Laryngeal responses and airflow geometry in ALS during mechanically assisted cough

Abstract

Introduction: In patients with Amyotrophic Lateral Sclerosis (ALS), Mechanical Insufflation-Exsufflation (MI-E) pressures may evoke adverse laryngeal responses that lead to treatment failure. Aims: Explore possible relationships between visualized laryngeal response patterns and airflow geometry (pressure and flow characteristics) during MI-E in healthy controls and patients with ALS. Methods: Descriptive observational study. We analysed 61 examinations of 10 healthy controls and 51 ALS subtypes (25 spinal, 16 pseudobulbar and 10 progressive bulbar) using MI-E with a protocol utilizing pressure range of ±20 to ±50 cmH2O with subjects instructed to both exhale and cough. Transnasal fiberoptic laryngoscopy was performed concurrent with flow and pressure recordings. Airflow geometry patterns were compared to visualized laryngeal events and to participant category. Results: Efforts to cough or exhale during exsufflation affected the airflow geometry. Laryngeal adduction clearly interfered with airflow geometry, but we were unable to link visualized laryngeal response characteristics to unique airflow geometry patterns. We identified four MI-E airflow geometry patterns that were associated with being healthy and the ALS subtypes. Conclusions: Recording airflow geometry during MI-E provides information that can be used to design tailored flow and pressure settings, possibly facilitating prolonged successful use of MI-E treatment in ALS.