Study of Monitoring Exhaled NO in Symptomatic Asthmatic Adults and Children During Anti-inflammatory Treatment

Asthma is a chronic inflammatory disorder of the airways. Chronically inflamed airways are hyperresponsive; they become obstructed and airflow is limited (by bronchoconstriction, mucus plugs, and increased inflammation) when airways are exposed to various risk factors. Asthma causes recurring episodes of wheezing, breathlessness, chest tightness, and coughing particularly at night or in the early morning. NO is an important endogenous regulatory molecule that is widely distributed throughout the body. The detection of NO in exhaled air was first reported in 1991, and, soon after it was shown that the levels NO in exhaled air are elevated in patients with asthma. There is now much evidence showing that measurement of the concentration of NO in exhaled air offers a useful non-invasive method of assessing inflammatory airway disease. Exhaled NO is not increased during bronchospasm unless there is coexisting inflammation. Exhaled NO may have a valuable role in differentiating between the inflammatory and bronchospastic components of clinical asthma, and is also useful for guiding the therapeutic use of steroids and other anti-inflammatory agents. A study on asthmatics and non-asthmatics subjects has shown that substantial equivalence exists between the stationary device NIOX® and the hand held device NIOX MINO® when comparing NO measurements, when similar conditions are considered and examinations are made as consistently as possible. In a study with the stationary device NIOX®, exhaled NO was measured before and after two weeks of inhaled corticosteroid treatment in unstable steroid-naïve adult and paediatric asthmatic subjects. The result was a 50.5% mean reduction of exhaled NO. The change in exhaled NO was also compared to change in standard asthma outcome measures, asthma symptoms and spirometry.