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Hyperbaric oxygen therapy (HBOT) is a treatment modality that has been used
in chronic wounds for about 40 years (1,2)
- teatment involves placing the patient in a compression chamber, increasing
the environmental pressure within the chamber, and administering 100% oxygen
for respiration. In this way, it is possible to deliver a greatly increased
partial pressure of oxygen to the tissues
- typically, treatments involve pressurisation to between 2.0 and 2.5
atmospheres absolute (ATA) for periods between 60 and 120 minutes once
or twice daily. A typical course might involve 15 to 30 such treatments
- rationale for HBOT is that, despite the wide range of causative pathologies,
the common denominator in many wounds is tissue hypoxia
- wound healing is a complex and incompletely understood process.
While it appears that in acute wounds healing is enabled by the initial
hypoxia, low pH, and high lactate concentrations found in freshly
injured tissue, some elements of tissue repair are extremely oxygen
dependent, for example collagen elaboration and deposition by fibroblasts
and bacterial killing by macrophages. In a complicated balance between
wound hypoxia and peri-wound oxygenation, it would seem that successful
healing relies on adequate tissue oxygenation in the area surrounding
the fresh wound. Certainly, wounds that lie in hypoxic tissue beds
are those that most often display poor or absent healing (2)
- in wound healing, insufficient supply of oxygen may prevent
normal healing processes
- intermittent presentation of oxygen to those hypoxic tissues,
therefore, may allow a resumption of normal healing. HBOT
administration in man has been demonstrated to cause hyper-oxygenation
of tissue, vasoconstriction, fibroblast activation, down regulation
of inflammatory cytokines, up-regulation of growth factors,
antibacterial effects, potentiation of antibiotics, and a
reduction in leukocyte chemotaxis
- adverse effects
- oxygen in high doses is toxic to normally perfused tissue,
in particular the brain and lungs. Therefore it is not possible
to expose patients to typical wound treatment pressures for
longer than 1 to 2 hours on a regular basis
- HBOT is associated with some risk of adverse effects including
damage to the ears, sinuses and lungs from the effects of
pressure, temporary worsening of short-sightedness, claustrophobia
and oxygen poisoning
- two independent systematic reviews on HBOT (1,2) concluded that systemic
HBOT may reduce the incidence of major amputation in people with diabetic
foot ulcers
- however, most of the studies evaluated were relatively small. Therefore,
further evidence is required from larger, more robust, and blinded studies.
Nonetheless, systemic HBOT may be considered in patients with ischaemic
ulcers and where revascularization is not possible (3)
Reference:
Last reviewed 01/2018
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