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Last Updated: Sunday, 12 September, 2004, 23:55 GMT 00:55 UK
Deep-sea diving gas helps asthma
Image of divers
The gas is used by deep-sea divers
A breathing mixture commonly used by deep-sea divers shows promise for treating asthma attacks.

Two studies presented at the European Respiratory Society meeting in Glasgow this week showed a mixture of helium and oxygen was therapeutic.

The gases eased asthma attacks and improved the amount of exercise patients with chronic obstructive pulmonary disease were able to do.

The mixture studied by the French and British scientists is called Heliox.

Breathe easy

Replacing the nitrogen component of air with helium, makes heliox four times less dense than air.

This means it is four times easier to breathe, so it can be inhaled with less effort.

Researchers from the Bel Air Hospital in Metz-Thionville, France, and a separate team at the Royal Hallamshire Hospital in Sheffield, reasoned that because of this property, heliox might be good for treating lung diseases.

The French team gave 203 patients suffering an asthma attack either heliox or oxygen, plus usual treatment with bronchodilator drugs which help expand the narrowed airways causing the attack.

After one hour, both groups showed similar improvements in asthma symptoms.

Attacks eased

But the group that received heliox had better test results on one important measure of airway function - the peak expiratory flow rate which measures how fast a person can exhale air.

What is more, less than half as many patients in the heliox group had to stay in intensive care for more than four days.

They were also seven times less likely to need a breathing tube to help them breathe.

This is good news for lung disease patients and the NHS
Professor Andrew Peacock of the British Thoracic Society

Dr Philippe Sattonnet who ran the French study said: "If we compare the lungs to a bottle of oil from which it is difficult to pour, the usual solution is to expand the neck of the bottle, and this is what bronchodilatory drugs do.

"When air is replaced by helium and oxygen, it's as if the oil was replaced by water, which comes out more easily."

In the UK study, Dr Liz Laude and colleagues gave 82 patients with moderately severe COPD four different gas mixtures.

These were medical air with 21% oxygen, air with a slightly enriched oxygen content of 28% and two heliox mixtures, heliox 21 and heliox 28, in which the nitrogen component of the first two gases was replaced by helium.

A new therapy

The researchers then compared how far the patients could walk, patients' blood oxygen concentration at rest and their how hard each found it to breathe following exertion when breathing the four gases.

Heliox 21 was found to be equivalent to the 28% oxygen mixture in improving walking endurance and slightly better at reducing post-exertion dyspnoea.

But the heliox 28 had far greater benefits than the other gases.

Dr Laude said: "It provided an average 64% improvement in the distance covered and maintained a better blood oxygen concentration even though the distance walked was greater."

Professor Andrew Peacock of the British Thoracic Society said: "This study shows that Heliox can not only help deep sea divers to breathe but also help asthmatics undergoing a severe attack.

"This is good news for lung disease patients and the NHS.

"Wider use of Heliox could cut the duration and severity of asthma attacks."

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