Innovation: Positive breath test

A simple non-invasive test that measures nitric oxide in the air breathed out by patients may distiguish asthma from other lung diseases and help to monitor response to asthma drugs.

A study by a team of researchers at London's National Heart and Lung Institute, the research arm of the Royal Brompton Hospital, led by Peter Barnes, has found that the exhaled air from 61 non-steroid- treated asthmatics had a concentration of the gas more than three times higher than in air exhaled by 67 healthy volunteers.

The average concentration of nitric oxide in the air exhaled by 52 asthma sufferers taking inhaled steroids was similar to that of healthy volunteers.