AIn 1662, a British clergyman and
physician now known only as Henshaw created the first hyperbaric
chamber for therapeutic purposes. While this chamber was merely a
sealed room with a system of bellows and valves, Henshaw theorized
that the pressure changes he could modulate in his “domicilium” were
of a benefit to both acute and chronic illnesses. In the more than
three centuries since, hyperbaric oxygen treatments have proven
effective for myriad conditions including decompression sickness
(the “bends”), carbon monoxide poisoning, burn,s and non-healing
wounds. And new research out of Tel Aviv University suggests that
hyperbaric oxygen might also promote neuroplasticity and dramatic
improvements in outcomes after brain damage.
How it works
It is the increased overall pressure found in hyperbaric oxygen
chambers that helps reduce the volume of inert gas bubbles to treat
conditions like the bends. But another side effect of the pressure
change is an increased level of oxygen the pressure compresses the
oxygen molecules, providing an environment that can deliver oxygen
to the body at ten times the amount available in normal atmospheric
conditions.
Hyperbaric Oxygen Therapy and Autism
“I call it a supernatural treatment,” says George Mychaskiw, chair
of the department of anesthesiology at Nemours Children’s Hospital
in Florida and an expert in hyperbaric medicine. “Not that it’s
magic. But we don’t normally live at two or three atmospheres of
pressure. Except for a few bottom-dwelling organisms in the sea, the
behavior of oxygen at these difference pressures is outside the
normal realm of biology, certainly outside the normal realm of human
biology.”
That “supernatural” oxygenation has been shown to help promote
healing in different types of wounds. “The tissue around a chronic
wound may be getting very little oxygen because there’s very little
blood flow to the center of the wound,” says Col. Brian McCrary, an
Air Force physician and expert in hyperbaric medicine. “So by
increasing the oxygen to the tissues, you help drive healing.
Hyperbaric treatment also helps stimulate new blood vessel growth,
which drives new capillaries into an area to help get more blood and
oxygen into the affected area. And it’s also been shown to reduce
inflammation, too.”
The combination of these benefits has led many to hypothesize that
hyperbaric oxygen could be a good treatment for brain damage.
Mychaskiw has demonstrated exactly that in animal models, yet it has
been more difficult to prove in human trials. But Shai Efrati, a
neuroscientist at Tel Aviv University's Sackler Faculty of Medicine,
recently tested hyperbaric oxygen treatments on seventy-four people
who had had strokes and were no longer improving.
Healing after stroke
Efrati and his colleagues had half the study participants undergo
hyperbaric oxygen treatment for two hours daily five times a week
for a total of forty sessions. The second control group received no
treatment for two months, followed by two months of hyperbaric
treatments. The researchers found that the patients who received
hyperbaric treatment in the first two months showed remarkable
clinical improvements including increased sensation, language
skills, and movement ability even if it had been years since the
initial damage. Neuroimaging analyses also showed significant
increased neural activity in damaged brain areas. The results were
published in PLoS ONE earlier this year.
“After a brain injury, you’ll see several types of brain damage. The
most severe is necrosis. That tissue is dead and nothing can be
done. But surrounding that necrotic tissue, you see areas that still
have some metabolic function. Those areas can be improved,” says
Efrati. He argues that those cells are compromised, with enough
metabolic activity to stay alive but not enough to fire and promote
action potentials. The extra oxygen delivered by hyperbaric
treatment, over time, helps those cells heal and regain normal
metabolic function and firing potential.
Efrati and his team are currently running two similar trials on
people with traumatic brain injury and Alzheimer’s.
A question of control
While many agree that Efrati’s data are promising, a prior study run
by the U.S. Air Force found no significant differences between
hyperbaric oxygen treatment and a sham treatment on patients with
mild traumatic brain injury (TBI). Both groups showed significant
improvement over the course of the trial. Those results were
published in the November 2012 issue of the Journal of Neurotrauma.
Stroke & Hyperbaric Chambers HBOT
“The sham treatment was just air at a slightly increased pressure,”
says McCrary. “There are several possible explanations for why there
were equivalent improvements but the most likely scenario is a
placebo effect or just the effects of the intensive treatment and
attention that the patients received over the course of the six-week
trial.” McCrary says that future trials should be able to rule out
those scenarios.
Mychaskiw is not surprised by the contradictory results. He argues
that it is very difficult to design a good study to test the
efficacy of hyperbaric oxygen treatments. “Patients are very aware
of their surroundings, so people in any control group have to
believe they are receiving some kind of pressure. It’s hard to rule
out placebo or just the effect of receiving a treatment, any
treatment ,” he says. “But it’s also possible that it’s not the
oxygen that has the effect. It’s possible that the pressure itself
has a therapeutic effect. There are a lot of factors at play and
it’s a very complicated thing to study.”
The Air Force is completing the analysis on three more trials that
will be published later this year, which McCrary hopes will finally
provide more definitive answers. But despite the lack of clear-cut
clinical results, hyperbaric oxygen is already being used to treat
brain damage resulting from conditions ranging from TBI to dementia
to autism at specialized clinics across the globe.
Source
“At the end of the day, hyperbaric oxygen is a relatively benign
therapy. It’s very hard to hurt someone with hyperbaric oxygen at
the pressures that are used,” says Mychaskiw. “And those who are
currently using it become very evangelistic about it because they
see, at least in their minds, dramatic, clinical improvement. My
hope is that future studies will give us a better understanding of
how and where and why it works. But we haven’t gotten those answers
yet.”
