Use of Laryngeal Ultrasound to Observe Laryngeal Movements During Noninvasive Ventilation in Healthy Volunteers.

Background: Transnasal fiberoptic laryngoscopy (TFL) has revealed that laryngeal obstruction can hamper assisted ventilation. TFL may be considered invasive, and laryngeal ultrasound (US) could be a noninvasive alternative. The objective of this study was to investigate the feasibility of using laryngeal US to study laryngeal movements in healthy adult volunteers undergoing noninvasive ventilation (NIV) and to compare the observations with those of simultaneous TFL.

Methods: In this cross-sectional study, 30 participants (19 females, age 22-65 y) underwent simultaneous video-recorded TFL and laryngeal US, breathing with and without NIV. Laryngeal US was repeated for anterior and both lateral approaches; the last 5 breaths from each assessment were analyzed. The participants rated discomfort using a numeric rating scale (NRS) from 0 (no discomfort)-10 (worst). Two blinded raters separately described and scored the TFL and laryngeal US recordings, and the findings were subsequently compared. The last 10 laryngeal US recordings were tested for interrater reliability.

Results: All participants were successfully assessed using the anterior and both lateral laryngeal US approaches during NIV. Both techniques were well tolerated; 5/30 scored 0 on NRS for TFL and 22/30 for laryngeal US. The visualization rate for all recorded breaths was 99.1% for TFL compared to 81.7% for laryngeal US; overall concordance rate was 84.6%. The discordance rate for the TFL versus laryngeal US observations was 11.1% for vocal fold movements and 11.7% for aryepiglottic fold movements. Interrater reliability showed substantial agreement (0.71).

Conclusions: Laryngeal US emerged as a feasible method to describe laryngeal movements during NIV, providing high-quality observations and high concordance with TFL.