Palatal prolapse as a signature of expiratory flow limitation and inspiratory palatal collapse in patients with obstructive sleep apnoea

Key points •Some patients with obstructive sleep apnoea (OSA) respond well to oral appliance therapy, whereas others do not for reasons that are unclear. •In the present study, we used gold‐standard measurements to demonstrate that patients with a posteriorly‐located tongue (natural sleep endoscopy) exhibit a preferential improvement in collapsibility (lowered critical closing pressure) with oral appliances. •We also show that patients with both posteriorly‐located tongue and less severe collapsibility (predicted responder phenotype) exhibit greater improvements in severity of obstructive sleep apnoea (i.e. reduction in event frequency by 83%, in contrast to 48% in predicted non‐responders). •The present study suggests that the structure and severity of pharyngeal obstruction determine the phenotype of sleep apnoea patients who benefit maximally from oral appliance efficacy. Abstract A major limitation to the administration of oral appliance therapy for obstructive sleep apnoea (OSA) is that therapeutic responses remain unpredictable. In the present study, we tested the hypotheses that oral appliance therapy (i) reduces pharyngeal collapsibility preferentially in patients with posteriorly‐located tongue and (ii) is most efficacious (reduction in apnoea‐hypopnea index; AHI) in patients with a posteriorly‐located tongue and less‐severe baseline pharyngeal collapsibility. Twenty‐five OSA patients underwent upper airway endoscopy during natural sleep to assess tongue position (type I: vallecula entirely visible; type II: vallecula obscured; type III: vallecula and glottis obscured), as well as obstruction as a result of other pharyngeal structures (e.g. epiglottis). Additional sleep studies with and without oral appliance were performed to measure collapsibility (critical closing pressure; Pcrit) and assess treatment efficacy. Overall, oral appliance therapy reduced Pcrit by 3.9 ± 2.4 cmH2O (mean ± SD) and AHI by 69 ± 19%. Therapy lowered Pcrit by an additional 2.7 ± 0.9 cmH2O in patients with posteriorly‐located tongue (types II and III) compared to those without (type I) (P < 0.008). Posteriorly‐located tongue (p = 0.03) and lower collapsibility (p = 0.04) at baseline were significant determinants of (greater‐than‐average) treatment efficacy. Predicted responders (type II and III and Pcrit < 1 cmH2O) exhibited a greater reduction in the AHI (83 ± 9 vs. 48 ± 8% baseline, P < 0.001) and a lower treatment AHI (9 ± 6 vs. 32 ± 15 events h–1, P < 0.001) than predicted non‐responders. The site and severity of pharyngeal collapse combine to determine oral appliance efficacy. Specifically, patients with a posteriorly‐located tongue plus less‐severe collapsibility are the strongest candidates for oral appliance therapy.

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“…; Azarbarzin et al . ). Similalrly, pharyngeal collapsibility can now be estimated from routine diagnostic polysomnography (Azarbarzin et al .…”

Section: Discussionmentioning

confidence: 97%

Structure and severity of pharyngeal obstruction determine oral appliance efficacy in sleep apnoea

Marques

Genta

Azarbarzin

et al. 2019

The Journal of Physiology

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“…The velum and the uvula can also prolapse into the velopharynx during expiration, causing air to escape through the mouth. 23 This palatal prolapse during DISE has been shown to limit expiratory flow. Researchers concluded that the phenomenon of expiratory palatal prolapse could be caused by an elongated palate, a swollen uvula, or excess soft palatal tissue.…”

Section: Velummentioning

confidence: 99%

“…Researchers concluded that the phenomenon of expiratory palatal prolapse could be caused by an elongated palate, a swollen uvula, or excess soft palatal tissue. 23 This increase in expiratory pressure and fluttering of tissue could lead to oral exhalation. Additionally, it was also hypothesized that this mechanism could lead patients to become mouthbreathers, as it has been shown that children who mouthbreathe are at a higher risk of tongue base collapse.…”

Section: Velummentioning

confidence: 99%

Children with Upper Airway Dysfunction: At Risk of Obstructive Sleep Apnea

Sisniega

Katwa

2019

JCS

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Obstructive sleep apnea is characterized by prolonged partial upper airway obstruction or intermittent complete obstruction that disrupts normal ventilation during sleep and alters normal sleep patterns. Patients with obstructive sleep apnea tend to develop neurocognitive, cardiovascular, behavioral, attention issues, and poor academic performance. Therefore, it is essential to diagnose and treat obstructive sleep apnea early and avoid significant and long-lasting adverse outcomes. Most commonly, upper airway obstruction is caused by enlarged lymphoid tissues within the upper airway, and therefore adenotonsillectomy is considered as the first-line treatment of obstructive sleep apnea in children. Fifty to 70% of patients who have obstructive sleep apnea and treated by surgery are not entirely cured on follow-up polysomnography. In light of this, it is recommended that patients with suspected obstructive sleep apnea undergo a thorough evaluation, and all potential risk factors are identified and treated. The purpose of this review is to familiarize pediatricians with developmental, anatomical, and physiological risk factors involved in the development of obstructive sleep apnea. Additionally, we will present an array of evaluation techniques that can offer adequate assessment of the patient's upper airway anatomy and physiology.

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“…This suggests that the airway is most prone to collapse towards end expiration. However, recent studies that have investigated inspiratory (Genta et al 2017) and expiratory flow (Azarbarzin et al 2018) limitation have highlighted the propensity for inspiratory collapse in many individuals. These studies have also highlighted the link between the structures that contribute to pharyngeal collapse and the pattern and timing of airflow limitation.…”

Section: Introductionmentioning

confidence: 99%

Changes in pharyngeal collapsibility and genioglossus reflex responses to negative pressure during the respiratory cycle in obstructive sleep apnoea

Osman

Carberry

Gandevia

et al. 2020

The Journal of Physiology

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Key pointsr Impaired pharyngeal anatomy and increased airway collapsibility is a major cause of obstructive sleep apnoea (OSA) and a mediator of its severity.r Upper airway reflexes to changes in airway pressure provide important protection against airway closure. r This study shows increased pharyngeal collapsibility and attenuated genioglossus reflex responses during expiration in people with OSA.Abstract Upper airway collapse contributes to obstructive sleep apnoea (OSA) pathogenesis. Pharyngeal dilator muscle activity varies throughout the respiratory cycle and may contribute to dynamic changes in pharyngeal collapsibility. However, whether upper airway collapsibility and reflex responses to changes in airway pressure vary throughout the respiratory cycle in OSA is unclear. Thus, this study quantified differences in upper airway collapsibility and genioglossus electromyographic (EMG) activity and reflex responses during different phases of the respiratory cycle. Twelve middle-aged people with OSA (2 female) were fitted with standard polysomnography equipment: a nasal mask, pneumotachograph, two fine-wire intramuscular electrodes into the genioglossus, and a pressure catheter positioned at the epiglottis and a second at the choanae (the collapsible portion of the upper airway). At least 20 brief (ß250 ms) pressure pulses (ß−11 cmH 2 O at the mask) were delivered every 2-10 breaths during four conditions: (1) early inspiration, (2) mid-inspiration, (3) early expiration, and (4) mid-expiration. Mean baseline genioglossus EMG activity 100 ms prior to pulse delivery Amal Osman is a Research Associate at the Adelaide Institute for Sleep Health, Flinders University. She completed her PhD at the University of New South Wales and Neuroscience Research Australia. She is investigating development of simple clinical tools to measure upper airway collapsibility in obstructive sleep apnoea, a critical component in the pathogenesis of this common sleep-related breathing disorder. Current interests include understanding the mechanisms that contribute to airway closure in sleep apnoea. The hope is that this work brings us closer to developing new clinical tools to predict and optimize responses to targeted and novel treatments. J Physiol 598.3 and genioglossus reflex responses were quantified for each condition. The upper airway collapsibility index (UACI), quantified as 100 × (nadir choanal − epiglottic pressure)/nadir choanal pressure during negative pressure pulses, varied throughout the respiratory cycle (early inspiration = 43 ± 25%, mid-inspiration = 29 ± 19%, early expiration = 83 ± 19% and mid-expiration = 95 ± 11% (mean ± SD) P < 0.01). Genioglossus EMG activity was lower during expiration (e.g. mid-expiration vs. mid-inspiration = 76 ± 23 vs. 127 ± 41% of early-inspiration, P < 0.001). Similarly, genioglossus reflex excitation was delayed (39 ± 11 vs. 23 ± 7 ms, P < 0.001) and reflex excitation amplitude attenuated during mid-expiration versus early inspiration (209 ± 36 vs. 286 ± 80%, P = 0.009). These findings ...

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Palatal prolapse as a signature of expiratory flow limitation and inspiratory palatal collapse in patients with obstructive sleep apnoea

Cited by 38 publications

References 46 publications

Structure and severity of pharyngeal obstruction determine oral appliance efficacy in sleep apnoea

Structure and severity of pharyngeal obstruction determine oral appliance efficacy in sleep apnoea

Children with Upper Airway Dysfunction: At Risk of Obstructive Sleep Apnea

Changes in pharyngeal collapsibility and genioglossus reflex responses to negative pressure during the respiratory cycle in obstructive sleep apnoea

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