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KCE Reports 74 Hyperbaric Oxygenation Therapy 11
Apart from these ‘accepted’ indications there is a multitude of other conditions for
which more or less evidence is available, but where treatment is mainly experimental.
Those indications for which evidence is available will also be briefly described in the
next chapter.
2.4 POTENTIAL HARMS, SAFETY AND PRECAUTIONS
HBOT appears to be relatively safe with few serious adverse effects. Adverse effects are
often mild and reversible but could, potentially, be severe and life threatening. 1, 11 As a
consequence, strict precautions must be taken while administering HBOT to avoid
those complications. In addition, proper installation and maintenance of a HBOT facility
and adequate staffing with specifically trained personnel is pivotal. There is always a risk,
albeit small, of fire and explosion and it may also be difficult to deal with medical
emergencies, especially if a patient is isolated in a chamber. In some countries, such as
France, it is reported that the use of monoplace chambers has been completely
abandoned and there appears to be growing consensus that the use of monoplace
chambers should be avoided.
2.4.1 Barotrauma
Barotrauma is a general term to indicate injury to a tissue through the action of
differential pressures and it can occur in body areas where tissue and gas interface, such
as the middle ear, the sinuses and the lungs. Middle ear barotrauma is the most
commonly reported acute side effect of HBOT, and it was reported to occur in 2% of
patients. 1, 8 A prospective study reported that almost one-fifth of all patients
experienced some ear pain or discomfort related to problems in middle ear pressure
equalization, while visual otological examination confirmed barotraumatic lesions in 3.8%
of patients. 12 Barotrauma can be avoided by careful patient selection, excluding patient
with contraindications for HBOT such as emphysema, by patient education and by the
termination of HBOT when early symptoms occur. Pulmonary barotrauma is a potential
problem mainly during the decompression phase of HBOT since the volume of gas in
the lungs increases due to the reduced pressure and this extra volume needs to be
breathed out. However, the occurrence of this complication has only been reported in
1, 8
sporadic cases.
2.4.2 Oxygen toxicity
Oxygen has to be considered as a drug and it can give rise to the formation of free
radicals during high dose oxygen breathing. These free radicals can lead to the oxidation
of chemical components of tissue. While in principle any tissue could be affected, it
occurs most frequently in the lungs, brain and eyes. 1, 8 Reported forms of ocular toxicity
are reversible myopia and cataract development. 1, 13 Cerebral toxicity leading to an
acute epileptic seizure has been reported occasionally, although this condition appears
to be self-limiting without apparent long-term sequels. 1, 12 Pulmonary toxicity has been
described for more than a hundred years and infrequently appears to occur even
following low doses of oxygen. 1
2.4.3 Other hazards
Decompression illness itself is a risk inherent to HBOT for care personnel inside the
pressurised chamber not breathing oxygen, but can be avoided by careful usage of
compression and decompression schemes. The confinement to a relatively small and
closed container can give rise to claustrophobia which in severe cases can make HBOT
impossible. a Distraction schemes or occasionally light sedation can help overcome these
problems. Fire, obviously, is a major hazard since oxygen supports combustion.
Therefore, a hyperbaric air-filled chamber where only the patients breathe 100% oxygen
through a mask or hood is generally preferred.
a However, claustrophobia has even been described as an indication for HBOT in one case report. 14 It is
unclear whether increased atmospheric pressure or the administration of oxygen has an important role in
this indication.