SCOTLAND'S health watchdog has launched an investigation into the use of "bends" therapy for a growing number of medical conditions.

Hyperbaric oxygen therapy was initially developed to treat cases of divers suffering from decompression sickness, but has since been used for other conditions such as multiple sclerosis and cerebral palsy. However medical opinion is divided over its effectiveness.

Now a new study by NHS Quality Improvement Scotland (QIS) will assess how successful and cost-efficient the therapy is for a range of illnesses and publish a set of guidelines to be used by doctors in the UK and internationally.

A spokesman for NHS QIS said the information from studies which had been carried out on the oxygen treatment had never been collated. "There are a lot of studies out there, but there is a need to pull all of this together so that if someone wants to use it to treat something like multiple sclerosis they can refer to our report," he said.

"There is a need in Scotland for some kind of guidance on how cost-effective this treatment is in particular settings and for particular conditions.

"We will do this as national lead (for the UK), but there is also an understanding that there is a need internationally for this kind of protocol as well."

Hyperbaric oxygen treatment involves administering pure oxygen under increased atmospheric pressure while the patient is enclosed in an airtight chamber. This results in higher levels of oxygen getting into the blood stream, which can assist the healing process of damaged tissues.

NHS QIS, which will publish its guidelines in February next year, lists a total of 100 conditions which oxygen therapy has been used to treat or manage, including HIV infection, autism, dementia, migraine, stroke, skin burns, cancer, frostbite, sports injuries and spider bites.

The NHS-funded Hyperbaric Medicine Unit at Aberdeen - which also oversees decompression chambers in Orkney, Millport, and Oban - treats patients with diving-related illness most frequently, with around 80 to 100 cases per year.

Dr John Ross, honorary consultant at NHS Grampian, said the therapy was also commonly used for the treatment of post-radiotherapy damage in patients with oral cancer. But he said that multiple sclerosis was not among the conditions which they would treat, as there have been a number of trials indicating it had "no significant effect".

"There are a number of conditions that hyperbaric oxygen is thrown at, which are commonly incurable, but with really very little indication currently that hyperbaric oxygen does anything," he added.

That view was backed by Capability Scotland, which said that it would not recommend the treatment for cerebral palsy, as there was only "poor quality" or anecdotal evidence for its effectiveness.

Sheila Williams, head of disability initiatives at the charity, said: "There is also some evidence stating that the treatment may be potentially harmful, for example, to the ear. The treatment is not available on the NHS as benefits are unproven."

Mark Hazelwood, director of MS Society Scotland, said that some people who used hyperbaric oxygen therapy for treatment of multiple sclerosis reported an improvement in their condition.

But he added: "The clinical evidence supporting the efficacy of treatment for people with MS is certainly limited, so we welcome this review and hope that it will help to clarify its effectiveness."

However Philip James, professor of hyperbaric medicine at Ninewells Hospital, Dundee - which has the only hospital-based hyperbaric chamber in Scotland - said it was not surprising the therapy had been tried in so many differing conditions.

"When you get an injured or diseased tissue, it needs oxygen to get better," he said. "Not only are the cells of the tissue damaged, so are the capillaries within that tissue, and if you damage blood supply, you limit the oxygen delivery.

"You realise when you use oxygen in relation to the problems that we get in diving, that it is a very powerful way of treating someone who is lacking oxygen," he added.

James treated cancer patient Lisa Norris, who died last year, with oxygen therapy after she suffered a massive overdose of radiation treatment. He argued there was a lack of awareness among medics of its benefits.

"If a doctor sees a problem like that radiotherapy overdose and doesn't know there is a solution, they are not obviously going to press for it," he said. "We are dealing with a primary failure of medical education - I call it a black-hole' in medicine."