Topical Oxygen Therapy is not Hyperbaric Therapy and the Two Treatments Should Not be Confused

Dear Editors,The recent article describing the use of the Delphi method to provide clinical guidance on the use of topical oxygen for chronic wounds (1) does not do justice to the Journal or enhance the science of wound care.The Delphi method relies on a panel of experts to answer questionnaires in rounds, revising their answers in light of the replies of other panel members with the goal of converging towards the best approach.It presupposes that the information provided to the group is accurate and that the group has sufficient expertise with which to interpret the information.Unfortunately, neither condition appears to be satisfied.It is not factual to state that 'topical oxygen therapy is also considered hyperbaric therapy' (see page 273).In hyperbaric oxygen therapy (HBOT), the patient's entire body is placed into a pressure vessel and the ambient pressure is increased within the vessel to pressures between 1•5 and 3•0 atmospheres absolute (ATA) while the patient breathes 100% oxygen.At 2 ATA, a patient will have an arterial oxygen tension of 1000 mmHg and a muscle oxygen tension over 200 mmHg (2).At 3 ATA, the amount of oxygen dissolved in the blood plasma is enough to sustain life in the absence of circulating haemoglobin, hence its use in acute blood loss anaemia.This oxygen is available to all tissues (e.g.brain, bone, muscle).In topical oxygen treatment, the pressures achieved are approximately 1•0004 ATA and, assuming no barrier to diffusion, (e.g. a wound free from any necrotic debris), a small amount of oxygen can diffuse, at most, 2 mm from the surface of the wound.While 1•004 ATA is technically above atmospheric pressure, it does not fall within the definition of hyperbaric therapy (>1•5 ATA).In the USA, the Center for Medicare Services states unequivocally that, 'topical oxygen does not meet the definition of HBOT' (http://www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/downloads/R129CIM.pdf).Furthermore, the US Food and Drug Administration (FDA) does not consider topical oxygen to be a form of HBOT.In describing a HBOT chamber, the FDA states, 'This device does not include topical oxygen chambers for extremities'.Contrary to what is stated in the paper, the FDA does not 'approve' these class II medical devices, but it does clear them for use as part of its responsibility to regulate the way in which these devices are promoted and advertised.In 21 CFR 878.5650, the FDA identifies a topical oxygen chamber for extremities as, 'a device . . . to aid healing of chronic skin ulcers such as bedsores'.There is an entirely separate FDA clearance document for hyperbaric oxygen chambers.Since 1978, the FDA has yielded to the Undersea and Hyperbaric Medical Society (UHMS) Committee report in determining

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