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Each year, several thousand Britons are victims of carbon monoxide poisoning.
As a treatment, some people are given oxygen to breathe but this may not
clear the blood of the poison rapidly enough to prevent tissue damage. Oxygen
can be assimilated more rapidly if it is delivered at high pressure – under
so-called ‘hyperbaric’ conditions. To achieve this the patient must be put
inside a steel pressure vessel or chamber where the air pressure is up to
four times normal atmospheric pressure. Patients breath pure oxygen under
pressure through a mask. Yet few GPs or hospital doctors who diagnose carbon
monoxide poisoning even consider prescribing hyperbaric oxygen.

Many doctors practising outside Britain would be shocked at their British
colleagues’ ignorance of hyperbaric oxygen therapy. In America, a victim
of carbon monoxide poisoning who suffered permanent brain damage sued the
doctor who neglected to prescribe hyperbaric oxygen and was awarded damages
of $3 million.

Oxygen under pressure is routinely prescribed in many hospitals in Continental
Europe and not only for the treatment of carbon monoxide poisoning. Every
major hospital in Belgium has a small chamber used to treat wounds, infections
and surgical patients. In the Netherlands, cases are referred to the hyperbaric
medicine unit of the Amsterdam Medical Centre, which has a room-sized chamber
providing treatment for about 30 patients a day. In Japan, hyperbaric oxygen
is considered valuable enough for the health department to have established
a network of chambers around the country to ensure that no one is more than
a two-hour ambulance ride away from one.

Meanwhile, Britain’s NHS operates only a handful of chambers. There
are only two in southeastern England: both are at Whipps Cross Hospital
in east London and each one holds only a single patient lying down. Yet
in the 1960s, more than 20 NHS hyperbaric facilities operated in the London
area alone, and it has been estimated that Britain still has more chambers
per capita than any country in the European Community except Italy. Only
a small proportion of Britain’s chambers remain operational, however, and
most of these are used to treat only the occasional diving accident.

So what happened to hyperbaric therapy in Britain? According to Ian
McCallum, chairman of a working group on hyperbaric oxygen chambers set
up last year by the Royal College of Physicians’ faculty of occupational
medicine, ‘the long history of birth, death and rebirth in the field of
hyper-baric medicine provides a good illustration of the confusion that
results when, through lack of money or will, medical experience isn’t backed
up with good quality research’.

The birth of hyperbaric oxygen was recorded in 1662, when a Dr Henshaw
built an airtight room which he compressed with bellows. The British physician
proposed the use of his ‘domicilium’ to aid digestion and prevent afflictions
of the lungs. There is no account of anyone taking up the proposal until
two centuries later, when it had become possible to build chambers and compressors
which would expose patients to pressures of up to four atmospheres. By the
second half of the 19th century, there were hyperbaric centres in all major
European cities and were often advertised as being comparable to health
spas. One French advocate referred to his treatment as ‘le bain d’air comprime’,
the compressed-air bath.

The treatment was one of the many therapies that died out as medicine
became more scientific and rational. Its final and most enthusiastic advocate
was an American doctor, John Cunningham, who in 1928 contructed a huge spherical
chamber in Cleveland, Ohio. It was six stories high and had 72 rooms. Cunningham
used it to treat people with all sorts of ills, including syphilis, hypertension,
diabetes and cancer. The American Medical Association censured Cunningham
for providing no evidence to demonstrate that his treatment was effective.
In 1937 the Cleveland chamber was broken up and sold for scrap metal.

Within a few years, however, hyperbaric medicine was reborn, with one
important difference. This time the patients were given pure oxygen to breathe
while under pressure. This practice was quickly shown to be effective in
the treatment of the decompression sickness suffered by divers and tunnel
workers after breathing compressed air for long periods. Doctors hoped it
would also have wider applications.

Many medical conditions are caused or exacerbated by inadequate blood
circulation, which results in tissues being starved of oxygen. Could increasing
the concentration of oxygen breathed by victims of stroke, for example,
limit brain damage or even prevent it? Could it sustain the life of a cardiac
patient while surgeons worked to repair a damaged heart? Early research
suggested that the answers to these questions might be yes, and in the 1960s
the intensive care units of many British hospitals were kitted out with
a hyperbaric chamber. The research that followed, however, raised more questions
than it answered.

Reports of results achieved in uncontrolled studies of small groups
of patients suggested that hyperbaric oxygen may be beneficial in more than
100 conditions, including senile dementia and impotence. It was even reported
to be of value in stimulating breast enlargement. It is perhaps not surprising
that the therapy seemed so powerful in uncontrolled clinical studies. Having
hyperbaric therapy provides you with exactly the sort of experience known
to generate a placebo effect. You enter a bullet-shaped steel chamber, the
door clangs shut behind you and, after much hissing and popping of ears,
you spend an hour or so just breathing.

But however ineffectual and harmless this sounds, oxygen itself is far
from inert. Oxygen is physiologically a very active subtance, and is toxic
if given in high doses. Breathing oxygen at more than four times atmospheric
pressure can lead to tingling and twitching of the lips as oxygen makes
the nerve endings hypersensitive. At higher doses, more nerves are affected
and at pressures greater than six atmospheres breathing oxygen causes convulsions
and death.

Increasing oxygen concentration in the body also stimulates the growth
of cells of connective tissue, the fibroblasts, and the manufacture of collagen.
This had tragic consequences for some children born in the 1950s, when premature
babies were given pure oxygen to breathe. Some became blind as a result.
Researchers later discovered that high oxygen concentrations had induced
fibroblasts and blood vessels to grow into the light-sensitive tissue of
the retina.

Oxygen’s ability to stimulate the growth of fibroblasts can also have
beneficial effects, however. The proliferation of fibroblasts to establish
a collagen matrix is an essential first step in wound repair and the reconstruction
of a blood supply to damaged tissue. This gives biological justification
to the many published reports that wounds heal more quickly if patients
breath oxygen in a chamber every day.

People with chronic infections also reportedly benefit from hyperbaric
oxygen and, again, this makes biological sense. Chronic infections tend
to become established in wounds with a damaged blood supply or in tissues
such as bone which have a poor blood supply. While many infecting microorganisms
can grow anaerobically, the biochemical weaponry of the immune system needs
oxygen to work effectively. The immune system’s phagocytic cells, which
engulf invaders, are particularly sensitive to oxygen concentrations: their
activity increases with the amount of dissolved oxygen. Breathing oxygen
under pressure can also improve the oxygenation of tissues poorly supplied
with blood vessels. Far more oxygen dissolves in the blood plasma, diffusing
into the infected area and shifting the odds in favour of the immune system.

By the early 1970s, most researchers suspected that hyperbaric oxygen
might improve the treatment of chronic wounds and infections. But in Britain
it was the physicians in the intensive care units who were in charge of
the equipment for delivering hyperbaric oxygen. They found little use for
their chambers, apart from the treatment of carbon monoxide poisoning. As
the switch from ‘town gas’ to North Sea gas was virtually complete, many
doctors believed that carbon monoxide poisoning would soon be rare.

Today only two intensive care units, at Whipps Cross and at Peterborough
District Hospital, have hyperbaric chambers. And, apart from publicity-inspired
investigations into the value of hyperbaric oxygen in the treatment of multiple
sclerosis in the early 1980s , virtually no research into hyperbaric therapy
has been performed in Britain since the 1960s. Outside Britain, however,
hyperbaric therapy lived on and last year an association called the British
Isles Group of Hyperbaric Therapists (BIGHT) formed to encourage discussion
about the therapy and press for research into its effectiveness. Its membership
of just over 30 includes technicians who administer oxygen in hyperbaric
conditions as well as the doctors who prescribe it.

‘Most of our members came into the field through diving medicine,’ says
BIGHT’s chairman, Philip Bryson. Others work at hospitals where hyperbaric
therapy has been practised almost underground for years. ‘Once it became
known that we were setting up an organisation, hyperbaricists we had never
heard of started coming out of the closet.’ The problem everyone shares,
Bryson says, is five decades of ‘quite appalling’ scientific research. ‘The
results may have looked good to the experimenters concerned but in most
cases the design of the study was so bad that the results weren’t worth
reporting,’ he says. ‘It has given the whole field a very bad name.’

Most members of BIGHT complain about the difficulties of swimming against
the stream of British medical opinion. John Clark, a surgeon at Glan Clwyd
Hospital in North Wales, says: ‘One has to be careful about mentioning that
you give your patients hyperbaric oxygen. You may find yourself discounted
as a crank.’

Clark first used hyperbaric oxygen five years ago after performing a
difficult operation to reattach a man’s severed arm. He worried that the
arm would not survive and decided to try hyperbaric oxygen. The patient
was transferred to a hospital in Manchester for regular treatments. The
arm did survive and, once recovered, the man mounted a fund-raising campaign
to buy a chamber for the hospital. Clark now uses the chamber to provide
hyperbaric oxygen treatments before and after difficult skin and bone grafts,
facial reconstructions and operations to manage diabetic ulcers.

‘Once doctors are convinced that a treatment can improve the welfare
of patients, they naturally want to share their conviction with colleagues.
The frustration is not having the time to devote to the sort of study which
would provide convincing clinical data,’ says Clark. ‘Funding is also a
problem. Funds are hard enough to come by for established medical research
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According to Paul Reed, a consultant anaesthetist at Peterborough District
Hospital, some surgeons already share Clark’s views. Reed became involved
in hyperbaric medicine almost by accident. ‘When my predecessor retired,
the hospital was considering getting rid of the chamber to make more room
for ordinary intensive care beds, but the orthopaedic surgeons asked us
to keep it. They said they found it invaluable in many cases.’ Reed agreed,
and the hospital now uses the chamber to treat 75 patients a year.

The Diving Diseases Research Centre in Plymouth has two chambers, each
of 11 cubic metres, which were donated to the charity when the diving vessel
Oregis was scrapped in 1983. The chambers were the sleeping quarters of
some of the first deep-saturation divers to work the North Sea oilfields.
Now they are more likely to accommodate people with chronic infections or
carbon monoxide poisoning than sick divers.

Bryson and his colleague Maurice Cross have been using the chambers
to treat non-diving patients since 1988. The turning point came when the
area health authority asked them if hyperbaric oxygen might be of help in
treating the radiation burns of some of the patients who received an accidental
overdose at the Royal Devon and Exeter Hospital.

‘I had no experience of using hyperbaric oxygen in this way,’ says Cross,
‘so I quickly phoned a few American contacts to see how they would handle
it.’ Some American radiotherapists routinely prescribe much higher doses
of radiation than is common in Britain and many combine it with hyperbaric
oxygen treatments, believing that this will prevent or cure the more serious
radiation injuries that result.

Cross agreed to treat the radiotherapy patients but when they arrived
he had doubts whether their wounds would heal. ‘In some of the patients,
the damaged tissue had already become necrotic because the blood supply
had been destroyed. But the results we got were quite impressive.’ The wounds
healed remarkably quickly, he says, and healthy tissue grew in from the
edges to replace the damaged tissue.

That experience left Cross much more interested in using hyperbaric
oxygen to treat non-diving patients. The problem is deciding which conditions
to treat. ‘Our policy is now to treat patients referred to us with one of
the conditions for which hyperbaric oxygen makes sense biologically, such
as chronic infections and wounds.’ Cross thinks the treatments have helped
patients. ‘But I wish I could support my opinion by referring to some convincing
clinical research.’

‘A person would be mad not to be sceptical about hyperbaric oxygen when
you consider some of the extraordinary claims that have been made for it,’
says Bryson. ‘The problem is, most doctors in Britain aren’t sceptical about
hyperbaric oxygen. Either they haven’t heard of it, or they vaguely remember
it as a discredited therapy that was abandoned several years ago.’ Properly
controlled clinical trials are urgently needed, Bryson argues. ‘But the
ignorance about the treatment is so profound in Britain it’s hard to generate
interest in such trials.’

Oxygen cannot be classified as a drug, even though it is a chemical
with profound physiological effects. So government regulatory agencies such
as the Committee on Safety of Medicines in Britain or the Food and Drug
Administration in the US have no duty to examine the efficacy of the treatment.
Industry will not finance the necessary research because the practice of
providing oxygen under hyperbaric conditions cannot be patented. The government
or medical charities remain the only possible sources of research funding.

At the Diving Diseases Research Centre, optimism is growing that the
NHS’s new research strategy, launched by the Department of Health last spring,
might lead to clinical trials on hyperbaric oxygen. Cross and Bryson want
first to set up a trial to investigate the treatment of chronic leg ulcers.
‘As well as being painful and disabling for the patient, leg ulcers are
very expensive for the health service,’ says Cross. ‘They often require
daily visits from a district nurse who cleans and dresses the wound.’ He
adds that if hyperbaric oxygen treatments are as effective as some people
claim, the savings they bring to the NHS could match the cost of setting
up the hyperbaric facitilies.

Lesley Newson is a science writer based in Plymouth.

* * *

Misleading messages from multiple sclerosis

Most British doctors who recognise the phrase ‘hyperbaric oxygen’ remember
it as one of the many treatments that have been suggested for multiple sclerosis.
Reports that victims of the neurological disease improved after treatment
in a ‘diver’s pressure chamber’ attracted a great deal of press attention
in the early 1980s, especially when one of the patients turned out to be
Vivian Neeves, a model who had achieved fame a few years earlier by being
the first woman to appear nude in The Times.

Doctors then treating multiple sclerosis were still coping with their
patients’ questions following a television report that injections of snake
venom might offer some hope to people with the disease. The idea that wheeling
patients into diving bells would help seemed equally improbable.

Anecdotal reports that multiple sclerosis patients had benefited from
hyperbaric oxygen began appearing in the late 1970s. No mechanism for such
improvement was found, but in 1978 researchers found that guinea pigs with
an experimentally induced disease similar to multiple sclerosis deteriorated
more slowly when they received oxygen under pressure.

In 1983, Britain’s Multiple Sclerosis Society devoted £185 000
of its research budget to fund double blind controlled trials of hyperbaric
oxygen at the University of Newcastle, Whipps Cross Hospital and St Thomas’s
Hospital in London. Neurologists advising the charity were sceptical about
the claims for the therapy and were concerned that it could have damaging
side effects. Meanwhile, multiple sclerosis patients were joining waiting
lists for treatment in hyperbaric chambers being set up by another charity,
Action for Research into Multiple Sclerosis.

The neurologists conducting the three trials in Britain found very little
difference between patients receiving treatment and those in the control
group; similar trials in other countries generally came up with the same
findings. Despite this, ARMS still operates 53 hyperbaric chambers in Britain,
providing 3000 treatments a week.

British hyperbaric therapists feel that the multiple sclerosis episode
still hinders their attempts to make other doctors consider hyperbaric oxygen
treatment. They also lament the fact that hyperbaric oxygen treatment of
a high-profile disease such as multiple sclerosis was deemed worthy of investigation,
while more scientifically valid proposals are ignored.