['Inflammometry' with nitric oxide in exhaled air: a new test for lung diseases].

The gas nitric oxide (NO) is produced in increased amounts in certain types of inflammatory responses and its presence in exhaled air can be demonstrated. The nitric oxide fraction in exhaled air (FeNO) is elevated in patients with asthma and lowered in the case of several other lung diseases such as cystic fibrosis and primary ciliary dyskinesia. The FeNO can be quickly measured in a non-invasive and reproducible manner: on-line if the patient (adult or child), having taken a deep breath in, breathes out with a low flow rate into the NO measuring device or off-line if the expired air is collected in an NO inert reservoir. Confounding factors are contamination of inhaled air with ambient NO and contamination of exhaled air with NO that has been produced in the paranasal sinuses and the nose. The possible applications of FeNO measurement as a new lung function test include diagnostic tests for chronic respiratory symptoms and the possible guidance of anti-inflammatory therapy for asthma and, perhaps, other respiratory disorders.