I recently read the BMC Pediatrics article, “Hyperbaric treatment for children with autism: a multicenter, randomized, double-blind, controlled trial”1. I know this paper is attracting a lot of attention in the media, and it is certainly being ballyhooed about the internet. Hell, I’ve even received e-mail spam about this study! But I’m sorry to say, I don’t really share the excitement. In fact, I see what looks like a pretty significant error in the methodology of this study. It’s one of those types of potential errors that stand out like a strobe light or a siren – it’s really tough for me to pretend it’s not there.
Once again, I’m going to ask readers to set aside, for the moment, anything they may know about the role of hemoglobin in oxygen transport and how the minute increases (probably around 3-4%) in total blood oxygen content afforded by this kind of hyperbaric therapy, or simple O2 therapy for that matter, are probably pretty likely to be insignificant.
Both the paper and ClinicalTrials.gov2 list the Center for Autism Research and Education, Phoenix, Arizona, as a study location. This is a problem, because the stated treatment pressure in the study (1.3ATM) seems highly unlikely to actually be achievable in Phoenix with the equipment that was apparently used for this study.
As described in the section titled, “Interventions”:
“These procedures included covering control switches, inflating and deflating the chambers to simulate pressure changes, and masking the sounds from the chambers.”
The use of inflatable monoplace hyperbaric chambers, is a clear indication that the actual total pressures (and quite likely results of this study) would have been affected by the ambient air pressures at the times and locations of treatment. In fact, the ambient air pressure is the largest component of the stated treatment pressure in this study (ambient pressure + added treatment pressure = total treatment pressure).
Ambient pressure
Local atmospheric pressure is typically reported as sea-level pressure3 for its utility to aviation, and the meaningful interpretation of weather maps, etc., but the actual station pressure is affected by the elevation. The expected ambient atmospheric pressure, corrected for altitude, (or station pressure) in Phoenix, Arizona4 is 28.69 in Hg (where there is a modest elevation of 1161’ AMSL). Wanting to give this paper the benefit of the doubt, and knowing that “high pressure” weather is typical of the Phoenix climate, I looked at 30-day data5 for actual station pressure in Phoenix at a station of slightly lower altitude than the Center for Autism Research and Education. The 30-day mean station pressure is 28.81 in Hg, so I’ll use that one for calculations, as it will yield results more likely to be in the study’s favor.
Added treatment pressure
The actual operating pressure of the inflatable chambers, as stated by the manufacturer, is 4 PSI. 6,7 This pressure is also indicated on the Center for Autism Research and Education’s website:
“The chambers used at care utilize a pressure of 4 psi.”8
Total treatment pressure
The total treatment pressure can be easily calculated with the following conversions:
in Hg * 0.491 = PSI
PSI + PSIG = Total PSI
Total PSI * .068 = ATA
For Phoenix, Arizona, this gives a calculated total treatment pressure of 1.23 ATA.
28.81 * 0.491 = 14.15 PSI
14.15 PSI + 4 PSIG = 18.15 PSI
18.15 PSI * .068 = 1.23 ATA
Damn, that’s a pretty big difference from the paper’s stated 1.3 ATM – representing an addition of only .23 ATM (instead of .30 ATM) above mean sea-level pressure of 1 ATM.
I’ve corresponded with the lead author of this study in the past, and he stated that he observes gauge pressure of 4.15 PSI. Despite the manufacturer specs, the FDA-cleared medical device premarket notification, and the Center for Autism Research and Education’s website (which all indicate operating pressure of 4 PSI), and wanting to give the benefit of the doubt, I’ll use 4.15 PSI for the next calculation, as it will be more likely to yield results in the study’s favor.
28.81 * 0.491 = 14.15 PSI
14.15 PSI + 4.15 PSIG = 18.30 PSI
18.30 PSI * .068 = 1.24 ATA
It could be argued that treatment pressure for the other study locations were properly rounded up to 1.3 ATM (even though the actual pressures were quite likely to be considerably lower), however, even with all the calculations purposely leaned in favor of a higher number for Phoenix, Arizona, the study’s stated treatment pressure, there, should have properly rounded to 1.2 ATA! This suggests an overstatement of the added treatment pressure for the Phoenix location of 50% (.3 ATM is 150% of .2 ATM). Even if given the benefit of the doubt yet again, and an exception to proper rounding were made for solely for the Phoenix location in this study, the study’s likely overstatement in added treatment pressure for Phoenix is still a full 25%. (.3 ATM is 125% of .24 ATM – 25% more added pressure above 1 ATM was claimed in this paper, than was probably delivered).
I think this is a big enough boo-boo, that the editors of BMC Pediatrics should call for detailed errata. In the interest of scientific accuracy, it would seem prudent for BMC Pediatrics to:
1. Clarify for its readership and the scientific community, that the stated pressure of 1.3 ATM in this study is rounded up, and includes the ambient air pressure, or alternatively, state the estimated pressure in terms of ATA.
2. Clarify for its readership and the scientific community, that the stated pressure of 1.3 ATM in this study is an estimated pressure, since no actual measurements of ambient station pressure for the locations, and dates/times of treatments were reported.
3. Note for its readership and the scientific community, that the stated pressure of 1.3 ATM was not likely to be uniformly achievable across all study locations due to the use of inflatable hyperbaric chambers and changes in elevation (and atmospheric pressure) across study locations, potentially confounding the results of this study.
4. Note for its readership and the scientific community, that estimated pressures in the placebo control group are affected by these same issues that affect the treatment group, potentially confounding the results of this study further.
What do you think?
1 BMC Pediatrics 2009, 9:21doi:10.1186/1471-2431-9-21
http://www.biomedcentral.com/1471-2431/9/21/abstract
2 http://clinicaltrials.gov/ct2/show/NCT00335790
3Federal Meteorological Handbook No. 1 – Table 11-2
http://www.nws.noaa.gov/oso/oso1/oso12/fmh1/fmh1ch11.htm
4 LAT/LON 33.5º N 118.08º W
5 http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=psr&sid=KPHX&num=720
6 Medical device pre-market notification (FDA-cleared)
7 Manufacturer product sheet
Left Brain Right Brain 
DoC, thanks for that.
?Surely this study would indicate that autistic symptoms would increase and development will be slowed at higher altitude?…
Thoughts?
I’m sorry, but all you have to do is look at the authors of this study: Rossignol, Neubrander, Mumper. Names just loaded with credibility. I’ll read such a study when it comes from respected members of the research community.
The journal that published this article does allow for posting comments. I think a discussion such as you have here would be completely appropriate and could serve to alert readers as to potential deficiencies in the paper.
Quite simply, your calculations are right( icant make them stack up) and the study is flawed because of an alleged atmospheric pressure difference (being less than the study indicates.)This would prove that the therapy works even better than the study indicates because the pressure in the chambers was less than your hypothesis more pressure means more absorption of oxygen in the blood.. Simply ,the 4psi is the air pressure produced by the compressor inlet into the chambers while the chambers reach the desired pressure 1.3ATM.
I cannot think for one second that oxygen is ever bad for anyone unless you live in Pharma Land..
Does Dr. Rossignol in particular or HBOT proponents in general recommend that children who live at high altitude should move to the coast? That would seem to be a straightforward conclusion of his hypothesis if it is true. That would make more sense than buying a chamber and undergoing limited treatments. It would be kind of odd if Dr. Rossignol hasn’t though of that.
First of all you appear to have several typos in your formulas. I am assuming that you mean to be using this formula
Hg * 0.491 = PSI
Yet in your actual calculations you list .0491 instead of 0.491.
Second your analysis of the results is very dependent on what you take to be Hg reading for the site. For each change of 0.1 in Hg, the resulting ATA figure changes by about 0.00334.
So if your Hg figure is off by by .19 and you use 4.15 for the chamber then the resulting figure is 1.250452 which could be properly rounded to 1.3.
Looking at the page from NOAA that you linked to there is a sufficient variance in the data that your figure could be off by that amount.
Furthermore, you do not have the data for what the actual conditions are at the center itself let alone what the conditions in the room where the chamber is located.
So given the sensitivity to the change in Hg figure and the lack of accurate data I think it is safe to say that your analysis is flawed.
If you wanted to have an accurate criticism of the study I suggest that you contact either the author or the study or the center and get the actual data to use in your calculations.
@daedalus2, I submitted a comment on 3/14, and received a confirmation e-mail that it had been recieved. Despite a stated two-day moderation decision, it has not been posted.
@One Queer Fish, This is a possibility – if the chamber is underwater or inside of another hyperbaric chamber. The study did not say anything about this.
@MJ, The template calcuation was correct, values unaffected, and the subsequent typos corrected – thank you.
Exactly! I’m so glad you get it. This applies (although less so) to the Lynchburg and Naperville locations as well.
If the data is off. It may be, but since the study authors did not provide any relevant atmospheric data, it’s difficult know exactly what the actual added treatment pressure would have been. By the way, the standard deviation in the linked data is .14 (as of yesterday). Even if every data point of 720 data points is off by an amount equal to the standard deviation (in your favor) it’s still 1.2 ATA (at 2 significant figures).
It may be, but keep in mind that this then applies to the study as well.
It’s a definitely potential confound.
@Socrates and @Joseph, interesting points.
As an example, the change in pressure (due to elevation alone) by moving from Boulder, Colorado to a coastal city would be about .2 ATA
“These procedures included covering control switches, inflating and deflating the chambers to simulate pressure changes, and masking the sounds from the chambers.”
Despite the blinding attempt, it would have been trivial for someone inside the inflated “nylon” chamber to guess wether it was inflated at 1.03 or 1.3 ATM, by touching the side of the chamber, and guessing if it was drawn tight or loose.
I’m inclined to agree @_Arthur
More on the blinding in this study by Steven Novella over at the Neurologica blog.
quite simply, this analysis is at best dangerous. Because you know what, the pressure inside these chambers is controlled by an operator outside so the said tapping of chambers to realise a chamber pressure is absurd, a joke.
4psi is the compressor inlet pressure NOT the max pressure of the chamber simple as that,. if there are any flaws in the study it is only, fair to hypothesise and say, that, if it were used at “correct ” pressure the results on the children would be better as the absorption of oygen would be greater not lesser at a more deeper depth.
Get a life guys .. Pressure gauges are pressure gauges and not open to
There are probably other ways. What I want to know is whether the parents who participated in the study (and many of them did get into the chambers) were first-timers at HBOT. The paper didn’t say, unless I missed it.
The statistics of the study also seem unconvincing. There’s only 1 statistically significant between-groups effect among 9 measures taken using ATEC and ABC.
@One Queer Fish, you appear completely lost. The compressors’ maximum pressure has to be way more than 4 PSI to ensure adequate airflow at 4 PSI (and prevent CO2 buildup).
The pressure in these chambers is regulated by manufacturer-installed air-exchange valves – not the compressor! When the chamber reaches maximum operating pressure, the valves crack open, and vent the air. The only way to beat this built-in safety mechanism, would be to illegally modify the chamber (oversize the compresser, modify the air-exchange valves, etc.).
@One Queer Fish, you appear completely lost. The compressors’ maximum pressure has to be way more than 4 PSI to ensure adequate airflow at 4 PSI (and prevent CO2 buildup).
Says who??
Basic, freshman-level, physics.
There has to be a pressure difference between the source (the compressor) and the HBOT balloon, or there will be no flow of gas.
If the pressure is lower at the compressor, gas flows towards the compressor.
If the pressure is the same in the compressor, gas doesn’t flow.
If the pressure is higher at the compressor, gas flows from the compressor into the balloon.
Sully your an expert are you??
Simply, carry the maths and your logic to pumping up your car tyre at the garage The tyre pressure is e.g. 66lbs psi ,so your compressor pressure has to be 66lbs psi.. if that’s what your saying that is sooo wrong :.quite simply, you see the little bit that you attach the hose to on your tyre its called an air inlet valve ,which allows air in but not out and funnily enough the pressure inside the tyre goes up despite the inlet air pressure being as low as 2lbs psi to push open the the air inlet valve regulator open ,allowing the the air in..The exact same principles are applied to HBOT chambers you could have 2psi putting you down to to 5 ATM only disadvantage in this is the time it would take..As for Co2 build up you had better explain that one never ever read heard anything about it in a chamber..and if your wearing an oxygen mask ?how are you going to breath in Co2 ?
Your dangerous mate putting out sums like you have and you don’t even understand the basics…
1. As an example, the change in pressure (due to elevation alone) by moving from Boulder, Colorado to a coastal city would be about .2 ATA
Doc your quite simply, wrong here and so is your maths ..
When your “chamber pressure” gauge starts it only starts to go up when you reach atmospheric pressure, simply, whether your 16,000ft up the mountain or 2 feet away from the sea ; it is irrelevant whether your in Blackpool by the sea or on top of Everest ..the pressure gauge starts at Atmospheric pressure within the chamber and until you reach atmospheric pressure the chamber pressure gauge will not rise …Quite simply,if you are beside the sea the gauge will go up instantly if your up Kilimanjaro it will take a while even to reach Atmospheric pressure..and then continue to your desired pressure.
you wonder why you never got a response to your questions , but its 1st day ,basics your asking about and then you try to make out the study is dangerous , quiet simply you are the dangerous one..
Doesn’t take an expert to understand basic physics.
You could check the manufacturer’s website if simple physics is still confusing.
I think it shows a very sloppy approach by the authors. It gives the appearance of a careful study to quote such accuracy. But, it shows that the authors appear to be unconcerned about accuracy.
If a pharmaceutical company gave a study where the doses varied by 50% and weren’t accurately tracked or reported, the same people touting this study would be up in arms.
Frankly, I think that this is one of the smaller problems with this paper. The diagnostic instruments (if I can call them that) are inadequate for drawing any real conclusions.
In thinking about this further, I’m inclined to agree Sullivan.
However, in light of the potential problems with the blinding, it would seem to suggest that the reported effects might be explained by placebo-effect-by-proxy. Although a potential confounder and an apparent inaccuracy in the methodology, the difference in added treatment pressure at such low pressures may be totally irrelvant.
Just keep talking Sully and Doc your slipping down the slippy plank faster than I had anticipated..
Sully quite simply ,the reason’s ,the tests are so accurate is simply because HBOT has been around since about the mid 1880`s and pharma doesn’t have anything to do with it because “you cant patent oxygen” so the treatment has evolved naturally and accurately .
The “diagnostic instruments “ you call have to be accurate, simply ,its the same with any compressed air and gas use, so again Sully your spouting of and know absolutely diddly ,but profess to hold forth and make a total idiot of yourself again.
And Doc if you ever get down from your podium try and read Prof James work he used HBOT in Dundee for 30 years on the NHS and other places .
Prof James on low pressure HBOT treatment .Simply, if there are any bits of the physics you don’t understand just say..heres a report from the “eminent “ “Vaccine Land Pharma” monthly tabloid the Lancet (so it must be right???)
“Dr. James mentioned that the McGill study, reported in Lancet, showed important clinical benefits in children treated at 1.3 ATA and normal air. At this level, the plasma oxygen tension rises by almost 50%, and the same is true for oxygen al the mitochondrial level.
A TV Director filming a program at 16,737 ft, developed severe altitude sickness. He was relieved by rapid descent within 40 minutes to 5362 Ft. This caused an atmospheric pressure difference of of only 0.1 ATA, with only an increase of 0.05 atm abs in partial oxygen pressure. This minor increase in oxygenation was enough to revive him.
This suggests that the rate at which level of oxygen is increased is important and that there is a critical threshold for oxygenation.”
You see how accurate these guys are and the standards of evidence required SPECT scans etc are used also a suitble check if appropriate ,
quite simply, there are over 30,000 published scientific studies on HBOT, unlike this forum where no evidence is required just journo speak, such as in the Judge Eady letters , no evidence required …just blustering ,hot gas, with a massive tad of smoke and mirrors
@Fish: There’s no reason to think any autism instruments are “accurate,” however that might be defined. The instruments they use (they aren’t diagnostic instruments) are the ABC and the ATEC. If you consider all 9 measures with these 2 instruments, the study did not find HBOT to be better than placebo.
The paper finds 1 statistically significant between-groups effect with those 2 instruments. But it would be naive to think this means something. When you have multiple measures, the odds of a false positive increase. With 9 measures, you should expect 0.45 of them to be false positives.
Apart from ABC and ATEC, they look at “global impressions.” With these, they do find effects that look more convincing. (Although I’m not sure they can still claim a statistically significant effect overall when all the measures are considered.)
Now, in “global impressions” a parent or a physician decides if the treated individual is worse, a little worse, better or much better in a number of areas. Obviously, this would be very subjective.
There’s some subjectivity to the ABC and ATEC, but they are considerably more systematic. Basically, you have to answer YES or NO to a number of questions like, “Does the child have eye contact?”
So why would there be a big effect in the very subjective “global impressions” but not much of an effect in the more systematic ABC or ATEC measures?
I think the simplest explanation is that the blinding was breached somehow.
The problem with blinding is quite serious.
To put this in numbers many people have experience with–
1.3 ATM (ATA is incorrect per thi blog post) is the equivalent of being 9.6′ underwater–think the deep end of a pool. The pain/pressure on the ears is substantial.
the control group got 1.03ATM. That is equivalent to 0.96′ underwater.
I know that I would have readily known which group I was in, were I a parent accompanying my child on these tests.
Sully ,listen up..
1 ATM = 33 feet your wrong above…pretty deep pool if you ask me ,big people stay around your town, by chance?
Simply, you imply ears hurting substantially(hardly) ,Ever been in a commercial airplane taking off , that’s a lot worse than being in an HBOT tank because the change in airplane plane air pressure is more extreme and they cant stop. Quite simply, should we all know stop using air flight, and stop our kids from learning to swim preposterous,! ,most people that go into HBOT tanks do not even get a slight “squeeze” and if they do they stop the dive until the ears “equalise” to the tank pressure and if they don’t “equalise” they cancel the dive no discomfort allowed..simple as that.
Of course Joseph, simply, they below , all the very highly qualified experienced professionals , conspired to achieve the results and all the parents conspired also ,and they hoodwinked everyone and anyone involved with these children also that the kids are better through trickery? but nobody outside this forum has twigged it yet ??Wakey! wakey ! who’s the conspiracy theorist now..?? kettle and pot spring to mind.. Your theories are on the pharma apologist spectrum, even the dreamers have to get real sometime ..suggest you do..
Daniel A. Rossignol1§, Lanier W. Rossignol1, Scott Smith1, Cindy Schneider2, Sally Logerquist2,
Anju Usman3, Jim Neubrander4, Eric M. Madren5, Gregg Hintz6, Barry Grushkin7, Elizabeth A.
Mumper8
1International Child Development Resource Center, Melbourne, FL, USA
2Center for Autism Research and Education, Phoenix, AZ, USA
3True Health Medical Center, Naperville, IL, USA
4 Edison, NJ, USA
5Princess Anne Medical Associates, Virginia Beach, VA, USA
6Therapeutic Pathways, East Troy, WI, USA
7Biognosys, Nanuet, NY, USA
8Rimland Center, Lynchburg, VA, USA
Conclusions
Children with autism who received hyperbaric treatment at 1.3 atm and 24% oxygen for 40 hourly sessions had significant improvements in overall functioning, receptive language, social interaction, eye contact, and sensory/cognitive awareness compared to children who received slightly pressurized room air. Trial Registration: clinicaltrials.gov NCT00335790
Straw man. Quite simply, the statistics in the study don’t consider the problem of multiple outcome measures. (Something similar came up with the timerosal study, Thompson et al. 2007 if you recall.) Second, because there’s a bigger effect with the more subjective measures, I’m saying I suspect the blinding was breached. I didn’t say the parents and/or evaluators conspired to breach the blinding. Breaching of blinding can happen inadvertently.
I’m expecting someone will take the time to do a formal write-up of these sorts of problems with the study.
@Fish,
We’re not talking about HBOT “tanks”, we’re talking about inflatable bags (which are directly affected by the ambient atmospheric pressure). Go back and re-read the post and all of the referenced links if you need to, please, your complete ignorance of the physics involved here (specific to this study) is getting/has gotten very old.
The pressure on an ocean diver at a depth of 33′ = 2 ATA (1ATM atmospheric pressure, and roughly 1 ATM for every 33′ of sea water). I know it’s tempting to think the authors used “ATM” in the typical sense to indicate “gauge pressure”, but that’s not the case. The pressure in this study, stated as 1.3 ATM, includes the 1 ATM of already present atmospheric pressure (at sea-level). Sure that’s somewhat misleading, and has probably led to your obvious confusion, but take that up with the study authors.
The added .27 ATM (above the ambient atmospheric pressure) provided by the 4 PSI “gauge pressure” of the chamber is equivalent to the added pressure of submersion to the deep end of some pools – about 9′.
Simply Joeseph would you be looking for” multiple outcome measures.” if the results had faired the opposite way , nooo you wouldn’t .. Quite simply to attempt to convolute oxygen in with thimcrosal ,(mercury) is just cheap journo media manipulation bot are the opposite of one another mercury an oxygen inhibitor ,These studies stand and will do for some time to come and the children treated will go onto make further improvements( autism isnt treatable they say????)
“Dr. Rossignol and colleagues pointed out that 73% of parents of children in the control group reported some clinical improvement, which was similar to the active-treatment group although the mean degree of reported improvement was not as large.
This, the researchers said, “suggests that the blinding procedure was adequate, because if parents thought that their child was in the control group, they probably would have been less likely to rate an improvement after treatment.”
and D`oc what can I say ,muddle time again is it?..As is said previously the ambient pressure does not affect the dive when the dive proceeds the pressure guage needles don’t start moving until you make Atmospheric pressure 1atm then they move
Simply, ,HBOT, tanks, chambers, bells, chambers, multi chambers, hard chambers ,”inflatable bags “ AKA as soft chambers, ALL work under the same principles and use the exact same pressure guages ,valves etc.. and are stringently tested to meet or exceed current requirements of ASME, PVHO-1, NFPA-99 Chapter 20, 21 Code of Federal Regulations, Chapter 1, Part 820 and are registered with the National Board of Boiler and Pressure Vessel Inspectors
This might be true with a rigid hyperbaric chamber equipped with an absolute pressure gauge (with a reference pressure of 1ATM).
Ambient pressure abosolutely affects the dive, just as it does in any underwater dive.
Let’s go to the manufacturer’s website, shall we?
http://www.oxyhealth.com/hyperbaric_therapy.html
What the hell? Don’t they know that the gauge doesn’t move until they make atmospheric pressure 1 ATM? It should simulate a dive to 9 FSW, instead of only a descent to about 6,157′ AMSL. What have they screwed up here?
Perhaps they understand that these inflatable chambers only increase the pressure 4 PSI above the ambient atmospheric pressure, and perhaps that’s why they list the operating pressure of the bags as 4 PSI!
Of course not. If the results had all been negative, there’s no reason to assume it’s because of multiple outcome measures. You could assume it’s because the effect is not that big, and the groups too small, necessitating a bigger study. But that’s a different matter.
In the ABC sociability scale, the placebo group did better than the treatment group, but not significantly better. In physician global impressions, the treatment group did better in sociability. How did that happen?
For the record, I do think an independent replication attempt might be warranted given the results of this study. They could make some improvements, such as: neither parents nor evaluators should be anywhere near the chambers while treatment is taking place.
Doc
“What the hell? Don’t they..” think about it doc your up the mountain at 12,000 feet you go in the bag zip it up the operator switches on the compressor the tank pressure guage will not move until you reach sea level..
Simply until you understand there is no difference between using a soft chamber and a hard chamber I might as well be writing in Swahili.The principles remain whether it be hard or soft the , physics’ remain the same.. the effects on the blood remain the same etc.The only difference between a hard chamber and a soft chamber is that the hard chambers can go to any depth they are made for some of them 1.8miles simulation. The soft chambers that you directed me to are VENTED to 4psi they are tested to 30psi so if you contacted the company they could modify it for you to a greater pressure. The compressor output is still 4psi…they are made with an operating pressure of the shelf of 4psi this model is 4psi
If you want to get calculations on altitude look up “cross corrections”
Its all very accurate nothing left to chance whatsoever..
Joseph what about the 30,000 published scientific studies on HBOT are they all wrong as well they are all done with the same exact procedures as in the autism studies… To prove whether the children improved is easily proven all you would need is an MRI scan before and after showing brain function useage..a bit like the study be shouted for by autistic parents comparing vaccinated V`s un vaccinated children. very simple but not on “vaccine land” where evidence isn’t required just as in the Judge Eady complaint letters which Mr Deer cant produce for fear of being proven wrong
This is the first double-blind study of HBOT that I know of. Frankly, studies that are not at least controlled and randomized provide little information when it comes to autism and developmental disabilities. That’s because it’s common for placebo to have a 30% improvement rate or more.
Incorrect. What part of
“For example, a treatment at an elevation of 12,000 feet above sea level using a 4 psi (1.27 ATA) can simulate a decent of ~5,843 feet to 6,157 feet above sea level”
leads you to conclude sea-level pressure is ever reached?
It isn’t. See that word “above”? It’s used to indicate “greater than”. Seriously, are you having trouble understanding that sentence?
“Sully quite simply ,the reason’s ,the tests are so accurate is simply because HBOT has been around since about the mid 1880`s and pharma doesn’t have anything to do with it because “you cant patent oxygen” so the treatment has evolved naturally and accurately .”
No, you can’t patent oxygen, but you can certainly patent hyberbaric chambers. They’ve been around a while, so you’d have to be careful not to a) infringe on somebody’s existing patent and b) come up with a device or manufacturing method that’s actually novel in some way. But it’s perfectly doable. I have no doubt that many components involved in HBOT are indeed patented or patent pending.
Joseph
if you look up double blind HBOT studies there are many of them .It would seem, this is the first time you have looked into HBOT.
Doc
Quite simply its not ,it is simulating conditions equivalent of between 5,843 feet to 6,157 feet above sea level @4psi pressure inside the soft chamber @12000 feet useage.
As said previously
“A TV Director filming a program at 16,737 ft, developed severe altitude sickness. He was relieved by rapid descent within 40 minutes to 5362 Ft. This caused an atmospheric pressure difference of of only 0.1 ATA, with only an increase of 0.05 atm abs in partial oxygen pressure. This minor increase in oxygenation was enough to revive him.
This suggests that the rate at which level of oxygen is increased is important and that there is a critical threshold for oxygenation.”
As said, “If you want calculations “cross corrections” for the pressure to take you to sea level diving @ 12,000 feet. look up hbot cross corrections tables .
Calli Arcale
Patents on HBOT “the better mouse trap” springs to mind not a lot in it ,and the science is the exact same…the evidence provided is the children before and after SPEC,MRI scans as evidence prove the workings of oxygen , evidence something a miss on here like the Judge Eady complaint letters evidence..
I meant for autism, obviously. But I wonder, are there any positive double-blind studies of HBOT in other developmental disabilities?
The studies of HBOT as a treatment of cerebral palsy, for example, are telling. Basically, it doesn’t work vs. placebo, even though it’s promoted as a treatment.
Joseph
“I meant for autism, obviously”….
Quite simply,The obvious is that which is never seen until someone expresses it simply”..
http://www.hyperbaricsrx.com/hbot-cerebral-palsy.html
HBOT in Multiple Sclerosis double blind
http://www.hbotnm.com/ms.html
Fibromyalgia & Hyperbaric Oxygen Therapy double blind
http://www.haelenhyperbarics.com/for-patients/treated-conditions/fibromyalgia.html
There are many more double blind HBOT studies ,pointless to list them all ,quite simply , this is a quote from Professor James of Dundee on CP
A Tragic Medical Mistake for 45 Years!
It is unfortunate that nearly all newborns today are deprived of appropriate oxygen
therapy because of the fear it will cause the formation of fibrous tissue in the eye
(retrolental fibroplasia) causing blindness. This is due to the effects of the
introduction of oxygen tents andincubators following World War II. Premature infants
were given supplementary oxygen to improve their chances of survival, and levels up
to 70 percent were given for extended periods. Epidemics of blindness followed in
the 1950s, which led to a restriction of the level of supplemental oxygen to 40
percent. A reduction in the incidence of blindness followed, which confirmed the
involvement of oxygen in the eye disease (retinopathy).
Since that time, every medical student has been taught that the retinopathy of the
premature (ROP) is caused by oxygen toxicity. With the use of oxygen restricted, by
1964, Dr. A. D. McDonald had recorded a significant rise in the incidence of cerebral
palsy compared with levels before then. However, research brought to light only
within the last few months by P. B. James, M.D., of Scotland, has demonstrated that
it was the withdrawal from the oxygen environment that caused retinal problems.
Resubmersion, time and time again, completely rectified the problem. Thousands of
cases of CP developed needlessly because of this fear of oxygen toxicity.
HYPERBARIC oxygenation does not cause retrolental fibroplasia and now offers a
new modality whereby the reduction in spasticity may be significantly decreased. We
must immediately
institute this practice to rectify what has been a tragic medical mistake. `
Fear of being proven wrong again the same fear Mr Deer has by not providing the Judge Eady complaint letters another mistake,,
One Queer Fish (OQF) has shown depths of ignorance I was unaware existed in modern society – I suppose that’s what I get for working in an “Ivory Tower” (although most of the “towers” around this campus are brick or concrete).
Differential vs absolute pressure:
OQF seems very confused about the pressure gauges used on the HBOT “soft chambers” and what they are measuring. If you go to the manufacturer’s technical specs, you’ll find that the “soft chambers” (those used in “HBOT” for autism) are not rated for more than 4 psi (26 kPa, 0.27 atm) differential pressure – which means that the difference in pressure from inside to outside cannot exceed 4 psi (26 kPa).
Do’C is absolutely correct that this means the 4 psi is added to the ambient pressure to obtain the absolute pressure inside the chamber. So, if the chamber is used at a higher altitude (where the ambient pressure is lower), the absolute pressure inside will be lower than it is at sea level.
Since Phoenix has an ambient pressure of 0.96 atm, the absolute pressure inside the soft HBOT chamber will be 0.04 atm lower there than it would be at, say, Miami.
Oxygen Benefits vs Toxicity:
OQF also appears to be unaware of the extensive literature showing that even short exposure to high oxygen concentrations can be destructive – not only to the retinas of premature infants, but to the lung cells (type 2 pneumocytes) of even adults. It seems particularly ironic that the same “practitioners” who parrot the “oxidative damage” hypothesis of autism causation will – in the same breath – promote the use of HBOT in autism.
All that HBOT does is increase the partial pressure of the inhaled gasses above what can be achieved at ambient pressure. The same can be achieved by giving supplemental oxygen. The equivalent of this study’s 24% at 1.3 atm would be 31% oxygen at sea level pressure.
Pressure effects:
The argument that the pressure of this treatment is somehow relevant is ludicrous – the amount of compression of the cell that occurs at 1.3 atm is below the threshold of measurement. I suggest that OQF look up “bulk modulus” and try to calculate the compression of cells at 1.3 atm. [hint: 0.0001%]
Pressure effects on the central nervous system are well-known (irritability, twitching, seizures) but are only seen at truly high pressures – 19 atm and above. Even assuming that the “HBOT” therapy did have some homeopathic pressure effects, they would be in the direction of increasing irritability and decreasing function.
Statistical Errors:
Although this study claims to have seen statistically significant effects, their statistical analysis failed to account for the fact that they looked at multiple measures and only found “improvement” in a few.
By simple chance, we would expect that 1 out of 20 measurements would show a “statistically significant” difference if we fail to correct for multiple comparisons. When that correction is made, the results of this “study” fall below statistical significance.
I doubt this will convince OQF, who appears to be of marginal literacy, but I hope that other people reading this will realize that his/her arguments are wrong.
Prometheus
As a matter of follow-up:
@daedalus2 wrote:
To which I responded:
That was on March 21st. BMC Pediatrics did in fact publish my comments on April 1st.
I think that what you posted made a ton of sense. But, think about this, what if you were to write a awesome post
title? I mean, I don’t want to tell you how to run your website, however suppose you added something to possibly get a person’s attention?
I mean Autism, HBOT, and the new study by Rossignol et al.
| Left Brain Right Brain is kinda plain. You ought to
glance at Yahoo’s front page and note how they create article titles to grab viewers to open the links. You might add a related video or a picture or two to grab readers excited about everything’ve got to say.
Just my opinion, it would bring your posts a little bit more interesting.
Hi all,
our son has previously visited rosignol’s centre in irvine, California. We have done dives ranging from 2.0 ata down to 1.3 ata.
We purchased a soft chamber which goes to 1.4 ata, and also has an oxygenator 10 litres per minute flow, as this was seen to be yield the best results, and allow for intensity.
I work with pressure most days in aviation.
On our chamber, There is an inner and outer pressure gauge. the inner will always read 1.4 ata, and the outer will fluctuate above or below depending on the atmospheric air pressure outdoors.
I have calculated our actual pressure using the same formula as dr Rossignol and agree 100%.
I have one question though and think that Dr rossignol may have overlooked on point..
the reason why the outside gauge is due to changes in atmospheric pressure, which he already highlighted.
The reason why the gauge on the inside does not change is because, it is not the compressor that sets the pressure limit inside the chamber, it the outflow valves at the end of the chamber, which regulate chamber pressure. This means that in order to order to maintain 1.4 ata, the valves will be open at 1.4 ata, if pressure increases, the valves will open more to allow more air to flow out of the chamber at a faster rate, which in turn will result in a pressure drop or reduction.
likewise, if the pressure has not reached 1.4 ata yet, then the valves will be almost closed, to allow pressure to build.
These chamber valves are not electronic, they do not care about environmental pressure. All they care about is maintaining 1.4 ata. This inside chamber figure is a true pressure. This inside gauge is not affected by outside air pressure. Hence why it always maintains 1.4 ata, unlike the outside gauge, which Dr Rossignol refers to in his comments.
No disrespect intended, as really like all the work Dr Rossignol has done. He is the main reason why myself and so many others are no able to help our children recover.
Thanks
With all due respect, Rossignol, while a nice guy, has promoted this for some time in spite of the lack of evidence (and now evidence against) efficacy.
What is the partial pressure of O2 when you use air at 1.4 atm? Answer: much less than if you used an oxygen mask. And yet he claims that HBOT with air is effective. Why would less O2 be more effective?
Is your HBOT chamber rated for enriched air?