The Food and Drug Administration (FDA) cleared for marketing a first-of-a-kind, non-invasive test system to measure the concentration of nitric oxide in exhaled human breath. The test system should help make it easier for doctors to monitor a patient's asthma.

Doctors can use the device in their office to evaluate their patient's response to anti-inflammatory treatment. A decrease in exhaled nitric oxide concentration suggests that the anti-inflammatory treatment may be decreasing the lung inflammation associated with asthma. Recent evidence has shown that nitric oxide levels are increased in the breath of people with asthma and that changes in nitric oxide levels may indicate whether or not treatment for asthma is working.

The test system, called the NIOX Nitric Oxide Test System, is made by Aerocrine AB, of Sweden. It combines equipment that detects nitric oxide and equipment that analyzes exhaled breath with a special computer system.

To use this new device, the patient places a mouthpiece, connected by a breathing tube to the computer, over his mouth. S/he inhales nitric oxide-free air to total lung capacity, then slowly exhales into the mouthpiece. The nitric oxide concentration is displayed immediately on the computer screen.

FDA cleared the NIOX system based on clinical studies conducted by the manufacturer of 65 patients, both adults and children aged four years and older, with confirmed diagnoses of asthma. The patients were tested with the NIOX system before they began drug treatment and again two weeks later. The studies were conducted at nine medical centers in the United States. The results showed that most patients had a 30%-70% decrease of nitric oxide levels after two weeks of treatment with inhaled steroids. In this study, elevated nitric oxide levels above 30 parts per billion correlated with moderate to severe asthma.

Asthma is a highly variable disease affecting millions of people worldwide. With asthma, the lungs become inflamed and constrict, limiting airflow and making breathing difficult. The incidence of asthma in the United States has increased in recent years and it now affects about 15 million Americans, including almost five million children. Every year, asthma causes roughly 2 million emergency room visits, approximately 500,000 hospitalizations, and 4,500 deaths.