CHEST CLINICAL COPD & ASTHMA IMMERSION PROGRAM - AUGUST 14, 2024-FeNO

FeNO_Methacholine Bronchoprovocation
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Dr. Sandhya Khurana's presentation at the CHEST Asthma Immersion in Rochester discussed the utilization of Fractional exhaled Nitric Oxide (FeNO) and oscillometry in asthma diagnosis and management. The primary learning objectives included understanding FeNO's biological basis, its diagnostic utility, and the principles of oscillometry.<br /><br />FeNO involves a deep inhalation followed by exhalation at a constant flow rate. Levels above 25 ppb (or 20 ppb in children) are considered elevated, often reflecting Type 2 inflammation in asthma patients. Inducible nitric oxide synthase (iNOS) plays a key role, producing higher NO levels in asthmatics due to IL4/IL13 response. Elevated FeNO is associated with frequent exacerbations and can predict responses to inhaled corticosteroids (ICS) and biologic treatments like omalizumab, dupilumab, and tezepelumab.<br /><br />Clinical scenarios highlighted the efficacy of FeNO in managing asthma:<br />- Sarah, a 10-year-old with recurrent wheezing, was diagnosed with asthma and improved with ICS after high FeNO levels were observed.<br />- John, a 45-year-old with increased asthma symptoms, showed elevated FeNO levels indicating increased airway inflammation, leading to improved control after ICS dose adjustment.<br />- Emily, 25, with severe asthma and frequent exacerbations, showed high FeNO levels and benefited from biologic therapy like dupilumab.<br /><br />Oscillometry, involving pressure wave application during tidal breathing, measures lung mechanics across frequencies, with variables such as resistance (Rrs) and reactance (Xrs) offering insights into airway conditions. It is advantageous due to less effort dependency and sensitivity to airflow limitations but faces challenges like technical issues and poor specificity. Oscillometry helps differentiate between healthy and obstructed lungs and detect bronchoconstriction, evidenced in studies with asthmatic children.<br /><br />Overall, while FeNO provides a valuable tool in asthma diagnosis and treatment monitoring, confounding factors necessitate its combined use with broader clinical evaluations. Oscillometry offers complementary mechanics insights, albeit with its own limitations.
Keywords
Asthma
FeNO
Oscillometry
Diagnosis
Management
Inflammation
Corticosteroids
Biologic therapy
Lung mechanics
Airway conditions