Good for preserving food...
... and even for Acute Altitude Sickness
"The comments and discussions concerning this zip-lock® baggy and its application outside of acute altitude sickness has been discussed, analyzed, addressed, refuted and dispensed with a long time ago. It is being dragged up for discussion now to our generation ... all without any physical science, but certainly for profit."
Under Pressure to Heal. 2001
"The comments and discussions concerning this zip-lock® baggy and its application outside of acute altitude sickness has been discussed, analyzed, addressed, refuted and dispensed with a long time ago. It is being dragged up for discussion now to our generation ... all without any physical science, but certainly for profit."Under Pressure to Heal. 2001
Hyperbaric Oxygen is defined as the administration of 100% oxygen at a pressure greater than Standard atmospheric pressure. Normal or Standard atmospheric pressure is identified as 14.7 pounds per square inch (PSI) at sea-level. Equivalent units of measures for this pressure include 760 mm Hg,1.0 Bar, 101.3 kPa or 1.0 ATA.
"The term ‘hyperbaric oxygenation' (HBO) was recommended in 1971 by the First All-Union Conference (Moscow) on the application of oxygen under pressure in medicine." [Burakovsky VI, Bockeria LA. Common Questions of the Theory of Hyperbaric Oxygenation. In: Hyperbaric Oxygenation and Its Value in Cardiovascular Surgery." MIR Publishers, Moscow. 1981; 14-15.]
In a therapeutic capacity, Hyperbaric Oxygen may be used for a wide range of applications; there are an equally diverse number of protocols for the applied pressure and the duration of inhalation of oxygen. Hyperbaric Oxygen may be applied as either High Pressure (OHP) or Low Pressure (OLP). The physical, operational and mechanical demarcation of these two therapeutic categories is 2.0 atmospheres absolute (ATA). Protocols that apply pressures less than 2.0 ATA are defined as Low Pressure, while applications in excess of 2.0 ATA are High Pressure.
International convention generally recognizes that Low Pressure Hyperbaric Oxygen has a minimum applied pressure of 1.4 ATA. Historical research methodology in Hyperbaric Oxygen has traditionally utilized 1.3 ATA as a placebo pressure for control groups. This practice has contributed to an internationally accepted designation that Low Pressure Hyperbaric Oxygen ranges from 1.4 ATA to 2.0 ATA while inhaling 100% oxygen. This standard definition is confirmed in the Merck Manual of Diagnosis and Therapy:
"Hyperbaric oxygen therapy: A medical treatment in which the patient is entirely enclosed in a pressure chamber breathing 100% O2 at > 1.4 times atmospheric pressure."
The definition and practice of Hyperbaric Oxygen is not inclusive of any breathing gas administered at any pressure with a normal oxygen content (fraction of inspired oxygen, FiO2, = 0.21 or 21%). Hyperbaric Oxygen does not encompass any application where the enhanced oxygen content of the inspired gas is less than 100% oxygen (FiO2 = 1.0).
The defined exclusions of therapeutic Hyperbaric Oxygen also applies to the misappropriate, misleading and misconstrued use, application, marketing and sale of any such "low-pressure", portable compression bag used for the correction of altitude induced hypoxia.
This so-called "mild hyperbaric chamber" was derived from the original, portable chamber called the mountain bag or Gamow Bag. This device was originally developed to treat altitude sickness experienced by mountain climbers. The function and purpose of the bag was to correct hypoxia at high altitudes (hypotonic anoxemia or anoxic anoxia). In this application, it was valid and effective.
While having a functional purpose, the bags fell out of popular use when the mountaineering industry realized that the correction of altitude induced hypoxia was just as effectively achieved by the use of direct inhalation of 100% oxygen through a mask or nasal cannulus. The necessary equipment for this was substantially less costly and, more importantly, far more compact than the use of the bags. As a result of the substantial loss in market, it appears that misconceptions and misunderstandings of the true biology, physiology and bio-chemistry in Hyperbaric Oxygen have left the market open for the misrepresentation of the altitude bags as being Hyperbaric Oxygen.
In application for the correction of altitude induced hypoxia, these bags may be effective and valid; they are not, however, Hyperbaric Oxygen Therapy.
The "mild hyperbaric chamber" is a soft material construction, portable bag that is capable of increasing the interior pressure. This "hyperbaric chamber" is pressurized by a portable compressor. The occupant is confined to an atmospheric pressure increase of 3 psi with normal air (a gas content of 79% nitrogen and 21% oxygen, an FiO2=0.21).
The bag, sold as "mild hyperbaric", but also marketed as Hyperbaric Oxygen, does not use 100% oxygen as the inspired gas medium; rather it only provides the same atmospheric air that is available on the exterior of the chamber. The only effect of the chamber is an Hyperbaric increase of 3 psi inpressure to the occupant.
The bag and its operational pressure is incapable of hyperbaric hyperoxia... filled with air and pressurized to "mild" pressures, the bag does not physically add any significant quantity of dissolved molecular oxygen to blood plasma - or any other body fluid for that matter. Neither the normal air nor the pressures available in the bag are sufficient to induce any consequential amount of oxygen into plasma. In fact, the limitations of this procedure becames apparent even before the incremental effects reach the alveoli, or the inside lining of in the lungs, let alone having any increase in the quantity of oxygen dissolved into plasma.
Since the compressor system only provides normal atmospheric air, the percentage of oxygen for inhalation remains at 21% since atmospheric air is 79% Nitrogen and 21% Oxygen. The total barometric pressure of this air, for both gases, would be 760 mmHg before pressurization. Of this total ambient pressure, the oxygen still accounts for 21% (Dalton's Law), which would be approximately 160 mmHg pressure.
[1] 760 mmHg X 21% = 160 mmHg OXYGEN PRESSURE
An increase of 3 psi to the pressure applied to the occupant of the bag translates to an increase of 155 mmHg.
[2] 3 psi X 51.7 mmHg / psi = 155.1 mmHg INCREASE
Thus, the total ambient pressure inside the bag and at the point of inhalation of the air [at the nose] would be 914 mmHg.
[3] 760 + 155 = 915 mmHg TOTAL BAG PRESSURE
Again, with the oxygen being 21% of this total pressure, the partial pressure of oxygen [PO2] would be only 192 mmHg at the point of entry for inhalation.
[4] 915 mmHg X 21% = 192 mmHg BAG OXYGEN PRESSURE
So, the bag only produces a 32 mmHg increase in the total pressure or force of oxygen available at the intake of the nasal passage.
[5] 192 mmHg (Bag) - 160 mmHg (Normal) = 32 mmHg
Once the oxygen has entered the nasal passage, there is a host of factors and variables that will begin to reduce the pressure. This processing of air, or gases, is called the "Oxygen Cascade". Due to this processing, and the automatic, natural reduction in oxygen pressure, this 32 mmHg increase would be negligible by the time the oxygen reaches the interior lining of the lungs.
In contrast to providing the "mild" hyperbaric application, with nothing more than a 3 psi increase in ambient pressure, 100% oxygen may be administered through a breathing mask at normal pressure (normobaric hyperoxia).
By just breathing 100% oxygen [FiO2 = 1.0], it is possible to exceed the oxygen pressure [PO2] increase available in the bag.
The typical clear "plastic" oxygen masks used by hospitals and paramedics uses 100% oxygen. Breathed at normal ambient pressure (760 mmHg), the total pressure of the oxygen would be 100% of the pressure; the PO2 would be 760 mmHg.
[6] 760 mmHg X 100% = 760 mmHg MASK OXYGEN PRESSURE
By providing 100% oxygen, the PO2 rises from 160 mmHg (normal air at normal pressure) to 760 mmHg (100% oxygen at normal pressure) - this compared to the 192 mmHg increase available with the "mild" hyperbaric bag.
Providing 100% oxygen by a mask increases the PO2 a total of 568 mmHg more than the "mild" hyperbaric application.
[7] 760 [mask O2 pressure] - 192 [baG O2 pressure] = 568 mmHg MORE O2
Another method used to administer oxygen for breathing is a nasal cannulus;the cannulus typically provides a PO2 of 34%, even though oxygen is 100% of the gas provided. This substantial drop in concentration is due to the entrainment of air with each inhalation or breath. With each breath, ambient air is drawn in along with the oxygen, resulting in an automatic reduction of the percent oxygen due to the dilution with ambient air.
The PO2 of a nasal cannulus is 258 mmHg. This is 66 mmHg of oxygen pressure over that which is provided by the "mild" hyperbaric.
[8] 258 [mask O2 pressure] - 192 [baG O2 pressure] = 66 mmHg MORE O2
In other words, the administration of 100% oxygen, by whatever means, even without the added increase of ambient pressure will produce a higher PO2 than the bag in all considerations. [ see Figure ]
In 1984, Dr. Julius Jacobson, then the President of the International Congress on Hyperbaric Medicine and an internationally recognized pioneer in Hyperbaric Oxygen, lamented:
"We shall simply repeat the history of the 19th century when there were hundreds of chambers in existence which had as much scientific validity as the mineral water spa."
The therapeutic practice referred to by Dr. Jacobson was not Hyperbaric Oxygen, but in reality these chambers were Compressed Air Therapy. The association and assimilation of Hyperbaric Oxygen with compressed air are still a prevalent perception today. The historical stigma of the Compressed Air Therapy is still attached to and associated with Hyperbaric Oxygen.
As with any business, it is Buyer Beware. The commercial advertising, applications and claims associated with the portable bag type of "chamber" - marketed as "Mild Hyperbaric" and "Hyperbaric Oxygen" - are in the same category as Dr. Jones' Magical Elixir of Life... it is an embarrassment and assault to the scientific, medical and public credibility of Hyperbaric Oxygen. It is difficult enough to maintain the validity of Hyperbaric Oxygen as a viable therapeutic modality for the current insured indications, let alone advancing additional indications, without having the credibility of the therapy outrightly slammed by the purveyors of potions and prestidigitation.
For some, the idea of charging anyone, any amount of money for breathing air, is not only unprofessional and unethical but it should be illegal. Utilization of a low pressure air bag, in any pretense of a professional manner, as being Hyperbaric Oxygen is outright misrepresentation of the factual science and therapeutic pratice.
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