There have been case reports suggesting that hyperbaric oxygen therapy (HBOT) might improve the symptoms of Long Covid, but case studies are relatively weak evidence. Now, we have a well-designed study on HBOT that involves a placebo control group. The study found that HBOT does indeed lead to real improvements among long haulers. But the amount of improvement is relatively small, and the cost of the treatment is rather high. Most places reporting on this study haven’t really scrutinized the data or considered the real consequences of the research - they are just repeating the same exciting spin that other media sources have reported. Let’s look a bit deeper.
“Hyperbaric oxygen therapy improves neurocognitive functions and symptoms of post-COVID condition: randomized controlled trial.” Scientific Reports, 12 Jul 2022, https://www.nature.com/articles/s41598-022-15565-0.
The study divided 73 people with long covid into two groups: 37 got real hyperbaric oxygen therapy, and 36 went into a tank and got a placebo session - they breathed somewhat enriched levels of oxygen - but they were not pressurized, they did not get real hyperbaric therapy.
How Much Improvement Was Seen?
The improvements to the cognitive scores were relatively small when comparing the two groups of patients. The statistics tell us it is ‘significant’ - but that doesn’t tell us that was remarkably successful. Statistical significance is something that tells us how certain we are that there is a difference. The statistics tell us there is a difference between HBOT and sham HBOT. But the degree of improvement is something different, and it is not that large.
Consider this table from the study:
The overall cognitive score improved by roughly 5.8 points in the HBOT group, but only 2.4 points in the control group. At first glance, it might appear that HBOT is twice as good as doing nothing. But it isn’t that simple.
If we treat the control group as a measure of the background noise, we can subtract that number from the improvement seen in the people who got real HBOT. So the total improvement that first appears to be 5.8 points is really something more like an improvement of around 3.4 points.
That 3.4 points of improvement was on top of a starting score of 98.3 points. So the total improvement in the score for people who got HBOT is under 4%. That cognitive testing scale might not be linear - a 3.4 point change in cognitive function might affect a persons’ ability to function more (or less) than 4 percent. But that amount of change does not point to a dramatic or remarkable improvement.
How Many HBOT Sessions - and How Much Does It Cost?
This study involved 40 HBOT sessions, given once a day, typically five days a week, for 8 weeks. Each session was 90 minutes long. If a person has to travel 1/2 hour to get to a hyperbaric clinic and 1/2 hour to get home, and if there is any waiting time in the clinic, the total time commitment is over 100 hours.
In most cases, insurance will not pay for hyperbaric oxygen for long covid - they are not yet convinced that it is effective or cost-effective. So most patients who want to try this option today will pay out of pocket.
In the United States, prices for HBOT therapy range from $100 to $400 per session. If the average price is $250 per session, a 40-session package would come out to around $10,000. That might be a good deal if the therapy resulted in dramatic improvements. But if the improvements are marginal, it would not be a good investment for most people … and the evidence does not point to a dramatic improvement.
This study involved pressures of 2 ATA, which is double normal atmospheric pressure at sea level. Most of the medical research on HBOT involves pressures of 1.5 to 2 ATA. Some of the ‘spa’ HBOT centers use less expensive flexible ‘bags’ which are not capable of maintaining higher pressure. It is not completely clear how pressure relates to effectiveness in hyperbaric therapy. We do know that breathing 100% oxygen at normal pressure doesn’t have all of the therapeutic effects seen with high pressure. But we don’t really know how effective 1.2 or 1.3 ATA devices in a spa setting are compared to higher pressure devices used in a medical setting… the research has not been done. Those bargain-priced sessions? They might not be high pressure; they might not work as well.
How Does Hyperbaric Oxygen Therapy Work
Science doesn’t understand all the hows and whys, but it is clear that repeated HBOT sessions can trigger the growth of new capillaries and improve circulation. It has been approved in many countries for treating slow-healing wounds because it has been documented to help with these. Many researchers have speculated that having a higher gradient of oxygen is the key for stimulating new blood vessel growth. The general idea is that when the blood is saturated with oxygen, areas with good circulation get lots of O2 - but areas where there is injury or poor circulation don’t see as much of an increase… and at the border between high and low oxygen, the body responds by growing new blood vessels.
This model of healing coincides with many observations that the SARS2/Covid-19 disease increases the formation of blood clots and microclots. HBOT might be giving the body signals to grow new blood vessels, which could pipe fresh blood into areas that are currently blocked or stagnant. If the blood-brain-barrier is clogged up with small blood clots, that would certainly impact brain function.
Safety
Performed carefully in a medical setting, hyperbaric oxygen therapy is fairly safe. The most common side effects include popping of the ears and sinus headache (which people also get from flying in airplanes or driving up into the mountains). Some individuals might experience claustrophobia or other types of emotional distress from being enclosed in the chamber.
If done carelessly, HBOT presents two distinct hazards. 1) If a pressurized chamber fails and a person is rapidly depressurized, they can get ‘the bends’ - air bubbles can form in the blood, and they can cause very serious issues (and potentially, death). 2) Higher concentrations of oxygen make fires burn hotter and faster, and it is easier to spark a fire when oxygen levels are up near 100%. I am aware of at least one fire that started in 2009 in a Florida hyperbaric facility.
Long-term side effects might be possible when a person is saturating the blood with 100% oxygen for hours a day, for weeks on end. While the body has an absolute need for oxygen, more is not always better. Oxygen oxidizes proteins in the body. In people who take high levels of oxygen for other conditions (like emphysema), the oxygen itself might have adverse effects over time. Anti-oxidants might partially prevent this over-oxidation, presumably without interfering with the benefits.
Bottom Line
If I were a millionaire, I might be tempted to get my own hyperbaric chamber. If insurance provided this therapy at little or no cost … sure, why not? But as a person with average means, I look at the price tag, the time involved, and the modest benefits … and I think that there might be better options.
In future posts, I will be looking at ways of increasing the growth of new blood vessels that do not involve as much time or money. Things like diet, supplements, pharmaceuticals, and exercise have all been shown to boost the formation of new blood vessels to some degree, or to favor the dissolution of blood clots. Natto is one example of the latter. Stay tuned by subscribing and you will get a free weekly email with all of the new posts.