Computed Tomography Imaging of Patients With Obstructive Sleep Apnea

ECG based apnea detection by multirate processing hybrid of wavelet-empirical decomposition Hjorth features extraction and neural networks

Sleep Apnea (SA) can cause health complications including heart stroke and neurological disorders. The Polysomnography (PSG) test can detect the severity of sleep disturbance. However, it is expensive and requires a dedicated sleep laboratory and expertise to examine the patients. Therefore, it is not available to a large population in developing countries. This leads to the development of cost-effective and automated patient examination methods for the detection of sleep apnea. This study suggests an approach of using the ECG signals to categorize sleep apnea. In this work, we have devised an original technique of feature space designing by intelligently hybridizing the multirate processing, a mix of wavelet-empirical mode decomposition (W-EMD), modes-based Hjorth features extraction, and Adam-based optimized Multilayer perceptron neural network (MLPNN) for automated categorization of apnea. A publicly available ECG dataset is used for evaluating the performance of the suggested approach. Experiments are performed for four different sub-bands of the considered ECG signals. For each selected sub-band, five "Intrinsic Mode Functions" (IMFs) are extracted. Onward, three Hjorth features: complexity, activity, and mobility are mined from each IMF. In this way, four feature sets are formed based on wavelet-driven selected sub-bands. The performance of optimized MLPNN, for the apnea categorization, is compared for each feature set. Five different evaluation parameters are used to assess the performance. For the same dataset, a systematic comparison with current state-of-the-artwork has been done. Results have shown a classification accuracy of 98.12%.

Airway Resistance and Respiratory Distress in Laryngeal Cancer: A Computational Fluid Dynamics Study

BACKGROUND

Obstructive upper airway pathologies are a great clinical challenge for the airway surgeon. Protection against acute obstruction is critical, but avoidance of unnecessary tracheostomy must also be considered. Decision-making regarding airway, although supported by some objective findings, is largely guided by subjective experience and training. This investigation aims to study the relationship between clinical respiratory distress and objective measures of airway resistance in laryngeal cancer as determined by computational fluid dynamic (CFD) and morphometric analysis.

METHODS

Retrospective CT and clinical data were obtained for series of 20 cases, defined as newly diagnosed laryngeal cancer patients who required admission or urgent airway surgery, and 20 controls. Cases and controls were matched based on T-staging. Image segmentation and morphometric analysis were first performed. Computational models based on the lattice Boltzmann method were then created and used to quantify the continuous mass flow, rigid wall, and constant static pressure inlet boundary conditions.

RESULTS

The analysis demonstrated a significant relationship between airway resistance and acute obstruction (OR 1.018, 95% CI 1.001-1.045). Morphometric analysis similarly demonstrated a significant relationship when relating measurements based on the minimum cross-section, but not on length of stenosis. Morphometric measurements also showed significance in predicting CFD results, and their relationship demonstrated that airway pressures increase exponentially below 2.5 mm. Tumor subsite did not show a significant difference, although the glottic subgroup tended to have higher resistances.

CONCLUSION

Airway resistance analysis from CFD computation correlated with presence of acute distress requiring emergent management. Morphometric analysis showed a similar correlation, demonstrating a radiologic airway assessment technique on which future risk estimation could be performed.

LEVEL OF EVIDENCE

4 (case-control study) Laryngoscope, 133:2734-2741, 2023.

Does Head and Neck Posture Affect Cone-Beam Computed Tomography Assessment of the Upper Airway?

PURPOSE

Radiographic analysis is often used as a screening tool to assess for risk of sleep-related breathing disorders. This study aimed to address 2 questions: (1) Does head posture significantly affect the minimum cross-sectional area (MCA)? and (2) Is the NBC3 (nasion-basion-C3) angle a reliable measurement to control for alteration of head position in cone-beam computed tomography (CBCT) scans?

METHODS

Study design: prospective cohort study.

SETTING

Private practices affiliated with a research institution.

PARTICIPANTS

convenience sample of adult volunteers.

VARIABLES

CBCT scans were taken in 2 conditions: baseline (natural head position, NHP) and 1 of 5 experimental conditions (head tilted up, head tilted down, sitting vs standing, use of chin-rest, and swallow variation). For the primary aim of our study, the primary predictor variable was head posture and the main outcome variable was percentage change in MCA. For the secondary aim, the primary predictor variable was head posture and the main outcome variable was degree change in NBC3 angle.

RESULTS

Ninety subjects were included (age 40.7 ± 13.7 years, 70% female). Mean NBC3 at baseline was 112.4 ± 8.3°. Head tilted down significantly decreased (-41.4 ± 18.5 mm², P = .03∗) and head tilted up significantly increased MCA (+147.4 ± 43.3 mm², P = .0018∗). Head tilted down significantly reduced the NBC3 angle measurement (-10.5 ± 6.8°, P = .006) and head tilted up significantly increased the NBC3 angle measurement (+14.4 ± 5.8°, P = .0004). A quadratic regression model was fitted with moderately strong correlation (R² = 0.54) showing an exponential effect of small changes in the NBC3 angle on MCA, P < .0001. The model predicts that increasing NBC3 by +5 and + 10° resulted in MCA changes of +25% and +88%, whereas a decrease in NBC3 by -5 and -10° results in MCA changes of -21% and -23%, respectively.

CONCLUSION

Alterations in head posture significantly affect the MCA of the upper airway on CBCT. The NBC3 angle can be used to reliably assess changes in cranio-cervical extension and validate comparisons of MCA between CBCT scans for the same patient. A standardized protocol for CBCT acquisition is proposed.

Predictors for short-term and long-term automatic PAP compliance

STUDY OBJECTIVES

Positive airway pressure (PAP) is considered a standard treatment for obstructive sleep apnea (OSA), but there are compliance issues. As compliance to PAP tends to decrease with time, it is necessary to consider reasons affecting compliance at each period. Therefore, this study aimed to define factors affecting short-term and long-term compliance to PAP therapy.

METHODS

One hundred eighty-seven patients with OSA who started PAP treatment between July 2018 to March 2020 were included. Acceptance and compliance rates were monitored. Demographics, polysomnography (PSG) profiles, cephalometric data, and physical examination results were analyzed to identify factors predictive of PAP compliance at short-term (3 months) and long-term (12 months) periods.

RESULTS

The acceptance rate of PAP was 92.5%. Compliance at 3 months and 12 months was 79.1% and 51.3%, respectively. Higher apnea-hypopnea index (odds ratio [OR] 1.018, P = .049) and older age (OR 1.032, P = .039) were predictive factors of good automatic PAP (APAP) compliance at 3 months. However, long-term compliance was affected by the percentage of duration with O2 desaturation of < 90% (CT90; OR 1.032, P = .011) and baseline self-reported symptom scores such as nasal obstruction (OR 0.819, P = .038) and awakening (OR 0.796, P = .045).

CONCLUSIONS

In PAP use, indicators of OSA severity such as apnea-hypopnea index affect short-term compliance. On the other hand, the mandibular plane to hyoid distance and self-reported symptoms such as nasal obstruction and awakening can affect long-term compliance.

CITATION

Park SI, Kim BK, Lee KE, Hong SD, Jung YG, Kim HY. Predictors for short-term and long-term automatic PAP compliance. J Clin Sleep Med. 2023;19(1):17-26.

Volume of parapharyngeal fat pad in obstructive sleep apnea syndrome: prognostic role for multilevel sleep surgery

STUDY OBJECTIVES

To evaluate the prognostic role of volume of parapharyngeal fat pad (VPPFP) after multilevel sleep surgery in patients with obstructive sleep apnea syndrome.

METHODS

This retrospective cohort study was conducted in 50 patients with moderate to severe obstructive sleep apnea syndrome who underwent polysomnography (preoperative and postoperative 6 months) and preoperative facial computed tomography with multilevel sleep surgery between May 2010 and February 2019. All patients had failed or refused positive airway pressure treatment.

RESULTS

Of the 50 patients with moderate to severe obstructive sleep apnea syndrome who underwent multilevel sleep surgery, 46 were male (92.0%) with mean ± standard deviation age of 41.2 ± 12.5 years. On the preoperative polysomnography, mean ± standard deviation of apnea-hypopnea index and CT90 (cumulative percentage of time spent at oxygen saturation less than 90%) were 43.4 ± 19.3 events/h and 5.6 ± 9.6%, respectively. The average VPPFP measured by facial computed tomography scan was 4.9 ± 1.9 cm3. Multiple linear regression analysis showed that VPPFP was significantly correlated (R2 = 0.38) with age (β = 0.05; 95% confidence interval [CI], 0.01-0.09) and body mass index (β = 0.31; 95% CI, 0.16-0.45). Surgical success rate was 38%, and VPPFP higher than 5.1 cm3 was significantly associated with surgical failure after covariate adjustment (P = .01; odds ratio = 0.09; 95% CI, 0.02-0.48). Postoperative apnea-hypopnea index was positively correlated (R2 = 0.40) with CT90 (β = 1.33; 95% CI, 0.74-1.92) and VPPFP (β = 3.52; 95% CI, 0.30-6.74).

CONCLUSIONS

VPPFP correlated with age and body mass index, and high VPPFP and CT90 were associated with high postoperative apnea-hypopnea index. VPPFP larger than 5.1 cm3 was a possible risk factor for surgical failure, which may inform a decision on multilevel sleep surgery as salvage therapy for positive airway pressure treatment.

CITATION

Kim BK, Park SI, Hong SD, Jung YG, Kim HY. Volume of parapharyngeal fat pad in obstructive sleep apnea syndrome: prognostic role for multilevel sleep surgery. J Clin Sleep Med. 2022;18(12):2819-2828.

Prediction of Moderate to Severe Obstructive Sleep Apnea Using Neck Computed Tomography With Computational Fluid Dynamics Study

BACKGROUND

Moderate to severe obstructive sleep apnea (OSA) is associated with cardiovascular disease. Polysomnography is time intensive and difficult to access for diagnosis of OSA. Neck computed tomography (CT) provides upper airway delineation but not diagnostic criteria for moderate to severe OSA. We explored neck CT with computational fluid dynamics (CFD) study for airway pressure and airflow velocity to predict moderate to severe OSA.

METHODS

Enrolled from February 1, 2020, to June 30, 2021, patients with OSA with overnight oxygen desaturation (sPO2 <90%) received awake neck CT with a CFD study of their airway pressure and airflow velocity. CTL12 and CTL34 were defined as airflow velocity <3 and ≥3 m/s, respectively, and airway pressure <10 and ≥10 pa, respectively, in the narrowest upper airway.

RESULTS

Sixty-two patients (42 male and 20 female; mean age: 50.4 ± 14.6 years) were included; 12 and 50 patients had mild OSA and moderate to severe OSA, respectively. The minimum sPO2 in the supine position was 80.7 ± 9.1%. The total time of sPO2 <90% at overnight oximetry was 29.3 ± 51.1 min. Most (85.5%) neck CT examinations with CFD study presented CTL34. Patients with CTL34 had a lower minimum sPO2 in the supine position (78.4 vs. 88.1%, P = 0.004) and longer duration of sPO2 <90% at overnight oximetry (33.9 vs. 1.9 min, P = 0.001) than those with CTL12. The values of the area under the receiver operating characteristic curves of airway pressure and of airflow velocity at the narrowest upper airway were 0.788 and 0.733, respectively.

CONCLUSION

Neck CT with CFD study of airway pressure and airflow velocity may provide a quick prediction of moderate to severe OSA.

Association of Snoring Characteristics with Predominant Site of Collapse of Upper Airway in Obstructive Sleep Apnoea Patients

STUDY OBJECTIVES

Acoustic analysis of isolated events and snoring by previous researchers suggests a correlation between individual acoustic features and individual site of collapse events. In this study, we hypothesised that multi-parameter evaluation of snore sounds during natural sleep would provide a robust prediction of the predominant site of airway collapse.

METHODS

The audio signals of 58 OSA patients were recorded simultaneously with full night polysomnography. The site of collapse was determined by manual analysis of the shape of the airflow signal during hypopnoea events and corresponding audio signal segments containing snore were manually extracted and processed. Machine learning algorithms were developed to automatically annotate the site of collapse of each hypopnoea event into three classes (lateral wall, palate and tongue-base). The predominant site of collapse for a sleep period was determined from the individual hypopnoea annotations and compared to the manually determined annotations. This was a retrospective study that used cross-validation to estimate performance.

RESULTS

Cluster analysis showed that the data fits well in two clusters with a mean silhouette coefficient of 0.79 and an accuracy of 68% for classifying tongue/non-tongue collapse. A classification model using linear discriminants achieved an overall accuracy of 81% for discriminating tongue/non-tongue predominant site of collapse and accuracy of 64% for all site of collapse classes.

CONCLUSIONS

Our results reveal that the snore signal during hypopnoea can provide information regarding the predominant site of collapse in the upper airway. Therefore, the audio signal recorded during sleep could potentially be used as a new tool in identifying the predominant site of collapse and consequently improving the treatment selection and outcome.

Age- and Sex-Related Measurements of Total Craniofacial Soft Tissue Thickness and Fat in a Central Chinese Population

ABSTRACT

In this study, data related to the total soft tissue thickness and fat layer thickness of 41 anatomical landmarks were extracted from the craniofacial computerized tomography data of 280 Chinese individuals (160 males and 120 females). The measurements were assessed according to the following factors: a. sex, b. age, and c. sex × age. Descriptive statistics and a differential analysis were carried out in each group to analyze both the total soft tissue thickness and fat layer thickness. The results showed the following. 1. The results showed that the greater the total thickness of the soft tissue, the thicker the fat layer. 2. The thicknesses of the head and face soft tissues are strongly affected by sex. The total thickness of all landmark points in the men, except for the zygomatic points, was on average greater than that in the women. In contrast to the total thickness, the fat layer, except for the point of rhinion, in the women was larger than that in the men. 3. In the comparison of the 4 age groups, most feature points did not show an evident increasing or decreasing trend with age in the total thickness of the soft tissue. However, regarding the thickness of fat, the thickness at the other points, except for the feature infraorbital fossa point, decreased with age. 4. In the analysis of the sex × age group, no statistically significant differences were found at any landmark points. This paper is significant for facial reconstruction and cosmetic surgery in the Chinese population.

Tongue and Upper Airway Dimensions: A Comparative Study between Three Popular Brachycephalic Breeds

Simple Summary

Brachycephalic obstructive airway syndrome is a debilitating disease complex, that affects severely brachycephalic dogs, impairs their quality of life and shortens life expectancy. Macroglossia has been identified as part of the soft tissue conditions that characterize brachycephalic breeds. Despite similar degrees of brachycephalism comparing the common breeds French bulldogs, English bulldogs and pugs, several breed specific characteristics contributing to brachycephalic obstructive airway syndrome have been described in the past. The present study aimed to examine the tongue volume and at three levels cross-sectional areas of the tongue, oropharyngeal airways, soft palate and nasopharyngeal airways in the aforementioned breeds. Assessment of computed tomography scans revealed smaller tongues in pugs compared to French and English bulldogs, with values being close to previously published data in mesaticephalic breeds. Comparing the cross-sectional areas between breeds, several differences were identified, however, calculating the impact of soft tissue on total airways areas uncovered only differences between pugs and French bulldogs at the most caudal location, where the latter breed had a greater ratio, presumably in consequence to a significantly larger oropharyngeal airway area. These findings corroborate the importance of respecting breed specific differences in regard to surgical treatment of brachycephalic obstructive airway syndrome.

Abstract

Relative macroglossia has been identified in brachycephalic compared to mesaticephalic dogs. This study assessed the tongue volume comparing three common brachycephalic breeds, including 30 French bulldogs, 30 pugs, and 15 English bulldogs. Computed tomography scans of intubated dogs with the hard palate suspended were examined for total tongue volume and cross-sectional areas (CSAs) of the tongue, oropharynx, soft palate, and nasopharyngeal airways at three levels: 1, caudal tip of the hard palate; 2, caudal tip of the hamulus; 3 cranial to the basihyoid bone. Tongue volume normalized to bodyweight, was significantly higher in English and French bulldogs than in pugs. Normalized to skull length, CSA of the tongue was smaller in pugs than in French and English bulldogs. At level 3, French bulldogs had larger oropharyngeal CSA than English bulldogs and pugs. Soft palate CSA was the largest in English bulldogs at level 3. At levels 1 and 2, soft palate and nasopharyngeal CSA was the smallest in pugs. At level 3, French bulldogs had higher total airway/soft tissue ratios than pugs. The smaller tongue volume in pugs questions the accuracy of the term macroglossia in this breed and these findings should be considered if surgical correction is sought.

The correlation between drug-induced sleep endoscopy findings and severity of obstructive sleep apnea

OBJECTIVE

This study aimed to assess the relationship between anthropometric data, drug-induced sleep endoscopy (DISE) findings, and severity of obstructive sleep apnea (OSA).

METHODS

From August 2016 to August 2017, a total of 147 surgically naïve adult patients with OSA underwent DISE. Factors that were analyzed included anthropometric data and DISE findings.

RESULTS

When anthropometric data and DISE findings were analyzed with AHI by univariate analysis, the results showed that Epworth Sleepiness Scale (ESS), body mass index (BMI), neck circumference, concentric collapse of the velum, lateral oropharyngeal collapse, and anterior-posterior collapse of the tongue base were considered potentially independent predictors (p = 0.024, p < 0 .001, p < 0 .001, p < 0.001, p < 0.001, p < 0 .001, respectively, by Spearman correlation). When all important factors were evaluated in a stepwise multiple linear regression analysis, BMI, lateral oropharyngeal collapse, and anterior-posterior collapse of the tongue base were identified as significant predictors for the severity of OSA. The final model was listed as below: AHI score = 2.19 BMI + 7.56 Oropharynx/Lateral degree + 8.23 Tongue base/ Anterior-Posterior degree - 40.59.

CONCLUSION

By analyzing anthropometric data and DISE findings with AHI score, the results indicated that BMI, lateral oropharyngeal collapse, and anterior-posterior collapse of the tongue base were important factors associated with the severity of OSA.

Imaging of sleep-disordered breathing in adults

Sleep-disordered breathing (SDB) is a term that includes several chronic conditions in which partial or complete cessation of breathing occurs multiple times throughout the night. Central sleep apnoea (CSA) is uncommon and defined by the episodic cessation of airflow without respiratory effort. Lesions involving the respiratory centre in the brainstem or the origin of the phrenic nerve from the mid-cervical cord are the commonest structural causes of CSA; magnetic resonance imaging (MRI) will demonstrate the lesion and frequently suggest the likely aetiology. In contrast, obstructive sleep apnoea (OSA) is defined as upper airway obstruction despite ongoing respiratory effort. Repetitive episodes of narrowing or closure of the upper airway are the predominant cause leading to snoring and OSA, respectively. OSA affects 33-40% of the adult population and is associated with multiple adverse health consequences, including a significantly increased risk of serious morbidity and mortality. The incidence is increasing proportionally to the worldwide rise in obesity. Imaging, performed primarily without the involvement of radiologists, has been integral to understanding the anatomical basis of SDB and especially OSA. This article will review the pathophysiology, imaging findings, and sequelae of these common conditions. The role of imaging both in suggesting the incidental diagnoses of SDB and in the investigation of these conditions when the diagnosis is suspected or has been established are also discussed.

Upper airway morphological changes in obstructive sleep apnoea: effect of age on pharyngeal anatomy

OBJECTIVE

To evaluate the upper airway morphology changes associated with ageing in adult Chinese patients with obstructive sleep apnoea.

METHODS

A total of 124 male patients diagnosed with obstructive sleep apnoea by overnight polysomnography, who underwent upper airway computed tomography, were enrolled. The linear dimensions, cross-sectional area and volume of the upper airway region and the surrounding bony frame were measured. The association between ageing and upper airway morphology was analysed.

RESULTS

Soft palate length, minimum cross-sectional area of the retroglossal region, lateral dimensions at the minimum cross-sectional area of the retropalatal and retroglossal regions, nasopharyngeal volume, and average cross-sectional area of the nasopharyngeal region were found to significantly increase with ageing in all patients, while the upper airway shape flattened with ageing. The volume of the retropalatal region increased with ageing among the patients with a body mass index of less than 24 kg/m2. The volume of parapharyngeal fat pad increased with ageing among patients with a body mass index greater than 28 kg/m2.

CONCLUSION

A number of dimensional, cross-sectional and volumetric parameters of the pharynx increased with age, indicating that non-anatomical factors may play a more important role in the pathogenesis of obstructive sleep apnoea in aged patients.

Adult obstructive sleep apnoea: Pathogenesis, importance, diagnosis and imaging

Obstructive sleep apnoea (OSA) is a serious worldwide health problem. Moderate-to-severe OSA has been found in up to 50% of men and 25% of women in the middle-aged population. It results in a fourfold increase in all causes of mortality. The prevalence of OSA is underestimated, partly due to absence of symptoms but also lack of knowledge amongst the population at large as well as sectors of the medical profession. Imaging, performed predominantly by clinicians and research scientists, has been integral to evaluating the anatomical basis of OSA. Increased nasal resistance and a narrowed and elongated oropharynx lead to increased collapsibility of the upper airway, predisposing to airway collapse and apnoea during sleep when there is reduction in tone of the pharyngeal dilator muscles. Unfortunately, a significantly narrowed upper airway is usually ignored by radiologists: it is not part of their reporting 'check-list'. The imaging findings in the upper airway that are strongly associated with OSA and its sequelae in various organ systems are discussed. Imaging can strongly suggest OSA; the diagnosis requires a polysomnogram for confirmation. Treatment of moderate-to-severe disease is primarily with positive airway pressure applied by a nasal or oral mask which splints the upper airway. Although highly effective, compliance is limited and other treatment modalities are increasingly being utilized.

Regularized logistic regression for obstructive sleep apnea screening during wakefulness using daytime tracheal breathing sounds and anthropometric information

Obstructive sleep apnea (OSA) is a prevalent health problem. Developing a technology for quick OSA screening is momentous. In this study, we used regularized logistic regression to predict the OSA severity level of 199 individuals (116 males) with apnea/hypopnea index (AHI) ≥ 15 (moderate/severe OSA) and AHI < 5 (non-OSA) using their tracheal breathing sounds (TBS) recorded during daytime, while they were awake. The participants were guided to breathe through their nose, and then through their mouth at their deep breathing rate. The least absolute shrinkage and selection operator (LASSO) feature selection approach was used to select the discriminative features from the power spectra of the TBS and the anthropometric information. Using a five-fold cross-validation procedure, five different training sets and their corresponding blind-testing sets were formed. The average blind-testing classification accuracy over the five different folds was found to be 79.3% ± 6.1 with the sensitivity (specificity) of 82.2% ± 7.2% (75.8% ± 9.9%). The accuracy for the entire dataset was found to be 81.1% with sensitivity (specificity) of 84.4% (77.0%). The feature selection and classification procedures were intelligible and fast. The selected features were physiologically meaningful. Overall, the results show that TBS analysis can be used as a quick and reliable prediction of the presence and severity of OSA during wakefulness without a sleep study. Graphical abstract Wakefulness screening of obstructive sleep apnea using tracheal breathing sounds and anthropometric information by means of regularized logistic regression with the least absolute shrinkage and selection operator approach for feature selection and classification.

The impact of tongue dimension on air volume in brachycephalic dogs

OBJECTIVE

To compare the dimensions and density of the tongue in brachycephalic and mesaticephalic dog breeds and to document the relative extents of the nasopharyngeal and oropharyngeal airways occupied by the tongue and palatal tissues.

STUDY DESIGN

Case control study.

ANIMALS

Sixteen brachycephalic dogs and 12 mesaticephalic dogs.

METHODS

The volume of the tongue was measured with computed tomography in all dogs. Cross-sectional areas of tongue, oropharynx, nasopharynx, and palatal soft tissue were evaluated at two levels, the caudal aspect of the hard palate and the level of the hamulae of the pterygoid. Density of the tongue and soft palate were measured. All variables were compared between brachycephalic and mesaticephalic dogs (P ≤ .05).

RESULTS

Absolute tongue volumes did not differ between groups, the volume of the tongue was greater in brachycephalic dogs than in mesaticephalic dogs when expressed relative to (a) body weight (median 5650, interquartile range [IQR] 4833-6522 vs median 4454, IQR 4309-4743, respectively), (b) ratio between skull length/width (70 833, IQR 62490-126 209 vs 48 064, IQR 22984-64 279, respectively), and (c) skull length (689.93, IQR 618.55-970.61 vs 460.04, IQR 288.77-561.69, respectively). The proportion of air (oropharyngeal and nasopharyngeal)/soft tissue (tongue and palatal tissue) in brachycephalic dogs was decreased by approximately 60%, and the tongue was approximately 10 times denser in brachycephalic dogs than in mesaticephalic dogs.

CONCLUSION

A relative macroglossia was detected in brachycephalic dogs along with reduced air volume in the upper airway. Tongues of brachycephalic dogs were denser than those of mesaticephalic dogs.

CLINICAL SIGNIFICANCE

The relative macroglossia in brachycephalic breeds may contribute to upper airway obstruction.

The effect of body position on airway patency in obstructive sleep apnea: CT imaging analysis

PURPOSE

Positional change during sleep influences upper airway patency. However, few studies have used imaging techniques to demonstrate the change. This study aims to determine the effect of positional change on the upper airway space.

METHODS

A total of 118 subjects with sleep breathing disorders were analyzed. Participants underwent upper airway CT scans in the supine and lateral decubitus positions (right and left). They were divided into non-obstructive sleep apnea (n = 28) and obstructive sleep apnea (n = 90) groups. We measured the minimal cross-sectional area of the retropalatal/retroglossal spaces and compared the differences of those two spaces in the supine and lateral positions. CT was performed while patients were awake.

RESULTS

The minimal cross-sectional area in the OSA group was significantly smaller than non-OSA group in both supine (median[interquartile range], 8.3[0.0-25.1] vs 22.2[1.0-39.6]; P = 0.018) and lateral decubitus positions (5.2[0.0-16.9] vs 21.3[6.1-38.4]; P = 0.002). As the body position of OSA patients shifted from supine to lateral, the retroglossal space increased significantly (67.3[25.1-116.3] vs 93.3[43.4-160.1]; P < 0.001). However, there was no significant difference in the retropalatal space between the supine and lateral decubitus positions.

CONCLUSIONS

Positional change from the supine to lateral decubitus position expands the upper airway lumen, especially the retroglossal space. Positional OSA may be related to anatomical change of the upper airway lumen based on body position.

The Interaction Between Craniofacial Computed Tomographic Dimensional Parameters and BMI in Obstructive Sleep Apnea

Introduction

The impact of the dimensional parameters of the pharyngeal bony frame by its length, width and the position of the hyoid upon the severity of obstructive sleep apnea syndrome (OSAS) has not been investigated in depth. Interactions of those parameters with body mass index (BMI) and their overall reciprocal effect on OSAS severity have also not been established.

Materials and Methods

This retrospective cross-sectional study was conducted on 108 male OSAS patients followed in OSAS outpatient clinics between November 2014 and October 2015. They all underwent a polysomnography test, and an apnea-hypopnea index (AHI) was calculated. They also underwent an upper airway computerized tomographic scan in which three craniofacial parameters were evaluated: inter-pterygoid distance (IPD), hard palate-to-hyoid (HP-H) distance, and gnathion plane-to-hyoid (GP-H) distance.

Results

A longer pharynx and an inferiorly placed hyoid bone correlated with the AHI (r = 0.33, p = 0.001 and r = 0.226, p = 0.03, respectively). GP-H correlated with body mass index (BMI) (r = 0.3243, p < 0.001), while HP-H and IPD did not. We found an interaction between BMI and HP-H, but none between GP-H and BMI. IPD did not correlate with OSAS severity, but it correlates with the age of the OSAS patients (r = 0.235, p = 0.015).

Conclusion

Pharynx length and hyoid position have significant effects upon OSAS severity, and they interact differently with BMI in terms of those effects. Hard palate width increases with age but has no correlation with OSAS severity.

Comparison of Imaging Softwares for Upper Airway Evaluation: Preliminary Study

The interest about upper airway evaluation has increased lately. Therefore, many softwares have been developed aiming to improve and facilitate the analysis of airway volume. The objective of this study was to compare two different softwares packages, Mimics and Dolphin, in their accuracy and precision in upper airway space measurements. Preoperative cone beam computed tomography scans of nine nonsyndromic patients submitted to surgically assisted rapid maxillary expansion were included in this study. The imaging exams were converted to DICOM (digital imaging and communications in medicine) files and imported to the softwares. The mean volume for the Dolphin group (G1) was 10.791 cm ³ (SD = 4.269 cm ³ ) and for the Mimics group (G2) was 10.553 cm ³ (SD = 4.564 cm ³ ). There was no statistically significant difference between the two groups ( p  = 0.105).

Airway increase after open bite closure with temporary anchorage devices for intrusion of the upper posteriors: Evidence from 2D cephalometric measurements and 3D magnetic resonance imaging

OBJECTIVE

The aim of this study was to analyse morphological changes in the upper airways in patients with anterior open bite treated with temporary anchorage devices for intrusion of upper posterior teeth.

MATERIALS AND METHODS

Twelve nonobese (body mass index: <25) anterior open bite patients between the ages of 19 and 44 years (mean age: 22.83 ± 8.19 years) were recruited for this study. Cephalometric radiographs and magnetic resonance imaging (MRI) scans before and after anterior bite closure without bracketing on anterior teeth were used to measure the upper airway, which was divided into retropalatal and retroglossal regions.

RESULTS

The mandibular plane angle and lower facial height were significantly reduced by intrusion of the upper posteriors and autorotation of the mandible. The retroglossal airway width (AW2) and retroglossal area (RG area) measured on cephalometric radiographs both increased significantly after treatment. Retroglossal volume increased and the retroglossal width/length ratio decreased significantly in MRI analysis. All other measurements were not significantly changed. However, no statistically significant correlations were observed between all measurements in 2D and 3D images, with the exception of the AW2 linear measurement in 2D images correlating with the AP length in MRI axial view images (r = 0.56, P = 0.0430).

CONCLUSION

Counterclockwise rotation of the mandible after anterior open bite closed using orthodontic treatment changed the airway morphology. Retroglossal volume significantly increased and the airway shape became less elliptical after bite closure.

Upper airway dynamic imaging during tidal breathing in awake and asleep subjects with obstructive sleep apnea and healthy controls

We used magnetic resonance imaging (MRI) to quantify change in upper airway dimension during tidal breathing in subjects with obstructive sleep apnea (OSA, N = 7) and BMI-matched healthy controls (N = 7) during both wakefulness and natural sleep. Dynamic MR images of the upper airway were obtained on a 1.5 T MR scanner in contiguous 7.5 mm-thick axial slices from the hard palate to the epiglottis along with synchronous MRI-compatible electroencephalogram and nasal/oral flow measurements. The physiologic data were retrospectively scored to identify sleep state, and synchronized with dynamic MR images. For each image, the upper airway was characterized by its area, and linear dimensions (lateral and anterior-posterior). The dynamic behavior of the upper airway was assessed by the maximum change in these parameters over the tidal breath. Mean upper airway caliber was obtained by averaging data over the tidal breath. There was no major difference in the upper airway structure between OSA and controls except for a narrower airway at the low-retropalatal/high-retroglossal level in OSA than in controls. Changes in upper airway size over the tidal breath ((maximum - minimum)/mean) were significantly larger in the OSA than in the control group in the low retropalatal/high retroglossal region during both wakefulness and sleep. In the four OSA subjects who experienced obstructive apneas during MR imaging, the site of airway collapse during sleep corresponded to the region of the upper airway where changes in caliber during awake tidal breathing were the greatest. These observations suggest a potential role for dynamic OSA imaging during wakefulness.

Imaging of adult obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is characterised by recurrent upper airway collapse during sleep resulting in chronic and repetitive hypoxia, hypercapnia, subsequent arousal and fragmented sleep. Symptoms are insidious and diagnosis is usually delayed. Moderate to severe OSA has serious health implications with significant increase in all causes of mortality in patients with the condition as compared with unaffected individuals. The prevalence of OSA in the 30-70 year age group is estimated at 27% of males and 11% of females and it increases with age. 80% of affected individuals are obese and as obesity rates rise, so has the prevalence of OSA. An overnight polysomnogram (PSG) is required for a definitive diagnosis of OSA. Imaging has played a fundamental role in the evaluation of the anatomical factors associated with recurrent upper airway collapse and the pathogenesis of OSA. The upper airway is frequently imaged by radiologists, providing an opportunity to detect features that are strongly associated with unsuspected OSA and to raise the possibility of this diagnosis. The gold standard of treatment is continuous positive airway pressure (CPAP) which acts as a pneumatic splint for the upper airway. However, efficacy is frequently limited by poor tolerance; clinicians and patients are increasingly opting for one of a range of surgical procedures. Dedicated imaging protocols can be performed for evaluation of the upper airway to aid surgical planning.

Upper Airway Areas, Volumes, and Linear Measurements Determined on Computed Tomography During Different Phases of Respiration Predict the Presence of Severe Obstructive Sleep Apnea

PURPOSE

The objective of this study was to analyze the potential of using low-dose volumetric computed tomography (CT) during different phases of respiration for identifying patients likely to have severe obstructive sleep apnea (OSA), defined as a respiratory disturbance index (RDI) higher than 30.

PATIENTS AND METHODS

A prospective study was undertaken at the Ramathibodi Hospital (Bangkok, Thailand). Patients with diagnosed OSA (N = 82) were recruited and separated into group 1 (RDI, ≤30; n = 36) and group 2 (RDI, >30; n = 46). The 2 groups were scanned by low-dose volumetric CT while they were 1) breathing quietly, 2) at the end of inspiration, and 3) at the end of expiration. Values for CT variables were obtained from linear measurements on lateral scout images during quiet breathing and from the upper airway area and volume measurements were obtained on axial cross-sections during different phases of respiration. All CT variables were compared between study groups. A logistic regression model was constructed to calculate a patient's likelihood of having an RDI higher than 30 and the predictive value of each variable and of the final model.

RESULTS

The minimum cross-sectional area (MCA) measured at the end of inspiration (cutoff point, ≤0.33 cm²) was the most predictive variable for the identification of patients likely to have an RDI higher than 30 (adjusted odds ratio [OR] = 5.50; 95% confidence interval [CI], 1.76-17.20; sensitivity, 74%; specificity, 72%,), followed by the MCA measured at the end of expiration (cutoff point, ≤0.21 cm²; adjusted OR = 3.28; 95% CI, 1.05-10.24; sensitivity, 70%; specificity, 68%).

CONCLUSION

CT scanning at the ends of inspiration and expiration helped identify patients with an RDI higher than 30 based on measurement of the MCA. Low-dose volumetric CT can be a useful tool to help the clinician rapidly identify patients with severe OSA and decide on the urgency to obtain a full-night polysomnographic study and to start treatment.

Fat accumulation in the tongue is associated with male gender, abnormal upper airway patency and whole-body adiposity

OBJECTIVE

To examine associations between tongue adiposity with upper airway measures, whole-body adiposity and gender. We hypothesized that increased tongue adiposity is higher in males and positively associated with abnormal upper airway measures and whole-body adiposity.

METHODS

We studied subjects who underwent whole-body positron emission tomography/computed tomography to obtain tongue attenuation (TA) values and cross-sectional area, pharyngeal length (PL) and mandibular plane to hyoid distance (MPH), as well as abdominal circumference, abdominal subcutaneous and visceral (VAT) adipose tissue areas, neck circumference (NC) and neck adipose tissue area. Metabolic syndrome was determined from available clinical and laboratory data.

RESULTS

We identified 206 patients (104 females, 102 males) with mean age 56±17years and mean body mass index (BMI) 28±6kg/m² (range 16-47kg/m²). Males had lower TA values (P=0.0002) and higher upper airway measures (P<0.0001) independent of age and BMI (P<0.001). In all subjects, TA was negatively associated with upper airway measures (P<0.001). TA was negatively associated with body composition parameters (all P<0.0001), most notably with VAT (r=-0.53) and NC (r=-0.47). TA values were lower in subjects with metabolic syndrome (P<0.0001).

CONCLUSION

Increased tongue adiposity is influenced by gender and is associated with abnormal upper airway patency and body composition parameters.

Upper Airway Collapsibility Assessed by Negative Expiratory Pressure while Awake is Associated with Upper Airway Anatomy

STUDY OBJECTIVES

There is a growing interest to develop a simple method to characterize the mechanisms leading to upper airway collapse in order to guide treatment options in patients with obstructive sleep apnea (OSA). Critical closing pressure (Pcrit) during sleep is able to predict the anatomical component of OSA. However, Pcrit is a laborious method that is only used for research purposes. The application of negative expiratory pressure (NEP) is a simple method to assess upper airway collapsibility that can be easily performed during wakefulness. We hypothesized that NEP will be, similarly to Pcrit, associated with upper airway anatomy assessed by computed tomography (CT) scan.

METHODS

Patients under investigation for OSA underwent polysomnography, CT of the upper airway, NEP while awake, and Pcrit during sleep. NEP was performed with -5 cm H₂O in supine position using a nasal mask. Pcrit was measured during sleep induced by low doses of midazolam.

RESULTS

Twenty-eight male subjects were studied (age 45 ± 13 y, body mass index 29.4 ± 4.9 kg/m², apnea-hypopnea index (AHI) 30 ± 26, range 2 to 86 events/h). NEP and Pcrit were similarly associated with tongue area (r = 0.646 and r = 0.585), tongue volume (r = 0.565 and r = 0.613) and pharyngeal length (r = 0.580 and r = 0.611), respectively (p < 0.05 for all comparisons). NEP and Pcrit were also significantly correlated with AHI (r = 0.490 and r = 0.531). NEP and Pcrit were significantly higher in patients with severe OSA than the remaining population.

CONCLUSIONS

NEP is a simple and promising method that is associated with the anatomical component of upper airway collapsibility. NEP may be valuable to select patients for noncontinuous positive airway pressure alternative therapies for OSA.

Use of modified barium swallow study to measure posterior airway space in obstructive sleep apnea

Conclusion Measurement of the posterior airway space (PAS) using modified barium swallow (MBS) appears to correlate well with CT imaging. This data suggests MBS may be a low-cost alternative imaging modality to assess obstructive sleep apnea patients. Objectives Obstructive sleep apnea research has focused on imaging modalities that supplement polysomnography in evaluation of potential sites of airway obstruction. While several techniques have been used to assess the PAS, many incur significant costs and risks to the patient. This study proposes use of MBS as a simple modality to measure PAS. Advantages include its simplicity, lower radiation, and dynamic tongue base visualization, which may help predict surgical outcomes. It is hypothesized that cephalometric measurements obtained using MBS will correlate well with CT. Methods Thirty-six adult patients who underwent both CT imaging and MBS for head and neck cancer were included. Cephalometric measurements of the PAS were obtained using each imaging modality. Statistical analysis focused on correlating measurements taken using CT and MBS. Results The average PAS measurements were 12.53 ± 1.81 mm and 12.80 ± 1.75 mm by MBS and CT imaging, respectively. In comparing the two modalities, Pearson correlation between CT and MBS measurements revealed significant positive correlations between r = 0.769 and 0.937.

Effects of Age and Bolus Volume on Velocity of Hyolaryngeal Excursion in Healthy Adults

Reduced movement velocity has been identified as a risk marker for movement impairment in older adults. Hyolaryngeal excursion is a key movement feature of normal swallowing function which is known to change with age and other extrinsic variables such as bolus volume. However, velocity of hyolaryngeal excursion has received limited attention in the literature on normal or abnormal swallowing. This study evaluated the effects of age and bolus volume on the velocity of hyoid and laryngeal excursion during swallowing in healthy adults. Forty-four healthy volunteers were grouped into three age bands (young: 20-35 years, middle age: 36-55 years, older: 56 ≥ years). All subjects swallowed 5 and 20 mL of thin liquid during fluoroscopic recording. Fluoroscopic images were extracted for each swallow representing the onset and maximum excursion positions of the hyoid and larynx. Superior and anterior excursion distance (excursion magnitude) and the time difference between rest and maximum excursion (excursion duration) were calculated. Velocity was calculated as a ratio of distance over time. Superior hyoid excursion magnitude was significantly increased for the 20 mL volume. Anterior laryngeal excursion magnitude was also significantly increased for the 20 mL volume. No kinematic duration measure demonstrated significant change across age or bolus conditions. Superior hyoid excursion velocity was significantly faster for the 20 mL volume. Superior and anterior laryngeal excursion velocity were significantly faster for the 20 mL volume only in the older group. Results of this study indicate that magnitude and velocity of hyoid and laryngeal excursion vary with age and volume. Comprising both excursion magnitude and duration, kinematic velocity may be a more complete metric to evaluate age-related swallowing performance.

Upper airway collapsibility is associated with obesity and hyoid position

STUDY OBJECTIVES

Upper airway anatomy plays a major role in obstructive sleep apnea (OSA) pathogenesis. An inferiorly displaced hyoid as measured by the mandibular plane to hyoid distance (MPH) has been consistently associated with OSA. The hyoid is also a common landmark for pharyngeal length, upper airway volume, and tongue base. Tongue dimensions, pharyngeal length, and obesity are associated with OSA severity, although the link between these anatomical variables and pharyngeal collapsibility is less well known. We hypothesized that obesity as measured by body mass index (BMI), neck and waist circumferences, and variables associated with hyoid position (pharyngeal length, upper airway volume, and tongue dimensions) would be associated with passive pharyngeal critical closing pressure (Pcrit).

DESIGN

Cross-sectional.

SETTING

Academic hospital.

PATIENTS

34 Japanese-Brazilian males age 21 to 70 y.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

We performed computed tomography scans of the upper airway, overnight polysomnography, and Pcrit measurements in all subjects. On average, subjects were overweight (BMI = 28 ± 4 kg/m(2)) and OSA was moderately severe (apnea-hypopnea index = 29 [13-51], range 1-90 events/h). Factor analysis identified two factors among the studied variables: obesity (extracted from BMI, neck and waist circumferences) and hyoid position (MPH, pharyngeal length, tongue length, tongue volume, and upper airway volume). Both obesity and hyoid position correlated with Pcrit (r = 0.470 and 0.630, respectively) (P < 0.01). In addition, tongue volume, tongue length, pharyngeal length, and MPH correlated with waist and neck circumferences (P < 0.05).

CONCLUSIONS

Pharyngeal critical closing pressure is associated with obesity and hyoid position. Tongue dimensions, pharyngeal length, and the mandibular plane to hyoid distance are associated with obesity variables. These findings provide novel insight into the potential factors mediating upper airway collapse in obstructive sleep apnea.

Clinical predictors of nocturia in the sleep apnea population

OBJECTIVES

This study aims to evaluate clinical predictors of nocturia in patients with obstructive sleep apnea (OSA).

MATERIALS AND METHODS

In retrospective manner, a total of 200 patients with OSA were randomly included. Group I contained 100 patients with OSA and no nocturia, and Group II included 100 patients with OSA and nocturia. Bivariate logistic analyses were used to identify variables most likely to contribute to nocturia. Multivariate logistic regression of age, waist circumference, STOP score (Snore, Tired, Obstruction and Pressure), and Apnea-Hypopnea Index (AHI) was performed to evaluate predictors of nocturia. Statistical significance was defined as P < 0.05.

RESULTS

Median nocturia episodes were 2.2 in Group II. Patients were younger in Group I, with a mean age of 45 vs 50 years (P = 0.008). Mean BMI of 30 was similar in both groups, but there were more overweight patients in Group II (28% vs 18%). AHI approached significance between groups-18 vs 23 in group I and II, respectively (P = 0.071). In multivariate analysis, age over 70 years and moderate AHI were statistically significant predictors of nocturia (coefficients 0.6 and -0.2 with P = 0.003 and 0.03, respectively).

CONCLUSIONS

This study identifies age and AHI score as predictors of nocturia in patients with OSA. This may indicate the usefulness of incorporating nocturia in the screening of patients with OSA. Future studies are needed to further evaluate mechanism of action, clinical significance, and effect of treatment for nocturia in patients with OSA.

Velopharyngeal anatomy in patients with obstructive sleep apnea versus normal subjects

PURPOSE

Obesity can cause disturbed breathing and is one of the most significant risk factors for obstructive sleep apnea (OSA). However, the anatomic basis of OSA and, specifically, the anatomic mechanisms leading from obesity to OSA are still unclear. We examined the anatomic features of the velopharynx in patients with OSA versus those without in correlation with the body mass index (BMI), age, history of snoring, and OSA severity and re-evaluated the contribution of adding a frontal view to the cephalometric analysis of patients with OSA.

MATERIALS AND METHODS

Lateral and frontal cephalometric measurements were taken to assess the velopharyngeal anatomic features of 306 men with various degrees of OSA and 64 men without OSA and without a history of snoring. The demographic, polysomnographic, and cephalometric features were compared.

RESULTS

The patients with OSA had an increased pharyngeal length, thicker velum, a thicker posterior pharyngeal wall, a reduced pharyngeal width, and a consequent narrowing of the pharyngeal lumen. As the BMI increased, the OSA severity increased. Also, in parallel, the velum and posterior pharyngeal wall thickness increased and the pharyngeal width decreased. Three types of velopharyngeal narrowing, with an increased occurrence in severe degrees of OSA, were identified: bottle shape, hourglass shape, and tube shape. These aerodynamically unfavorable changes might cause increased upper airway resistance, explaining the development of both OSA and hypoventilation syndrome in obese patients.

CONCLUSIONS

Velopharyngeal thickening and lumen narrowing were shown to be features of obese men with OSA. However, these features developed only above a threshold BMI value. The combination of frontal and lateral cephalometry is important for comprehensive evaluation of patients with OSA.

The impact of pharyngeal fat tissue on the pathogenesis of obstructive sleep apnea

PURPOSE

Obesity is the most important risk factor for obstructive sleep apnea (OSA); however, the exact underlying mechanisms are still not fully understood. The aim of this study was to examine the morphology of upper airways in overweight habitual snorers and in mild OSA patients. Furthermore, the associations between weight loss, parapharyngeal fat pad area and OSA were assessed in a 1-year randomised, controlled follow-up study originally conducted to determine the effects of lifestyle changes with weight reduction as a treatment of OSA.

METHODS

Thirty-six overweight adult patients with mild OSA [apnea-hypopnea index (AHI) 5-15 events/h] and 24 weight-matched habitual snorers (AHI < 5 events/h) were included in the study. All patients underwent nocturnal cardiorespiratory recordings and multislice computed tomography (CT) of parapharyngeal fat pad area, the smallest diameter and area in naso-, oro- and hypopharynx, the smallest diameter and area of the whole pharyngeal airway, the distance from the hyoid bone to the mandibular plane and to cervical tangent as well as the distance between mandibular symphysis and cervical spine. In addition, OSA patients were further randomised to receive either an active 1-year lifestyle intervention with an early weight loss programme or routine lifestyle counselling. After 1 year, the cardiorespiratory recordings and CT scans were repeated.

RESULTS

The pharyngeal fat pad area was significantly larger, and the distance from the hyoid bone to cervical spine was longer in patients with OSA than in habitual snorers (p = 0.002 and p = 0.018, respectively). The multiple regression analysis showed that besides a large pharyngeal fat pad area and a long distance from the cervical spine to hyoid bone, also a short distance from the mandibular symphysis to cervical tangent increased a risk to OSA. During the 1-year follow-up in OSA patients, the pharyngeal fat pad area and AHI decreased significantly in the intervention group (p = 0.003 and p < 0.001, respectively).

CONCLUSIONS

In the early stages of OSA, the pharyngeal fat pad seems to play an important role in the development of disease in overweight patients. Furthermore, weight reduction by lifestyle intervention-based programme reduces both central obesity and pharyngeal fat pads, resulting in an improvement of OSA.

Predictive value of lingua/pharynx ratio for retroglossal obstruction in patients with obstructive sleep apnea hypopnea syndrome

CONCLUSIONS

The lingua/pharynx (L/P) ratio has high sensitivity and specificity in predicting the severity of retroglossal obstruction in patients with obstructive sleep apnea hypopnea syndrome (OSAHS).

OBJECTIVE

To evaluate the diagnostic value of the L/P ratio in predicting the severity of retroglossal obstruction in patients with OSAHS.

METHODS

Airway computed tomography (CT) was performed in 115 patients with OSAHS. The retroglossal cross-sectional area (RCSA) was measured at the axial level of the hypopharynx, immediately superior to the tip of the epiglottis. Moreover, nine lines, which were lined up in the order of n = 1, 2, 3, …, 9, were drawn from the genial tubercle (point G) to nine points (point P n ) proximally on the posterior pharyngeal wall and hard palate in the sagittal plane. Meanwhile, the nine lines intersected the lingual surface at point Ln, respectively. The L/P ratios of the lingual segment (G to L n distance) to the pharyngeal segment (G to P n distance) were measured. We analyzed the correlations between nine L/P values (L/P n ) and RCSA.

RESULTS

Both simple linear correlation analysis and multiple linear regression analysis showed that L/P6 and L/P9 had significant negative correlations with RCSA.

Aging-related geniohyoid muscle atrophy is related to aspiration status in healthy older adults

BACKGROUND

Age-related muscle weakness due to atrophy and fatty infiltration in orofacial muscles may be related to swallowing deficits in older adults. An important component of safe swallowing is the geniohyoid (GH) muscle, which helps elevate and stabilize the hyoid bone, thus protecting the airway. This study aimed to explore whether aging and aspiration in older adults were related to GH muscle atrophy and fatty infiltration.

METHOD

Eighty computed tomography scans of the head and neck from 40 healthy older (average age 78 years) and 40 younger adults (average age 32 years) were analyzed. Twenty aspirators and 20 nonaspirators from the 40 older adults had been identified previously. Two-dimensional views in the sagittal and coronal planes were used to measure the GH cross-sectional area and fatty infiltration.

RESULTS

GH cross-sectional area was larger in men than in women (p < .05). Decreased cross-sectional area was associated with aging (p < .05), and cross-sectional area was significantly smaller in aspirators compared with nonaspirators, but only among the older men (p < .01). Increasing fatty infiltration was associated with aging in the middle (p < .05) and posterior (p < .01) portions of the GH muscle. There was no significant difference in fatty infiltration of the GH muscle among aspirators and nonaspirators.

CONCLUSION

GH muscle atrophy was associated with aging and aspiration. Fatty infiltration in the GH muscle was increased with aging but not related to aspiration status. These findings suggest that GH muscle atrophy may be a component of decreased swallowing safety and aspiration in older adults and warrants further investigation.

The reciprocal interaction between obesity and obstructive sleep apnoea

Obesity is a significant risk factor in the pathogenesis of obstructive sleep apnoea (OSA) altering airway anatomy and collapsibility, and respiratory control. The association between obesity and OSA has led to an increasing focus on the role of weight loss as a potential treatment for OSA. To date, most discussion of obesity and OSA assumes a one-way cause and effect relationship, with obesity contributing to the pathogenesis of OSA. However, OSA itself may contribute to the development of obesity. OSA has a potential role in the development and reinforcement of obesity via changes to energy expenditure during sleep and wake periods, dietary habits, the neurohormonal mechanisms that control satiety and hunger, and sleep duration arising from fragmented sleep. Thus, there is emerging evidence that OSA itself feeds back into a complex mechanism that leads either to the development or reinforcement of the obese state. Whilst current evidence does not confirm that treatment of OSA directly influences weight loss, it does suggest that the potential role OSA plays in obesity and weight loss deserves further research.

Tongue adiposity and strength in healthy older adults

OBJECTIVES/HYPOTHESIS

To identify treatable risk factors for aspiration in older adults, particularly those associated with sarcopenia, we examined tongue composition. We hypothesized that isometric and swallowing posterior tongue strength would positively correlate with posterior tongue adiposity, and healthy older adults who aspirate would have greater tongue adiposity than healthy older adults who did not aspirate.

STUDY DESIGN

Prospective.

METHODS

Participants were 40 healthy adults, comprised of 20 aspirators (mean age, 78 years) and 20 nonaspirators (mean age, 81 years), as identified via flexible endoscopic evaluation of swallowing. Measures of maximal isometric posterior tongue strength and posterior swallowing tongue strength were acquired via tongue manometry. An index of posterior tongue adiposity was acquired via computed tomography for a 1-cm region of interest.

RESULTS

Posterior tongue adiposity was correlated with posterior tongue isometric (r = 0.32, P = .05) but not swallowing pressures (P > .05) as examined with separate partial correlation analyses. Tongue adiposity did not significantly differ as a function of age, gender, or aspiration status (P > .05).

CONCLUSIONS

Lower posterior isometric tongue strength was associated with greater posterior tongue adiposity. However, aspiration in healthy older adults was not affected by posterior tongue adiposity. This finding offers insight into the roles of tongue composition and strength in healthy older adults.

Cone beam computed tomography: craniofacial and airway analysis

Imaging plays a role in the anatomic assessment of the airway and adjacent structures. This article discusses the use of 3-dimensional (3D) imaging (cone beam computed tomography [CBCT]) to evaluate the airway and selected regional anatomic variables that may contribute to obstructive sleep-disordered breathing (OSDB) in patients. CBCT technology uses a cone-shaped x-ray beam with a special image intensifier and a solid-state sensor or an amorphous silicon plate for capturing the image. Incorporation of 3D imaging into daily practice will allow practitioners to readily evaluate and screen patients for phenotypes associated with OSDB.

Is laryngeal descent associated with increased risk for obstructive sleep apnea?

BACKGROUND

A lower (more caudal) position of the larynx may result in a longer collapsible segment of the upper airway. One could thus hypothesize that the lower the larynx the greater the risk for obstructive sleep apnea (OSA). To test this hypothesis, we measured the upper airway length to the level of the vocal cord and the horizontal and vertical segments of the supralaryngeal vocal cord tract (SVT) using multislice CT scan in Japanese patients with OSA.

METHODS

We recruited 249 consecutive patients who had polysomnography for suspected OSA (age, 47.8 ± 14.8 years; BMI, 24.8 ± 4.3 kg/m(2)). Using CT images, we measured airway length (AL), airway length to vocal cord (ALVC), ALVC-AL, horizontal segment of SVT (SVTH), and vertical segment of SVT (SVTV). The ratio SVTR (SVTH to SVTV) was calculated. The correlation between these measurements and age, BMI, and AHI were evaluated.

RESULTS

Men had a longer ALVC than women. AL, ALVC, and SVTR were significantly correlated with age and AHI in all patients. Logistic regression analysis showed that ALVC > 0.24 (OR, 4.2; CI, 2.3-7.6) and BMI > 25 (OR, 4.8; CI, 2.7-8.5) were significant variables predicting AHI > 30. Even after controlling for BMI, the effect of ALVC was still significant.

CONCLUSIONS

The laryngeal position is lower in men than women. Aging is associated with a lower laryngeal position, and a longer ALVC is independently associated with OSA severity in Japanese patients. We conclude that both laryngeal descent and BMI may be risk factors for OSA.

Anatomic predictors of retropalatal mechanical loads in patients with obstructive sleep apnea

BACKGROUND

The retropalatal airway is one of the most collapsible sites during sleep in patients with obstructive sleep apnea (OSA). The primary anatomical contributors to increased collapsibility in the retropalatal segment remain unclear.

OBJECTIVES

This study seeks to investigate how the balance between pharyngeal soft tissues and the bony enclosure influences retropalatal mechanical loads in patients with OSA.

METHODS

The segmental mechanical load of the retropalatal pharynx was determined by the region's critical closing pressure in 30 anesthetized, paralyzed and intubated subjects with OSA. The volumetric anatomical parameters of the retropalatal airway were evaluated using magnetic resonance imaging, and their associations with retropalatal closing pressures were analyzed.

RESULTS

Increased retropalatal closing pressure was associated with the increased proportion of volumetric pharyngeal soft tissues to the surrounding cervicomandibular bony frame (r = 0.791, p < 0.001), enlarged soft tissues of the lateral wall (r = 0.752, p < 0.001) and soft palate (r = 0.726, p < 0.001). The decreased volume of the nasopharynx (r = -0.650, p < 0.001) and pharyngeal cavity (r = -0.653, p < 0.001) indicated a relatively higher retropalatal closing pressure. The multivariate linear regression model demonstrated that the proportion of retropalatal soft tissues to the bony frame and volume of the soft palate predicted 69.4% of the variability in closing pressure (F = 30.674, p < 0.001).

CONCLUSIONS

The increased volumetric proportion of pharyngeal soft tissue to the bone enclosure may be an important contributor to increased retropalatal mechanical loads.

Maxillary, mandibular, and chin advancement: treatment planning based on airway anatomy in obstructive sleep apnea

Surgical correction of obstructive sleep apnea (OSA) syndrome involves understanding a number of parameters, of which the 3-dimensional airway anatomy is important. Visualization of the upper airway based on cone beam computed tomography scans and automated computer analysis is an aid in understanding normal and abnormal airway conditions and their response to surgery. The goal of surgical treatment of OSA syndrome is to enlarge the velo-oropharyngeal airway by anterior/lateral displacement of the soft tissues and musculature by maxillary, mandibular, and possibly, genioglossus advancement. Knowledge of the specific airway obstruction and characteristics based on 3-dimensional studies permits a directed surgical treatment plan that can successfully address the area or areas of airway obstruction. The end occlusal result can be improved when orthodontic treatment is combined with the surgical plan. The individual with OSA, though, is more complicated than the usual orthognathic patient, and both the medical condition and treatment length need to be judiciously managed when OSA and associated conditions are present. The perioperative management of the patient with OSA is more complex and the margin for error is reduced, and this needs to be taken into consideration and the care altered as indicated.

Anatomy and physiology of the upper airway

The nose is the major portal of air exchange between the internal and external environment. The nose participates in the vital functions of conditioning inspired air toward a temperature of 37°C and 100% relative humidity, providing local defense and filtering inhaled particulate matter and gases. It also functions in olfaction, which provides both a defense and pleasure for the individual. Understanding normal physiology provides the basis for recognizing abnormalities.