Obstructive Sleep Apnea Airway Research Articles

0732 Sonographic Phenotyping of the Upper Airway in OSA Using Backscattered Imaging Analyzed by Machine-Learning

Abstract Introduction Anatomic characterization of the upper airway remains important in directing and monitoring care of patients with obstructive sleep apnea (OSA). Nasopharyngoscopy is routine in clinical practice, but it is invasive, non-reproducible, and only allows subjective assessment. We used machine-learning enabled ultrasonography to correlate upper airway tissue characteristics with OSA severity. Methods Sixty-three subjects (14 female) with a mean age of 39.4±12.6 years, BMI of 26.4±4.6 kg/m2, and AHI of 19.0±16.1 were consented from Stanford Sleep Surgery (July 2020 to May 2021). Standardized ultrasound protocol was used to image the soft palate, oropharynx, and tongue-base. Via machine learning, an FDA-cleared backscattered ultrasound imaging (BUI) of the upper airway was performed. Combined with B-mode measurements of airway muscular cross-sections, a logistic regression model was built to correlate with OSA severity. Results BUI of subjects with mild OSA was different from moderate-severe (AHI≥15) OSA at the soft palate (p=0.0007). The axial-to-lateral ratio of upper airway length was reduced in the lower soft palate of the moderate-severe group (p =0.0207). The logistic regression model with BUI, axial-to-lateral ratio at the soft palate, and BMI showed an Area Under the Receiver Operating Characteristic (AUROC) curve of 0.84 (95% CI 0.726 to 0.920) in moderate-severe OSA. Conclusion A non-invasive yet replicable technique to visualize and phenotype the upper airway is critical in the management of patients with sleep-disordered breathing. Sonographic BUI combined with B-mode airway measurements analyzed by machine learning show promise in characterizing the upper airway in patients with moderate-severe OSA. Support (If Any)

Critical to Know Pcrit: A Review on Pharyngeal Critical Closing Pressure in Obstructive Sleep Apnea.

It is crucial to understand the underlying pathophysiology of obstructive sleep apnea (OSA). Upper airway collapsibility is an important pathophysiological factor that affects the upper airway in OSA. The aim of the current study was to review the existing body of knowledge on the pharyngeal collapsibility in OSA. After a thorough search through Medline, PubMed, Scopus, and Web of science, the relevant articles were found and used in this study. Critical closing pressure (Pcrit) is the gold standard measure for the degree of collapsibility of the pharyngeal airway. Various physiological factors and treatments affect upper airway collapsibility. Recently, it has been shown that the baseline value of Pcrit is helpful in the upfront selection of therapy options. The standard techniques to measure Pcrit are labor-intensive and time-consuming. Therefore, despite the importance of Pcrit, it is not routinely measured in clinical practice. New emerging surrogates, such as finite element (FE) modeling or the use of peak inspiratory flow measurements during a routine overnight polysomnography, may enable clinicians to have an estimate of the pharyngeal collapsibility. However, validation of these techniques is needed.

Unsupervised Approach for the Identification of the Predominant Site of Upper Airway Collapse in Obstructive Sleep Apnoea Patients Using Snore Signals.

Knowledge regarding the site-of-collapse in the upper airway in obstructive sleep apnoea (OSA) has implications for treatment options and their outcomes. However, current methods to identify the site-of-collapse are not suitable for clinical practice due to the invasive nature, the time/cost of the tests and the inconsistency of the obstruction site identified with natural and drug-induced sleep. In this study, we adopted an unsupervised algorithm to identify the predominant site-of-collapse of the upper airway during natural sleep using nocturnal audio recordings. Nocturnal audio was recorded together with full-night polysomnography using a ceiling microphone. Various acoustic features of the snore signal during hypopnoea events were extracted. We developed a feature selection algorithm combining silhouette analysis with the Laplacian score algorithm to select the high performing features. A k-means clustering model was developed to form clusters using the features extracted from snore data and analyse the correlation between the clusters generated and the predominant site-of-collapse. Cluster analysis showed that the data tends to fit well in two clusters with a mean silhouette coefficient of 0.79 and with an accuracy of 68% for classifying tongue/non-tongue collapse. The results indicate a correlation between snoring and the predominant site-of-collapse. Therefore, it could potentially be used as a practical, non-invasive, low-cost diagnosis tool for improving the selection of appropriate therapy for OSA patients without any additional burden to the patients undergoing a sleep test.

Physiological responses and perceived comfort to high-flow nasal cannula therapy in awake adults: effects of flow magnitude and temperature.

Clinical use of heated, high-flow nasal cannula (HFNC) for noninvasive respiratory support is increasing and may have a therapeutic role in stabilizing the upper airway in obstructive sleep apnea (OSA). However, physiological mechanisms by which HFNC therapy may improve upper airway function and effects of different temperature modes are unclear. Accordingly, this study aimed to determine effects of incremental flows and temperature modes (heated and nonheated) of HFNC on upper airway muscle activity (genioglossus), pharyngeal airway pressure, breathing parameters, and perceived comfort. Six participants (2 females, aged 35 ± 14 yr) were studied during wakefulness in the supine position and received HFNC at variable flows (0-60 L/min) during heated (37°C) and nonheated (21°C) modes. Breathing parameters via calibrated Respitrace inductance bands (chest and abdomen), upper airway pressures via airway transducers, and genioglossus muscle activity via intramuscular bipolar fine wire electrodes were measured. Comfort levels during HFNC were quantified using a visual analog scale. Increasing HFNC flows did not increase genioglossus muscle activation despite increased negative epiglottic pressure swings (P = 0.009). HFNC provided ∼7 cmH2O positive airway pressure at 60 L/min in nonheated and heated modes. In addition, increasing the magnitude of HFNC flow reduced breathing frequency (P = 0.045), increased expiratory time (P = 0.040), increased peak inspiratory flow (P = 0.002), and increased discomfort (P = 0.004). Greater discomfort occurred at higher flows in the nonheated versus the heated mode (P = 0.034). These findings provide novel insight into key physiological changes that occur with HFNC for respiratory support and indicate that the primary mechanism for improved upper airway stability is positive airway pressure, not increased pharyngeal muscle activity.NEW & NOTEWORTHY This study evaluated upper airway muscle function, breathing, and comfort across different HFNC flows and temperatures. There were no increases in genioglossus muscle activity at higher flows despite greater negative epiglottic pressure swings. Increasing negative pressure swings was associated with increasing discomfort in the nonheated mode. HFNC was associated with ∼7 cmH2O increase in positive airway pressure, which may be the primary mechanism for upper airway stability with HFNC rather than increases in pharyngeal muscle activity.

Myoelectric characteristics of tensor palatini and collapsibility of upper airway in OSA patients with different phenotypes under DISE.

This study aims to evaluate the combination of myoelectric characteristics of tensor palatini muscle (TP) and collapsibility of upper airway in obstructive sleep apnea (OSA) patients with different external phenotypes of collapse pattern at velum level under drug-induced sleep endoscopy (DISE). Case series with planned data collection. Operation room. 36 mainly collapse pattern at velum level OSA subjects underwent DISE with synchronous tensor palatini electromyograms (TP EMG), and polysomnography (ALICE 6). According to the phenotype of collapse pattern at velum level in DISE, the subjects were divided into group 1 (concentric collapse), group 2 (anteroposterior collapse), and group 3 (lateral collapse). Each group consisted of 13, 14, and 9 subjects, respectively, and was observed the electromyographic indexes at awake, sleep onset, during apnea and the third respiratory cycle after apnea. The active and passive upper airway critical closing pressure (Pcrit) of each group were measured at the same time, and the difference of neuromuscular response between different groups was evaluated. In tonic TPEMG, group 1 showed the highest value during awake and sleep onset, while group 2 was the highest during apnea and after apnea. In peak TPEMG, group 1 showed the highest value during awake. Group 2 showed the highest value during other states. In passive Pcrit and D value (difference between passive Pcrit and active Pcrit), group 2 was the highest, while group 1 was the highest in active Pcrit. Difference was statistically significant. Under different states of awake, sleep onset, apnea and after apnea, the response force of tensor palatini muscle of OSA subjects with different phenotypes under DISE was different. Group 1 showed the highest EMG values only when awake and sleep onset, and it was most prone to collapse. Group 2 had the highest anatomical load (passive Pcrit) and the highest neuromuscular compensatory effect (D value).

Numerical simulations and experimental measurements on flow features in a patient-specific upper airway model with obstructive sleep apnea

In this article, the turbulent flow features in a patient-specific upper airway model with obstructive sleep apnea before and after surgery are numerically and experimentally studied by applying the large eddy simulation and laser Doppler anemometry. Two three-dimensional anatomically accurate numerical models are reconstructed based on the CT-scan of one severe obstructive sleep apnea patient for both pre- and post-surgery. Two experimental models of the same upper airway are established by using the three-dimensional printing technique according to the numerical models. The first direct comparison of flow velocity profiles between measurement and simulation at different locations and cross-sections is conducted in two upper airway models. The simulated result indicates that the especially large axial velocity and negative pressure appear in the narrowest cross-section before surgery, but they either reduce or vanish after surgery. Both measurement and simulation can capture the “pharyngeal jet” flow and the reversed flow in two upper airway models, and the agreement between the measured and calculated velocity profiles at different locations and cross-sections is excellent, which gives us great confidence that the large eddy simulation can be a reliable method for predicting the flow features associated with obstructive sleep apnea airway. Although this work represents significant advance, there still exists some limitations, such as the discrepancies between measurement and simulation in the interface of main stream velocity and reverse velocity due to the flow complexity, in the reversed flow region owing to the uncertainty of laser Doppler anemometry measurement at low velocity range, and the incapability of capturing flow near the wall due to the intrinsic feature of laser Doppler anemometry measurement. Besides, it is very difficult to find the corresponding locations exactly between experimental and numerical models, which could also cause the deviation between experiment and simulation.

Characterisation of upper airway obstructions using wide-band snoring sounds

Background: Obstructive sleep apnea (OSA) is associated with partial (hypopnea) and full (apnea) upper airway obstructions. The standard method for identifying these obstructions and leading to OSA diagnosis is overnight polysomnography (PSG). One of the important outcomes of PSG is the apnea-hypopnea index (AHI), which represents the average number of obstructions per hour, computed over the total duration of sleep. AHI is a single number summary of the dynamics of the upper airway during sleep. PSG is complicated, requires more than 20 body-contact sensors and is not available for population screening. There is a need for simple and automated technologies that can characterise the upper airways in more detail. In this paper, we address this need by proposing a method to identify individual apnea and hypopnea events via the analysis of breathing and snoring sounds collected through a microphone, which requires no physical contact with a subject. We also explore snoring and breathing sounds over a wide frequency band, exceeding the capacity of human hearing. Hypothesis: Our primary hypothesis is that snoring sounds carry sufficient information to characterise partial and full collapses of the upper airway in OSA. We also hypothesise that snoring sounds have a frequency spectrum extending beyond the human hearing range, and the spectrum's high-frequency components can provide critical information on airway collapses. Method: We recorded streams of respiratory sounds using a bedside microphone (4 Hz–100 kHz) from patients undergoing PSG studies in a sleep laboratory. Audio streams were divided into non-overlapping segments of 5 s durations. Segments containing partial or full snores were manually extracted for further investigation. Altogether we extracted 19,715 such segments from 18 subjects. We then obtained the power spectrum of each of the segments and estimated spectral energies in 16 frequency bands covering the range: 4 Hz–35 kHz. Significantly, when the upper airway narrows during or in the vicinity of apnea/hypopnea events, spectral energy tends to shift to higher frequencies. In this research, we developed indices which capture these energy shifts and function as surrogate measures of airway patency. We then calibrated proposed sound based indices using PSG derived apnea and hypopnea events. Our indices allowed us to individually pick apnea and hypopnea events and estimate a sound based AHI which we named the frequency spectrum index. Results: Our results indicated that snoring sounds extend to frequencies beyond the upper limit of the nominal hearing range, i.e. 20 kHz (p < 0.0001). At the patient level, the frequency spectrum index shows a correlation of r = 0.80 with the PSG based hypopnea index, with the highest correlation in the frequency band of 5–15 kHz. Similarly, the frequency spectrum index showed a correlation of r = 0.82 with the PSG based obstructive apnea index, where, interestingly, the highest correlation occurs in the 25–30 kHz band, which is outside the human range of hearing band. Conclusion: The snoring sound based frequency spectrum index has the potential to characterise full and partial closures of the upper airway. Snoring sounds are spread over a wide spectrum and critical information on the full closure of the upper airway is predominantly carried in frequencies beyond human hearing capacity.

Obstructive sleep apnea as a risk factor associated with difficult airway management - A narrative review

Study objectiveThe association between obstructive sleep apnea (OSA) and difficult airway had been studied in various clinical trials but the relationship between the two conditions has not been clearly established. The objective of this narrative review is to determine if OSA is a risk factor associated with difficult airway. DesignThe OVID Medline in process, Medline (vis Pub Med), EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Web of Science and SCOPUS were searched up to April 2016 using specific keywords. Inclusion criteria were: [1] airway management in patients with a diagnosis of OSA, [2] comparison of airway management between OSA and non-OSA patients, [3] publications or abstracts in the English language. The incidence of difficult airway between OSA and non-OSA patients was compared using Chi-square analysis or Fisher's exact test. Main resultsTen studies were included in the final review. Overall, the incidence of difficult tracheal intubation was higher in OSA patients versus non-OSA patients [56/386 (14.5%) vs. 69/897 (7.7%); P=0.0002]. OSA patients also have a higher incidence of difficult mask ventilation [115/4626 (2.5%) vs. 471/64,684 (0.7%); P<0.0001]. Compared to non-OSA patients, OSA was not associated with difficulty in the use of a supraglottic airway (SGA) device [10/663 (1.5%) vs. 162/15,171 (1.1%); P=0.38]. No studies compared difficult surgical airway in OSA and non-OSA patients. ConclusionsOSA was found to be a risk factor associated with difficult tracheal intubation and difficult mask ventilation. There was no association between OSA and difficult SGA use.

Analyses of aerodynamic characteristics of the oropharynx applying CBCT: obstructive sleep apnea patients versus control subjects.

To determine the most relevant aerodynamic characteristic of the oropharynx related to the collapse of the upper airway in obstructive sleep apnea (OSA) patients; and to determine the correlation between the most relevant aerodynamic characteristic(s) of the oropharynx and anatomical characteristics of the oropharynx in OSA patients. 31 mild to moderate OSA patients (mean ± SD age = 43.5 ± 9.7 years) and 13 control subjects (mean ± SD age = 48.5 ± 16.2 years) were included in this prospective study. The diagnosis of OSA patients was based on an overnight polysomnographic recording. To exclude the presence of OSA in the control subjects, they were asked to fill out a validated questionnaire to determine the risk of OSA. NewTom5G cone beam CT (CBCT) scans were obtained from both OSA patients and control subjects. Computational models of the oropharynx were reconstructed based on CBCT images. The aerodynamic characteristics of the oropharynx were calculated based on these computational models. Pearson correlation analysis was used to analyse the correlation between the most relevant aerodynamic characteristic(s) and anatomical characteristics of the oropharynx in OSA patients. Compared with controls, the airway resistance during expiration (Rex) of the OSA patients was significantly higher (p = 0.04). There was a significant negative correlation between Rex and the minimum cross-sectional area (CSAmin) of the oropharynx (r = -0.41, p = 0.02), and between Rex and the volume of the oropharynx (r = -0.48, p = 0.01) in OSA patients. After excluding an outlier, there is only significant correlation between Rex and the CSAmin of the oropharynx (r = -0.45, p = 0.01). Within the limitations of this study, we concluded that the most relevant aerodynamic characteristic of the oropharynx in the collapse of the upper airway in OSA patients is Rex. Therefore, the repetitive collapse of the upper airway in OSA patients may be explained by a high Rex, which is related to the CSAmin of the oropharynx.

Multidisciplinary Alternatives to CPAP Program for CPAP-Intolerant Patients.

Continuous positive airway pressure (CPAP) intolerance remains a persistent problem for many obstructive sleep apnea patients. Clinicians and researchers continue to search for other effective treatment modalities given the well-documented sequelae associated with untreated obstructive sleep apnea. A multidisciplinary "Alternatives to CPAP program" (ALT) can facilitate systematic evaluation of non-CPAP therapies appropriate for an individual patient. We review successful strategies and barriers encountered during implementation of an ALT at our institution. Creation of similar programs in private practice and academic settings can help medical, dental, and surgical sleep medicine specialists coordinate evaluation and treatment of CPAP-intolerant patients.

Dynamic Volume Computed Tomography Imaging of the Upper Airway in Obstructive Sleep Apnea.

To describe a dynamic three-dimensional (3D) computed tomography (CT) technique for the upper airway and compare the required radiation dose to that used for common clinical studies of a similar anatomical area, such as for subjects undergoing routine clinical facial CT. Dynamic upper-airway CT was performed on eight subjects with persistent obstructive sleep apnea, four of whom were undergoing magnetic resonance imaging and an additional four subjects who had a contraindication to magnetic resonance imaging. This Health Insurance Portability and Accountability Act-compliant study was approved by our institutional review board, and informed consent was obtained. The control subjects (n = 41) for comparison of radiation dose were obtained from a retrospective review of the clinical picture-archiving computer system to identify 10 age-matched patients per age-based control group undergoing facial CT. Dynamic 3D CT can be performed with an effective radiation dose of less than 0.38 mSv, a dose that is less than or comparable to that used for clinical facial CT. The resulting data- set is a uniquely complete, dynamic 3D volume of the upper airway through a full respiratory cycle that can be processed for clinical and modeling analyses. A dynamic 3D CT technique of the upper airway is described that can be performed with a clinically reasonable radiation dose and sets a benchmark for future use.

Abstract: A Nationwide Comparison of Pharyngeal and Jaw Surgery for Sleep Apnea: Socioeconomic Differences and Complications

INTRODUCTION: A report by the American Academy of Sleep Medicine suggests that maxillomandibular jaw advancement surgery is the most effective surgical intervention beyond tracheotomy for patients with severe obstructive sleep apnea.1 Nonetheless, pharyngeal procedures are more commonly performed.2 The aims of this study were to 1) identify socioeconomic factors associated with this phenomenon, and 2) determine differences in complications between adult patients receiving pharyngeal and jaw procedures for sleep apnea. MATERIALS AND METHODS: All patients, age 14 or older, with a primary hospital diagnosis of sleep apnea were identified using the Nationwide Inpatient Sample (NIS) database obtained through the Healthcare Cost and Utilization Project (HCUP) from 2005–2012. The NIS is the largest available all-payer inpatient database in the United States, and approximates a 20% stratified sample of discharges from US community hospitals.3 ICD9 codes were used to determine if a pharyngeal or jaw procedure was performed. Patient demographics, comorbidities and complications were compared. Chi squared test and Student’s t-test were used for analysis. RESULTS: Among 6,316 sleep surgeries, 5,964 (94.4%) were pharyngeal and 352 (5.6%) were jaw procedures. Women were significantly more likely to receive jaw surgery than men (OR 1.68, p=0.0007). African Americans (OR 0.19, p<0.0001), Hispanics (OR 0.42, p=0.0009), Asians (OR 0.41, p=0.0009), and other non-Caucasians (OR 0.19, p=0.0008) had a significantly lower odds of receiving jaw surgery than Caucasians. Patients falling into annual income brackets less than $63,000 (<$39,000, OR 0.39, p=0.02; and $48,000–62,999, OR 0.57, p=0.04), and patients with Medicare compared to private or HMO insurance (OR 0.46, p=0.008) also had significantly decreased odds of undergoing jaw surgery. Comorbidities were similar between surgical groups, and there were no significant differences in bleeding, infection, or cardiopulmonary complications. CONCLUSION: Jaw surgery accounted for a minority of sleep procedures over the eight-year study period, even though there was no significant difference in complication rates compared to pharyngeal surgery and there are data to suggest greater treatment efficacy. African American, Hispanic, and Asian patients, in addition to lower income patients and patients with Medicare had a significantly lower odds of receiving jaw surgery. Awareness of these disparities may help guide future initiatives to improve patients’ surgical options for sleep apnea. DISCLOSURE/FINANCIAL SUPPORT:None REFERENCES: 1. Aurora RN, Casey KR, Kristo D, et al. Practice parameters for the surgical modifications of the upper airway for obstructive sleep apnea in adults. Sleep. 2010;33:1408–1413 2. Petersen EJ, Reiter ER. Hospital use in the treatment of sleep apnea. Laryngoscope. 2004;114:460–466 3. Healthcare Cost and Utilization Project. Introduction to the HCUP National Inpatient Sample (NIS), 2012. Available at: https://www.hcup-us.ahrq.gov/db/nation/nis/NIS_Introduction_2012.jsp. Accessed April 21, 2016

Localizing Effects of Leptin on Upper Airway and Respiratory Control during Sleep.

Obesity hypoventilation and obstructive sleep apnea are common complications of obesity linked to defects in respiratory pump and upper airway neural control. Leptin-deficient ob/ob mice have impaired ventilatory control and inspiratory flow limitation during sleep, which are both reversed with leptin. We aimed to localize central nervous system (CNS) site(s) of leptin action on respiratory and upper airway neuroventilatory control. We localized the effect of leptin to medulla versus hypothalamus by administering intracerbroventricular leptin (10 μg/2 μL) versus vehicle to the lateral (n = 14) versus fourth ventricle (n = 11) of ob/ob mice followed by polysomnographic recording. Analyses were stratified for effects on respiratory (nonflow-limited breaths) and upper airway (inspiratory flow limitation) functions. CNS loci were identified by (1) leptin-induced signal transducer and activator of transcription 3 (STAT3) phosphorylation and (2) projections of respiratory and upper airway motoneurons with a retrograde transsynaptic tracer (pseudorabies virus). Both routes of leptin administration increased minute ventilation during nonflow-limited breathing in sleep. Phrenic motoneurons were synaptically coupled to the nucleus of the solitary tract, which also showed STAT3 phosphorylation, but not to the hypothalamus. Inspiratory flow limitation and obstructive hypopneas were attenuated by leptin administration to the lateral but not to the fourth cerebral ventricle. Upper airway motoneurons were synaptically coupled with the dorsomedial hypothalamus, which exhibited STAT3 phosphorylation. Leptin relieves upper airway obstruction in sleep apnea by activating the forebrain, possibly in the dorsomedial hypothalamus. In contrast, leptin upregulates ventilatory control through hindbrain sites of action, possibly in the nucleus of the solitary tract.

Computational Modeling of Airway Obstruction in Sleep Apnea in Down Syndrome: A Feasibility Study.

Current treatment options are successful in 40% to 60% of children with persistent obstructive sleep apnea after adenotonsillectomy. Residual obstruction assessments are largely subjective and do not clearly define multilevel obstruction. We endeavor to use computational fluid dynamics to perform virtual surgery and assess airflow changes in patients with Down syndrome and persistent obstructive sleep apnea. Three-dimensional airway models were reconstructed from respiratory-gated computed tomography and magnetic resonance imaging. Virtual surgeries were performed on 10 patients, mirroring actual surgeries. They demonstrated how surgical changes affect airflow resistance. Airflow and upper airway resistance was calculated from computational fluid dynamics. Virtual and actual surgery outcomes were compared with obstructive apnea-hypopnea index values. Actual surgery successfully treated 6 of 10 patients (postoperative obstructive apnea-hypopnea index <5). In 8 of 10 subjects, both apnea-hypopnea index and the calculated upper airway resistance after virtual surgery decreased as compared with baseline values. This is a feasibility and proof-of-concept study. Further studies are needed before using these techniques in surgical planning.

Cone-beam CT analysis of patients with obstructive sleep apnea compared to normal controls.

PurposeTo evaluate the upper airway dimensions of obstructive sleep apnea (OSA) and control subjects using a cone-beam computed tomography (CBCT) unit commonly applied in clinical practice in order to assess airway dimensions in the same fashion as that routinely employed in a clinical setting.Materials and MethodsThis was a retrospective analysis utilizing existing CBCT scans to evaluate the dimensions of the upper airway in OSA and control subjects. The CBCT data of sixteen OSA and sixteen control subjects were compared. The average area, average volume, total volume, and total length of the upper airway were computed. Width and anterior-posterior (AP) measurements were obtained on the smallest axial slice.ResultsOSA subjects had a significantly smaller average airway area, average airway volume, total airway volume, and mean airway width. OSA subjects had a significantly larger airway length measurement. The mean A-P distance was not significantly different between groups.ConclusionOSA subjects have a smaller upper airway compared to controls with the exception of airway length. The lack of a significant difference in the mean A-P distance may indicate that patient position during imaging (upright vs. supine) can affect this measurement. Comparison of this study with a future prospective study design will allow for validation of these results.

Maxillofacial surgery in patients with obstructive sleep apnea and snoring

The present survey systematizes the modern foreign literature devoted to the recent advances in the surgical management of the patients with obstructive sleep apnea and snoring. The results from the application of a variety of contemporaty methods are briefly described. A special attention is paid to the maxillomandibular advancement that represents the most common maxillofacial surgical technique in this interdisciplinary field. The promising perspectives of multi-level surgery of the upper airway for obstructive sleep apnea are mentioned, too.

Effect of diuretics and sodium-restricted diet on sleep apnea severity: study protocol for a randomized controlled trial.

BackgroundObstructive sleep apnea occurs as a result of increased collapsibility of the upper airway. Overnight fluid displacement from the legs to the neck causes pharyngeal narrowing and increased apnea severity. Sodium intake is associated with apnea severity. We hypothesized that interventions that decrease bodily fluid content might reduce the severity of sleep apnea.Methods/designThis is a randomized clinical trial including men with an apnea-hypopnea index greater than 30 events/hour, previously diagnosed by full-night in-laboratory polysomnography. A total of 54 men will be included and randomly assigned to three groups: Diuretic (n = 18), sodium-restricted diet (n = 18), and control (n = 18). The intervention will last one week. Intention-to-treat and per-protocol analyses will be performed. The diuretic group will receive combined spironolactone 100 mg plus furosemide 20 mg daily, taken in the morning. The diet group will receive a regimen with a maximum intake of 3 g of sodium per day. The control group will receive a placebo pill and will maintain all eating habits while keeping a recall diary of their dietary behavior. The primary outcome measure will be change in apnea-hypopnea index. The secondary outcome measures will be variations of: anthropometric and bioelectrical impedance variables, office blood pressure, respiratory variables from in-home level III polysomnography, excessive daytime sleepiness, glycolipid profile, C-reactive protein, 24 h urinary variables, and adverse events.DiscussionDespite the high efficacy of continuous positive airway pressure to reverse upper airway obstruction in sleep apnea, partial adherence to this form of treatment reduces its efficiency. Thus, additional forms of treating apnea need to be investigated. If the results of this proof-of-concept trial show that decreases in bodily fluid content, either by diuretic or dietary intervention, reduces the severity of sleep apnea, further investigation will be necessary before these results can be translated and adopted as an adjunct apnea therapy.Trial registrationclinicaltrials.gov NCT01945801.

Anatomy and physiology of the upper airway in obstructive sleep apnea

Obstructive sleep apnea, a common disease, is associated with increased morbidity and mortality. Patients with obstructive sleep apnea suffer from excessive daytime sleepiness as well as an increased risk of cardiovascular disease. The cause is complex, involving many interacting factors that contribute to the pathogenesis of the disease. It is important to understand the anatomy and physiology of the upper airway, particularly what determines its stability and collapsibility.

Neurogenic changes in the upper airway of obstructive sleep apnoea.

Obstructive sleep apnoea (OSA) is linked to local neural injury that evokes airway muscle remodelling. The upper airway muscles of patients with OSA are exposed to intermittent hypoxia as well as vibration induced by snoring. A range of electrophysiological and other studies have established altered motor and sensory function of the airway in OSA. The extent to which these changes impair upper airway muscle function and their relationship to the progression of OSA remains undefined. This review will collate the evidence for upper airway remodelling in OSA, particularly the electromyographic changes in upper airway muscles of patients with OSA.

Volumetric Evaluation of Upper Airway in Obstructive Sleep Apnea

Introduction: Obstructive sleep apnea (OSA) occurs by recurrent collapse of the upper airway during sleep, resulting in total (apnea) or partial (hypopnea) reduction or airflow and has intimate relation with changes in the upper airway (UA). Cone Beam CT allows the analysis of the UA and its volume by three-dimensional reconstruction.