Breathing 102—bringing the woo

(This one is cross-posted over at Science-Based Medicine. FYI. –PalMD)

If you’ve been a regular reader of SBM or denialism blog, you know that plausibility plays an important part in science-based medicine. If plausibility is discounted, clinical studies of improbable medical claims can show apparently positive results. But once pre-test probability is factored in, the truth is revealed—magic water can’t treat disease, no matter what a particular study may say. So it was with great dismay that I read an email from a reader telling me about parents buying hyperbaric chambers for their autistic children. Let’s review some science.

In Breathing 101, we talked about how the oxygen delivered to your lungs depends on both the percentage of oxygen in the air, and the air pressure. We looked at how diminishing atmospheric pressure, for example at altitude, makes it harder to breathe.

Of course it is also possible to expose people to increased atmospheric pressure, which has therapeutic uses in the form of hyperbaric oxygen therapy (HBOT).

Oxygen delivery to tissue depends on several factors. We already talked about the air itself. Once air gets enters the lungs, most of the oxygen transported to your tissues is carried by the hemoglobin molecules in your red blood cells (under normal conditions). A small amount is directly dissolved in the blood. The amount dissolved in the blood is dependent on (no surprise) the percentage of oxygen and the atmospheric pressure. By increasing the atmospheric pressure from 1 atm (760 torr) to 3 atm, the amount of oxygen dissolved in the blood is enough to meet your body’s needs independent of heme-associated oxygen.

This is a good thing.

For example, up here in the Midwest, we have a lot of cases of carbon monoxide (CO) poisoning during the winter. CO binds to hemoglobin much more strongly than oxygen, so even after victims are removed to a normal environment, they are still asphyxiating.

Carbon monoxide intoxication is one of the primary uses of HBOT. Under pressure, enough oxygen is delivered to the tissues for the patient to survive. Additionally, the increased pressure helps oxygen displace CO so that heme molecules are free to go back to the work of transporting oxygen.

The original use for HBOT was of course “the bends”. When a person (for example a diver) is exposed to high pressures for a long period of time, nitrogen, which is normally not very soluble in blood, dissolves much more readily. When the diver ascends, the nitrogen bubbles are released from the blood into the tissues, causing widespread damage. HBOT can be used to help a diver “ascend” more slowly, so that the nitrogen comes out of solution in a much less damaging fashion.

HBOT can also be used to treat a variety of other conditions that are responsive to increased oxygen tension, such as anaerobic bacterial infections. But hyperbaric chambers are not without risk. Small errors can cause big problems, including death.

Strangely enough, though, you can buy your very own hyperbaric chamber for use in your own home, and parents of autistic children are doing just that.

So why does anyone think that HBOT might be appropriate for the treatment of autism? Is it even plausible? Autism spectrum disorder (ASD) is a very broad diagnostic category. Autism is a neurobehavioral disorder of inconsistent severity and unknown cause. There has been some decent research into etiology, and in some cases genetic causes have been implicated. There is no reason to suspect that autism has anything to do with decreased oxygen tension.

As you have no doubt read in this space, autism attracts a wide range of quackery, and HBOT for autism is quacks pretty loudly.

Whose idea is this, anyway?

All signs point to a guy named Dan Rossignol. Dr. Rossignol is apparently into every form of autism crankery, including mercury poisoning, mitochondrial dysfunction, and oxidative stress (although I can’t imagine that increased PaO2 is an effective treatment for “oxidative stress”). After spending a few minutes looking through is web-based material, I’m starting to think that this guy can give the Geier’s a run for their money.

True to form, Rossignol is a “pioneer” and a “maverick”. He goes where legitimate clinicians haven’t dared. Based on an implausible hypothesis, he (apparently) subjects autistic children to potentially dangerous hyperbaric oxygen therapy. He has published his ideas in the crank-magnet “Medical Hypotheses”, and in BMC Pediatrics, a journal devoted to rapid, “flexible” publication.

Even if his data were to support his nonsensical hypothesis (again, increased O2 to treat oxidative stress??), should we believe it?

Well, someone does, and that someone apparently sells hyperbaric therapy, and not just for autism. They also treat Lyme disease, multiple sclerosis, and cerebral palsy—and anything else you can spell. The site does, however, have a very small Quack Miranda Warning on the left sidebar.

There is an unbroken chain of bad medicine here. Some guy decides that a potentially dangerous treatment might help a protean syndrome. He publishes his ideas in low quality journals. Then, someone sells his treatments uncritically.

HBOT is serious medicine. Off-label use in children with autism isn’t just foolish—it’s dangerous, and should be illegal.


Rossignol DA. Hyperbaric oxygen therapy might improve certain pathophysiological findings in autism. Medical Hypotheses. 2007;68(6):1208-27. Epub 2006 Dec 4.

Rossignol DA, Rossignol LW. Hyperbaric oxygen therapy may improve symptoms in autistic children. Medical Hypotheses. 2006;67(2):216-28. Epub 2006 Mar 22.

Rossignol DA, Rossignol LW, James SJ, Melnyk S, Mumper E. The effects of hyperbaric oxygen therapy on oxidative stress, inflammation, and symptoms in children with autism: an open-label pilot study. BMC Pediatr. 2007 Nov 16;7:36.


  1. GIVE THEM SOMETHING. In the absence of any plausible treatment for their children, these parents will find something to fill the void. All of the recent studies regarding autism seem to focus on discounting the quackery – which is good, but should not be ALL. No parent can sit around and do nothing for their sick or non-normal child. Unlike so many other illnesses and syndromes we have given these parents virtually no guidelines or recommendations for treatment. Can you really blame them? And can you continue ridicule them and expect to change their minds? I realize we are on a new frontier with autism and I do understand that your main target is HBOT off label use, but I am frustrated by the divisiveness of the rhetoric on BOTH sides of this issue.

  2. Can you really blame them?

    Can you “blame” the parents? Tricky question. Can you blame the alt-med practitioners for offering untested (for safety or efficacy) therapies? Yes.

    Which is worse–the doctor who tells a patent an honest, “we don’t know what therapies work–or could cause harm–for this condition” or the doctor who says, “I have an untested idea about your condition. Therefore, I offer you a therapy which may or may not treat the condition…also, since I haven’t tested it, I don’t know what the adverse effects might be.”

    PaulMD: can I add the text of this page to:

  3. Feel free to repost with link/attribution. Thanks.

  4. Mad Hussein LOLscientist, FCD

    Isn’t hyperbaric oxygen also used legitimately to treat severe burns? I seem to recall it speeds healing and reduced scarring. Hmmmmmmm……. yeah. I just Googled it and also found it’s used to fight anaerobic bacterial infections.

    But autism? WTF! Is there no limit to the quackery?

  5. D. C. Sessions

    The great thing about hyperbaric oxygen chambers for autistic kids is that you can lock them in and skip all that stressful “human interaction” thing for hours at a time.

  6. Which is worse–the doctor who tells a patent an honest, “we don’t know what therapies work–or could cause harm–for this condition” or the doctor who says, “I have an untested idea about your condition. Therefore, I offer you a therapy which may or may not treat the condition…also, since I haven’t tested it, I don’t know what the adverse effects might be.”

    I wish that the dialogue were that honest.

    In reality, what most parents are told by the “alternative” practitioners is:

    “I have a treatment that has worked on some/many/most/all autistic children I’ve treated with it. It works by unslithing the toves so that they don’t gimble in the wabe.” (or words to that effect).

    It would be notable to find an “alternative” practitioner who is frank enough to admit:

    [1] Their “hypothesis” about the cause of autism is untested.
    [2] Their proposed “treatment” for autism is untested – apart from “testimonials”.
    [3] They have no idea if their proposed “treatment” will have any adverse consequences.

    If they did all that, I wouldn’t have any problem with “alternative” practitioners. I also suspect that they would be a lot less busy – but not out of work, since there are always parents who are desperate enough to try anything. Even if it risks the life of their child.

    By the way, expect to hear from some proponents of HBOT for autism that claim that the pressure is the aspect of HBOT treating autism. Expect them to not understand the concept of bulk modulus.

    Good work!


  7. Katy,
    I am a parent and I do not detect a divisive rhetoric on both sides. One side is promoting treatments for autism based on very dubious science. Some of these treatments may be harmless quackery but some, like HBOT, have the potential to cause lasting harm to children. The other side cites well founded studies that refute the scientific claims for and challenge the safety and efficacy of the quack cures.

    It is indeed a pity that a minority of parents have bought into this nonsense. A credulous media continues to give them uncritical coverage. But I think it is unfair to say that parents fall for their rhetoric because the medical profession has defaulted on its obligations to parents. Speech and language therapy, occupational therapy and early educational intervention are all associated with positive outcomes. The real problem is availability of services and meeting their costs.

    Arguments about causation which revolve around blaming vaccines and promoting quack cures detract from the real scandal that most parents know what we want for our children but it is often unavailable or unaffordable. And it does us and our children no favours if a vocal minority and their media allies are out to persuade the public and the policy makers that autism is preventable and curable. The implication is, “Why fund services if we can cure it instead?”

    That is the difference. Their rhetoric has the potential to cause harm. There is no equivalence between the two sides on scientific, medical or moral grounds.

  8. I don’t know what the physical sensastions are of being in the chamber, do you feel a lot of pressure?

    If so, I remember reading Temple Grandin’s book Thinking in Pictures”, and she talked about the various ways that she would find to put pressure on her body, because she found it soothing.

    It seems like it might be a good idea to suggest some less…um…heroic? meathods of acheiving the sense of physical pressure, in a less dangerous way.

    The danger is, I wonder if some parents will actually see some results from this in their kids and attribute it to the quack science rather than simply the effect of pressure on the body which could be done other ways.

  9. Also, it seems like the Quack Miranda warning is insufficient for something like a hyperbaric chamber.

    I mean, its one thing to put up a little disclaimer on a bottle of herbs that a person might buy on an impulse or to try just so they can tell crazy old aunt Bertha that they tried St. John’s Wort or whatever to shut her up…
    …but it seems pretty clear that when someone drops serious dime on something like this, they clearly expect that it has been proven to do something…and somebody gave them that expectation.

    I’m no lawyer, but doesn’t the cost and potential harm of this product reach some threshold where a “wink-and-a-nod’ won’t cover you?

  10. BTW,

    I’d like to point out that I am in no way implying that “pressure” cures autism…only noting that one person with autism described pressure as soothing…a temporary relief from the results of overstimulation…a coping mechanism for one person.

  11. I can’t speak to the low pressure (1.4 – 1.5 atm) “soft-chambers” that most people are using for autism, but apart from middle ear and sinus “squeeze” (if you can’t equalize pressure), there is no sensation of pressure up to 6 atm.

    The real danger of these “soft chambers” comes from the “mavericks” who use supplemental oxygen in them. Even at atmospheric pressure, an oxygen-enriched environment is a serious fire hazard. The “soft chambers” are not approved for use with any supplemental oxygen because their material is flammable (and may also increase the danger of static sparks).

    The health effects of elevated oxygen partial pressure are generally subtle (until you reach the seizure threshold), but the effects of an oxygen-fed fire are not. This is not a “theoretical” risk, either – just ring up your local fire brigade and ask them about the dangers of home oxygen.

    I sincerely hope that we will never have to hear about some poor autistic child being killed or seriously burned due to this ridiculous “therapy”, but the odds are not pointing that direction.

    As more and more “practitioners” are using “HBOT” in their clinics and offices and as more parents buy and use “soft chambers” for home HBOT with supplemental oxygen, it becomes inevitable that someone will eventually suffer the consequences.


  12. People are adding oxygen to pressurized chambers with children inside? Holy crap. Someone show them this.

  13. Denice Walter

    How can an MD believe this? In Rossignol’s bio, it mentions that his own two kids are diagnosed with autism.Another MD, James Laidler (of, describes his own desperation and fall into the woo puddle following *his* kids” diagnoses.Laidler recovered.

  14. [quote]GIVE THEM SOMETHING. In the absence of any plausible treatment for their children, these parents will find something to fill the void.[/quote]
    The difficulty is that there simply isn’t anything.

  15. mandrake

    mike stanton:
    Thank you. That was one of the most intelligent posts I’ve read on the subject.
    I do want to add that it’s not only the cost and availability of helpful programs that is a problem. Speech and language therapies, etc, are not *simple*. They can take a lot of time and results can be slow, adding up gradually. The causes, effects, and solutions to autism are going to be complex.
    People would rather hear something they can immediately grasp, even if it doesn’t make sense, and find something to “fix” it. Not that parents are stupid; people just want to hear “I know how to fix it” in black and white.
    a. Mercury bad! Get mercury out! All better.
    b. Autism is a complex disorder that we do not completely understand, and any therapy may be slow to work or may not work at all. It is possible that your child may have to live with autism, though with time, therapy, and lots of interaction the symptoms can be ameliorated.
    I think you can see the problem.

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