Upper Esophageal Sphincter Response to Laryngeal Adductor Reflex Elicitation in Humans

Abstract

The laryngeal adductor reflex (LAR) is an important mechanism to secure the airways from potential foreign body aspiration. An involvement of the upper esophageal sphincter (UES) in terms of a laryngo-UES contractile reflex has been identified after laryngeal mucosa stimulation. However, the LAR-UES relationship has not yet been fully explained. This study aimed to determine the magnitude, latency, and occurrence rate of the UES pressure response when the LAR is triggered in order to elucidate the functional relationship between the larynx and the UES.Methods: This prospective study included seven healthy volunteers (5 female, 2 male, age 22-34 years). Laryngeal penetration was simulated by eliciting the LAR 20 times in each individual by applying water-based microdroplets onto the laryngeal mucosa. UES pressures were measured simultaneously using high-resolution manometry.Results: Two distinct pressure phases (P1, P2) associated with the LAR were identified. P1 corresponded with a shortterm UES pressure decrease in two subjects and a pressure increase in five subjects occurring 200 to 500 ms after the stimulus. In P2, all subjects experienced an increase in UES pressure with a latency time of approximately 800 to 1700 ms and an average of 40 to 90 mmHg above the UES resting tone.Conclusion: Foreign bodies penetrating the laryngeal inlet lead to a reflex contraction of the UES. Phase P1 could be a result of vocal fold activity caused by the LAR, leading to pressure changes in the UES. The constriction during P2 could strengthen the barrier function of the UES in preparation to a subsequent cough that may be triggered to clear the airways.

Computational Analysis of the Droplet‐Stimulated Laryngeal Adductor Reflex in High‐Speed Sequences

“…A set of 165 LHSS with a frame rate of and a resolution of pixels, obtained from 18 healthy human test subjects using the original MIT‐LAR system 11 in previous clinical studies, 13,23 was available for analysis. A total of 31 LHSS showing water droplet‐evoked LAR events were removed from this set due to analysis‐preventing factors, such as nonvisible droplet impact or LAR onset, resulting in a reduced set of 134 sequences from 15 test subjects.…”

“…Ethical approval : The studies conducted to obtain the LHSS evaluated in the present contribution were performed in accordance with the 1964 Declaration of Helsinki and its later amendments, Good Clinical Practices, and applicable regulatory requirements. The studies were approved by the ethics committee of Hannover Medical School (approval IDs 6616 13 and 3145/2016 23 ).…”

Stereo Laryngoscopic Impact Site Prediction for Droplet-Based Stimulation of the Laryngeal Adductor Reflex

“…12. The laryngoscopic views were recorded in four different subjects with the original, monoscopic MIT-LAR system in previous clinical studies [24], [50]. Five copies of each target were prepared using a high-resolution color laser printer (MP C5504exSP, Ricoh Co., Ltd., Tokyo, Japan), yielding a total of 20 targets for each system configuration.…”