From the Guidelines
For asthma patients with elevated fractional exhaled nitric oxide (FeNO) levels, inhaled corticosteroids (ICS) are the recommended first-line treatment. Patients should typically start with a medium-dose ICS such as fluticasone (250-500 mcg twice daily), budesonide (400-800 mcg twice daily), or beclomethasone (200-400 mcg twice daily) 1. Elevated FeNO levels (generally >25 ppb in adults or >20 ppb in children) indicate type 2 airway inflammation, which responds particularly well to ICS therapy.
Key Considerations
- The weight of the evidence suggests that when used as part of an asthma management strategy, FENO monitoring is effective in preventing exacerbations only when used frequently (such as every 2–3 months) 1.
- If symptoms persist despite medium-dose ICS, adding a long-acting beta-agonist (LABA) like salmeterol or formoterol is recommended, followed by increasing to high-dose ICS if needed.
- For patients with severe asthma and persistently high FeNO despite these treatments, biologics targeting type 2 inflammation such as anti-IgE (omalizumab), anti-IL5 (mepolizumab, benralizumab), or anti-IL4/IL13 (dupilumab) may be considered.
Monitoring and Adjustments
- Regular monitoring of FeNO levels every 3-6 months helps assess treatment response, with a goal of reducing levels below 25 ppb.
- ICS effectiveness in these patients stems from their ability to suppress the IL-4 and IL-13 driven inflammatory pathways that increase nitric oxide production in the airways.
- Clinicians must interpret FENO levels in conjunction with other clinical data because these levels are affected by comorbid conditions, including allergic rhinitis and atopy 1.
From the Research
Recommended Treatment Plan for Asthma Patients with Elevated FeNO Levels
- The treatment plan for asthma patients with elevated fractional exhaled nitric oxide (FeNO) levels involves the use of FeNO testing to guide treatment decisions 2.
- FeNO testing is recommended as a point-of-care test to assess airway inflammation and guide treatment in patients with asthma 3.
- The American Thoracic Society (ATS) guidelines recommend the use of FeNO testing to diagnose eosinophilic airway inflammation and determine the likelihood of responsiveness to steroids 4.
FeNO-Based Treatment
- FeNO-based treatment involves adjusting the dose of inhaled corticosteroids (ICS) based on FeNO levels, with the goal of reducing airway inflammation and improving asthma outcomes 2.
- However, the evidence for FeNO-based treatment is inconsistent, and further research is needed to determine its effectiveness in reducing ICS dose or improving asthma outcomes 4.
- A study found that FeNO-based treatment reduced exacerbations in pregnant women with asthma, suggesting that FeNO measurement may be useful in certain patient populations 4.
Factors Influencing FeNO Levels
- Sex is an independent factor affecting FeNO levels, with higher levels observed in women than in men 5.
- Other factors that can influence FeNO levels include diet, smoking, and spirometry, which should be avoided or taken into account when measuring FeNO 4.
- FeNO levels can also be affected by the presence of eosinophilic bronchitis or chronic obstructive pulmonary disease (COPD), which can make interpretation of FeNO results more challenging 4.
Clinical Application of FeNO Measurement
- FeNO measurement can be used as an adjunct to diagnose asthma and guide treatment decisions 3, 4.
- FeNO measurement can also be used to monitor airway inflammation and adjust treatment accordingly 3.
- However, FeNO measurement is not a substitute for traditional diagnostic tests, such as spirometry and bronchoprovocation tests, which are still necessary to confirm the diagnosis of asthma 5.