues is to raise the ambient pressure surrounding the patient. This being so we can view the hyperbaric chamber as the “syringe” needed to “inject” oxygen in clinically significant doses.

The first recorded use of pressure being used to treat patients was by the British physician Henshaw in 1664. Considerable interest in hyperbaric air therapy developed in Europe in the 18 th and 19 th centuries and there were many facilities providing treatment. It was not until 1887 that the first use of hyperbaric oxygen was reported in the Lancet. Interest in deep-diving spawned the first major application for hyperbaric oxygen therapy in the 1930’s as the treatment of choice for decompression illness and gas embolism. Prior to this the basic physics and physiology of hyperbaric medicine had been established over several centuries by luminaries such as Boyle, Priestley, Lavoisier, Bert, Lorraine-Smith, and Haldane who in a paper published in 1917 on the therapeutic application of oxygen wrote:

“It may be argued that such measures as the administration of oxygen are at best only palliative and are of no real use, since they do not remove the cause of the pathological condition. As a physiologist, I cannot for one moment agree with this reasoning. The living body is no machine, but an organism constantly tending to revert to the normal and the respite afforded by such measures as the temporary administration of oxygen is not wasted, but utilized for recuperation….The mistake is often made of not grasping the serious, widespread, and lasting effects caused by want of oxygen….”

Haldane JS: The therapeutic administration of oxygen. Brit Med J; Feb 10, 181-183, 1917.

It was, however, interest in the effects of oxygen in human physiology in deep-diving, aviation and space exploration that spurred research and provided the firm basis for the clinical research and activity that began in the 1950’s and 60’s. Building on the groundbreaking work carried out by Boerema in Amsterdam and Churchill-Davidson and Illingworth in the United Kingdom the development of clinical HBO has been a slow process. The formation of learned societies such as the Undersea and Hyperbaric Medical Society (UHMS) here in the United States provided the platform that enabled clinical hyperbaric oxygen therapy to advance. Globally, the potential value of HBO has been explored in a significant number of adjunctive applications. In the United States at this time, however, only a limited number of these are accepted and reimbursed by CMS and Third Party payors.

Without question hyperbaric oxygen therapy has polarized the medical community. When commenting on the results of a double blind controlled study into chronic leg ulceration, T.K. Hunt M.D., Professor of Surgery, University of California, San Francisco, School of Medicine, Wound Healing Research Laboratory wrote:

“…..Few subjects have been so controversial for so long as hyperbaric oxygen – especially hyperbaric oxygen for chronic wounds. Prior clinical studies, although almost exclusively positive and optimistic, have not been randomized, blinded, or prospective. Though other medical modalities have grown faster on less data, hyperbaric oxygen has drawn a dramatic line between those who do not have a hyperbaric chamber and are skeptics and those who do have one and believe. The individual assessment of data, one suspects, has been made more on the basis of available equipment rather than available facts….

“…the difference between hyperbaric oxygen and many other developing therapies, for which clinical studies are incomplete, is simply that in the case of hyperbaric oxygen, the background has been carefully prepared. The effects of tissue PO2 on collagen synthesis, angiogenesis, white cell antibacterial function, and epithelialization have all been worked out in human and animal cells, and in various types of animal and human wounds. The rationale for hyperbaric oxygen is complete…..”

Thomas K. Hunt M.D., Plastic and Reconstructive Surgery, April 1994: p834. Discussion on Hyperbaric Oxygen Reduced Size of Chronic Leg Ulcers: A Randomized, Double-Blind Trial. Hammarlund C., Sundberg T. Plastic and Reconstructive Surgery, April 1994: 835-841.

Today, HBO is accepted as the primary therapy in few conditions only, decompression sickness, gas embolism, gas gangrene, and acute anoxia such as carbon monoxide poisoning. In the other indications, it is an adjunctive therapy.

One of the most widespread and growing applications for HBO is that of wound healing. Despite improvements in clinical care, a very high percentage of diabetics develop indolent, ulcerating wounds that are refractory to traditional management techniques. The rise in numbers of ulcerating wounds caused by peripheral vascular disease is a direct result of increased life expectancy and an aging population. The current demand for wound care can be expected to increase further as the more and more “baby boomers” reach their seniority. The dramatic results HBO can provide for non-healing “problem” wounds is bringing increased acceptance of this powerful modality among physicians. As hospitals seek ways to deal with the pressure to reduce healthcare costs, the introduction of HBO into the range of services provided opens up a new avenue for revenue generation while meeting the goal of improving service to the community.