Clinical usefulness of checking wheezing and flow volume loop in methacholine bronchoprovocation test

Choi, Inseon S; Kang, Kwang Won; Lim, Ho

Abstract

BACKGROUND
In methacholine bronchoprovocation test, lung function is traditionally measured by using forced vital capacity maneuver which depends on patient's effort. And insufficient breath may result in a false positive test.
OBJECTIVE
To evaluate the additional indices of airflow obstruction in the interpretation of methacholine bronchoprovocation test. METHOD: FEV1/FVC, configuration index of flow-volume loop (Slope-Ratio), modified Borg dyspnea score, and wheezing in addition to FEV1 were measured before and after methacholine challenge.
RESULTS
The changes of the measurements after methacholine challenge were significantly greater in patients with airway hyperresponsiveness (AHR). However, only 9 out of 29 (31.0%) patients with AHR developed all of indices and 6.9% did not show any evidence of obstruction except dyspnea. On the contrary, 40% of patients without AHR showed positive in two or more indices and 2 of them were hyperresponsive to histamine. Among patients with AHR, those without dyspnea and wheezing on challenge showed significantly lower baseline Borg score, FEV1, FEV1/FVC, and PC20, and were older than those with them (p<0.05).
CONCLUSION
Methacholine-induced deltaFEV1 is related to, but not concordant with other indices of airflow obstruction. Development of dyspnea and wheezing depends on age, etc. For an accurate interpretation of methacholine bronchoprovocation test, it maybe necessary to consider these variables.