Introduction Reduced exercise capacity is a common problem for patients with severe asthma, yet the reason for this remains unclear. Exercise induced laryngeal obstruction (EILO) is now recognised to cause dyspnoea on exertion but has never been studied in patients with severe asthma. We therefore undertook this study, utilising a gold standard endoscopic visualisation technique, to evaluate laryngeal function during exercise, in a well-characterised cohort of patients with severe asthma.
Methods Adult patients with severe asthma were recruited following a systematic assessment of their disease. All subjects reported impairment of activities of daily living despite treatment. Subjects underwent a symptom-limited continuous laryngoscopy during exercise (CLE) test. Laryngeal function / EILO was graded against a validated score. Measures of asthma control, perceived dyspnoea, lung function and procedure tolerability were recorded.
Results 32 patients (n = 25; female) completed CLE evaluation (Table 1). All patients were prescribed step 4/5 BTS treatment; 75% were prescribed maintenance oral corticosteroid. Despite this, patients reported poor disease control and high perceived dyspnoea (Table 1). EILO of at least moderate severity (graded ≥2 from max 3) was evident in 14 (44%) patients. The pattern and respiratory phase of EILO varied; inspiratory phase predominant (n = 7; 22%), expiratory phase predominant (n = 5, 16%), present in both phases (n = 2). Subjects with expiratory predominant EILO were more likely to have obstruction at the glottic level (i.e. vocal cord abduction) and poorer lung function. The CLE test was well tolerated; majority of subjects reported no/minimal procedural discomfort.
Conclusion Exercise induced laryngeal obstruction is highly prevalent in patients with severe asthma and is associated with dyspnoea. This abnormal laryngeal function was not evident at rest and may impair physical exercise capacity. Further work is required to explore underlying mechanisms and relationships with dyspnoea during activities of daily living.