Friday, April 20, 2007

Under Pressure

photo credit- =Doy

Hyperbaric Oxygen Therapy (HBO, HBOT) has been proposed as a "cure" for autism. There is a little theoretical basis for this, if you consider autism as a form of brain damage. There are some papers (but no conclusive evidence) that HBO may be beneficial in patients with acute and chronic brain injury, as well as multiple sclerosis and cerebal palsy. None of these indications is supported by one of the major professional organizations involved with HBO, the Undersea and Hyperbaric Medical Society (UHMS), as the only papers with proper controls show no definite improvement. The UHMS holds open the possibility that certain subgroups of brain injured patients may be shown to benefit from HBO.

Classically, HBO was first instituted as a treatment for divers suffering from "the bends", which is caused by too much nitrogen dissolving in your blood under pressure when diving, then "bubbling out" into your joints (and other spaces) when you surfaced.

The indications for HBO have been widened to include things such as air gas embolism (bubbles of air or other gases in your brain or other places they don't belong), carbon monoxide poisoning, certain soft tissue and bony infections, to promote healing in problem wounds and skin grafts, and brain abscesses.

I recently saw an announcement that a hyperbaric center was going to start a study of HBO use in autism. As I don't completely discount that it might have some effects, studying it would be a good thing. Then I took a look at the announcement:

...The Hyperbaric Medicine Center's Autism Study begins this month with 20 children, and each child will be treated with 20 hours of hyperbaric oxygen therapy. Each child will be tested by experienced clinicians in the community both before and after their 20 hours of therapy, and the results are expected to be published by late June, 2007. ...

While you certainly can't believe everything you read in the paper, if this is the stuy's design, it sucks. There's one thing worse than no scientific data on a subject. That's data obtained from poorly designed and poorly performed experiments. I see no mention of a triple blind (subjects, people performing interventions, and testers all blinded to who got what) study with a placebo control group. Without such a design, you can't believe anything that comes out of this study.

I've been vaguely aware that HBO was being advocated by some for treatment of autism, but was unaware of how widespread this practice was, and how exactly it was being instituted, until Autism Diva pointed me to an old post of hers on the subject.

I had previously believed, when I heard that parents were using HBO to treat autism, that they were buying time at recognized hyperbaric chambers. These chambers are often located in hospitals, are staffed by professionals, and are costly to operate. Silly me.

What most people using HBO in autism are using is the Vitaeris 320, which is billed as a "Mild Hyperbaric Chamber". These chambers develop pressures up to almost 1.3 atm (the equivalent of being at the bottom of a 11 foot swimming pool) rather than the 3 atm (66 feet) or more capability of "real" hyperbaric chambers.

The Vitaeris "chamber" is really a pressurized zippered bag. It was originally designed as a portable device that mountain climbers could take with them to combat mild altitude sickness. It is now sold to doctors offering hyperbaric treatment for "unconventional" indications (like multiple sclerosis, cerebal palsy, and autism).

Some of these doctors (as well as some parents that have also bought these chambers with a doctor's prescription) have added supplemental oxygen to their chambers, in order to increase the amount of oxygen that is supplied during the procedure. This is where the real danger in using this therapy lies.

Up until I read about the oxygen being added to these "Mild Hyperbaric Chambers" I wasn't overly concerned about using HBO to treat autism. Like all unproven treatments, there is concern about incurring even small unnecessary risks. But if autistics were being treated in "real" HBO chambers, they were being tended to by trained and certified technicians, who followed accepted protocols and safety precautions.

There is minimal (though not zero) risk associated with "diving" in a hyperbaric chamber. The most common risks entail claustrophobia (unless you like being zipped in an over sized piece of luggage), barotrauma (damage to your ears, lungs, or sinuses from not "equalizing" pressures properly), and temporary vision changes.

Properly used, there is little risk of danger in using the Vitaeris 320, or similar "mild" hyperbaric devices. The pressures developed are a lot less than conventional chambers, and supplementing oxygen to the chamber is not supported by the company's literature. This is probably why the FDA does not require the presence of specially trained personnel to use these "mild" HBO chambers.

Supplementing oxygen in any way when using these chambers (either with an external oxygen concentrator supplying O2 to an air intake, or by administering bottled oxygen within the chamber) totally changes the risk equation.

photo credit- NASA

Although it has been 40 years since the Apollo 1 tragic fire that killed it's three astronauts, the principles still apply. Enriched oxygen environments (especially under pressure) are dangerous. That is why conventional chambers are regulated, inspected, and have specially trained individuals operating them.

So the bottom line? "Mild Hyperbaric Chambers" are expensive toys in the treatment of autism. They expose those treated to minimal risks, but are certainly safer than something like chelation. Those who add oxygen to these chambers, on the other hand, incur extreme risk of fire and explosion. There is no science to support the use of HBO in the treatment of autism at present, and the only study I see scheduled is likely flawed from the outset. But my greatest ire is reserved for those who should know better (doctors) and yet not only provide treatments that are not useful, they are downright dangerous.


Steve D said...

I have often wondered whether any risk factors were associated with HBOT. A cursory search of PubMed did not reveal anything, which led me to believe safety was not an issue. This, of course, did not make me want to subject my son to it, but at least I felt it could be stricken from the list of dangerous treatments.
Thanks for covering this issue.

Do'C said...

There may be a good reason the gammow bags (like the vitaeris 320) are apparently gaining popularity as an offering among DAN! 'docs' (and beauty/health spas).


More about HBOT for autism with the vitaeris:


kristina said...

Thanks so much for posting about this---your critique is much needed. There is actually a place (as I'll refer to it) that does HBO in the town where we live---I drive by it everyday (and say to myself, no thank you).

Club 166 said...


Thanks for those links. I had read your posting before, but didn't remember who had done it. That was a very nice treatment on the subject.

There is nothing inherently bad about making money practicing medicine. It sounds bad to say something is profitable, but unless doing something pays the bills, you can't afford to keep the doors open and provide anyone any kind of service. It's when profit becomes the prime motivator that problems creep in. And that is what I see with quack docs.


As I said, properly performed, HBO in a regulated chamber or using the Gamow bags (Mild Hyperbaric Chambers) are both fairly safe (no treatment is 100% safe), though not proved effective. But anyone that adds oxygen to those Vitaeris bags is creating a disaster waiting to happen.

What worries me most is a trend towards junk research. I think that many people are starting to turn out junk studies (few patients, poor or no controls, short duration), and then use those studies to "prove" that various treatments are valid.

Tibetan Star said...

I had never heard of that stuff.
We came to the point where we avoid so-called 'experts' as the plague!

Club 166 said...

...We came to the point where we avoid so-called 'experts' as the plague!

That is so sad.

None of us can be experts in everything. And one always needs to evaluate the advice anyone gives (even "experts") in the context of your/your child's individual situation. But when the quacks and huxters of the world spew falsehoods to the extent that people stop paying attention to the real experts, that hurts us all.

Do'C said...

There is nothing inherently bad about making money practicing medicine. It sounds bad to say something is profitable, but unless doing something pays the bills, you can't afford to keep the doors open and provide anyone any kind of service.

I couldn't agree more.

It's when profit becomes the prime motivator that problems creep in. And that is what I see with quack docs.

Yep. To look at some of the parent forums out there (and going rates), and compare discussion to the linked ROI page, it becomes clear pretty quickly that profit appears to be a prime motivator with the gammow bag setups.

I went back and read the wiki article about the Apollo 1 fire you linked. It's been years since I read about that, and one word comes to mind - Gnarly!

Club 166 said...


I guess we just grew up in different 'hoods.

Gnarly would be something we'd use to describe something like a steep tricky descent on a mountain bike trail. My buddy Doug in LA would sometimes use it in a similar reference to difficult (yet satisfying) waves when surfing (the ocean, not the web :) ).

I think the word I'd use to describe being cooked alive would be gruesome.

daedalus2u said...

I think I would use the word horrific.

The risk of death from fire in hyperbaric chambers designed for oxygen and operated by trained operators is well known(hyperbaric chamber injuries 1923 - 1998). In pure oxygen, everything organic will burn. The only cloth that won't burn is fiberglass. Asbestos would work too, but that has been banned. Most metals will burn too, aluminum, iron, steel, even stainless steel can burn in pure oxygen. That is the technique that is used for cutting steel, heat it enough to get it to start burning, then a stream of pure O2 will keep it burning.