Effect of Noninvasive Ventilation on the Upper Airway in Patients With Amyotrophic Lateral Sclerosis: The Role of Upper-Airway Endoscopy

Abstract

Background: Upper-airway obstruction (UAO) in amyotrophic lateral sclerosis (ALS) may reduce the efficacy of noninvasive ventilation (NIV). NIV can cause or worsen this obstruction, further worsening the disease prognosis. This study aims to describe UAO in ALS patients using upper-airway endoscopy (UA-End) during spontaneous breathing (SB) and NIV and to evaluate the usefulness of UA-End in adjusting NIV parameters to correct any observed obstruction. Methods: This prospective study (2017-2019) involved subjects with ALS and indications for NIV. After optimizing ventilation following standardized procedures, an awake UA-End was performed, first during SB and then during NIV. Endoscopic assessments included identification of the site of UAO using the VOTE classification, assessment of vocal cords, and adjustments of NIV settings to correct any identified obstructions. Afterward, a post hoc analysis was conducted comparing gasometrical and nocturnal oximetry variables between the groups with and without NIV obstruction at 3 and 6 months. Results: In total, 25 subjects were enrolled. UAO was observed in 9 cases (37%) during SB, whereas 12 cases (50%) showed obstruction during NIV, 7 newly appearing. Hypopharyngeal constriction and backward movement of the epiglottis were the most frequent findings. Adjustments in NIV settings during endoscopy improved UAO in all but one case. Survival rates were similar after UA-End adjustments for subjects on NIV, both with and without UAO. Conclusions: This study is, to the best of our knowledge, the first to show the usefulness of UA-End in assessing and correcting UAO in subjects with ALS at NIV initiation. Furthermore, correction of such events through UA-End may have a positive impact on ventilation control and survival.

Keywords: amyotrophic lateral sclerosis; noninvasive ventilation; upper-airway endoscopy; upper-airway obstruction.