Airway hyperresponsiveness to hypertonic saline as a predictive index of exercise-induced bronchoconstriction

Choi, Inseon S; Chung, Se Woong; Koh, Youngil I; Sim, Myoung Ki; Hong, Seo Na; Moon, Jang Sik

Abstract

BACKGROUND: Altered airway mucosal osmolarity is an underlying mechanism of bronchoconstrictive response to both exercise and hypertonic saline (HS). The purpose of this study was to examine whether the osmotic challenge test using HS could predict the exercise-induced bronchospasm (EIB) in asthma.
METHODS
Thirty-six consecutive young male patients with asthma visited Chonnam National Univertisy Hospital underwent bronchial challenge tests using 4.5% HS, exercise (>24 hours later), and methacholine (MCh). The relationship in the responses between HS and exercise was observed in comparison with that between MCh and exercise.
RESULTS
The maximal fall in forced expiratory volume in one second following exercise was significantly higher in the HS-responders (n=19) than that in the HS-nonresponders (n=17)(35.9 +/- 4.1% vs. 17.9 +/- 2.7%, p<0.001). There was a significant correlation between the severity of EIB and HS-airway hyperresponsiveness (AHR). Compared with the MCh-AHR test in diagnosing for EIB, the HS-AHR test showed a higher specificity (71.4% vs. 42.9%), but a lower sensitivity (58.6% vs. 89.7%) and a lower negative predictive value (29.4% vs. 50.0%). At the cutoff value for moderate AHR, the MCh-AHR test had specificity comparable with and predictive values higher than those of the HS-AHR test.
CONCLUSION
The HS-AHR test was more specific than the MCh-AHR test, but less sensitive and had poor negative predictive value precluding from use of it as a screening test for EIB. The MCh-AHR test at the cutoff value for moderate AHR may be more useful in predicting EIB in asthma.