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8 Hyperbaric Oxygenation Therapy KCE Reports 74
2 HYPERBARIC OXYGENATION THERAPY:
HISTORY AND TECHNICAL DESCRIPTION
2.1 BRIEF HISTORY
Hyperbaric therapy refers to therapeutic conditions with ambient pressures higher than
normal atmospheric pressure at sea level. This pressure can be expressed in relation to
this sea level pressure as Atmosphere pressure absolute (ATA). Hyperbaric conditions
thus correspond to pressures higher than 1 ATA and typically occur during underwater
diving. At a depth of 10 meters pressure is approximately 2 ATA, and every additional
10 meters of depth corresponds to about one extra ATA.
As early as the 17 th century, strong airtight vessels combined with pumps capable of
compressing air could be produced and where sporadically even used as treatments for
various conditions. 1-3 Serious hyperbaric therapy, however, only began as a treatment of
caisson disease, a disease occurring in engineering workers who had to labour in
caissons under conditions of compressed air, mainly during the construction of tunnels
and bridges in the late 19 th 2, 4
century.
The first reports of decompression sickness described this condition as ‘the bends’,
since caisson workers assumed a bent posture to help relieve the pain caused by the
nitrogen accrual in their joints. Although the physiology of the disease was only
understood much later, recompression therapy at first with normal air, was proposed
as early as 1854, 1, 2 and for a long time caisson disease, or decompression sickness
(DCS) as it was later called, remained the main therapeutic indication for hyperbaric
therapy. As a result of the introduction of a series of improvements of the working
environment, including recompression therapy, mortality from this disease that ran as
high as 25% originally, was dramatically reduced. 1, 4 Apart from this therapeutic use,
however, all kinds of potential beneficial effects were ascribed to modest hyperbaric
pressures and hyperbaric chambers were even introduced in health spas. In the
nineteen twenties a 5-storey high hyperbaric building was built by O.J. Cunningham, the
largest ever. 2, 3 Serious medical interest, however, quickly faded.
With World War II interest in hyperbaric physiology and medicine re-emerged due to
the increased demands not only on divers but also increasingly on aviators and later also
astronauts who had to work in both hyperbaric and hypobaric conditions. By then also,
the use of normal air in hyperbaric chambers had been replaced by that of 100% oxygen
or by different mixtures of oxygen, air or helium.
Early experiments in the 19 th and 20 th century had shown that breathing oxygen while
raising the atmospheric pressure could lead to an increased amount of oxygen in the
blood and tissues, but mainstream medical interest was only revived when the Dutch
cardiac surgeon Ite Boerema reported in 1956 on the use of an operating room with
raised atmospheric pressure to allow longer operating time during circulatory arrest in
babies and young children with congenital heart defects. 2, 5, 6 His reports marked the
beginning of a proliferation of hyperbaric chambers in hospitals around the world,
although very soon they would become unnecessary for the original purpose due to the
development of new operation methods and of new equipment to perform them. To
use and justify the existing hyperbaric chambers new and sometimes bizarre indications
were proposed. In 1987, Gabb and Robin published a manuscript entitled ‘Hyperbaric
oxygen, a therapy in search of diseases’ in which they list over a hundred indications that
had, by then, been suggested. 7 Those indications ranged from CO poisoning to senility,
the preservation of youthfulness and the treatment of baldness. Many of the reported
indications were based on very little or only anecdotic evidence.
In an effort to respond to those shortcomings, medical societies such as the Undersea
and Hyperbaric Medical Society (UHMS, www.uhms.org) 8 and the European Committee
for Hyperbaric Medicine (ECHM, www.echm.org) 9 were established with the explicit
aim to examine the indications for HBOT.