Dysfunctional breathing induces vocal cord dysfunction following COVID-19 infection.

Abstract

Introduction/Aim: SARS-CoV-2 (COVID-19) has affected over 60 million people world-wide. In most cases symptoms are mild, however some people have ongoing symptoms lasting longer known as 'long COVID'. Exertional breathlessness is a common complaint in these patients. Dysfunctional breathing (DB) and vocal cord dysfunction (VCD) are two underappreciated causes of breathlessness. We hypothesized that in individuals who had experienced COVID-19, dysfunctional breathing could give rise to VCD. Method(s): Nine convenience-sampled participants with confirmed COVID-19 infection were included following resolution of the acute illness. Vocal cords movements were visualised via continuous laryngoscopy. Hyperventilation was employed as a surrogate for DB, using a standard protocol of 40 breathes per minute (bpm). Participants breathed through a flow sensor with concomitant laryngoscopy, and we monitored hyperventilation, gas exchange measurements and laryngeal movements. After 12-weeks patients returned for repeat hyperventilation testing. Result(s): The nine participants consisted of five females and four males, age range 24-66 years. Three of the nine participants developed classic inspiratory VCD during hyperventilation. Patients with VCD were female, younger (<45), reported significantly reduced exercise tolerance post infection and had been physically very active prior to COVID infection. In two participants VCD associated with hyperventilation had resolved on laryngoscopy at 12-weeks. In these two participants who had VCD, breathlessness and reduced exercise tolerance resolved at 12-weeks following laryngeal retraining. In one person evidence of VCD and reduced exercise tolerance persisted post 12-weeks review. Conclusion(s): This study provides the first evidence that COVID-19 may facilitate VCD via DB, causing unexplained breathlessness. Our findings suggest that this disease process may be implicated in 'long COVID' and provide a rationale for therapies such as breathing and laryngeal retraining.