The Editor

JAMA Internal Medicine

26th November 2014

Sir

Compressed air has physiological actions and is neither sham nor placebo

Using controlled conditions, Scott Miller et al1 have added yet more evidence that hyperbaric treatment is of benefit to patients with mild neurological conditions. This was clearly not the intention of this pilot study but the attribution of the remarkable improvements recorded to ‘ritual’ demonstrates that the science involved is not understood. A 20% increase in ambient air pressure cannot be regarded as a "sham" treatment because the concentration of the respired oxygen increases from 158 to 190 mm Hg (at a barometric pressure of 760 mm Hg). As the alveolar water vapour and carbon dioxide partial pressures remain constant there is a proportionally greater increase in the plasma oxygen tension and an abrupt increase in respired gas concentrations is also accompanied by beneficial osmotic changes at cellular level.2 The dramatic effect of a higher oxygen concentration is evident in fossil records: when the Earth’s atmosphere was about 35% the wingspan of dragonflies reached 30 inches. Neglected is the recent research showing that cellular oxygen concentrations regulate the expression of our most important genes, including vascular endothelial growth factor and those controlling inflammation.3

Recent studies of using compressed-air as a treatment for brain damaged infants have shown the same remarkable improvement,4,5 but the most dramatic confirmation of the importance of a modest increase of air pressure comes from experience at high altitude. All high altitude climbers know that both pulmonary and neurological symptoms are improved, indeed usually resolved, by the increase in air pressure produced by a descent. During WW2 a pressure bag was used to great effect in treating altitude sickness in experiments conducted in a B24 Liberator - the forerunner of the portable hyperbaric chambers now used by high altitude climbers and the US Army Special Operations Command. As a small increase in air pressure can resolve a mountaineer’s life-threatening pulmonary and cerebral oedema, the subtle residual problems that follow concussion will surely benefit from hyperbaric air treatment. The pressure needed can easily be achieved by pressurising a commercial aircraft on the ground: a Boeing 747 would allow hundreds of service men to be treated at a time at minimal cost.

Few medical professionals outside of aviation, space and underwater medicine understand the importance of barometric pressure. The use of hyperbaric oxygen treatment must be included in the curricula of our medical schools: we have no substitute for the gas.

Philip B James MB ChB DIH PhD FFOM

Emeritus Professor of Medicine

University of Dundee

Nethergate

Dundee DD1 4HN

The word count is 393.

References

  1. Scott Miller R, Weaver LK, Bahraini N. et al. Effects of hyperbaric oxygen on symptoms and quality of life among service members with persistent postconcussion symptoms. JAMA Intern Med. 2014; doi: 10.1001/jamainternmed.2014.5479.
  2. Babchin A, Levich E, Melamed Y, Sivashinsky G. Osmotic phenomena in application of hyperbaric oxygen treatment. Colloids Surf B Biointerfaces 2010;83:128-132.
  3. Cramer T, Yamanishi Y, Clausen BE, et al. HIF 1α is essential for myeloid cell-mediated inflammation. Cell 2003;112:645-657.
  4. Collet JP, Vanasse M, Marois P, et al. Hyperbaric oxygen for children with cerebral palsy: a randomised multicentre trial. Lancet 2001;357:582-586.
  5. Muhkerjee A, Raison M, Sahani T, et al. Intensive rehabilitation combined with HBO2 therapy in children with cerebral palsy: A longitudinal study. Undersea Hyperb Med 2014;41:77-83.

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