Timing and nature of wheezing at the endpoint of a bronchial challenge in preschool children

Abstract

Bronchial reactivity to inhaled agents in preschool children can be undertaken by auscultating the lungs to detect wheezing, but there is a lack of information on when wheeze first appears at the endpoint of the challenge and on the acoustic characteristics of the wheeze. We recorded breath sounds continuously during tidal breathing inhalation challenges with adenosine 5'-monophosphate, using sensors attached over each upper lobe in 80 preschool children. In 35 children, the challenge was considered positive by a pediatrician who determined the endpoint by detecting wheeze on auscultation after an inhalation. Using acoustic analysis, we determined that the first wheeze appeared during the 2-min period of nebulization in 31% of positive challenges; it was unilateral in 37%, and only inspiratory in 46%. A running window of 6 sec was used to detect at least two wheezes without reference to phase of breathing, and this index had a sensitivity of 97.6% and specificity of 99.7% for determining the endpoint of a challenge. Detecting wheeze acoustically adds safety to the technique by enabling the challenge to be stopped earlier, while the lack of a need to document the phase of breathing simplifies the technique.

Airway hyper‐responsiveness to adenosine 5′‐monophosphate in preschool‐age children with asthma

“…Airway responsiveness to AMP has been shown to be more specific for asthma diagnosis both in preschool-age (21) and school-age children (22). It has even been used in some clinics as the bronchial challenge of choice in young children who were referred for a possible diagnosis of asthma with a chief complaint of unexplained cough without wheezing (23,24). In contrast to its popularity, there is very limited data about the rate of AHR to AMP in childhood asthma (21,22,25).…”

The highs and lows of wheezing: A review of the most popular adventitious lung sound

“…19 While forced expiratory wheezing has been attractive for theoretical modelling and physiologic experimentation in humans, inspiratory wheezes are also a common finding in medical practice. [25][26][27][28] However, aside from laryngeal noises, they cannot be generated by healthy subjects even with maximum effort. Forgacs recognized the theoretical problems of wheezing during inspiration when airways should be pulled open.…”

Sensitivity of Bronchial Responsiveness Measurements in Young Infants

“…40 The usefulness of lung sound analysis using electronic equipment requires further investigation. 46 Bronchial responsiveness testing in infants is not standardized, 47 neither with respect to the choice of bronchoconstrictor agent nor the administration of aerosol. 48 We chose direct-acting methacholine because it has few side effects and a relatively long duration of action compared to histamine.…”