INTRODUCTION: Exercise-induced laryngeal obstruction (EILO) is a key differential diagnosis for asthma in the presence of exertional respiratory symptoms. Continuous laryngoscopy during exercise (CLE), the current gold standard diagnostic test for EILO, has practical limitations. We aimed to establish if inspiratory flow data obtained during standard bronchoprovocation testing, to establish the presence of extra-thoracic hyper-responsiveness, may prove diagnostic for EILO and thus preclude requirement for CLE testing.

METHODS: We consecutively evaluated 37 adult subjects with exertional dyspnea and possible asthma referred over 6 months. All subjects received comprehensive assessment including a detailed clinical evaluation; pulmonary function testing, indirect and direct bronchial provocation testing, and CLE testing.

RESULTS: Out of 37 subjects, moderate or severe EILO was diagnosed in 8 subjects (22%, all female) while 5 (14%) had both asthma and EILO. There was no correlation between degree of EILO during CLE and mean decrease in forced inspiratory flow (%FIF50) obtained during neither the Methacholine (r = -0.15; p = 0.38) nor Mannitol (r = 0.04; p = 0.84) provocation tests.

CONCLUSION: Inspiratory flow parameters obtained during bronchoprovocation tests did not reliably detect EILO. It remains that CLE is an important and key investigation modality in establishing a secure diagnosis of EILO.