Can flow-volume loops be used to diagnose exercise induced laryngeal obstructions? A comparison study examining the accuracy and inter-rater agreement of flow volume loops as a diagnostic tool.

Background: Pre- and post-exercise flow-volume loops are often recommended as an easy non-invasive method for diagnosing or excluding exercise-induced laryngeal obstructions in patients with exercise-related respiratory symptoms. However, at present there is no evidence for this recommendation.

Aims: To compare physician evaluated pre- and post-exercise flow-volume loops and flow data with laryngoscopic findings during exercise.

Methods: Data from 100 consecutive exercise tests with continuous laryngoscopy during the test were analysed. Laryngoscopic images were compared with the corresponding pre- and post-exercise flow-volume loops assessed by four separate physicians and with data from the loops (forced inspiratory flow (FIF) at 25% vs. FIF at 75% of forced inspiratory vital capacity (FIVC), forced expiratory flow at 50% of forced expiratory volume vs. FIF at 50% of FIVC, and FIVC vs. FIF at 50% of FIVC).

Results: There was no significant association between the laryngoscopic findings and the flow-volume data. There was no agreement between the four physicians in their assessment of the flow-volume loops (kappa <0.00), and none of the individual physician's assessments were significantly associated with the laryngoscopic findings.

Conclusions: Exercise-induced laryngeal obstructions cannot be diagnosed or excluded by physician evaluated pre- and post-exercise flow-volume loops or flow data alone.