Evaluation of airflow limitation using a new modality of lung sound analysis in asthmatic children

Abstract

It was possible to evaluate airway dysfunction of asthma using ic700, which was calculated non-invasively by analyzing lung sounds alone, without measuring body size and airflow.

Treatment evaluation using lung sound analysis in asthmatic children

“…As for the next problem, non‐paroxysmal lung sounds are affected by individual differences such as body size and airflow. We confirmed that the ic700 was not affected by individual differences when using only lung sound data . Next, which is the index that is the most appropriate for the management of asthmatic small children?…”

“…These studies of breath sounds in asthmatic conditions have demonstrated that breath sounds are affected by changes in generation or transmission . We reported in 2009 that the intensity of inspiratory lung sounds reflects airway obstruction in asymptomatic asthmatic children . When the intermediate‐frequency components of lung sounds are transferred to the chest wall, the ic700 increases, implying that there is asthmatic airway dysfunction even when children are asymptomatic.…”

“…To avoid the effects of airflow on lung sounds, a wide‐band power of breath sounds between 150 and 1550 Hz was used instead of directly measuring the airflow. The predicted value of sub‐band power used for ic700 was determined by regression analysis using the wide‐band power in normal subjects . The frequency band of the sub‐band power was between 650 and 750 Hz.…”

“…We recently reported a method for simplifying this measurement and the development of a new index that requires the measurement of lung sounds at one location on the chest surface, the ic700 (index of the chest wall at 700 Hz, sound intensity at 700 Hz), which is the inspiratory lung sound power within the frequency band between 650 and 750 Hz relative to the band power predicted from the total power between 150 and 1550 Hz . The ic700 enables the evaluation of airflow limitation in asymptomatic asthmatic children with airway narrowing . In the present study, we evaluated the utility of the ic700 in evaluating ICS treatment in asthmatic children, including infants.…”

Lung sound analysis helps localize airway inflammation in patients with bronchial asthma

“…There have been reports that breath sound frequency components were correlated with the extent of airway obstruction as assessed by an airway hyperresponsiveness test, even in the absence of wheezing 4,5. Other studies have reported that inspiration sound pressure at 700 Hz increased with the severity of bronchial asthma in children without wheezing, demonstrating a significant correlation of the sound pressure at 700 Hz with the forced expiratory volume in 1 second/forced vital capacity (FEV 1.0 /FVC) ratio and the maximal expiratory flow rate at 50% of the vital capacity (FEF 50% predicted) 6. However, little information is available on the correlation between airway inflammation and lung sounds in bronchial asthma patients.…”