The Wound Healing Process
Oxygen is part of the body’s normal wound-repair process. It helps cells carry out some of the work involved in repair, including making energy and producing collagen. That explains why oxygen has been studied in wound care. It does not, by itself, prove that extra oxygen will heal a particular wound.
To understand the difference, it helps to look at what cells do when tissue is damaged—and what happens to oxygen in the body during hyperbaric oxygen therapy (HBOT).
How does the body repair a wound?
Wound healing is a sequence of overlapping processes. The body first stops the bleeding. Immune cells then help clear damaged tissue and respond to microbes. Later, cells build new tissue, form collagen and cover the wound with new skin.
These processes need more than oxygen. They also depend on factors such as blood supply, nutrients, infection control and, for some wounds, relieving pressure on the affected area. A wound may heal slowly if one or more of these factors is a problem.
How do cells use oxygen to make energy?
Cells need energy to carry out their tasks. They obtain that energy from nutrients such as glucose and fats, which are processed inside cells to make adenosine triphosphate, or ATP. Mitochondria use oxygen in this process, known as oxidative phosphorylation.
A simplified way to picture it is:
Nutrients + oxygen → cellular processes that produce ATP
ATP is then used to power work inside the cell. Oxygen is an important part of this process, but it is not energy on its own. And if a wound already has enough oxygen, supplying more does not automatically mean cells will produce more ATP.
Oxygen also has roles beyond energy production. Certain steps in collagen formation depend on oxygen. Immune cells use oxygen in some of their responses to microbes. These are biological reasons researchers have investigated oxygen-based treatments in wound care. They are not proof that an oxygen treatment will improve healing in every person.
What does HBOT change?
During Hyperbaric Oxygen Chamber Treatment (HBOT), a person breathes a high concentration of oxygen inside a chamber at increased pressure. The higher oxygen pressure increases the amount of oxygen that dissolves directly into blood plasma. This happens because gases dissolve more readily in liquids as their partial pressure rises, a relationship described by Henry’s law.
The blood carries that dissolved oxygen around the body. The increased oxygen pressure may also increase the gradient for oxygen to move from blood into nearby tissues during treatment. This is the proposed way HBOT may increase oxygen availability in selected tissues.
That is different from saying that HBOT sends energy directly into cells. It does not guarantee that a wound will receive enough oxygen to heal, that ATP production will rise, or that the wound will close faster. The wound’s blood supply, the condition of the tissue and other barriers to healing still matter.
What does the research say about diabetic foot ulcers?
Studies have reported mixed results. In the HODFU trial, a single-centre study of selected patients with long-standing diabetic foot ulcers, more ulcers had healed in the HBOT group than in the comparison group at one-year follow-up. Other trials, including the Fedorko trial and the multicentre DAMO₂CLES trial, did not find a significant improvement in healing or limb salvage overall.
A Cochrane review concluded that the studies suggested a possible short-term healing benefit, but that it was not evident at longer-term follow-up and the evidence had important limitations. The 2023 International Working Group on the Diabetic Foot guideline says HBOT may be considered as an add-on for selected neuro-ischaemic or ischaemic diabetic foot ulcers when standard care alone has failed. It grades this recommendation as conditional and based on low-certainty evidence.
UK guidance also matters. NICE’s current diabetic-foot recommendations say not to offer HBOT for diabetic foot ulcers except as part of a clinical trial. NICE is updating part of its guidance on oxygen treatment for diabetic foot ulcers, so check its latest recommendations before publication.
The practical takeaway
Oxygen is involved in normal wound repair. HBOT increases oxygen dissolved in the blood while a person is breathing oxygen under pressure. Those facts help explain the treatment’s proposed mechanism. They do not establish that HBOT is appropriate for every wound or will make a wound heal.
A diabetic foot wound, an infected wound, or a wound that is worsening needs assessment by an appropriate healthcare professional. HBOT should not replace wound assessment or the care plan recommended by a clinician.
Further reading
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