Upper airway collapsibility is associated with obesity and hyoid position

A nomogram for predicting tongue collapse in DISE based on UACT findings in OSA patients

OBJECTIVE

This study aimed to analyze the correlation between DISE and upper airway CT (UACT) in OSA patients and to establish and validate a predictive model for tongue base (TB) collapse in the upper airway of OSA patients.

METHODS

From October 2014 to March 2022, a total of 117 OSA patients diagnosed by polysomnography were enrolled. Three-dimensional CT measurements of the upper airway were conducted, and preoperative DISE examinations were performed. Surgical plans were determined based on VOTE scoring. We used logistic regression analysis to identify key predictors of tongue base (TB) collapse in patients with obstructive sleep apnea (OSA). Subsequently, a predictive model was constructed and validated using the R language.

RESULTS

Through univariate logistic regression analysis, distances between bilateral tonsils (BT), thickness of parapharyngeal space (PPS), thickness of lateral pharyngeal walls (LPW), distance from tongue to posterior pharyngeal wall (PAS), and transverse diameter of the epiglottis (TEP) (P ≤ 0.1) were included in the multivariate logistic regression analysis. Multivariate analysis revealed that the thickness of LPW (P < 0.05) and TEP (P < 0.001) were significant predictive factors for TB collapse in the predictive model. A nomogram model was created for predicting TB obstruction based on these factors, exhibiting an AUC of 0.729 (95% CI: 0.619 ~ 0.914). The internal validation of the model resulted in an AUC of 0.804 (95% CI: 0.688 ~ 0.878) within the validation population.

CONCLUSION

A significant correlation between TB obstruction observed under DISE and LPW (P < 0.05) and TEP as measured in UACT scans among OSA patients. Based on this, a predictive nomogram model for TB obstruction during DISE demonstrates good performance.

Visceral obesity and HFpEF: targets and therapeutic opportunities

The effectiveness of weight-loss drugs in heart failure (HF) with preserved ejection fraction (HFpEF) highlights the link between obesity (adipose tissue) and HF (the heart). Recent guidelines incorporating the waist:height ratio for diagnosing and treating obesity reflect the growing recognition of the significance of visceral adiposity. However, its unique impact on HFpEF and their complex relationship remain underexplored. With limited treatment options for obesity-related HFpEF, novel disease-modifying treatments are urgently needed. Here, we clarify the relationship between visceral obesity and HFpEF, introducing the concept of the visceral adipose tissue-heart axis to explore its mechanisms and therapeutic potential. We also discuss promising strategies targeting visceral obesity in HFpEF and propose directions for future research.

[From vibration trauma to pharyngeal muscle instability: A self-sustaining pathophysiological process (circulus vitiosus) in obstructive sleep apnea]

Pharyngeal stability is ensured by both anatomical and non-anatomical factors. In addition to the anatomical width, functional factors are also significant in determining the degree of obstruction of the upper airway. The functionality of the pharyngeal muscles depends on an undisturbed sensorimotor system. In patients with rhonchopathy or obstructive sleep apnea (OSA), sensorimotor function and muscle morphology change progressively. It is hypothesised that long-term snoring leads to vibration-induced sensorimotor neuropathy, resulting in the loss of function and structure of the pharyngeal muscles. Pharyngeal mechanoreceptors lose their sensitivity, and due to neural damage, information can no longer be adequately translated into motor responses. This raises the question of the timeframe within which irreversible vibration-induced receptor damage occurs due to snoring.

The Effect of Tongue Volume and Adipose Content on Obstructive Sleep Apnea: Meta-analysis & Systematic Review

Objective

Macroglossia is a risk factor for obstructive sleep apnea (OSA) and has been linked to an elevated apnea-hypopnea index (AHI). Obesity may contribute to macroglossia, but its exact relationship is unknown and likely multifactorial, and the degree to which increased adiposity of the tongue affects the development of OSA is not understood. The primary objective of this study was to evaluate how tongue fat and volume relate to the presence and severity of OSA.

Data Sources

Studies reporting the impact of tongue fat or volume were identified using predefined inclusion criteria from September 2002 to 2022.

Review Methods

All studies underwent a 2-stage blinded screening, extraction, and evaluation process. Primary outcomes were the effect of tongue fat and volume on OSA severity and evaluation of study quality. Secondary outcomes included the impact of obesity on tongue fat distribution and OSA severity.

Results

Out of 930 studies, 6 studies with 219 patients and 133 controls were included in meta-analysis. All 6 studies were case-control designs. Included studies showed low (4) and moderate (2) risks of bias. All studies compared tongue volume with an observed significant increase in tongue volume in OSA patients (P < .00001) with a weighted mean difference of 19.00 cm3 [15.53, 22.47]. Two studies compared tongue fat, and there was a significant increase in tongue fat in patients with OSA (P < .00001) with a weighted mean difference of 8.04 cm3 [4.25, 11.82].

Conclusion

This meta-analysis supports increased tongue volume and tongue adipose as important risk factors associated with OSA. Larger studies investigating tongue fat distribution and the effect of weight changes on tongue fat and volume and OSA severity are needed to characterize this relationship better.

A Comprehensive Analysis of the Interrelationship Between Craniofacial Variables in Cephalometric Analysis and Obstructive Sleep Apnea (OSA)

Background/Objectives: Obstructive sleep apnea syndrome (OSAS) is a global condition usually associated with poor health. While common, it appears underdiagnosed due to repeated episodes of upper airway obstruction during the sleep cycle. It is accompanied by other health risks like cardiovascular issues and conditions. Identifying craniofacial characteristics linked to OSAS may enhance diagnostic precision and treatment planning. The aim of our study was to examine the relationship between cephalometric variables and OSAS and determine whether craniofacial features influence the syndrome's development and severity. Methods: Thirty participants were split into two groups: 15 diagnosed with OSAS and 15 controls. Cephalometric evaluations were performed using standardized lateral imaging, with craniofacial, dental, and hyoid bone parameters assessed. Statistical analysis compared these variables between groups to identify significant differences. Results: OSAS patients exhibited significantly shorter maxillary and mandibular lengths, increased anterior facial height, and reduced posterior facial height compared to controls. Dental analysis revealed reduced interincisal angles and lower mandibular incisor positions in the OSAS group. The hyoid bone was positioned lower and more posteriorly in OSAS patients, with significant differences in its distance to the C3 vertebra and mandibular plane. Although the soft palate dimensions were larger in OSAS patients, the differences were not statistically significant. Conclusions: OSAS is associated with distinct craniofacial features, including shorter maxillary and mandibular lengths, altered facial height proportions, and lower hyoid bone positioning. These findings suggest that craniofacial morphology plays a significant role in OSAS pathophysiology. Future studies hinting at three-dimensional imaging could provide deeper insights into these associations.

Multimodal Treatment of Sleep Apnea

Obstructive sleep apnea (OSA) is a common condition linked with multiple comorbidities. Continuous positive airway pressure (CPAP) devices, though the gold standard for OSA treatment, often do not address the entirety of the disorder. Various treatment strategies exist to address OSA beyond CPAP, each targeting different OSA aspects. These include managing comorbid sleep disorders, anatomic considerations, endotype-directed therapy, and lifestyle interventions. These comprehensive approaches aim to improve the benefits of treatment, and reduce the complications associated with OSA.

Treatment Outcomes in Awake Endoscopy With Advanced Programming in Hypoglossal Nerve Stimulation

OBJECTIVES

Hypoglossal nerve stimulation (HNS) is a treatment option for patients with moderate-to-severe obstructive sleep apnea. In the post-implant period, awake endoscopy with advanced programming (AEAP) can be employed to improve apnea hypopnea index (AHI) reduction and/or patient comfort. This study describes response patterns to HNS after AEAP as well as patient-specific patterns in our patient population.

METHODS

Retrospective evaluation of 17 consecutive patients who underwent AEAP between June 2019 and December 2022. Post-AEAP AHIs were used to create 2 response groups, which facilitated analysis of patient-based characteristics. AHI reporting, deemed non-titration AHI (NT-AHI), is the whole-night AHI resulting from non-titration studies. Chi-squared, Pearson correlation coefficient, and independent samples t-test were used to determine significance deemed as P < .05.

RESULTS

Fifteen of 17 patients (88.2%) presented for failed NT-AHI reduction, and 2/17 (11.8%) presented for comfort measures. Eleven patients (65%) showed an improvement in post-AEAP NT-AHI; 6 (35%) patients failed to improve. Four patients with either lateral wall collapse or concentric wall collapse at the tongue base failed to improve NT-AHI compared to a single patient who showed an improved NT-AHI (P = .017). Of the 2 patients who presented with discomfort, patient 1/2 demonstrated improvement in device usage, and patient 2/2 reported improved comfort while maintaining average device usage.

CONCLUSION

AEAP is a powerful tool that offers the ability to identify settings conducive to increased therapy efficacy and improved treatment tolerability. Airway phenotypes are closely correlated with treatment efficacy, and as such, careful anatomical consideration of the upper airway must be performed when titrating therapy.

LAY SUMMARY

Amongst the different treatment options for obstructive sleep apnea, hypoglossal nerve stimulation has been shown to be effective in positive-airway-pressure intolerant patients. This article explores response patterns to AEAP and highlights the importance of careful anatomical considerations of the upper airway.

LEVEL OF EVIDENCE

Level 3.

Radiographic findings predictive of obstructive sleep apnea in adults: A systematic review and meta-analysis

Polysomnography remains the diagnostic gold standard for obstructive sleep apnea (OSA), but it cannot be easily performed in a timely fashion within the practice of a craniomaxillofacial surgeon. Hence, in this systematic review and meta-analysis, we aimed to identify radiographic indicators that could predict obstructive sleep apnea (OSA) diagnosis. We conducted a PRISMA-compliant systematic review and meta-analysis, including 109 studies with 9817 participants (3509 controls, 6308 OSA patients), predominantly male (79% controls, 85% OSA patients). The analysis focused on CT (36, 33%), MRI (23, 21%), and lateral cephalogram findings (50, 46%). The average age and BMI for the included patients were 44.4 ± 14.4 years and 26.4 ± 5.2 kg/m2 for controls, and 51.5 ± 40.4 years and 29.8 ± 6.4 kg/m2 for the OSA group. A random-effects model meta-analysis was conducted on the measurements that met our criteria. Due to measurement differences between studies, only lateral cephalogram measurements could be included in the meta-analysis: OSA correlated with increased soft palate length and thickness, increased mandibular plane to hyoid bone distance, and decreased SNA, SNB, BaSN, SN distance, and palatal length (ANS-PNS). Although the study underscores radiographic utility for screening, PSG is necessary to establish a diagnosis of OSA.

Sex-specific age-related worsening of pathological endotypic traits in patients with obstructive sleep apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is more prevalent in men and older adults. Few studies have explored variations in pathological endotypic traits by age and sex using a large patient sample, offering insights into the development of the disease. Our study aims to examine how endotype characteristics of OSA vary across ages in different sex.

METHODS

A cross-sectional study was conducted, enrolling 2296 adult patients referred for in-laboratory diagnostic polysomnography at a single sleep center in Taiwan. Among them, 1374 had an apnea-hypopnea index ≥5. Using the "Phenotyping Using Polysomnography" method, we estimated four endotypic traits-arousal threshold, upper airway collapsibility, loop gain, and upper airway muscle compensation. Demographic and polysomnographic characteristics were compared between sexes and age groups. Generalized linear regression and generalized additive models were employed to explore the associations of sex and age with endotypic traits.

RESULTS

Men with OSA exhibited higher collapsibility and lower compensation than women (difference: 4.32 %eupnea and 4.49 %eupnea, respectively). Younger patients with OSA had a higher prevalence of obesity, more snoring symptoms, and lower loop gain compared to older patients. For men, age was correlated with increased collapsibility, increased loop gain, and decreased arousal threshold after 37 years old. Whereas in women, endotypic traits were not associated with age, except for an increase in loop gain with advancing age.

CONCLUSIONS

Personalized treatment options for OSA should take into consideration age and sex. Reducing loop gain could be a treatment objective for older patients with OSA.

Anatomic Changes of Patients With Obstructive Sleep Apnea Syndrome at Different Stages

AIM

In this study, it was aimed to determine the changes in the anatomic structures of individuals with obstructive sleep apnea syndrome (OSAS) classified according to the apnea-hypopnea index (AHI).

MATERIALS AND METHODS

Individuals were divided into groups as group 1 (AHI=0, n=20), group 2 (AHI ˂5, n=20), group 3 (AHI=5-15, n=20), group 4 (AHI=16-30, n=20), group 5 (AHI ˃30, n=20). The individuals left lateral cervical vertebra radiographs were taken. Measurements were made from the morphometric points determined using the "Enlil PACS" program on the radiologic images (mm). These measurements are categorized into soft tissue, hyoid bone, airway size, and craniofacial variables.

RESULTS

As AHI increased, age, body mass index, neck circumference, and Epworth Sleep Scale scores increased in all groups. Soft palate and tongue length, hyoid-mandible, hyoid-posterior pharyngeal wall, and hyoid-spina nasalis posterior distances lengthened. An increase was found between spina nasalis anterior, spina nasalis posterior, distance between condylion and gnathion, and total facial length and lower face length in all groups.

CONCLUSIONS

It is thought that the results obtained due to the differentiation in anatomic structures may help the methods that will facilitate the diagnosis and treatment of OSAS.

Phenotypes of Velopharyngeal Tube Law in Obstructive Sleep Apnea

OBJECTIVE

The biomechanics of upper airway collapse in obstructive sleep apnea (OSA) remains poorly understood. The goal of this study is to compare the area-pressure relationship (tube law) of the velopharynx at peak inspiration and peak expiration.

STUDY DESIGN

Cross-sectional.

SETTING

Academic tertiary medical center.

METHODS

The velopharyngeal tube law was quantified in a convenience sample of 20 OSA patients via step reductions in nasal mask pressure during drug induced sleep endoscopy (DISE). The velopharyngeal airspace cross-sectional area was estimated from endoscopy while luminal pressure was recorded with a catheter. The tube law was quantified for nasal mask pressures from 14 to 0 cmH2O at peak inspiration and at peak expiration in all patients. The tube law was also quantified during the breathing cycle at a constant nasal mask pressure of 4 cmH2O in 3 patients representing different phenotypes.

RESULTS

Velopharyngeal compliance (the slope of the tube law) was not statistically different in the peak inspiration versus peak expiration tube laws. Three phenotypes were observed, namely inspiratory collapse (phenotype 1), expiratory collapse (phenotype 2 = palatal prolapse), and a mostly stable airway during inspiration and expiration that collapsed as CPAP was reduced (phenotype 3).

CONCLUSION

Velopharyngeal compliance is not significantly different at peak inspiration and peak expiration, which suggests that muscle tone is low when luminal pressure is above the closing pressure. Additional studies are needed to investigate how different phenotypes of velopharyngeal collapse may affect therapeutic outcomes.

Intraoral appliance treatment modulates inflammatory markers and oxidative damage in elderly with sleep apnea

Obstructive sleep apnea (OSA) causes intermittent hypoxia, increased production of reactive oxygen species, and inflammation, which may elevate morbidity and mortality from cardiovascular disease. The objective of the present study was to investigate the effect of the intraoral appliance (IOA) as a treatment for OSA when it comes to the modulation of inflammatory markers and oxidative damage in elderly individuals. This "before and after" clinical trial included 9 patients diagnosed with OSA recruited from a multicenter randomized clinical trial study that evaluated the treatment with IOA for 60 days. Demographic and anthropometric variables, apnea and hypopnea index (AHI), and oxygen desaturation index (ODI) were collected by type III polysomnography, Epworth Sleepiness Scale, and inflammatory and oxidative damage markers (interleukin 6 (1L-6); tumor necrosis factor α (TNF-α); interleukin 10 (IL-10); thiobarbituric acid reactive substances (TBARS); total thiols; advanced oxidation protein products (AOPP), and nitric oxide (NO)). Shapiro-Wilk test, paired t-test and Pearson's correlation tests were used to analyze the results, respectively (α=0.05). The sample had a mean age of 71.86 ± 4.63 years, the majority were women (55.55%), and had a significant reduction in AHI (p=0.003), ODI (p=0.038), IL-10 (p=0.0001), AOPP (p=0.038) and TBARS levels (p=0.0001). There was a significant correlation between IL-10 and NO (r=0.855) and between TBARS and IL-6 (r=0.669), both after treatment. This study demonstrated that treating elderly patients with OSA using an IOA for 60 days reduces oxidative damage through the modulation of AOPP and TBARS.

Influence of natural hyoid bone position and surgical repositioning on upper airway patency: a computational finite element modeling study

The hyoid bone's inferior baseline position in obstructive sleep apnea (OSA) has led to surgical hyoid repositioning (SHR) treatment, yet outcomes vary widely. The influence of baseline hyoid position (BHP; phenotype) and SHR on upper airway (UA) function remains unclear. We aimed to investigate their impact on the UA using computational modeling. A validated finite element model of the rabbit UA was advanced and used to simulate changes in BHP and SHR, alone and in combination. The hyoid was displaced in cranial, caudal, anterior, anterior-cranial, and anterior-caudal directions from 1 to 4 mm. Model outcomes included UA collapsibility, measured using closing pressure (Pclose), cross-sectional area (CSA), and soft tissue mechanics (displacement, stress, and strain). Graded BHP increments increased Pclose for all directions and up to 29%-43% at 4 mm (relative to the original BHP). Anterior-based SHR decreased Pclose (approximately -115% at 4 mm) and increased ΔCSA (approximately +35% at 4 mm). Cranial SHR decreased ΔPclose (-29%), minimally affecting CSA. Caudal SHR increased ΔPclose (+27%) and decreased ΔCSA (-7%). Anterior-cranial and anterior-caudal SHR produced the highest stresses and strains. SHR effects on UA outcomes were dependent on BHP, with more caudal BHPs leading to less effective surgeries. In conclusion, BHP (phenotype) and SHR both alter UA outcomes, with effects dependent on hyoid displacement direction and magnitude. BHP influences the effectiveness of SHR in reducing UA collapsibility. These findings provide further insights into the hyoid's role in UA patency and suggest that considering the hyoid's baseline position and surgical repositioning direction/increment may help improve hyoid surgeries for OSA treatment.NEW & NOTEWORTHY Using computational modeling, this study directly shows that any shift from the healthy natural hyoid bone position increases upper airway collapsibility. Surgical hyoid repositioning alters upper airway outcomes in a direction- and magnitude-dependent manner, with its effects influenced by the natural hyoid position. Accounting for both the natural hyoid position and individually prescribed surgical repositioning may enhance upper airway stability and improve outcomes in obstructive sleep apnea (OSA) treatment.

Obstructive sleep apnea and obesity: A review of epidemiology, pathophysiology and the effect of weight-loss treatments

Despite the commonly-accepted paradigm that patients with obstructive sleep apnea (OSA) also invariably have obesity, OSA prevalence extends beyond obesity. This necessitates a reevaluation of screening strategies, biomarkers of increased OSA risk, and heightened awareness among healthcare providers about the array of OSA treatments for diverse adult populations. While obesity contributes importantly to OSA pathogenesis, there is substantial evidence that non-anatomical factors also play a crucial role, especially in patients who do not have obesity. In recent years, notwithstanding the recognition of diverse contributors to OSA pathogenesis, research has frequently focused on weight reduction to address OSA. Insights from past experiences with bariatric surgery in OSA serve as a lens to anticipate potential outcomes of emerging anti-obesity pharmacotherapies. Pharmacological alternatives, particularly incretin agonists, exhibit promise in weight reduction and OSA improvement, but encounter obstacles such as potential side effects and high costs. With this comprehensive narrative review, we delve into the complex epidemiological and pathophysiological connections between OSA and obesity. Additionally, we emphasize the importance of a multifaceted approach to OSA treatment, recognizing that while weight management is crucial, there is a need for comprehensive strategies that go beyond traditional weight-centric perspectives.

Predicting complete concentric collapse at the palatal level during drug-induced sleep endoscopy: an analysis of 1761 cases

PURPOSE

Drug-induced sleep endoscopy (DISE) helps select patients with obstructive sleep apnea (OSA) for surgery by identifying upper airway collapse patterns. This study aimed to predict the probability of complete concentric collapse at the palatal level (CCCp) during DISE based on patient characteristics, specifically body mass index (BMI).

METHODS

We retrospectively reviewed records of OSA patients who underwent DISE from January 2018 to July 2023. Logistic regression with receiver operating characteristic (ROC) analysis and classification and regression tree (CART) analysis were used to assess the diagnostic efficiency of BMI and other predictors for CCCp.

RESULTS

A consecutive series of 1761 eligible patients was included for analysis. CCCp was observed in 22.3% of cases. The CCCp group had significantly higher BMI, neck circumference, apnea-hypopnea index (AHI) and height as well as increase in partial and complete collapse at oropharyngeal level. The ROC analysis for predicting CCCp for a BMI cut-off was similar for males and females 29.4 kg/m² and 29.5 kg/m², with an area under the curve (AUC) of 0.65 and 0.73, respectively. Adding predictors like tonsils, AHI, height and neck circumference improved the model's performance.

CONCLUSION

Although confirming an association between increasing BMI and presence of CCCp, we were unable to define an accurate BMI cut-off value for predicting CCCp. The multifactorial nature of this collapse pattern challenges BMI's efficacy as a sole predictor. Our findings underscore the continued importance of DISE in evaluating CCCp and other collapse patterns for clinical decision-making in patients considered for hypoglossal nerve stimulation therapy.

Predicting OSA Using Radiographs of the Airway Anatomy

Objective

This study aims to analyze the tongue body shape and upper airway anatomical parameters in patients with Obstructive Sleep Apnea (OSA) and to explore the anatomical causes of OSA.

Methods

A total of 345 subjects participated in this study. Lateral pharyngeal images of the upper respiratory tract were captured in both normal and mandibular advancement states using X-ray plain film. Measurements were taken for the following parameters: Tongue Length, Tongue Thickness, Distance from the Mandibular Plane to the Hyoid, Soft Palate Length, Posterior Oropharyngeal Depth, Palatal Airway Space, Tongue Depth Space, and Mental Posterior Space. The correlation between the Apnea-Hypopnea Index (AHI) and these upper airway anatomical factors was analyzed using both univariate and multivariate analyses to develop a predictive model for OSA.

Results

The anatomical structure of the upper airway in patients with OSA is narrower compared to non-OSA individuals, and these patients exhibit a longer and thicker tongue. During mandibular advancement, the pharyngeal airway widens; however, the tongue length decreases while its thickness increases. Univariate correlation analysis revealed that the severity of OSA was significantly associated with tongue length, the ratio of tongue length to tongue thickness, the distance from the mandibular plane to the hyoid, soft palate length, and body mass index (BMI) in both the normal position and during mandibular advancement (p < 0.001). Multivariate linear analysis indicated that the severity of OSA is linked with the mandibular plane to hyoid distance in the normal position (MPH(N)) and BMI. A nomogram was utilized to develop a predictive model for OSA, achieving an area under the receiver operating characteristic curve of 0.838.

Conclusion

The pathogenesis of OSA is related to pharyngeal anatomy and tongue length in the state of mandibular advancement, which can be predicted by the measurement indexes of normal and anterior mandibular displacement lateral pharyngeal radiograph. This may potentially aid in early screening and diagnosis of OSA.

Physiologic and anatomic determinants of hyoid motion during drug-induced sleep endoscopy

PURPOSE

To examine factors accounting for differences in hyoid motion during obstructive breathing events amongst obstructive sleep apnea (OSA) patients.

METHODS

This was a prospective cohort study from June 2022 to October 2022. Patients with OSA undergoing evaluation for PAP alternative therapies with drug-induced sleep endoscopy with positive airway pressure titration (DISE-PAP). All patients underwent DISE-PAP and concurrent hyoid-focused ultrasound. DISE-PAP enabled measurement of airway physiology (flow, respiratory effort) and airway collapsibility (pharyngeal opening pressure, PhOP). Hyoid-ultrasound enabled hyoid bone movement during obstructive breathing. Respiratory effort was measured using a retro-epiglottic pressure-sensitive catheter. Hyoid position was measured using a standardized, awake, CT protocol. Regression analyses adjusted for age, race, sex, and BMI were performed to associate indices of respiratory effort and CT data with hyoid motion.

RESULTS

On average, the 26 patients in this cohort were older (63.9 ± 10.5 years), male (69%), overweight (29.6 ± 3.99 kg/m2), and with moderate-to-severe OSA (26.8 ± 10.4 events/hour). Greater respiratory effort was associated with increased hyoid motion (β [95% CI] = 0.034 [0.016,0.052], standardized β = 0.261,p = 0.0003). Higher hyoid position was associated with greater hyoid displacement (β [95% CI] = -0.20 [-0.38,-0.01], Standardized β = -0.57, p = 0.036).

CONCLUSION

Our data demonstrate that greater respiratory effort, higher hyoid position, and higher airway collapsibility, but not airflow, are associated with greater hyoid motion during obstructive breathing in DISE. These findings suggest that downward hyoid movement represents a compensatory response to upper airway obstruction. Further studies should investigate the vectors of hyoid motion to better understand its role in sleep-related airway collapse.

3D analysis of upper airway morphology related to obstructive sleep apnea severity

BACKGROUND

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder characterized by repetitive collapse of the upper airway during sleep. However, little evidence is available on the differences between the sub-regions of the upper airway morphology and OSA severity. Since orthodontists frequently perform cone beam computed tomography (CBCT) in the neck area, we aimed to investigate the relationship and the differences between upper airway morphology and OSA severity using CBCT.

MATERIALS AND METHODS

The medical records, CBCT imaging of 21 OSA patients diagnosed by polysomnography, and the apnea-hypopnea index (AHI) results were included to classify OSA severity as mild, moderate, or severe. The minimum cross-sectional areas (MCA) and volumes of the upper pharyngeal airway boundaries in four sub-regions: nasopharynx, retropalatal, retroglossal, and hypopharynx were measured. Dolphin Imaging software was used for upper airway segmentation. The correlation coefficient (r), one-way ANOVA, and the least significant difference post hoc multiple comparison test were applied to fulfill the objectives.

RESULTS

A statistically significant relationship was found between the MCA of the nasopharynx and the AHI (r = -0.473, P < 0.05). Furthermore, a difference was found between mild and moderate and moderate and severe OSA severity in the MCA results of the retroglossal region (P < 0.05). However, no relationship was found between the upper airway volume and OSA severity.

CONCLUSIONS

MCA was moderately negatively correlated to AHI only in the nasopharynx subregion. Moderate OSA presented significantly less MCA than mild and severe OSA only in the oropharynx and retroglossal subregions.

Association Between Soft Tissue Measures From Computed Tomography and Upper Airway Collapsibility on Drug-Induced Sleep Endoscopy

OBJECTIVE

Positive airway pressure (PAP) titration during drug-induced sleep endoscopy (DISE) provides objective measures of upper airway collapsibility. While skeletal measurements relate to collapsibility measures on DISE, the influence of soft tissue dimensions on upper airway collapsibility is not known. We analyzed the relationship of measures of upper airway soft tissue volumes, specifically soft palate, pharyngeal lateral walls, and tongue, with metrics of collapsibility.

STUDY DESIGN

Cross-sectional analysis from a prospective cohort.

SETTING

Academic medical center.

METHODS

Patients seeking PAP alternative therapies for obstructive sleep apnea (OSA) underwent standardized supine computed tomography (CT) acquisition and DISE protocols. The CT analysis primarily focused on soft tissue volumes and, secondarily, on airway and skeletal volumetric measures. DISE with PAP administration (DISE-PAP) enabled the determination of the pressure at which inspiratory airflow first commenced (pharyngeal critical pressure, PcritA) and the pressure at which inspiratory flow limitation was abolished (pharyngeal opening pressure, PhOP). Both unadjusted and adjusted correlation analyses were performed to understand the relationship between upper airway anatomy and either PcritA or PhOP.

RESULTS

One hundred thirty-nine subjects completed both CT and DISE-PAP. On average, patients were male (70.5%), white (84.2%), middle-aged (56.6 ± 13.5 years), and overweight (29.6 ± 4.7 kg/m2), with moderate-severe apnea-hypopnea index (29.7 ± 21.3 events/h). Adjusted for age, sex, body mass index, and skeletal volumes, soft palate, and lateral pharyngeal wall volumes were not associated with PhOP or PcritA, but a larger tongue was associated with more positive PhOP (⍴ = 0.20, P = .02), and more positive PcritA (⍴ = 0.16, P = .07). Exploratory analyses revealed smaller minimum cross-sectional retropalatal area and intramandibular volume were also associated with increased collapsibility measures.

CONCLUSION

After controlling for clinical factors and skeletal volume, greater tongue volume was associated with more severe collapsibility during DISE. These results, in concert with previous work, suggest that greater tongue volume in a smaller skeletal dimensions contribute to the severity of airway collapsibility, a key driver of OSA pathogenesis.

Medicare volume and reimbursement trends in lingual and hyoid procedures for obstructive sleep apnea

OBJECTIVES

This study aims to analyze utilization and reimbursement trends in lingual and hyoid surgery for obstructive sleep apnea (OSA).

METHODS

Annual retrospective data on lingual and hyoid OSA surgeries was obtained from the 2000-2021 Medicare Part B National Summary Datafiles. Current Procedural Terminology (CPT) codes utilized included 21,685 (hyoid myotomy and suspension [HMS]), 41,512 (tongue base suspension [TBS]), 41,530 (radiofrequency ablation of the tongue [RFT]) and 42,870 (lingual tonsillectomy [LT]).

RESULTS

The number of lingual and hyoid OSA surgeries rose 2777 % from 121 in 2000 to 3481 in 2015, before falling 82.9 % to 594 in 2021. Accordingly, Medicare payments rose 17,899 % from an inflation-adjusted $46,958 in 2000 to $8.45 million in 2015, before falling drastically to $341,011 in 2021. As the number of HMSs (2000: 91; 2015: 84; 2021: 165), TBS (2009: 48; 2015: 31; 2021: 16), and LTs (2000: 121; 2015: 261; 2021: 234) only experienced modest changes in utilization, this change was largely driven by RFT (2009: 340; 2015: 3105; 2021: 179). Average Medicare payments for RFT rose from $1110 in 2009 to $2994 in 2015, before falling drastically to $737 in 2021.

CONCLUSION

Lingual and hyoid surgery for OSA has overall fallen in utilization among the Medicare population from 2000 to 2021. However, there was a brief spike in usage, peaking in 2015, driven by the adoption (and then quick dismissal) of RFT. The rise and fall in RFT use coincide with the rise and fall in reimbursement.

Adults with Treacher Collins Syndrome Share Comparable 3D Upper Airway Dimensions with Nonsyndromic Individuals

Purpose

Sleep apnea symptoms, such as snoring and daytime somnolence, are commonly observed in individuals with Treacher Collins Syndrome (TCS) and may be related to airway obstruction due to micro- and retro-gnathia. This study aims to three-dimensionally evaluate the upper airway using cone-beam computed tomography (CBCT) exams of adolescents (TCS-ADOL) and adults (TCS-ADUL) with TCS compared to a nonsyndromic group (CON).

Materials and Methods

Twenty-six CBCT exams were divided into three groups: TCS-ADOL (n = 7) (13.14 ± 1.67 years): CBCT exams of TCS adolescents; TCS-ADUL (n = 10) (21.80 ± 4.39 years): CBCT exams of TCS adults; and CON (n = 9) (25.33 ± 8.57 years): CBCT exams of adult nonsyndromic individuals with Class II skeletal pattern. The variables analyzed were (1) total upper airway volume; (2) nasal cavity volume; (3) total pharyngeal volume; (4) nasopharyngeal volume; (5) oropharyngeal volume; (6) pharyngeal minimal cross-sectional area; (7) pharyngeal length; and (8) pharyngeal depth. Scans were analyzed by two examiners, and intra- and inter-rater agreement was calculated. A p-value of ≤0.05 was considered significant.

Results

Although not statistically significant, the TCS-ADUL group showed decreased airway volume and minimal cross-sectional areas compared to the CON group. There were also significant differences between TCS-ADOL and TCS-ADUL, with significantly lower airway volumes in the TCS-ADOL group. Strong positive correlations were found between certain airway measurements in the TCS-ADOL group, which were not observed in adults.

Conclusions

The upper airways of adults with TCS are dimensionally similar to those of nonsyndromic individuals, despite absolute value reductions found in the syndromic group. The reduced airway in the adolescent population suggests significant potential for growth, mainly in pharyngeal dimensions.

Paediatric sleep diagnostics in the 21st century: the era of "sleep-omics"?

Paediatric sleep diagnostics is performed using complex multichannel tests in specialised centres, limiting access and availability and resulting in delayed diagnosis and management. Such investigations are often challenging due to patient size (prematurity), tolerability, and compliance with "gold standard" equipment. Children with sensory/behavioural issues, at increased risk of sleep disordered breathing (SDB), often find standard diagnostic equipment difficult.SDB can have implications for a child both in terms of physical health and neurocognitive development. Potential sequelae of untreated SDB includes failure to thrive, cardiopulmonary disease, impaired learning and behavioural issues. Prompt and accurate diagnosis of SDB is important to facilitate early intervention and improve outcomes.The current gold-standard diagnostic test for SDB is polysomnography (PSG), which is expensive, requiring the interpretation of a highly specialised physiologist. PSG is not feasible in low-income countries or outwith specialist sleep centres. During the coronavirus disease 2019 pandemic, efforts were made to improve remote monitoring and diagnostics in paediatric sleep medicine, resulting in a paradigm shift in SDB technology with a focus on automated diagnosis harnessing artificial intelligence (AI). AI enables interrogation of large datasets, setting the scene for an era of "sleep-omics", characterising the endotypic and phenotypic bedrock of SDB by drawing on genetic, lifestyle and demographic information. The National Institute for Health and Care Excellence recently announced a programme for the development of automated home-testing devices for SDB. Scorer-independent scalable diagnostic approaches for paediatric SDB have potential to improve diagnostic accuracy, accessibility and patient tolerability; reduce health inequalities; and yield downstream economic and environmental benefits.

Airway Collapsibility during Drug-Induced Sleep Endoscopy Relates with Clinical Features of Obstructive Sleep Apnea

INTRODUCTION

Increased pharyngeal collapsibility leads to obstructive sleep apnea (OSA). Positive airway pressure titration during drug-induced sleep endoscopy (DISE-PAP) provides objective collapsibility metrics, the pharyngeal opening pressure (PhOP), and active pharyngeal critical pressure (PcritA ). We examined the interrelationships between risk factors of OSA, airway collapsibility measures, and clinical manifestations of the disease.

METHODS

This is a cross-sectional analysis of consecutive OSA patients undergoing DISE-PAP. Nasal PAP was increased stepwise until inspiratory flow limitation was abolished, signifying PhOP. PcritA was derived from the resulting titration pressure-flow relationships. Clinical data including demographics, anthropometrics, sleep studies, and patient-symptom questionnaires were obtained from the electronic medical record. Multivariate regression was used to evaluate the relationship between risk factors, airway collapsibility, and clinical data.

RESULTS

On average, the 164 patients meeting inclusion criteria were middle-aged (54.2 ± 14.7 years), overweight/obese (BMI 29.9 ± 4.5 kg/m2 ), male (72.6%), White (79.3%) and had severe OSA (AHI 32.0 ± 20.5 events/hour). Mean PhOP was 7.5 ± 3.3 cm H2 O and mean PcritA was 0.80 ± 3.70 cm H2 O. Younger age (Standardized β = -0.191, p = 0.015) and higher BMI (Standardized β = 0.176, p = 0.028) were associated with higher PhOP, but not PcritA . PhOP and PcritA were both associated with AHI, supine AHI, and SpO2 nadir. Higher PhOP was associated with higher snoring scores (Standardized β = 0.246, p = 0.008), but not other patient-reported outcomes.

CONCLUSION

Objective assessment of passive and active airway mechanics during DISE relates with clinical risk factors for OSA. Quantitative measures of collapsibility provide accessible and meaningful data, enhancing the standard sleep surgery evaluation.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:1978-1985, 2024.

[The upper airway in obstructive sleep apnea patients is pathological even when awake]

Obstructive sleep apnea (OSA) is characterized by partial or complete obstruction of the pharyngeal airway. Anatomical factors can be distinguished from non-anatomical factors. Age and obesity are the main risk factors for OSA; however, approximately 50% of patients are not obese. In older patients (>60 years), the importance of obesity decreases. There is an increased prevalence of OSA among patients with normal weight. The effects of chronic intermittent hypoxemia, low-grade inflammation, increased sympathetic tone and mechanical stress contribute to a transformation of muscle fibers in the upper airway, resulting in reduced muscle mass and strength. Less frequently encountered non-anatomical factors include decreased muscle tone, increased arousal threshold, and altered sensitivity of CO2 chemoreceptors.

Obstructive sleep apnoea-hypopnoea syndrome

Obstructive sleep apnoea-hypopnoea syndrome (OSAHS) is a common disorder characterised by repetitive episodes of the complete or partial collapse of the pharyngeal airway during sleep. This results in cessation (apnoea) or reduction (hypopnoea) of airflow, leading to oxygen desaturation and sleep fragmentation. An individual's disposition to develop OSAHS depends on the collapsibility of a segment of the upper airway. The degree of collapsibility can be quantified by the balance between occluding or extraluminal pressures of the surrounding tissues. Patients can experience snoring, unrefreshing sleep, witnessed apnoeas, waking with a choking sensation and excessive daytime sleepiness. OSAHS has a broad range of consequences, including cardiovascular, metabolic, and neurocognitive sequelae. Treatment options include lifestyle measures, in particular weight loss, and strategies to maintain upper airway patency overnight, including continuous positive airway pressure, mandibular advancement devices and positional modifiers.

Characteristics and Mechanism of Upper Airway Collapse Revealed by Dynamic MRI During Natural Sleep in Patients with Severe Obstructive Sleep Apnea

Purpose

Upper airway collapse during sleep in patients with obstructive sleep apnea (OSA) is a complex and dynamic phenomenon. By observing and analyzing the dynamic changes in the upper airway and its surrounding tissues during airway obstruction, we aim to reveal dynamic characteristics in different obstruction patterns, and the relationship between anatomical features during normal breathing and dynamic characteristics of airway obstruction.

Patients and Methods

Dynamic MRI was performed in 23 male patients (age range 26-63) with severe OSA diagnosed by overnight polysomnography, and obstruction events were identified from their images. Dynamic changes in parameters of the upper airway and surrounding tissues were measured to assess the key characteristics in different obstruction patterns.

Results

We categorized airway obstruction into four types based on the obstruction location and motion characteristics of tissues during collapse, and detailed the alterations in the airway and surrounding tissues under each obstruction pattern. In all 112 obstruction events extracted from the dynamic images of 23 patients, type A (retropalatal obstruction caused by the soft palate separated from the tongue), BI, BII (both retropalatal obstructions caused by the soft palate attached to the tongue, and C (retropalatal and retroglossal obstruction caused by the soft palate and the tongue), accounted for 28.6%, 44.6%, 12.5%, and 14.3% respectively. In severe OSA patients with tongue and palatal obstruction related to type B or C, the more posterior hyoid position, shorter distance between tongue and uvula, and wider retropalatal space, the larger the tongue displacement and deformation during collapse, and the greater the reduction in airway space.

Conclusion

There are multiple airway obstruction patterns, each with its own anatomical characteristics and behaviors during collapse. Hyoid position, tongue and uvula distance, and retropalatal space play an important role in airway collapse and should be paid more attention in the treatment of OSA.

The Application of Ultrasound to Quantify Hyoid Motion During Drug-Induced Sleep Endoscopy

INTRODUCTION

The significance of hyoid dynamics in OSA pathophysiology remains unclear. Drug-induced sleep endoscopy (DISE) is often used for evaluating patients intolerant to positive airway pressure (PAP) therapy. We performed DISE with concurrent hyoid-focused ultrasonography to quantify hyoid dynamics during obstructive and non-obstructive breathing.

METHODS

A cross-sectional analysis from a prospective cohort of patients undergoing DISE with PAP titration (DISE-PAP) and hyoid-focused ultrasound was conducted. Hyoid ultrasound was performed during obstructive breathing, and non-obstructive breathing after PAP administration. Motion was quantified by generating displacement curves based on echo-tracking hyoid movement. The image analysis protocol for quantifying hyoid displacement was performed independently by two researchers, and reliability of measures was assessed. Univariate and multivariate regressions were performed for various clinical data and hyoid displacement during obstructive breathing.

RESULTS

Twenty patients met inclusion criteria. On average, the cohort was male (75%), elderly (65.9 ± 10 years), overweight (29.3 ± 3.99 kg/m2 ), and with moderate-to-severe OSA (29.3 ± 12.5 events/h). Mean hyoid displacement during obstructive breathing was 5.81 mm (±3.48). In all patients, hyoid displacement decreased after PAP administration (-3.94 mm [95% CI: -5.10, -2.78]; p < 0.0001). Inter-rater reliability for measures of hyoid displacement was excellent. After multivariate regression, hyoid displacement at baseline was associated with higher AHI (β [95% CI] = 0.18 [0.03, 0.33], p = 0.020).

CONCLUSION

During DISE, hyoid displacement is greater during obstructive breathing with significant variability amongst patients. Further, these ultrasonographic measurements had excellent intra- and inter-rater reliability. Additional, larger studies are needed to understand contributors to hyoid mobility.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:3221-3227, 2023.

Uvulopalatopharyngoplasty with and without modified thyrohyoid suspension for obstructive sleep apnea treatment: a randomized clinical trial

PURPOSE

This study aims to compare the efficacy of Uvulopalatopharyngoplasty + Tongue Base Radiofrequency (TB-RF) and Uvulopalatopharyngoplasty + modified thyrohyoid suspension techniques + TB-RF which aimed to suspend base of tongue muscles anteriorly toward thyroid cartilage.

METHODS

This randomized controlled trial study was conducted on 48 cases of confirmed OSA between Jan, 2019 and Aug, 2022. We divided patients into two groups. One group underwent Uvulopalatopharyngoplasty + modified thyrohyoid suspension + TB-RF technique, and another one underwent Uvulopalatopharyngoplasty + TB-RF. Then, Apnea-Hypopnea Index (AHI), mean and lowest O2 saturation, Drug-Induced Sleep Endoscopy (DISE), Epworth Sleepiness Scale (ESS), Digit Symbol Substitution Test (DSST), Stanford Subjective Snoring Scale (SSSS), and T90 indexes were evaluated before and after each surgery.

RESULTS

The mean ± SD age was 39.4 ± 11.17 years. Of the 48 patients, 79.1% (n = 33) were male and 20.9% (n = 15) were female. AHI and SSSS in the Uvulopalatopharyngoplasty + modified thyrohyoid suspension group were significantly better than Uvulopalatopharyngoplasty group (P-value; 0.010). Though, there was no significant difference in terms of mean saturation, lowest desaturation, ESS, DSST, and T90 scores. The success rate in the Uvulopalatopharyngoplasty + modified thyrohyoid suspension and Uvulopalatopharyngoplasty groups, according to the Sher criteria: a minimum of 50% reduction with a final AHI less than 20, were 75% (18/24) and 41.7% (10/24), respectively. It was significantly higher in the Uvulopalatopharyngoplasty + modified thyrohyoid suspension group (P-value: 0.021).

CONCLUSION

The addition of modified thyrohyoid suspension technique to Uvulopalatopharyngoplasty have better surgical outcomes and more success rate than Uvulopalatopharyngoplasty in OSA patients.

TRIAL REGISTRATION

IRCT: IRCT20190602043791N2. https://en.irct.ir/trial/53365 .

Transverse Maxillary Deficiency Predicts Increased Upper Airway Collapsibility during Drug-Induced Sleep Endoscopy

OBJECTIVE

To examine the relationship between craniofacial skeletal anatomy and objective measures of pharyngeal collapse obtained during drug-induced sleep endoscopy. We hypothesized that transverse maxillary deficiency and an increased pharyngeal length will be associated with higher levels of pharyngeal collapsibility.

STUDY DESIGN

Cross-sectional analysis in a prospective cohort.

SETTING

University Hospital.

METHODS

A cross-sectional analysis was conducted in a cohort of consecutive patients from the positive airway pressure (PAP) alternatives clinic who underwent computed tomography (CT) analysis and drug-induced sleep endoscopy for characterization of upper airway collapsibility. PAP titration was used to determine pharyngeal critical pressure (PCRIT ) and pharyngeal opening pressure (PhOP). CT metrics included: Transverse maxillary dimensions (interpremolar and intermolar distances) and pharyngeal length (posterior nasal spine to hyoid distance).

RESULTS

The cohort (n = 103) of severe obstructive sleep apnea (Apnea and Hipopnea Index 32.1 ± 21.3 events/h) was predominantly male (71.8%), Caucasian (81.6%), middle-aged (54.4 ± 14.3 years), and obese (body mass index [BMI] = 30.0 ± 4.9 kg/m2 ). Reduced transverse maxillary dimensions were associated with higher PCRIT (intermolar distance: β [95% confidence interval, CI] = -.25 [-0.14, -0.36] cmH2 O/mm; p = .03) and PhOP (Interpremolar distance: β = -.25 [-0.14, -0.36] cmH2 O/mm; p = .02). Longer pharyngeal length was also associated with higher PCRIT (β = .11 [0.08, 0.14] cmH2 O/mm, p = .04) and PhOP (β [95% CI] = .06 [0.03, 0.09] cmH2 O/mm, p = .04). These associations persisted after adjustments for sex, age, height, and BMI.

CONCLUSION

Our results further the concept that skeletal restriction in the transverse dimension and hyoid descent are associated with elevations in pharyngeal collapsibility during sleep, suggesting a role of transverse deficiency in the pathogenesis of airway obstruction.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Pharmacotherapy for obstructive sleep apnea: targeting specific pathophysiological traits

INTRODUCTION

The pathophysiology of obstructive sleep apnea (OSA) is multi-factorial and complex. Varying OSA's pathophysiological traits have been identified, including pharyngeal collapsibility, upper airway muscle reactivity, arousal threshold, and regulation of the ventilatory drive. Being CPAP of difficult tolerance and other interventions reserved to specific subpopulations new pharmacological treatments for OSA might be resolutive.

AREAS COVERED

Several existing and newly developed pharmacological drugs can impact one or more endotypes and could therefore be proposed as treatment options for sleep disordered breathing. With this review we will explore different pathophysiological traits as new targets for OSA therapy. This review will summarize the most promising pharmacological treatment for OSA accordingly with their mechanisms of action on upper airway collapsibility, muscle responsiveness, arousal threshold, and loop gain.

EXPERT OPINION

Only understanding the pathophysiological traits causing OSA in each patient and placing the disease in the framework of patient comorbidities, we will be able to evolve interventions toward OSA. The development of new drug's combinations will permit different approaches and different choices beside conventional treatments. In the next future, we hope that sleep specialists will select the treatment for a specific patient on the base of its pathophysiology, defining a precision medicine for OSA.

General Anesthetic Care of Obese Patients Undergoing Surgery: A Review of Current Anesthetic Considerations and Recent Advances

Obesity has long been linked to adverse health effects over time. As the prevalence of obesity continues to rise, it is important to anticipate and minimize the complications that obesity brings in the anesthesia setting during surgery. Anesthetic departments must recognize the innumerable risks when managing patients with obesity undergoing surgery, including anatomical and physiological changes as well as comorbidities such as diabetes, cardiovascular diseases, and malignancies. Therefore, the purpose of this review is to analyze the current literature and evaluate the current and recent advances in anesthetic care of obese patients undergoing surgery, to better understand the specific challenges this patient population faces. A greater understanding of the differences between anesthetic care for obese patients can help to improve patient care and the specificity of treatment. The examination of the literature will focus on differing patient outcomes and safety precautions in obese patients as compared to the general population. Specifically highlighting the differences in pre-operative, intra-operative, and post-operative care, with the aim to identify issues and present possible solutions.

Real-world data evaluation of PAP responsiveness in pediatric obstructive sleep apnea

STUDY OBJECTIVES

The use of positive airway pressure (PAP) in children is a complex process determined by multiple factors. There are limited data on the response of the pediatric population to PAP therapy at home. The goal of the study was to examine real-world responses using PAP home monitoring in children with obstructive sleep apnea.

METHODS

The study included PAP therapy data for 195 children aged between 1 month and 18 years with obstructive sleep apnea and polysomnogram baseline study. We collected demographics, clinical variables, and polysomnogram parameters in all study participants. The individual response to PAP therapy was calculated comparing the apnea-hypopnea index (AHI) in the initial polysomnogram with the mean AHI provided by the download of PAP devices. Multivariate models (logistic regression) were used to examine the predictors of positive PAP response defined as a reduction in AHI ≥ 75%.

RESULTS

We found excellent responses to PAP therapy in children (median 85% AHI reduction). However, there was substantial heterogeneity in AHI reductions while on PAP therapy. The best PAP responses were linked to more severe obstructive sleep apnea and higher PAP levels. We also identified that the response to PAP was higher in obese children and lower in males. The best predictive model for individual PAP response was biological sex, obesity, and obstructive AHI ≥ 20 events/h (area under the receiver operating characteristic curve of 0.791).

CONCLUSIONS

Real-world data show that PAP is overall an effective therapy in children but the response is heterogeneous. Obstructive sleep apnea parameters and individual factors can be used to predict individual AHI reductions while on PAP and optimize PAP responses at home.

CITATION

Aguilar H, Kahanowitch R, Weiss M, et al. Real-world data evaluation of PAP responsiveness in pediatric obstructive sleep apnea. J Clin Sleep Med. 2023;19(7):1313-1319.

Relationship of Upper Airway Collapse with Severity of Sleep Apnoea and Sleepiness

Introduction: Obstructive sleep apnoea (OSA) is characterized by repeated episodes of upper airway collapse. A review of literature shows limited and conflicting data regarding impact of upper pharyngeal collapse on severity of OSA and degree of sleepiness. Objective: To evaluate the association of the number of levels and degree of upper airway collapse and severity of OSA. Methods: This is a retrospective study including all patients with OSA over a two-year period. Data regarding neck circumference (NC), body mass index (BMI), nasopharyngolaryngoscopy with Muller's manoeuvre, Epworth sleepiness scale (ESS) questionnaire and a full night polysomnography were collected. Correlation of the number of sites involved and degree of collapse at each site (velum, lateral pharyngeal wall- Level I, base of tongue - Level II and epiglottis - Level III) with BMI, NC, AHI and ESS were assessed. Results: Of the 144 patients, 98% had collapse at Level I. 80% of patients had multisegmental collapse with 30% having collapse at all three levels. The number of levels and the severity of collapse did not have a proportionate effect on the AHI and ESS and were not directly dependent on the BMI. However, changes in NC had a significant effect on the severity of collapse.Conclusion: Severity of OSA and degree of sleepiness were not directly dependent on the severity and the number of levels of collapse. Since majority of the patients had multi segmental collapse, the study highlights the importance of careful assessment of all levels to tailor management strategies for optimum patient management.

Pathophysiological mechanisms and therapeutic approaches in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common breathing disorder in sleep in which the airways narrow or collapse during sleep, causing obstructive sleep apnea. The prevalence of OSAS continues to rise worldwide, particularly in middle-aged and elderly individuals. The mechanism of upper airway collapse is incompletely understood but is associated with several factors, including obesity, craniofacial changes, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck. The main characteristics of OSAS are recurrent pauses in respiration, which lead to intermittent hypoxia (IH) and hypercapnia, accompanied by blood oxygen desaturation and arousal during sleep, which sharply increases the risk of several diseases. This paper first briefly describes the epidemiology, incidence, and pathophysiological mechanisms of OSAS. Next, the alterations in relevant signaling pathways induced by IH are systematically reviewed and discussed. For example, IH can induce gut microbiota (GM) dysbiosis, impair the intestinal barrier, and alter intestinal metabolites. These mechanisms ultimately lead to secondary oxidative stress, systemic inflammation, and sympathetic activation. We then summarize the effects of IH on disease pathogenesis, including cardiocerebrovascular disorders, neurological disorders, metabolic diseases, cancer, reproductive disorders, and COVID-19. Finally, different therapeutic strategies for OSAS caused by different causes are proposed. Multidisciplinary approaches and shared decision-making are necessary for the successful treatment of OSAS in the future, but more randomized controlled trials are needed for further evaluation to define what treatments are best for specific OSAS patients.

Physical therapy for sleep apnea: a smartphone application for home-based physical therapy for patients with obstructive sleep apnea

Purpose

In this study, we described "PT for Sleep Apnea", a smartphone application for home-based physical therapy of patients with Obstructive Sleep Apnea (OSA).

Methods

The application was created in a joint program between the University of Medicine and Pharmacy at Ho Chi Minh City (UMP), Vietnam, and National Cheng Kung University (NCKU), Taiwan. Exercises maneuvers were derived from the exercise program previously published by the partner group at National Cheng Kung University. They included exercises for upper airway and respiratory muscle training and general endurance training.

Results

The application provides video and in-text tutorials for users to follow at home and a schedule function to assist the user in organizing the training program, which may improve the efficacy of home-based physical therapy in patients with Obstructive Sleep Apnea.

Conclusion

In the future, our group plans to conduct a user study and randomized-controlled trials to investigate whether our application can benefit patients with OSA.

Anatomical determinants of upper airway collapsibility in obstructive sleep apnea: A systematic review and meta-analysis

Upper airway (UA) collapsibility is one of the key factors that determine the severity of obstructive sleep apnea (OSA). Interventions for OSA are aimed at reducing UA collapsibility, but selecting the optimal alternative intervention for patients who fail CPAP is challenging because currently no validated method predicts how anatomical changes affect UA collapsibility. The gold standard objective measure of UA collapsibility is the pharyngeal critical pressure (Pcrit). A systematic literature review and meta-analysis were performed to identify the anatomical factors with the strongest correlation with Pcrit. A search using the PRISMA methodology was performed on PubMed for English language scientific papers that correlated Pcrit to anatomic variables and OSA severity as measured by the apnea-hypopnea index (AHI). A total of 29 papers that matched eligibility criteria were included in the quantitative synthesis. The meta-analysis suggested that AHI has only a moderate correlation with Pcrit (estimated Pearson correlation coefficient r = 0.46). The meta-analysis identified four key anatomical variables associated with UA collapsibility, namely hyoid position (r = 0.53), tongue volume (r = 0.51), pharyngeal length (r = 0.50), and waist circumference (r = 0.49). In the future, biomechanical models that quantify the relative importance of these anatomical factors in determining UA collapsibility may help identify the optimal intervention for each patient. Many anatomical and structural factors such as airspace cross-sectional areas, epiglottic collapse, and palatal prolapse have inadequate data and require further research.

The changes in oral volume and hyoid bone position after maxillomandibular advancement and genioglossus advancement for patients with obstructive sleep apnea

INTRODUCTION

Maxillomandibular advancement (MMA) and genioglossus advancement (GA) are surgeries for patients with obstructive sleep apnea (OSA). Postoperative evaluation is primarily based on the apnea-hypopnea index (AHI) measured by polysomnography. The purpose of this study was to identify the timing of hyoid bone relocation after MMA and GA surgery and to investigate whether or not hyoid bone relocation can be an indicator of postoperative evaluation of OSA.

METHODS

Patients with OSA underwent MMA and GA surgery. Changes in hyoid bone position and tongue-to-oral volume ratio were analyzed on lateral radiographs before, immediately after, and 1 year after surgery. Then, a correlation was verified between these changes and postoperative AHI.

RESULTS

In 18 patients studied, the position of the hyoid bone did not show a constant tendency immediately after surgery. One year after surgery, the bone had moved anteriorly and toward the oral cavity in all patients compared to its preoperative position. And AHI correlated with the movement of the hyoid bone to the oral side.

DISCUSSION

One year after surgery, the tongue was adapted to the newly enlarged oral space, and as a result, the low position of the hyoid bone before the operation was improved. The findings suggest that the degree of lowering of the hyoid bone may be an indicator of the improvement of AHI.

Muscle and visceral fat infiltration: A potential mechanism to explain the worsening of obstructive sleep apnea with age

STUDY OBJECTIVES

Aging is a major risk factor for obstructive sleep apnoea (OSA) and is associated with increased upper airway collapsibility, but the mechanisms are largely unknown. We hypothesized that the increase in OSA severity and upper airway collapsibility with age are partially mediated by upper airway, visceral and muscle fat infiltration.

METHODS

Male subjects underwent full polysomnography, upper airway collapsibility determination (Pcrit) after sleep induction with midazolam, upper airway and abdominal computed tomography. Tongue and abdominal muscle fat infiltration were assessed by the determination of muscle attenuation with computed tomography.

RESULTS

Eighty-four males with a wide range of age (47 ± 13 years, range 22-69 years) and apnea-hypopnea index (AHI) (30 [14-60] events/h, range 1-90 events/h), were studied. Younger and older males were grouped according to the mean age. Despite similar body mass-index (BMI), older subjects had higher AHI, higher Pcrit, larger neck and waist circumference, higher visceral and upper airway fat volumes (P < 0.01) as compared to younger subjects. Age was associated with OSA severity, Pcrit, neck and waist circumference, upper airway fat volume and visceral fat (P < 0.05), but not with BMI. Older subjects had lower tongue and abdominal muscle attenuation as compared to younger subjects (P < 0.001). Age was inversely associated with tongue and abdominal muscle attenuation, indicating muscle fat infiltration.

CONCLUSIONS

The associations between age, upper airway fat volume, visceral and muscle fat infiltration may help to explain the worsening of OSA and increased upper airway collapsibility with aging.

Tongue size matters: revisiting the Mallampati classification system in patients with obstructive sleep apnea

Objective: The Mallampati classification system has been used to predict obstructive sleep apnea (OSA). Upper airway soft tissue structures are prone to fat deposition, and the tongue is the largest of these structures. Given that a higher Mallampati score is associated with a crowded oropharynx, we hypothesized that the Mallampati score is associated with tongue volume and an imbalance between tongue and mandible volumes. Methods: Adult males underwent clinical evaluation, polysomnography, and upper airway CT scans. Tongue and mandible volumes were calculated and compared by Mallampati class. Results: Eighty patients were included (mean age, 46.8 years). On average, the study participants were overweight (BMI, 29.3 ± 4.0 kg/m2) and had moderate OSA (an apnea-hypopnea index of 26.2 ± 26.7 events/h). Mallampati class IV patients were older than Mallampati class II patients (53 ± 9 years vs. 40 ± 12 years; p < 0.01), had a larger neck circumference (43 ± 3 cm vs. 40 ± 3 cm; p < 0.05), had more severe OSA (51 ± 27 events/h vs. 24 ± 23 events/h; p < 0.01), and had a larger tongue volume (152 ± 19 cm3 vs. 135 ± 18 cm3; p < 0.01). Mallampati class IV patients also had a larger tongue volume than did Mallampati class III patients (152 ± 19 cm3 vs. 135 ± 13 cm3; p < 0.05), as well as having a higher tongue to mandible volume ratio (2.5 ± 0.5 cm3 vs. 2.1 ± 0.4 cm3; p < 0.05). The Mallampati score was associated with the apnea-hypopnea index (r = 0.431, p < 0.001), BMI (r = 0.405, p < 0.001), neck and waist circumference (r = 0.393, p < 0.001), tongue volume (r = 0.283, p < 0.001), and tongue/mandible volume (r = 0.280, p = 0.012). Conclusions: The Mallampati score appears to be influenced by obesity, tongue enlargement, and upper airway crowding.

Ramped versus sniffing position in the videolaryngoscopy-guided tracheal intubation of morbidly obese patients: a prospective randomized study

BACKGROUND

Ramped positioning is recommended for intubating obese patients undergoing direct laryngoscopy. However, whether the use of the ramped position can provide any benefit in videolaryngoscopy-guided intubation remains unclear. This study assessed intubation time using videolaryngoscopy in morbidly obese patients in the ramped versus sniffing positions.

METHODS

This is a prospective randomized study in patients with morbid obesity (n = 82; body mass index [BMI] ≥ 35 kg/m2). Patients were randomly allocated to either the ramped or the standard sniffing position groups. During the induction of general anesthesia, difficulty in mask ventilation was assessed using the Warters scale. Tracheal intubation was performed using a C-MAC® D-Blade videolaryngoscope, and intubation difficulty was assessed using the intubation difficulty scale (IDS). The primary endpoint was the total intubation time calculated as the sum of the laryngoscopy and tube insertion times.

RESULTS

The percentage of difficult mask ventilation (Warters scale ≥ 4) was significantly lower in the ramped (n = 40) than in the sniffing group (n = 41) (2.5% vs. 34.1%, P < 0.001). The percentage of easy intubation (IDS = 0) was significantly higher in the ramped than in the sniffing group (70.0% vs. 7.3%, P < 0.001). The total intubation time was significantly shorter in the ramped than in the sniffing group (22.5 ± 6.2 vs. 40.9 ± 9.0, P < 0.001).

CONCLUSIONS

Compared with the sniffing position, the ramped position reduced intubation time in morbidly obese patients and effectively facilitated both mask ventilation and tracheal intubation using videolaryngoscopy.

Potential ultrasonic anatomical markers of obstructive sleep apnoea-hypopnoea syndrome

AIM

To investigate the potential value of ultrasonography in evaluating the pathophysiology of obstructive sleep apnoea-hypopnoea syndrome (OSAHS) by assessing the correlation of critical ultrasonic anatomical characteristics of the oropharynx with the severity of OSAHS.

MATERIALS AND METHODS

One hundred and seventy-one patients with suspected OSAHS underwent oropharyngeal sonographic examination and overnight polysomnography. Ultrasonic measurement was compared with the apnoea-hypopnoea index (AHI) and other parameters. An ordinal logistic regression model was used to identify potential ultrasonic anatomical markers for OSAHS.

RESULTS

The AHI was significantly correlated with lingual height (r=0.40, p<0.01), maximal width of the tongue (r=0.35, p<0.01), and distance from the symphysis of the mandible to the hyoid bone (M-HB) (r=0.24, p<0.01). A positive relationship between Friedman tongue position (FTP) grades and lingual height (r=0.24, p<0.01), between FTP grades and maximal width of the tongue (r=0.23, p<0.01), and between FTP grades and width of tongue base (TB; r=0.17, p<0.05) was found. Multivariate models adjusted for sex, age, and body mass index (BMI) revealed that lingual height (95% confidence interval [CI]: 1.04-1.24; p=0.004) is independently associated with a higher risk for the severity of OSAHS.

CONCLUSIONS

Ultrasonography may be a potential imaging method for providing additional useful information about the correlation between ultrasound findings and the severity of OSAHS. Lingual height could be considered an ultrasonic anatomical marker for determining the severity of OSAHS patients independent of age, sex, and BMI.

Palatal Coupling Maneuvers Do Not Predict Hypoglossal Nerve Stimulator Treatment Efficacy

OBJECTIVE(S)

Maneuvers during drug-induced sleep endoscopy (DISE), for patients with obstructive sleep apnea (OSA), have been used as predictors for success with oral appliances. Hypoglossal nerve stimulation (HGNS) promotes opening at the velum through palatoglossus coupling. In this study, we evaluate maneuvers during DISE as predictors for HGNS treatment efficacy.

METHODS

We evaluated patients undergoing HGNS between November, 2014 and February, 2021. We assessed maneuvers including jaw thrust and chin lift during preoperative DISE. The impact of tongue base and palatal opening during these maneuvers were rated from 1 to 4 (1: no improvement, 2: mild improvement, 3: moderate improvement, 4: significant improvement). Patients were grouped by a score of 1-2 (weak response) or 3-4 (strong response). Apnea hypopnea index (AHI) change was calculated from the difference between preoperative and postoperative sleep study.

RESULTS

One hundred and seventy one patients were included. With jaw thrust, there was no significant difference in AHI change between patients with weak or strong response at the palate (n = 68 vs. 94, 9.5 vs. 13.6, p = 0.21) or tongue base (n = 24 vs. 138, 16.6 vs. 11.3, p = 0.24). On chin lift, there was no significant difference at the palate (n = 82 vs. 18, 13.9 vs. 11.4, p = 0.63) or tongue base (n = 92 vs. 72, 10.8 vs. 14.6, p = 0.24). On multiple linear regression analysis, lower body mass index, higher preoperative AHI, and higher preoperative oxygen nadir were associated with a larger AHI change.

CONCLUSION

Palatal coupling maneuvers during DISE are not predictive of AHI change with HGNS. Findings using these maneuvers should not preclude HGNS candidacy.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:431-436, 2023.

From Beneath the Skin to the Airway Wall: Understanding the Pathological Role of Adipose Tissue in Comorbid Asthma-Obesity

This article provides a contemporary report on the role of adipose tissue in respiratory dysfunction. Adipose tissue is distributed throughout the body, accumulating beneath the skin (subcutaneous), around organs (visceral), and importantly in the context of respiratory disease, has recently been shown to accumulate within the airway wall: "airway-associated adipose tissue." Excessive adipose tissue deposition compromises respiratory function and increases the severity of diseases such as asthma. The mechanisms of respiratory impairment are inflammatory, structural, and mechanical in nature, vary depending on the anatomical site of deposition and adipose tissue subtype, and likely contribute to different phenotypes of comorbid asthma-obesity. An understanding of adipose tissue-driven pathophysiology provides an opportunity for diagnostic advancement and patient-specific treatment. As an exemplar, the potential impact of airway-associated adipose tissue is highlighted, and how this may change the management of a patient with asthma who is also obese. © 2023 American Physiological Society. Compr Physiol 13:4321-4353, 2023.

The influence of mouth opening on pharyngeal pressure loss and its underlying mechanism: A computational fluid dynamic analysis

Objective: During inspiration, mechanical energy generated from respiratory muscle produces a negative pressure gradient to fulfill enough pulmonary ventilation. The pressure loss, a surrogate for energy loss, is considered as the portion of negative pressure without converting into the kinetic energy of airflow. Mouth opening (MO) during sleep is a common symptom in patients with obstructive sleep apnoea-hypopnea syndrome (OSAHS). This study aimed to evaluate the effects of mouth opening on pharyngeal pressure loss using computational fluid dynamics (CFD) simulation. Methods: A total of four subjects who were morphologically distinct in the pharyngeal characteristics based on Friedman tongue position (FTP) grades were selected. Upper airway computed tomography (CT) scan was performed under two conditions: Mouth closing (MC) and mouth opening, in order to reconstruct the upper airway models. computational fluid dynamics was used to simulate the flow on the two different occasions: Mouth closing and mouth opening. Results: The pharyngeal jet was the typical aerodynamic feature and its formation and development were different from mouth closing to mouth opening in subjects with different Friedman tongue position grades. For FTP I with mouth closing, a pharyngeal jet gradually formed with proximity to the velopharyngeal minimum area plane (plane_Amin). Downstream the plane_Amin, the jet impingement on the pharyngeal wall resulted in the frictional loss associated with wall shear stress (WSS). A rapid luminal expansion led to flow separation and large recirculation region, corresponding to the interior flow loss. They all contributed to the pharyngeal total pressure loss. While for FTP I with mouth opening, the improved velopharyngeal constriction led to smoother flow and a lower total pressure loss. For FTP IV, the narrower the plane_Amin after mouth opening, the stronger the jet formation and its impingement on the pharyngeal wall, predicting a higher frictional loss resulted from higher WSS. Besides, a longer length of the mouth opening-associated constant constrictive segment was another important morphological factor promoting frictional loss. Conclusion: For certain OSAHS patients with higher Friedman tongue position grade, mouth opening-related stronger jet formation, more jet breakdown and stronger jet flow separation might contribute to the increased pharyngeal pressure loss. It might require compensation from more inspiratory negative static pressure that would potentially increase the severity of OSAHS.

Role of surgical hyoid bone repositioning in modifying upper airway collapsibility

Background: Surgical hyoid bone repositioning procedures are being performed to treat obstructive sleep apnea (OSA), though outcomes are highly variable. This is likely due to lack of knowledge regarding the precise influence of hyoid bone position on upper airway patency. The aim of this study is to determine the effect of surgical hyoid bone repositioning on upper airway collapsibility. Methods: Seven anaesthetized, male, New Zealand White rabbits were positioned supine with head/neck position controlled. The rabbit's upper airway was surgically isolated and hyoid bone exposed to allow manipulation of its position using a custom-made device. A sealed facemask was fitted over the rabbit's snout, and mask/upper airway pressures were monitored. Collapsibility was quantified using upper airway closing pressure (Pclose). The hyoid bone was repositioned within the mid-sagittal plane from 0 to 5 mm (1 mm increments) in anterior, cranial, caudal, anterior-cranial (45°) and anterior-caudal (45°) directions. Results: Anterior displacement of the hyoid bone resulted in the greatest decrease in Pclose amongst all directions (p = 0.002). Pclose decreased progressively with each increment of anterior hyoid bone displacement, and down by -4.0 ± 1.3 cmH₂O at 5 mm. Cranial and caudal hyoid bone displacement did not alter Pclose (p > 0.35). Anterior-cranial and anterior-caudal hyoid bone displacements decreased Pclose significantly (p < 0.004) and at similar magnitudes to the anterior direction (p > 0.68). Conclusion: Changes in upper airway collapsibility following hyoid bone repositioning are both direction and magnitude dependent. Anterior-based repositioning directions have the greatest impact on reducing upper airway collapsibility, with no effect on collapsibility by cranial and caudal directions. Findings may have implications for guiding and improving the outcomes of surgical hyoid interventions for the treatment of OSA.

Mafa-dependent GABAergic activity promotes mouse neonatal apneas

While apneas are associated with multiple pathological and fatal conditions, the underlying molecular mechanisms remain elusive. We report that a mutated form of the transcription factor Mafa (Mafa^4A) that prevents phosphorylation of the Mafa protein leads to an abnormally high incidence of breath holding apneas and death in newborn Mafa^4A/4A mutant mice. This apneic breathing is phenocopied by restricting the mutation to central GABAergic inhibitory neurons and by activation of inhibitory Mafa neurons while reversed by inhibiting GABAergic transmission centrally. We find that Mafa activates the Gad2 promoter in vitro and that this activation is enhanced by the mutation that likely results in increased inhibitory drives onto target neurons. We also find that Mafa inhibitory neurons are absent from respiratory, sensory (primary and secondary) and pontine structures but are present in the vicinity of the hypoglossal motor nucleus including premotor neurons that innervate the geniohyoid muscle, to control upper airway patency. Altogether, our data reveal a role for Mafa phosphorylation in regulation of GABAergic drives and suggest a mechanism whereby reduced premotor drives to upper airway muscles may cause apneic breathing at birth.

Apneas are associated with many pathological conditions. Here, the authors show in a mouse model that stabilization of the transcription factor Mafa in brainstem GABAergic neurons may contribute to apnea, by decreasing motor drive to muscles controlling the airways.