Aim: Tracheal and chest auscultation for wheeze and transcutaneous oximetry have both been suggested as outcome measures of bronchial provocation tests in young children. The aims of this study were to compare the sensitivity of these two techniques as endpoints for methacholine challenge in young children with cough-variant asthma (CVA) and with classic asthma (CA), and to investigate whether oxygen saturation levels at the presence of wheezing differ in these two groups.
Methods: We performed a retrospective analysis of methacholine challenge test data from 4- to 6-year-old children with CVA (n = 41) and from those with CA (n = 53). The challenges used a modified auscultation method that set wheeze detection and/or oxygen desaturation for determining the endpoint.
Results: The frequency of wheeze detection at the endpoint was significantly lower than that of oxygen desaturation (46.3% vs. 78.0%) in the CVA group, which contrasted with findings (75.5% vs. 50.9%) in the CA group. Oxygen saturation levels at the presence of wheezing were significantly lower in the CVA group than in the CA group (94.5 +/- 1.5% vs. 95.9 +/- 1.8%, p = 0.006).
Conclusion: Wheeze detection is a less sensitive outcome measure than oxygen desaturation and is associated with a lower oxygen saturation level in young children with CVA, compared to those with CA.