Inflatable Chambers

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More Indications Air-Bag Chambers

Inflatable Chambers . . . Hyperbaric or HYPE ?

We asked one of our Science and Advisory Board members for his opinion on the zippered urethane inflatable chambers, now becoming popular in the United States and elsewhere. The essence of his comments . . . ."These so-called 'mild-hyperbaric' (mHBOT) chambers do not give any of the therapeutic results of regular 'hard' chambers and thus waste the patients' most precious resource -- their time."

"When you see these chambers used in hospitals, only then can you believe that this is serious medicine . . ."

"Any physician that advocates having patients spend hours zipped into an inflatable air chamber demonstrates a profound ignorance of physics, physiology and the many years of research into the effects of high density oxygen on the human body. If these physicians do understand the science and still use these 'bags' then their interest has to be based on profit rather than patient wellbeing and standards of care."

Robert L. Sands is uniquely qualified to comment on the science relating to the inflatable chambers. For three years Sands administered research and development for the Commonwealth of Australia and his first hyperbaric chamber patent application was lodged in 1983 for an inflatable chamber. Sands abandoned the inflatable concept after expending considerable resources and went on to design and build chambers in the “conventional” manner meeting American Society of Mechanical Engineers, Pressure Vessels for Human Occupancy (“ASME PVHO-1") standards. Sands eventually designed and developed the revolutionary transportable recompression chamber system that is now in fleet-wide use with the U.S. Navy, Marine Corps and Coast Guard. Sands holds the patent for that transportable chamber system.

Sands commented “There were many valid scientific and technical reasons to abandon the development of an inflatable chamber in 1985 and those reasons are still valid twenty years later in the year 2008. It is appropriate that I sum up the comments that I am about to justify:

One problem is the lack of pressure in these inflatable chambers. In actual fact, oxygen pressures lower than 1.3 ata (4.4 psig) promotes the growth of aerobic bacteria in injured tissue within the body. Pressures have to be increased to to sufficient levels for oxygen to become bacteriostatic. See footnote #1

Any chamber that will not hold more than 4 pounds per square inch (psig) pressure, and where the patient is breathing air rather than oxygen, fails most patients. It consumes their time and wastes their money.

Beneficial results for the patient using other means can be found at a fraction of the cost of either purchasing an air-bag or paying a practitioner to provide the service.

It is all about science:
In particular, three laws of physics known as the Universal Gas Laws. Boyle’s, Dalton’s and Henry’s laws. Linked at all times together, they become Universal. Alter or tweak any one and the other two adjust to keep pace. Henry’s seems the most prominent in HBOT because “gas becomes soluble according to its partial pressure.” Henry’s law is the explanation of how carbon dioxide melts into a soda, fizzing back into a gas when the bottle or can is popped open. Likewise, oxygen obeys these same gas laws and melts into the liquid human body when there is an increase in its partial pressure or density. The additional dissolved oxygen acts as an energy catapult and vigorously increases cellular oxidative metabolism, promoting healing and repair. Thus the growing popularity of hyperbaric (high density or dosage) oxygen therapy, or “HBOT.”

There are two ways to dissolve additional oxygen into the body. One is tinkering with the percentages of oxygen in the air we breathe. The other is to put the patient in a pressure chamber and increase the amount of molecules of oxygen or density.

Tinkering with oxygen percentage:
The air we breathe is approximately 80% nitrogen with the balance oxygen – about 20%. According to Dalton’s Law, we can increase partial pressures (density) of oxygen by altering the percentage of oxygen in the air we breathe. Paramedics carry oxygen all of the time to do just that. By giving a casualty 90% oxygen Dalton’s law dramatically kicks up the density (partial pressure) or the amount of oxygen molecules in each lungful and Henry’s Law keeps pace. The extra oxygen gaseous molecules dissolves and the dense oxygen, now chemical molecules, flood into plasma and clear fluids, easing the burden on the heart. The Universal Gas Laws working, saving many lives each day.

A paramedic’s sophisticated oxygen set-up to get this extra oxygen into the body is not the only way. Here are some low cost alternatives . . .

Nasal prongs increase oxygen partial pressure from normal air 20% to 36%
Hudson masks increase oxygen partial pressure from normal air 20% to 50%

Tinkering with pressure plus oxygen percentage:
To supersaturate the body, you do need a pressure vessel, commonly known as HBOT chambers. This extra pressure (Boyles’s Law) dramatically alters Dalton’s and Henry’s Law.
In Hospital quality HBOT chambers all patients breathe100% medical grade oxygen. All of these chambers reach pressures of 15 psig at minimum, some of these chambers can reach pressures of 100 psig. The Universal Gas Laws produce healing miracles in chambers that have 100% oxygen and correct pressure (or oxygen density) capability. Remember, pressure equals density and this equals the dose. Different illnesses require different treatment pressures. The "one size fits all" just is not so in a hyperbaric chamber because there is a distinct drug-dose response by the patient. Just as with prescription drugs, it is the physician who makes the dosage decision, the technicians operating the chambers merely dispense the high dosage oxygen according to orders.

To illustrate this, a couple of examples are appropriate. In such a hospital HBOT chamber, gas-gangrene is treated at 29 psig (3 ATA) of 100% oxygen. This provides the patient almost 16 times the partial pressure of oxygen of breathing room air at sea-level Diabetic ulcers respond to 19 psig (2.3 ATA) and heal quickly. Lyme disease and chronic fatigue syndrome patients need the same pressures to achieve a positive result. The air-bag fails to deliver both the required treatment pressure and oxygen percentage.

The air-bag is pressurized to a mere 4 pounds per square inch (“psig.”) By adding 4 psig air pressure, the oxygen density (partial pressure) makes an almost insignificant jump from 20% to 26%. That was my reason for abandoning the inflatable chamber concept in 1983 . . . the pressure it could hold was useless for treating most maladies that require HBOT, even though the patient could breath oxygen, not air. Apart from that, Britain's John Selby had already solved the pressure problem with a high-tech composite inflatable chamber he termed an “a hyperbaric ambulance” – now named SOS-Hyperlite. Because it can reach high pressures and give the patient 100% oxygen, the Hyperlite is now in use with the U.S. Military. Comparing Selby’s Hyperlite, with the urethane air-bag that is sold and used in the U.S. for "mild" HBOT is the same as comparing a Bell Jet-Ranger to a coffee table.

About the air-bag:
So, from room air 20% partial pressure of oxygen to being zipped up in an air-bag and only getting another 6% of oxygen – way less than the 36% of oxygen provided by nasal prongs? What’s going on here? Important questions must be asked since the inflatable air-bag is proliferating throughout the United States.

Is the inflatable air-bag treatment pressure adequate or even beneficial for most patients needing HBOT as life or limb salvage? Or to help eliminate chronic disease? The answer is a resounding “NO.”

Identical partial pressures of oxygen occur if you spend an hour at the bottom of a 9 foot deep swimming pool, breathing from a SCUBA tank and the physiological changes to the human body are virtually the same!

Code compliance – the FDA:
These inflatable air-bag chambers do have FDA “510(k)” clearance numbers. These use the “Gamow” bag as their predicate device. They are cleared by the FDA for marketing ONLY for the treatment of acute mountain sickness (where at higher elevations there is less oxygen in the air and climbers become ill)) known as AMS.

Mild hyperbaric chambers can only be legally marketed for AMS and it has a low world-wide incidence rate!

However, these inflatable chambers are becoming popular with health spas, chiropractors, sporting teams and caregivers. There has been an "underground" effort to promote the use of 100% oxygen (H cylinders) and oxygen concentrators in pressurizing these inflatable chambers. As well, some owners have modified the valves to increase the pressure past maximum allowable operating pressure of the inflatable chamber. There is one U.S. confirmed catastrophic failure of an inflatable chamber which burst when taken to 14 PSIG.

As an FDA Class II medical device, whether the bag is full of air or oxygen, a licensed physician or dental surgeons’ prescription is mandatory for any use. While many chiropractors and other health practitioners have great skills, the law is the law. Despite their skills, they cannot write that prescription. You must have a prescription from a physician (M.D. or D.O.) or a dental surgeon (D.D.S.) to purchase an inflatable air-bag. Referring to the air-bag as “mild” hyperbaric oxygen therapy (mHBOT) does not erase FDA rulings. Chiropractors (D.C.) naturopathic doctors (N.D.) or any other practitioners are breaking the law if they prescribe mild hyperbarics and face arrest by their local district attorney. Sadly, so too are any well-meaning caregivers that allow others to use their personal inflatable chambers.

Code compliance – the local fire department:
In addition to the FDA rules, the local fire marshal will insist that any clinic that uses hyperbaric chambers comply National Fire Protection Agency (NFPA) 99-11 codes with fire walls and certified fire doors, sprinklers and other code compliance.

Now the important part. The NFPA-99 mandates that all chambers that can increase pressure over 2 psig are designed to the fabrication codes of American Society of Mechanical Engineers (ASME) Pressure Vessel for Human Occupancy -- level 1 (PVHO-1) and embossed with the PVHO-1 stamp. Mild hyperbaric inflatable chambers have not been able to demonstrate that they comply with any recognized hyperbaric chamber design or fabrication standard. These enforceable statutes prohibit these non-PVHO-1 inflatable chambers from being used anywhere except in a home.

Inflatable chambers are not code compliant with PVHO-1. If the State where they are being used is a PVHO-1 State (e.g., CALIFORNIA) it is illegal to sell or use these "soft" bag chambers.

Eleven States and three U.S. cities are now enforcing the PVHO-1 codes and scrutinizing health care practitioners who advertise for patients.

Ethical questions for clinicians recommending or using the inflatable air-bag:
These air-bags cost little money (in comparison to ASME PVHO-1 chambers) and are selling well, probably because of the growing demand for affordable HBOT. However, many of the operators of these air-bags are charging prices that are only marginally less than the cost of a treatment in a "hard" 100% oxygen chamber and where their patients could be treated at a pressure that was medically proven to be appropriate for their illness. The ethical problem facing the practitioner who is presented with a patient who is in crisis is “Am I wasting the patient’s most precious resource – their time?”

1 footnote -- See Textbook of Hyperbaric Medicine, page 143,4th Revised Edition, K.K. Jain, et al.

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