Mild Hyperbaric Therapy and Hyperbaric Oxygen Therapy may easily be confused by the general public as being the same. Essentially the difference lies in the effective oxygen dose.

Oxygen is an extremely useful and efficacious drug in a wide range of medical conditions. Hyperbaric oxygen therapy (HBOT) is an established treatment for a number of health conditions. It is available at approximately 14 centres around Australia and New Zealand, including both Public hospitals and Private facilities.

The Undersea and Hyperbaric Medical Society (UHMS) is the peak world body representing practitioners in this area and defines Hyperbaric Oxygen Therapy as: ‘A treatment in which a patient breathes 100% oxygen while inside a treatment chamber at a pressure higher than sea level pressure (i.e. >1 atmosphere absolute or ATA)’.

These pressure vessels or chambers are typically operated at pressures above 202.6kPa (2 atmospheres absolute – ATA) for periods of 60 to 120 minutes for each session of treatment, with the patient breathing 100% oxygen.

Breathing 100% oxygen at 2.4 ATA, each breath taken contains oxygen at a pressure of 2.4 ATA (1,824 mmHg) and the arterial oxygen pressure will reach something around 2.0 ATA (1,500 mmHg).

Typically mild hyperbaric therapy or ‘low pressure hyperbaric therapy’ does not provide any more available oxygen to the body than oxygen administration at one atmosphere (sea level). It may be defined as ‘A treatment, usually administered in an inflatable portable chamber, in which a patient breathes air or oxygen enriched air at pressures between 1.2 and 1.5 ATA (slightly higher than sea level pressure).’

A typical mild Hyperbaric Therapy session will involve pressurisation to 1.3 ATA breathing 30% oxygen for about one hour. Under these conditions, each breath has an oxygen pressure of 0.4 ATA (296 mmHg) and the arterial pressure is likely to reach a more modest 0.3 ATA (230 mmHg). This is the same oxygen pressure that can be attained by breathing about 35% oxygen at sea level. To put it another way – this amount of oxygen can easily be achieved without the use of the chamber at all.

The ANZHMG (Australian and New Zealand Hyperbaric Medicine Group) is not aware of any reliable clinical evidence for therapeutic benefit from mild hyperbaric therapy and does not recommend the use of this modality for any medical purpose.


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