Hyperbaric Oxygen Therapy Simply Explained

1. What It Is About

In hyperbaric oxygen therapy, or HBOT for short, people sit or lie in a closed chamber. The air pressure inside is higher than usual, and they breathe pure oxygen. Because the pressure is higher, more oxygen can dissolve in the blood than during normal breathing. This allows the oxygen to reach tissue that is poorly supplied with blood. The procedure was first developed for divers who had become ill after diving. Today it is being investigated for, among other things, wound healing, recovery after brain injuries and inflammatory processes. The treatment usually runs in series: one session lasts about an hour, and often 40 or 60 sessions are carried out over several weeks. How long a session lasts and how high the pressure is differs depending on the area of application. In the studies, measurements are taken in very different ways, for example via questionnaires, memory and attention tests or brain scans.

2. What Studies Show

The effect on thinking, concentration and fatigue after a viral infection is best investigated. In a study with 73 people who suffered from persistent symptoms after a COVID-19 illness, the participants received the treatment or a sham treatment. In a sham treatment, the chamber is used but without increased pressure and with normal air. The group with the real treatment performed better afterwards in memory, attention and concentration. Energy, sleep and pain perception also improved. Brain scans showed changes in blood flow and fine structure 2. A second study with likewise 73 patients found matching changes in the connection between brain regions that were associated with the better attention values 7. These results are considered indications, but not yet as confirmed. How long the improvements last is open, because a later follow-up over a longer period is missing in these studies.

Similar findings appear with persistent symptoms after a mild head injury. In a study with 56 patients whose accident had occurred one to five years earlier, the treatment led to better scores in attention and mental performance as well as better quality of life 1. Another study with 63 people with symptoms after a head injury reported improvements in the symptoms themselves, in memory, in mood, in anxiety and in sleep. These improvements persisted two months after the end of treatment 4. In healthy older people over 64 years of age, attention and the speed at which they processed information improved. Blood flow in certain sections of the brain increased 3.

Results are also available for wounds. A summary of several studies on diabetic foot ulcers found that these wounds healed more frequently with additional oxygen therapy and that toes or feet had to be amputated less often 5. Regarding side effects, a large summary shows: they occurred more frequently in the treatment groups than in the comparison groups; the most common was ear pressure 6.

3. What Remains Unclear

Many studies are small and differ in design. The treatments differ in duration, pressure and number of sessions. Some investigations had no comparison group with a sham treatment. It is then not possible to separate reliably how much of an improvement is due to the treatment and how much to expectation or time. In a study with military personnel, almost half were additionally affected by a stress disorder, which complicates classification. Follow-ups over longer periods are still outstanding, so it remains open how sustainable the observed effects are. Results for bone healing are contradictory, and for antiviral effects there are so far only preclinical models, that is, laboratory and animal studies. This question has not yet been clarified in humans.

4. What This Means in Everyday Life

Hyperbaric oxygen therapy is neither a new nor a marginal procedure. There are many studies on it, and some of them show improvements, especially where recovery of the brain after injuries or infections is concerned. Other areas are less well researched. Readers of such results can pay attention to two things. First: what was the treatment compared with? A comparison with a sham treatment carries more weight than a comparison with people who received nothing at all. Second: what was measured? Brain scans and questionnaires are not the same as a difference noticeable in everyday life. The available studies indicate what needs to be clarified next: whether the effects persist over months, which people benefit most and how the course in an individual person can be assessed in measurable terms.

All details with study numbers and sources: detailed page on hyperbaric oxygen therapy. For children: hyperbaric oxygen therapy for children.