Monday, February 13, 2012

Hyperbaric oxygen, evidence-based medicine and death

A few days ago, a tragedy occurred at a horse rehabilitation center in Florida. A horse said to be receiving hyperbaric oxygen treatment for EPM [equine protozoal myeloencephalitis] and a 28-year-old woman who worked at the farm were killed when the chamber exploded. Another woman was injured in the blast which destroyed the facility. The horse apparently became agitated and kicked off a protective horseshoe cover. A spark from the shoe ignited the explosion. Debris from the blast covered a 1200 square foot area.

Could this accident have been prevented? Some accounts pointed out that the horse should have been outfitted with aluminum shoes, which would not have caused a spark. Two workers did not reach an emergency shut-off valve in time. But what was the real cause?

For many years, people who have hyperbaric chambers have been looking for things to do with them. There is no doubt that hyperbaric oxygen is a very effective treatment for decompression sickness in scuba divers. Other than that, there is no proof in humans or animals that hyperbaric oxygen is effective in any medical illness. Two recent Cochrane reviews have found no evidence to support its use in the most commonly cited medical conditions for which it is always proposed, carbon monoxide poisoning and wounds. Both reviews call for randomized controlled trials.

A thorough search for evidence that hyperbaric oxygen works in equine neurologic diseases or wounds revealed only anecdotes. Websites devoted to the diagnosis and treatment of EPM do not mention the use of hyperbaric oxygen. There are many animal hyperbaric chambers in the United States.

I realize that all treatments need not be evidence-based. I don’t need a randomized controlled trial to prove to me that aspirin cures headaches.

But for a woman and a horse to die during a dangerous and completely speculative treatment is a truly preventable tragedy.


Anonymous said...

The problem here was not that they were using an unproven treatment. The problem was that they used the treatment in an unsafe way.

Skeptical Scalpel said...

Thanks for commenting but are you saying the treatment is proven? Please provide a link to the proof?

Anonymous said...

Read more carefully. I did not say that the treatment is proven. I said that the problem was they were using this treatment in an unsafe way.

I wonder if you cannot get past your objection to people using treatments not backed by scientific data. You give a head nod to unproven treatments, but your response to my comment suggests that you can't see beyond that.

I focused on the problem; you focused on the treatment.

And for the record, I have no particular knowledge of hyperbaric oxygen treatment for anything. I was just commenting on what I felt was an error in your logic.

Although I am a scientist by training, I try to be open-minded to all treatment ideas, regardless of which "side of the fence" they come from. After all, there are no treatments that did not start out as "unproven." Being unproven doesn't make a treatment invalid.

Skeptical Scalpel said...

I use treatments unproven by randomized controlled studies every day. Some have estimated that 95% of what we do in medicine is not really "evidence-based." But putting a horse in a hyperbaric chamber is undoubtedly expensive and certainly dangerous as the story illustrates. I could not find even a suggestion that HBO is of any value whatsoever for equine neurologic disease or much else for that matter.

I am reasonably open-minded but there has to be some shred of proof that a treatment works.

Anonymous said...

Ok. My point was that the issue is not whether or not hyperbaric oxygen was an appropriate treatment. I accept that I have failed to make my point clear and will bow out.

medmechanic said...

Skeptical u really think the tragedy was because of using something that was not EBM driven?I agree intelligent horses don't kick when they read supportive cochrane evidence.
...that logic must then make Aristotal a happy man to be dead..

Skeptical Scalpel said...

I'm not blaming the horse. The concept was misguided. I wonder if everyone involved with this feels that the death of the woman was worth it. It's one thing to give a horse an unproven treatment like acupuncture, which is not likely to kill the horse or any handlers. It's a whole other thing to put a horse in a hyperbaric chamber.

David Davis, BS, RRT, CHT said...

Thank you for sharing your thoughts about the use and safety of hyperbaric oxygen (HBO) therapy. The loss of life truly saddens me. Perhaps we should ask if HBO therapy is currently being used safely and appropriately. HBO therapy has been well researched and approved for 13 medical indications. The following human indications are approved by the Undersea Hyperbaric Medical Society, the American College of Hyperbaric Medicine and the Centers for Medicare & Medicaid (CMS).

• Air or Gas Embolism
• Acute Carbon Monoxide Intoxication (Cyanide poisoning)
• Acute Peripheral Arterial Insufficiency
• Chronic Refractory Osteomyelitis
• Clostridial Myonecrosis (Gas Gangrene)
• Compromised Skin Grafts / Tissue Flaps
• Crush Injuries
• Compartment Syndrome and Acute Traumatic Ischemias
• Decompression Illness
• Diabetic Foot Ulcer
• Necrotizing Soft Tissue Infections
• Osteoradionecrosis
• Soft Tissue Radionecrosis

These organizations also give a list of medical conditions that are not currently approved indications for HBO therapy. For instance, CMS has not approved this therapy for the following partial list of conditions.

• Myocardial infarction
• Cardiogenic shock
• Sickle cell anemia
• Acute or chronic cerebral vascular insufficiency
• Systemic aerobic infection
• Organ transplantation
• Pulmonary emphysema

Safety is a key aspect of providing proper care. Hyperbaric oxygen therapy is no exception. However, when used appropriately HBO therapy is a limb and life saving treatment. Patient selection is essential to proper care and positive outcomes.

Anonymous said...

Squeak larkins of ocala fla swears HBO is a cure for epm in horses. She is actually taking money from people to cure their horses. No the horses were not confirmed epm cases but she says a blood test will show positive. Is this true?

Skeptical Scalpel said...

I am not a veterinarian. I don't treat horses. A cursory search on the Internet still shows that there is no proof that EPM is helped by hyperbaric oxygen treatments.

There are many blood tests for EPM with varying rates of false positive and false negative results. It does not appear that there is any test that is 100% reliable.

Anonymous said...

I am a vet student who is currently procrastinating by browsing the archives of your blog. I don't know if anyone will read a comment on a comment that was left half a year ago, but diagnosing EPM is not straightforward. In areas where EPM is endemic, a large proportion of horses will have antibodies to Sarcocystis neurona, the most common cause of EPM - in some areas, as many as half! New quantitative titers improve the specificity of the test, but in many cases a CSF sample is still tested for antibodies, or the horse is treated presumptively with the knowledge that it could be a false positive because the client does not wish to go to the trouble of obtaining a CSF sample. It CAN be done in the field but is usually done at a referral hospital.

Skeptical Scalpel said...

Anon, Thanks for reading my blog. At least one person read your comment--me. Would you advise treating EPM presumptively with hyperbaric oxygen? Seems a bit drastic to me.

Anonymous said...

The university I attend (with well-regarded, well-published neurology and equine internal medicine services) does not even have hyperbaric oxygen, and we have yet to even talk about it; I'm in third year and we already covered equine neurological diseases. Treatment for EPM consists of anti-inflammatories, anti-protozoals, tincture of time, and judicious controlled exercise in the less severely affected horses to encourage maintenance and recovery of function, just as you would send a human patient to PT. Owners are counseled that, on average, horses are expected to improve by 1 or 2 grades of ataxia - where 0 is normal and 5 is recumbent - and so there may be lasting deficits. We can kill the parasites but we can't bring upper motor neurons back from the dead. The cynic in me says that if we could, someone would be getting rich off of desperate spinal cord injury patients instead of treating horses...

Skeptical Scalpel said...

Thanks for the information. I appreciate it.

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