Feasibility of Constant Work Rate Testing to Detect Exercise-Induced Laryngeal Obstruction

Abstract

ABSTRACT Introduction Exercise-induced laryngeal obstruction (EILO) is a condition in which laryngeal structures inappropriately obstruct the upper airway during exercise. The standard diagnostic test for EILO is the continuous laryngoscopy during exercise (CLE) test, usually performed with an incremental work rate protocol regardless of the nature of the triggering event. Typically, laryngeal obstruction occurs only briefly at the end of an incremental test, near peak work capacity. We aim to investigate constant work rate (CWR) protocols for CLE testing to expand diagnostic test modalities and improve the understanding of EILO. Methods In this prospective, self-controlled feasibility study, ten patients with EILO performed both an incremental and a CWR CLE test at 70%, 80%, and 90% of maximal exercise capacity. Laryngoscopic video data were recorded and compared, and we evaluated the ability of CWR to reproduce the symptoms and laryngeal obstruction seen in incremental testing. Results In 70-90% of cases CWR testing induced at least the same severity of obstruction as incremental testing and CLE scores remained comparable across test modalities. CWR at 70% allowed observation of laryngeal obstruction for a significantly longer duration than in incremental testing (158 seconds; 95%-CI: 25 s;291 s, p = 0.027). Dyspnoea intensity appeared higher during CWR testing compared with incremental testing. Conclusions Submaximal CWR CLE testing is feasible and able to induce EILO equivalent to the standard incremental CLE test. This is the first step towards tailored CLE exercise protocols and further studies are now needed to establish the utility of CWR in clinical and research settings.