Diagnosing Asthma

Abstract

International guidelines recommend a range of clinical tests to confirm the diagnosis of asthma. These focus largely on identifying variable airflow obstruction and responses to bronchodilator or corticosteroid. More recently, exhaled nitric oxide (FE(NO)) measurements and induced sputum analysis to assess airway inflammation have been highlighted. However, to date, no systematic comparisons to confirm the diagnostic utility of each of these methods have been performed. To do so, we investigated 47 consecutive patients with symptoms suggestive of asthma, using a comprehensive fixed-sequence series of diagnostic tests. Sensitivities and specificities were obtained for peak flow measurements, spirometry, and changes in these parameters after a trial of steroid. Comparisons were made against FE(NO) and sputum cell counts. Sensitivities for each of the conventional tests (0-47%) were lower than for FE(NO) (88%) and sputum eosinophils (86%). Overall, the diagnostic accuracy when using FE(NO) and sputum eosinophils was significantly greater. Results for conventional tests were not improved, using a trial of steroid. We conclude that FE(NO) measurements and induced sputum analysis are superior to conventional approaches, with exhaled nitric oxide being most advantageous because the test is quick and easy to perform.

Exhaled Nitric Oxide Atopy, and Spirometry in Asthma and Rhinitis Patients in India

“…The normal range of FeNO levels varies from studies in a variety of countries considering the effects of these factors. The FeNO range in HC in a study from India was 12.73 ± 7.8 ppb, whereas other studies of the Chinese, African population, and data from asthma, and allergy research group had the mean FeNO levels ranging from 20 to 39ppb [12,[24][25][26][27][28]. The present study had FeNO levels of 12.91 ± 10.35 ppb.…”

Electronic Nose: Current Status and Future Trends

“…149,150 (2) In contrast, the substance of interest for the detection of asthma is an inorganic gas, namely, nitric oxide. [151][152][153] By means of an electronic nose, patients with asthma can be clearly discriminated from the control group, whereas the accuracy of classification of severity is less reliable. 154 Recently, a hand-held device was developed by Aerocrine, the NIOX MINO, which is able to determine the NO concentration in exhaled breath accurately.…”

Exhaled Nitric Oxide in a Population Sample of Adults

“…This may indicate that in atopic subjects the exposure is giving rise to airway inflammation and increased FENO. Measurement of FENO has been found to be a useful diagnostic tool for the screening of patients with a suspected diagnosis of asthma [14], with a high degree of discriminating power [15, 16] and greater diagnostic accuracy than conventional tests [17]. On the other hand, the relationship between FENO and the diagnosis of asthma in the general population is more complex and not fully elucidated.…”