The expiratory-inspiratory ratios of sound power in the low-frequency range (E-I LF) from 36 patients with asymptomatic asthma were compared with those of 14 healthy controls (here is the study link).
The mean E-I LF was higher in the patients with asthma and with increased sputum eosinophils than in those patients without increased sputum eosinophils (0.45 vs 0.20) or in the healthy controls (0.25). Sputum eosinophil ratio and exhaled nitric oxide were independently correlated with E-I LF.
For the prediction of increased sputum eosinophils and increased fractional exhaled nitric oxide levels, the E-I LF thresholds of 0.29 and 0.30 showed sensitivities of 0.80 and 0.74 and specificities of 0.83 and 0.77, respectively.
Lung sound analysis (LSA) could predict airway inflammation of patients with asymptomatic asthma.
Prediction of Airway Inflammation in Patients with Asymptomatic Asthma by Using Lung Sound Analysis - The Journal of Allergy and Clinical Immunology: In Practice http://buff.ly/1zJK0CX