Fractional exhaled nitric oxide (FeNo) as physiological marker for diagnosis and follow up asthma in comparison with spirometric parameters

Bronchial asthma is One of the most common causes of chronic inflammatory respiratory diseases which is diagnosed by clinical examination and pulmonary function tests (PFTs). The FeNO test is advised in detection asthma severity and the response to inhaled corticosteroid (ICS). This study aimed to assess the benefit of FeNO test for asthmatic patients and to correlate the severity of asthma with response to ICS in comparison with spirometric parameters.

The study was performed at private spiro-clinic in Hilla city/Iraq including 88 asthmatic patients who were given ICS for a period of 8 weeks (follow-up period) compared with 90 healthy subjects. The PFTs were measured by spirometry while the FeNO test was measured by exhaled breath analyzer (Medisoft Company, Belgium), at baseline and during follow-up visits. Results show significant differences in the mean FeNO levels in asthmatic patients in comparison with control (76.01±14.18 vs. 5.6±1.4 ppb) also there was significant decrease in the mean FeNO levels after taking ICS compared to levels before taking the treatment (14±3.2, 76.01±14.18 ppb respectively) in addition there was significant decrease in the mean FeNO levels after taking ICS compared to levels before taking the treatment in all subgroups of severity (mild, moderate and severe) (8±1.1 vs. 19±0.7, 12±2 vs. 35±3.1 and 20±5.6 vs. 85±6.4 ppb respectively, P = 0.001). The study also showed significant increase in the mean FEV1% predicted levels after taking the treatment compared to levels before taking the treatment in all subgroups of severity (mild, moderate and severe) (94±6.7 vs. 74±7.1, 88±8.6 vs. 53±3.3 and 78±5.2 vs. 36±2.4 as percent predicted respectively, P = 0.001), also this study revealed 20: 88 (22.7%) of asthmatic patients not diagnosed by spirometer while diagnosed by FeNO test. It can be concluded that This study emphasize the important role of FeNO test in diagnosis and follow up of ongoing airway inflammation and the study revealed that the FeNO test is more precise than spirometer.