Methacholine-induced asthma symptoms correlate with impulse oscillometry but not spirometry

Abstract

Previous studies showed poor correlation between asthma symptoms and spirometric-based bronchial provocation tests. Use of impulse oscillometry (IOS) in airways resistance measurement may be more sensitive. In 20 individuals with stable asthma, we analysed the relationship between methacholine-induced asthma symptoms scores, IOS and spirometry. Following a screening visit, methacholine challenge testing was performed twice (visits 1 and 2). Dyspnoea, tightness and wheeze were quantified using visual analogue scores. IOS and spirometry were conducted at each incremental dose of methacholine. The Pearson correlation coefficient and linear regression analyses were conducted to explore the relations. A significant correlation was observed between methacholine-induced dyspnoea scores and the change in IOS measures of R((5)) (r=0.62, p=0.004) and X(5) (r=0.51, p=0.022), but not with the spirometric changes in FEV((1)) (r=0.37(,)p=0.11) or MEF(50) (r=0.32, p=0.17). In a multiple linear regression model, R(5) was the only significant variable to explain dyspnoea variability (p=0.003). Results of correlation analyses for chest tightness were similar to those obtained with dyspnoea. However, the symptom of wheeze showed correlation with IOS and spirometry. We conclude that airway resistance measured by IOS during methacholine challenge correlates better with asthma symptoms than traditional spirometric measures implying a higher sensitivity index.

Small-airways dysfunction associates with respiratory symptoms and clinical features of asthma: A systematic review

“…The latter suggests that the increase in small-airways resistance was responsible for the onset of symptoms in these subjects (Fig 4). 47 These findings are in line with those of Mansur et al, 48 who showed that a higher smallairways reactance is associated with more severe dyspnea, wheezing, and chest tightness after provocation. Together, these studies show that the small airways are involved in BHR and that the response in the small airways is associated with the development of symptoms during a provocation test.…”

Disparity Between Proximal and Distal Airway Reactivity During Methacholine Challenge

“…Mansur et al demonstrated that methacholine-induced symptoms correlated better with changes in R 5 than with change in FEV 1 ; however, all subjects had changes in FEV 1 (54). The present study extends this observation by relating the onset of symptoms to development of isolated changes in oscillometric parameters when FEV 1 did not change.…”

Asthma outcomes: Pulmonary physiology

“…184 Changes in FOT parameters have been demonstrated when assessing airway responsiveness to bronchodilators and bronchoconstrictors; however, clinically significant changes have not been defined. 185, 186 Similarly, minimal clinically important changes following therapeutic interventions have not been defined. 182 …”