Abstract
Introduction: Mechanical insufflation-exsufflation (MI-E) is the most effective approach to increase peak cough flow in patients with neuromuscular diseases, thereby potentially augmenting airway clearance. Co-ordinated movements of the glottis are probably crucial for effect, but laryngeal response patterns to MI-E have not been studied.
Aims: Visualize laryngeal response patterns to MI-E in healthy subjects.
Methods: Ten healthy volunteers (21-26 years) were examined with video recorded flexibel transnasal fiberoptic laryngoscopy during MI-E (Cough Assist®, Respironics, USA) according to a standardized protocol at pressures of ±20 to 50 cmH2O. Participants were instructed to inhale during insufflation and to cough or actively exhale during exsufflation. Laryngeal patency and movements during MI-E was assessed from video recordings according to a pre-set scheme.
Results: In all subjects and regardless of the applied pressure and instructions, the vocal cords abducted during insufflation and exsufflation. Coordinated glottic closure and opening on instruction to cough was found in 10/10. At exsufflation pressures of -40 to -50 cmH2O, hypopharyngeal obstruction was observed in 6/10. Cough presented as sequential glottic closures in the majority. Retroflex movement of the epiglottis, partially occluding the laryngeal entrance, was observed in three subjects during insufflation, irrespective of pressures.
Conclusion: The laryngeal response patterns to MI-E in healthy subjects was as described for spontaneous cough. Negative pressures may cause temporary hypopharyngeal obstruction, and retroflex movement of the epiglottis may obstruct airflow. The examination was well tolerated and may be considered for use in patients.
- © 2011 ERS