FENO (Fractional Exhaled Nitric Oxide)
FeNO (Fractional Exhaled Nitric Oxide) is a non-invasive test that measures the concentration of nitric oxide in exhaled breath. Nitric oxide is a gas produced by the cells lining the airways, and its levels are typically elevated in conditions that cause airway inflammation, such as asthma. FeNO testing is primarily used to assess airway inflammation, monitor asthma control, and help guide the management of respiratory conditions.
How FeNO Works:
During the FeNO test, the patient exhales into a device that measures the concentration of nitric oxide in the breath. The patient is usually asked to take a slow, deep breath and exhale steadily into the device. The FeNO concentration is measured in parts per billion (ppb). The test is quick, easy to perform, and does not require any special preparation.
Significance of FeNO:
- Increased FeNO levels: Elevated levels of nitric oxide in exhaled breath are often seen in patients with asthma, especially when the asthma is not well-controlled or is associated with significant airway inflammation.
Normal or low FeNO levels: Low FeNO levels generally indicate that there is little or no airway inflammation, suggesting that the asthma or other respiratory conditions are well-controlled or absent.
Applications of FeNO Testing:
- Asthma Diagnosis: FeNO can be used as part of the diagnostic process for asthma. Elevated levels of FeNO, when combined with other clinical findings and tests (like spirometry), help support the diagnosis of asthma.
- Monitoring Inflammation: FeNO testing can be used to monitor airway inflammation in asthma and other conditions. It helps track the effectiveness of anti-inflammatory treatments, like corticosteroids, by observing changes in nitric oxide levels.
- Personalized Treatment: Measuring FeNO can assist healthcare providers in adjusting asthma treatment. For example, if FeNO levels remain elevated despite medication, it may indicate the need for a higher dose or a different treatment strategy.
- Assessing Non-compliance: High FeNO levels may suggest that the patient is not using inhaled corticosteroids as prescribed, even if they report using their medication regularly.
