Mandibular advancement splint improves upper airway collapsibility without changing genioglossus reflex responses in people with obstructive sleep apnea during wakefulness

A. Osman, P. Burke, F. Knapman, J. Carberry, J. Butler, L. Bilston, D. J. Eckert

Research output: Contribution to journalMeeting abstract

Abstract

Rationale: Mandibular advancement splints (MAS) improve upper airway collapsibility (Pcrit) during sleep in a dose-dependent manner. We have recently shown that a simple wakefulness test, the upper airway collapsibility index (UACI), is closely related to Pcrit during sleep. Here, as a proof-of-concept, we investigated whether the UACI technique can be used to detect improvements in upper airway collapsibility with MAS during wakefulness. A secondary aim was to measure the effect of MAS on the genioglossus reflex response to brief pulses of negative airway pressure. Methods: 25 people with obstructive sleep apnea (OSA) used a custom fitted MAS device. In addition to standard polysomnography equipment, all participants were instrumented with two pressure catheters (positioned at the level of the choanae and epiglottis), a sealed nasal mask fitted with a pressure sensor, a pneumotachograph to measure airflow and two fine-wire intramuscular electrodes into the genioglossus. Approximately 30 brief negative pressure pulses were applied to the mask (∼-14cmH2O) during early inspiration while participants breathed quietly in the supine position during wakefulness to quantify the UACI: 100x(nadir choanal-epiglottic pressure)/nadir choanal pressure during negative pressure pulses.This procedure was performed with and without MAS (order randomized). Results: The UACI at baseline (41±22%, mean±SD), was significantly improved with MAS (34±26%, p=0.017). Prestimulus baseline genioglossus muscle activity immediately prior (100ms) to negative pressure pulse delivery varied between individuals but on average was 157% higher with MAS than without (p=0.006). When present in both conditions, the onset latency (17±5 vs. 16±6ms, p=0.7, n=11), peak latency (27±6 vs. 29±11ms, p=0.7, n=11) and peak amplitude (531±543% vs. 528±325%, p=0.98) of the short-latency excitatory reflex response were not different with and without MAS. However, consistent with a scaling reflex, the amplitude of the short-latency peak excitation was closely related to the pre-stimulus baseline genioglossus muscle activity with and without MAS therapy (R 2= 0.5, p<0.001, n=11). Conclusions: MAS therapy improves the upper airway collapsibility index during wakefulness. Genioglossus short-latency excitatory reflex amplitude responses vary with MAS depending on the immediate baseline EMG activity during wakefulness. These findings provide proof-of-concept support for the UACI technique and highlight its clinical potential to inform patient selection for non-CPAP therapies. This research was supported by the CRC for Alertness, Safety and Productivity
Original languageEnglish
Article numberA6167
Number of pages1
JournalAmerican Journal of Respiratory and Critical Care Medicine
Volume201
Issue numberAbstract Issue 2020
DOIs
Publication statusPublished - 2020
Externally publishedYes
EventATS 2020: International Conference of the American Thoracic Society - Virtual
Duration: 5 Aug 202010 Aug 2020

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