Vocal cord dysfunction/inducible laryngeal obstruction induced by hyperventilation in healthy individuals, people with asthma, and following coronavirus infection.

OBJECTIVE

Vocal cord dysfunction/inducible laryngeal obstruction (VCD/ILO) commonly co-exists with asthma and can start after viral infections. In this setting evidence suggests that dysfunctional breathing may induce the disorder but this possibility has not been researched. We therefore postulated that dysfunctional breathing can induce VCD/ILO, more so in people with asthma and after viral infections.

METHODS

Eight healthy control subjects, 16 people with asthma and eight people who had recent COVID-19 infection (three with asthma) were recruited. Video-recorded laryngoscopy was performed at tidal breathing and during controlled hyperventilation (used as a proxy for dysfunctional breathing). VCD/ILO was diagnosed by laryngoscopy using accepted criteria and correlated with study cohorts, clinical attributes, asthma severity and spirometry.

RESULTS

Overall, 32 subjects were studied. Hyperventilation was verified in all subjects. None of the healthy control group or people with mild asthma developed VCD/ILO during or after hyperventilation but one person with moderate/severe asthma had clear evidence of VCD/ILO. In contrast, in people who had COVID-19 infection, hyperventilation induced VCD/ILO in 3/8 people (38%).

CONCLUSION

These proof-of-concept studies suggest that hyperventilation can provoke VCD/ILO in asthma and after a recent viral infection. How and why VCD/ILO develops is not known and these preliminary findings should prompt further studies of links between dysfunctional breathing, asthma, and viral infections.