Exhaled nitric oxide’s clinical applications: ATS Practice Guideline (AJRCCM)

 Exhaled Nitric Oxide Analysis for Respiratory Disease: ATS Guideline

A blue ribbon panel led by Raed Dweik releases this ATS practice guideline, recommending when & how to use exhaled nitric oxide (FE-NO) for use in diagnosing and treating inflammatory respiratory conditions. FE-NO’s uses, they say, include:

• Predicting responsiveness to corticosteroid therapy
• Helping diagnose asthma in uncertain situations
• Monitoring airway inflammation in asthma, and possibly adherence with steroid therapy
• Diagnosing eosinophilic airway inflammation (due to asthma or eosinophilic bronchitis)

As with many biomarkers, individuals vary widely in FE-NO, resulting in normal/abnormal overlap and useless reference ranges. Rather, cut-off points are suggested, based on various prevalence studies:

• >50 parts per billion FE-NO (>35 ppb in kids): a symptomatic patient will likely respond to corticosteroids.
• 25-50 ppb (20-35 ppb in kids): Indeterminate; use clinical judgment
• <25 ppb (<20 ppb in kids): Steroid responsiveness is unlikely.

A standard FE-NO analyzer (NIOS, Aerocrine) cost $43,000 recently. That company is marketing a smaller, more portable and far cheaper version. The idea being that (if third-party payers pay physicians adequately to use the machine) average pulmonary practices may adopt this technology and use it to fine-tune or personalize care for patients with asthma or other, rarer inflammatory lung diseases. Expect early-adopter academic centers and large community practices in urban areas to jump in first, competing for “cutting-edge asthma therapy” bragging rights.

Dweik RA et al. An Official ATS Clinical Practice Guideline: Interpretation of Exhaled Nitric Oxide Levels (FENO) for Clinical Applications. Am J Resp Crit Care Med 2011;184:602-615.