Category: Medicine

(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.

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A letter from a reader (thank you, Mr. “Smith”) got me thinking—could the fight against improbable medical claims be aided by a better knowledge of science? In another attempt to bring complicated science to the masses, today we will learn a bit about how we breathe. The first thing we need to understand is what we breathe.

Let us speak of air. We know we need it. Most of us know that the oxygen that makes up about twenty percent of it is necessary for life. If you think a little bit more, you probably realize that in addition to the oxygen content, there is another variable that is critical in making air breathable. When we climb a mountain or get in a plane, the air is less breathable. Why is that? The air up there is still 21% oxygen, so what’s the deal?

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As a physician, I have a lot of politically conservative colleagues. Much of this stems from our experience with the government. The influence of Medicare helps set prices, which we are not at liberty to change, and affects how we practice. On the other hand, Medicare is usually pretty good at paying its bills—except when it doesn’t. If our costs go up, say in increased rent, we can’t raise our prices. And if we get together with a group of doctors to try to negotiate fees, it can be considered collusion, and as such, illegal. So we’re in a bind.

On the other hand, the current system of multiple payers causes no end of headaches and paperwork. A single payer system could reduce costs through having us deal with a single entity. But Medicare is also subject to the whims of politics, as when earlier this year, Medicare held onto all physician payments while Congress and the President negotiated a new Medicare fee structure. This had a real world impact of making it hard to pay our bills.

But this isn’t about the advantages and disadvantages of a single payer system—neither candidate is proposing such a thing. This is about the disaster the McCain plan would wreak on all of us.
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I’ve written quite a bit about diabetes here and at my old blog, and I’ve explained to you how controlling blood pressure and cholesterol in diabetics prevents macrovascular disease, such as heart attack and stroke. I’ve also explained how controlling blood sugar prevents microvascular disease such as kidney failure and blindness. In type II diabetics, controlling blood sugar prevents disability and sometimes death. In type I diabetics, controlling diabetes with insulin is the only way to prevent a swift and painful death. Most non-diabetics, however, don’t know the details of how we control blood sugar.

Let’s take an example. A typical type I diabetic, who is completely dependent on insulin, will take a long acting (basal) insulin to keep glucose levels down between meals, and will also take a short acting insulin at meals to account for the extra glucose load. In order to know how much short-acting insulin to take, a diabetic has to insert a test strip into their glucometer, prick their finger with a small needle, and touch the drop of blood to the test strip. This is usually done (at least) on waking, before every meal, and at bedtime—at least four times per day. Thankfully, blood glucose monitors are quite inexpensive and last a long time. Test strips, however, are expensive and disposable. How expensive? Depending on the brand of meter being used, and how many times you need to test, $30-$200 per month. These strips are usually not covered by insurance.

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Yesterday, we looked at how real science works; today, in a repost from my old blog, we look at some really bad science. –PalMD

I’ve been meaning to touch on “Morgellons disease” (a form of delusional parasitosis) for a while, but haven’t figured out how to approach it. Thankfully, others have. In the first referenced discussion, a paper was cited. This paper was such a great example of how not to approach medical science that I just had to address it in detail, section by section…

Background

The authors argue for a newly described illness which they call “Morgellons”. It resembles in all ways except name delusional parasitosis, a condition where a person is falsely convinced that they have parasites in their skin. In general, if you wish to describe a possible new illness, you should start by coming up with a useful operational definition. This doesn’t happen. Instead we get anecdotes.

It begins with a single practitioner’s experiences. It’s hard to overstate how problematic this is. Early in the HIV epidemic, solo practitioners in a few cities found unusual diseases, communicated with each other, and discovered the AIDS epidemic—the difference was that the discovered real diseases with shared characteristics.

This physician saw some patients who shared similar characteristics, and, rather than picking the most likely diagnosis, went straight for the zebra. A more apt metaphor might be a unicorn—she made her diagnosis based on a “research foundation” devoted to an illness made up out of whole cloth.

History

The next mistake is in linking the new “disease” with an account from a 17th century observer. The observations are old, non-specific, and based on no current medical science. He described an odd constellation of symptoms, and the Morgellons Movement adopted it. There is no way to validate 400 year old observations.

After co-opting a 400 year-old name, one of the authors started a foundation which “began accepting registrations from people with symptoms of this unrecognized disease.” They lay out no clear case definition, and change the characteristics of the disease to fit the patient. “…[I]t soon became evident that other symptoms within this patient group, such as disabling fatigue, life-altering cognitive decline, joint pain, and mood disorders…” sometimes accompanied the skin symptoms. Shifting the goalposts in order to make your case definition more inclusive is not great science.

Symptoms

This section of the paper is devoted to a long list of symptoms which once again fails to give a case definition. In this paper, which purports to report an important emerging disease, it is disturbing that half-way through the paper, no disease has yet been defined. Perhaps one of the worst sins of this section is the confusion of correlation and causation based on a false premise. The authors assume (or beg the question) that Morgellons exists. Based on that assumption they assert that:

[t]he high incidence of psychopathology, which appears to be directly attributable to this disease, confounds the clinical picture for these patients as the seek validation for an insidious dermatologic condition that defies logic, while sometimes exhibiting obvious symptoms of mental illness.

Might they have put the cart before the, er, unicorn? If someone acts mentally ill, and has a bizarre set of illogical symptoms, why not put the blame where it belongs? To take a disease of the mind, and simply assert that it is a disease of the body, will help no one.

The next assertion is truly horrible. “It appears that the putative underlying infectious disease, which has been unrecognized and untreated, can cause psychopathology in many patients.”

Holy crap! Now it’s an infectious disease?!? Based on what? And it’s an infectious disease that affects the skin and central nervous system? Maybe it’s a variant of syphilis! How can these few clinicians (OK, only one is a clinician) have stumbled onto something so important and end up ignored?

Epidemiology and Transmission

OK…time for more unfounded assertions. “The total number of registrations on the Morgellons Research Foundation website is presently 2200, which is believed to be a fraction of the actual number of cases.” Believed by whom?

Then of course they run into the same problem they’ve had from the beginning: “There is some evidence to suggest that skin lesions and fibers may not be readily apparent in all individuals with this disease… .” Then what defines the disease? How does one track the epidemiology of a disease with a name and no definition?

Pathophysiology

And here is the real coup de grace.

Skin biopsies of patients with Morgellons disease typically reveal nonspecific pathology or an inflammatory process with no observable pathogens…In general, pathologists look for signs of known diseases and, thus, may miss clues of Morgellons disease in biopsies.

OK. I can’t go on. It’s not just that a mainstream journal would publish such crap. It’s that it makes my head hurt. But I will form a logical hypothesis that my headache has something to do with reading, sitting at the computer, and being frustrated. It seems unreasonable to posit that it is due to some unknown infectious agent that can be neither measured nor defined.

In the discussion section of the paper, the authors invoke Vienese physician Ignaz Semmelweis, a physician criticized as a crank in his own time, but later lauded as a hero. Robert Park said, “to wear the mantle of Galileo it is not enough that you be persecuted by an unkind establishment, you must also be right.” This paper is not right—it’s not even wrong.

References

Savely, V., Leitao, M. (2006). The Mystery of Morgellons Disease: Infection or Delusion?. American Journal of Clinical Dermatology, 7(1), 1-5.

In my earlier post about HIV therapy (a post I strongly recommend), I wrote, “After entering a cell (never mind how for now), HIV needs to find a way to makes copies of itself, which requires DNA.” Because of some recently released data, it’s time to look at how HIV enters the cell, and to expand a bit on the biology of HIV infection (but this is really a “Part II” so please refer to the above-linked post, even though this should stand on its own). This will also allow us another glimpse into how real science works. proceeding from observation, though hypothesis, and hypothesis testing.

Once again, as in all of my science-y posts, please forgive any oversimplification.

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As I continue to fight the good fight against my first respiratory infection of the season, I will serve you a few portions of learnin’ from the old blog. –PalMD

Cupping goes back millennia. In the U.S., the marks of cupping are often seen in immigrant communities, particularly those from Southeast Asia, and are often mis-identified as signs of abuse.

It’s an interesting practice, with many different explanations, depending on the culture. It’s often used to do the cultural equivalent of drawing out “ill humors”. Of course, there is no scientific basis for this. Historically it is interesting. At least, one would hope the interest were purely historic. Unfortunately, that’s not the case. Despite that fact that cupping is based on ancient, invalid ideas about health and disease, it is popular in cult medicine circles.

Take, for instance, this website.

Cupping therapy has been further developed as a means to open the ‘Meridians’ of the body. Meridians are the conduits in the body through which energy flows to every part of the body and through every organ and tissue. There are five meridians on the back that, when opened, allow invigorating energy to travel the whole length of the body. It has been found that cupping is probably the best way of opening those meridians.

Could someone please show me a meridian? If they truly “transport energy” it should be reasonably easy to find one.

Cupping has also been found to affect the body up to four inches into the tissues, causing tissues to release toxins, activate the lymphatic system, clear colon blockages, help activate and clear the veins, arteries and capillaries, activate the skin, clear stretch marks and improve varicose veins. Cupping is the best deep tissue massage available. Cupping, the technique, is very useful and very safe and can be easily learned and incorporated into your family health practices.

I actually like to see evidence of any of that. Colon?!? I never thought I’d see a connection between cupping and poo woo, but then, the cultists seem to be obsessed with the colon.

Cupping is an ancient medical technique based on pre-scientific understandings of human health. When you don’t have much to offer in the face of death and disease, you might naturally develop your own ideas about how the body works, and how to affect change.

Thankfully, we are no longer in a pre-scientific era. Most of us do not think its better to live in grass huts, hunt and eat disease ridden carcasses, and drink unsafe water. What is it about medicine that attracts such idiocy? Alternative medicine? What about alternative flying? Alternative physics? Alternative engineering?

References:

Journal of Pediatric Health Care. Volume 18, Issue 3, May-June 2004, Pages 123-129. DOI:10.1016/j.pedhc.2003.11.004.

As I continue to fight the good fight against my first respiratory infection of the season, I will serve you a few portions of learnin’ from the old blog. –PalMD

We’ve spoken a bit lately of the micro- and macrovascular complications of diabetes. Let’s see what that means in real life. One of the most devastating complications of diabetes is amputation, which is often due to the microvascular complication of peripheral neuropathy. This can begin as a tingling, burning pain in the feet, but can lead to loss of sensation. Small injuries can rapidly become limb-threatening…(Warning: Yucky picture under the fold)
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If you’ve spent any time at all reading science and medicine blogs, you know that many of us are quite critical of the way the traditional media covers science. The economics of the business allows for fewer and fewer dedicated science and medical journalists. In the blogosphere, writers have a certain freedom—-the freedom not to be paid, which means that the financial fortunes of our medium (the web) are not directly tied to how many readers I bring in with a headline. But all this is just a lot of words introducing my critique of a recent New York Times article.

The article is titled “Using Science to Sort Claims of Alternative Medicine”. It’s well-written and interesting, but suffers from a fatal flaw (or perhaps just recapitulates it)—like most of us, it fails to take into account how likely (or unlikely) a bizarre medical claim is when evaluating evidence for it.

The author doesn’t realize it, but he points out the fatal flaw in the modus operandi of the National Center for Complementary and Alternative Medicine (NCCAM). Lately, the alternative medicine community has seen some of its bigger trials fall apart.

The alternative medicine community has a few different sects. The largest is the group of various snake-oil salesmen out to make a buck on others’ suffering. Then there is the “supplement industry”. Finally there is the saddest sect—that of real scientists trying to use evidence-based medicine to evaluate improbable claims. These folks mean well, but they’ve picked the wrong tool for the job.

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I’m off to the west coast (of Michigan) for a few days, and if I don’t blog, I shall die…or something. So I have a few posts from my old blog to share with you.

Often in the discussion of cult medicines such as homeopathy, acupuncture, and reiki, supporters fall back on “the wisdom of the ancients”. This raises a question. Since “the ancients” had it wrong (i.e. their belief systems could not effectively treat disease), were they just stupid?

Any of my historian readers already know the answer, but it’s worth going over…

Our forebears were neither more nor less intelligent that we (unless you go back about 3 or 4 million years—that gets rather dicey). They were literate, intelligent, and damn good thinkers. They just had limits to their ability to investigate their environments.

Let’s take an example. This is from an English physician living in Paris in the mid-18th century, during the time inoculation against smallpox was spreading, but vaccination had not yet been invented.

By way of background, this new (to Europe) practice actually comprised many different practices, but the basics were the same: take a bit of material from a smallpox pustule, and rub, snort, or inject it into the skin of a healthy person. The healthy person would then (hopefully), develop a mild case of smallpox that would protect them from epidemic smallpox, which had a high rate of mortality and disfigurement.

Dr. Cantwell, an English physician in Paris, had some concerns about this procedure (translation unfortunately mine):

It is facts, and not the promise of them, and reason, that must truly interest the public. If they respond to the promises of the Inoculators, inoculation will establish itself despite all that can be said to show the danger and inutility of it. If, on the contrary, the facts directly dispute their promises, the public will be disabused and inoculation fall by the wayside.

As for my part, I would say that if among the Inoculators there is found even one who responds pertinently to the facts which I allege, I will be the first to swear to my defeat, and will side with these gentlemen. If not, justice demands that one always allow that new facts could be gathered against this method, and they must be rendered public with all pertinent arguments.

It is not enough to say that of one hundred persons inoculated, only one or two perished in the first forty days. It is a question of knowing FIRST if Inoculation gives lifelong protection from smallpox, and if one can be killed by a natural smallpox infection which may follow the artificial one…. SECOND it is necessary to know, again, if inoculation might accidentally spread smallpox, in the right conditions causing more people to perish of this contagion than would be saved by its application…(emphasis mine)

Dr. Cantwell was basically one of the earliest opponents of immunoprophylaxis (prevention of disease via inoculation or vaccine). Was he a crank?

Well, not by this excerpt. He asks the same questions that we do today regarding a vaccine: what is the mortality from the procedure, does it actually protect, and could it possibly spread disease.

This is very “modern” thinking. It turns out that Dr. Cantwell was both right and wrong in his apprehension about inoculation. There were, of course, no standard practices, and people were hurt, but in general, it tended to save lives during epidemics.

Thankfully, the much safer practice of vaccination came along, largely building on the knowledge of inoculation, and the discovery of healthy milk maids. (What was Jenner doing hanging out with the milk maids?)

So, the ancients did indeed possess wisdom; they just didn’t have all the tools to apply it, including statistics, microbiology, and a well-developed germ theory of disease.

It would be wise to remember that our forebears, though smart, didn’t have the tools we have today. To rely on their intelligence but eschew modern knowledge makes us look like the fools.