Identification of upper airway anatomic risk factors for obstructive sleep apnea with volumetric magnetic resonance imaging

Tongue Function: An Underrecognized Component in the Treatment of Obstructive Sleep Apnea with Mandibular Repositioning Appliance

Obstructive sleep apnea (OSA) is a common but still underrecognized disorder. A mandibular repositioning appliance (MRA) is used to treat OSA by advancing the mandible and thereby reducing the collapsibility of the upper airway. It has been found that an MRA increases the volume of the upper airway, especially the velopharyngeal area, in OSA patients. We hypothesize that this increase in the velopharyngeal volume is associated with an anterior displacement of the tongue, but likely not with a stretching of the soft tissue connecting the soft palate, lateral pharynx, palatopharyngeal arch, and mandible. Since the function and structure of the genioglossus and hypoglossal nerve are always abnormal in patients with OSA, the tongue does not always move simultaneously with the mandible when an MRA is being used. Oropharyngeal exercises, especially tongue exercises, can improve the quality of life of OSA patients, including reduction of daytime sleepiness and snoring, better quality of sleep, and partial decrease in the AHI. Further, in animal models, tongue exercise is also found to be effective in tongue function recovery and in the remodeling of the hypoglossal nucleus. We suggest that a combination of tongue exercises along with MRA is a promising approach for patients who do not respond to an MRA alone.

Risk factors associated with obstructive sleep apnea-hypopnea syndrome in Chinese children: A single center retrospective case-control study

Pediatric obstructive sleep apnea-hypopnea syndrome is caused by multiple factors. The present study aimed to investigate the potential risks of pediatric obstructive sleep apnea hypopnea syndrome (OSAHS) and their correlation with the disease severity. A total of 338 pediatric patients with OSAHS (polysomnography (PSG) diagnosis) were enrolled between June 2008 and October 2010. These pediatric patients were divided into mild, moderate and severe subgroups according to the obstructive apnea index (OAI) and/or apnea hypoventilation index (AHI). A total of 338 pediatric patients with vocal nodules who were without obstruction of the upper respiratory tract were enrolled as the control group. The patients were analyzed retrospectively. The average number of upper respiratory tract infections each year and tonsil hypertrophy, adenoid hypertrophy, positive serum tIgE, chronic sinusitis, nasal stenosis, craniofacial features and obesity were significantly higher in OSAHS compared with controls (P<0.01). The parameters the average number of upper respiratory tract infections each year (OR: 1.395, 95% CI: 1.256–1.550), adenoid hypertrophy (OR: 8.632, 95% CI: 3.990–18.672), tonsil hypertrophy (OR: 9.138, 95% CI: 4.621–18.073), nasal stenosis (8.023, 95% CI: 3.633–17.717) and chronic sinusitis (OR: 27.186, 95% CI: 13.310–55.527) were independent factors of pediatric OSAHS (P<0.01). The distribution of chronic sinusitis, nasal stenosis, craniofacial features and obesity indicated a gradual increasing trend in the severity of OSAHS (P<0.01). Number of upper respiratory tract infections per year, adenoid hypertrophy, tonsil hypertrophy, chronic sinusitis, nasal stenosis, infections, allergic reactions, craniofacial features and obesity may be potential risk factors of pediatric OSAHS.

Trans-Oral Robotic Tongue Reduction for OSA: Does Lingual Anatomy Influence the Surgical Outcome?

STUDY OBJECTIVES

To evaluate both the influence of the volume of the excised base of tongue (BOT) on the surgical outcome after robotic tongue reduction in patients affected by obstructive sleep apnea (OSA) and the role of the lymphatic or muscular predominance within the removed tissue.

METHODS

Fifty-one patients with OSA were included in this study. All patients were treated with a robotic tongue base reduction. Data registered for the analysis were: age, sex, preoperative body mass index, preoperative and postoperative apnea-hypopnea index (AHI), delta AHI (preoperative AHI - postoperative AHI), total volume of the excised BOT, total thickness of excised BOT, isolated lymphatic thickness and soft tissue thickness (including muscular component) of the excised BOT, and lymphatic/soft tissue ratio (lymphatic thickness / soft tissue thickness).

RESULTS

A statistically significant reduction of AHI values was seen postoperatively, and a success rate of 74.5% was recorded. However, no significant correlations between delta AHI and tongue volume in cubic centimeters, lymphatic/soft tissue ratio, and total thickness were found.

CONCLUSIONS

These findings reinforce the general opinion that OSA is not only influenced by anatomic factors but other phenomena may play a fundamental role in its genesis. A deeper understanding of OSA pathogenesis is needed in order to tailor an individual treatment strategy that could lead to a more effective therapy.

Evaluation of tongue/mandible volume ratio in children with obstructive sleep apnea

OBJECTIVE

The present study was an attempt to investigate tongue/mandible volume ratio in children, using volumetric magnetic resonance imaging (MRI) for early screening and to aid in treatment planning.

METHODS

Volumetric evaluation of tongue volume/mandible volume ratio (TV/MV ratio) in children with obstructive sleep apnea (OSA) using MRI was carried out retrospectively on available DICOM MR images of children in the age group of 10-14 years. MRI image records of patients diagnosed with OSA were obtained from interventional radiology department records, at Sharad Pawar Dental College and Hospital (Datta Meghe Institute of Medical Sciences, Nagpur/India). The age, gender, height and weight of the subjects were retrieved from patient database and registered. For the control group, available MRI images of healthy subjects without OSA were retrieved. Body mass index (BMI) was also calculated using the height and the weight present in the records. Measurements from MR images were made using DICOM image processing software. Soft tissue and bony structure segmentation was performed by manual tracing. The tongue volume and mandible volume were directly computed using the software. The tongue volume/mandible volume ratio (TV/MV) was generated using the above values and expressed as a percentage for both groups.

RESULTS

The difference between OSA group and control group with respect to TV/MV ratio was found to be highly significant at 0.05 level of significance. There was no significant correlation between BMI and TV/MV ratio in OSA group (p= 0.451) as well as in control group (p= 0.094).

CONCLUSION

TV/MV ratio may be an appropriate variable to evaluate the risk of OSA, representing the balance between skeletal morphology and soft tissue morphology in craniofacial complex.

Craniofacial Phenotyping in Chinese and Caucasian Patients With Sleep Apnea: Influence of Ethnicity and Sex

STUDY OBJECTIVES

Craniofacial abnormalities are a risk factor for obstructive sleep apnea (OSA). We have previously shown that phenotypic information derived from craniofacial photographs predict OSA in sleep clinic populations. However, there are likely ethnic and sex differences in craniofacial phenotypes related to OSA. We aimed to assess the use of craniofacial photography to identify interactions between OSA, ethnicity, and sex in craniofacial phenotype.

METHODS

Frontal and profile craniofacial photographs were analyzed from two sleep clinic populations of different ethnicity (Hong Kong Chinese, Australian Caucasians). OSA was defined as apnea-hypopnea index (AHI) > 10 events/h. Ten craniofacial measurements (three angles relating to jaw position and seven ratios describing proportions of the face) were examined for interactions between OSA status and sex or ethnicity) using factorial analysis of variance.

RESULTS

A total of 363 subjects (25% female) were included (n = 200 Chinese, n = 163 Caucasian), of which 33% were controls. There were two-way interactions for OSA with both sex (mandibular plane angle [F = 7.0, P = .009], face / eye width ratio [F = 4.7, P = .032], maxillary / mandibular volume ratio [F = 9.2, P = .003]) and ethnicity (face / nose width ratio [F = 4.0, P = .045], mandibular width / length ratio [F = 5.1, P = .024], maxillary / mandibular volume ratio [F = 11.0, P = .001]).

CONCLUSIONS

We provide evidence of ethnic and sex differences in facial phenotype related to OSA. Furthermore, we demonstrate that craniofacial photography can be used as a phenotypic tool to assess these differences and allow investigation of OSA phenotypes in large samples. This has relevance to personalizing OSA recognition strategies across different populations.

Decision making for position-dependent obstructive sleep apnea syndrome on the basis of patient information and physical examinations of the upper airway, acquired on an outpatient basis

CONCLUSIONS

Patients with body mass index (BMI) < 25 kg/m² and obstructive sleep apnea syndrome (OSAS) are highly suspicious for position-dependent OSAS. Diagnosis of position-dependent/position-independent OSAS can be difficult in patients satisfying both 'BMI >25 kg/m²' and 'any of tongue enlargement (TE), palatine tonsil hypertrophy (PTH) and obstruction by Muller's maneuver (OMM)'. Polysomnography is warranted in such patients.

OBJECTIVES

The objective was to retrospectively elucidate criteria for differentiating position-dependent OSAS on the basis of patient information and physical examinations of the upper airway obtainable in clinics.

METHODS

The 643 patients were categorized as positional patients (PPs) or non-positional patients (NPPs). The patient background factors examined were sex, age, BMI, and hypertension. TE, PTH, pharyngeal tonsil hypertrophy, and OMM were evaluated. Cross-validation was performed using even-numbered registrations as the training set group (Group A) and odd-numbered registrations as the test case group (Group B).

RESULTS

In Group A, patients with BMI <25 kg/m² were clearly more frequent among PP than among NPP. In Group A with BMI ≥25 kg/m², significant differences were found for TE, PTH and OMM. Significant differences were found between 0 and 1/2/3 for number of factors. Results generated from Group A were validated in Group B.

Clinical Predictors of Residual Sleep Apnea after Weight Loss Therapy in Obese Adolescents

OBJECTIVE

To investigate clinical factors that could predict residual sleep-disordered breathing (SDB) after weight loss.

STUDY DESIGN

Obese subjects between 10 and 19 years of age were recruited while entering an in-patient weight loss treatment program. All subjects underwent anthropometry and sleep screening using a portable device at baseline and after 4-6 months of therapy. Sleep and International Study of Asthma and Allergies in Childhood questionnaires were completed at baseline.

RESULTS

A total of 339 patients were included. Median age was 15.4 years (10.1-19.1). Body mass index z score at baseline was 2.75 ± 0.42, and 35% of subjects were boys. SDB was present in 32%. After a mean decrease in body mass index z score of 32%, residual SDB was found in 20% of subjects with SDB at baseline. Subjects with more severe SDB (OR 1.18; CI 1.01-1.34; P = .02) and respiratory allergies (OR 7.85; CI 1.20-51.39; P = .03) were at higher risk of developing residual SDB, unlike age, sex, and anthropometric variables.

CONCLUSIONS

Weight loss was successful for treating SDB in 80% of patients. More severe SDB and the presence of respiratory allergies at baseline were associated with a higher risk of residual SDB after weight loss.

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.

Correlation between metabolic syndrome and sleep apnea

The so-called “metabolic syndrome” (MS), constitutes a cluster of metabolic and cardiovascular abnormalities, including fasting glucose, blood pressure, triglycerides, high density lipoprotein cholesterol (HDL-C), and waist circumference that arise from insulin resistance. Obstructive sleep apnea (OSA) syndrome is characterized by recurrent episodes of partial or complete obstruction of the upper airway, involving cessation or significant decreased airflow, with intermittent hypoxemia, frequent arousals from sleep and recurrent oxyhemoglobin desaturations that interfere with normal sleep patterns generating difficulty falling asleep, unrefreshing sleep and loud snoring. The relation between these two entities is known as “Syndrome Z”, and there is no question about the impact of these risk factors on health and disease. This clinical condition presents a growing epidemic Worldwide, affecting approximately 60% of the general population with both MS and OSA due to the constant increase of body mass index in humans. This article presents evidence-based data that focuses on the direct relationship between MS and OSA.

Detection on pharyngeal wall floppiness in patients with nonstructural factor-induced obstructive sleep apnea-hypopnea syndrome: Difference in position detection

OBJECTIVES/HYPOTHESIS

To evaluate changes in pharyngeal wall floppiness (PWF) between patients with obstructive sleep apnea-hypopnea syndrome induced by non-upper-airway structural factors and normal subjects, as well as the clinical significance using acoustic pharyngealmetry technology.

STUDY DESIGN

Cohort study.

METHODS

The obstructive sleep apnea (OSA) group (n = 102) and the normal control group (n = 50) were identified using the Eccovision Acoustic Pharyngometer measuring instrument. The volume of the pharyngeal cavity in the sitting and supine positions during expiration and inspiration was recorded, respectively, and the PWF index in the sitting and supine positions was calculated for further statistical analysis.

RESULTS

PWF in the sitting (P < .001) and supine positions (P < .001) in the OSA group was notably higher than that in the control group. PWF in the supine position in both the OSA group and control group was remarkably higher than that in the sitting position (P < .001, P = .025, respectively). The difference in PWF between the supine and sitting positions (ΔPWF) (PWF_supine-PWF_sit) was distinctly higher than in control group (P < .01). PWF was positively correlated with age (P < .001) but not with body mass index (P > .05).

CONCLUSIONS

PWF, quantified as elevated PWF, is an important nonstructural factor for the pathogenesis of OSA patients. PWF in the supine position can more accurately reflect airway collapsibility in OSA patients. Our pilot study of a novel observation may help us in the choice of proper surgical candidates for OSA procedures.

LEVEL OF EVIDENCE

3b Laryngoscope, 128:2200-2205, 2018.

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.

Three-dimensional photography for the evaluation of facial profiles in obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Craniofacial structure is an important determinant of obstructive sleep apnoea (OSA) syndrome risk. Three-dimensional stereo-photogrammetry (3dMD) is a novel technique which allows quantification of the craniofacial profile. This study compares the facial images of OSA patients captured by 3dMD to three-dimensional computed tomography (3-D CT) and two-dimensional (2-D) digital photogrammetry. Measurements were correlated with indices of OSA severity.

METHODS

Thirty-eight patients diagnosed with OSA were included, and digital photogrammetry, 3dMD and 3-D CT were performed. Distances, areas, angles and volumes from the images captured by three methods were analysed.

RESULTS

Almost all measurements captured by 3dMD showed strong agreement with 3-D CT measurements. Results from 2-D digital photogrammetry showed poor agreement with 3-D CT. Mandibular width, neck perimeter size and maxillary volume measurements correlated well with the severity of OSA using all three imaging methods. Mandibular length, facial width, binocular width, neck width, cranial base triangle area, cranial base area 1 and middle cranial fossa volume correlated well with OSA severity using 3dMD and 3-D CT, but not with 2-D digital photogrammetry.

CONCLUSION

3dMD provided accurate craniofacial measurements of OSA patients, which were highly concordant with those obtained by CT, while avoiding the radiation associated with CT.

Prevalence of sleep-disordered breathing in Japanese medical students based on type-3 out-of-center sleep test

BACKGROUND

Sleep-disordered breathing (SDB), especially obstructive sleep apnea disorder (OSA), is thought to mainly affect men over the age of 40. Following findings that Asian people are more likely to experience severe OSA, regardless of obesity, we investigated the prevalence of SDB and OSA in a larger sample and in more younger age groups than those described in previous reports.

METHODS

Between 2011 and 2016, 487 medical students (358 males, mean age 24.8 ± 1.9 years; 129 females: mean age 23.8 ± 1.6 years) underwent an out-of-center sleep test using a type-3 portable monitor. The results were analyzed visually.

RESULTS

The mean ± standard deviation of the respiratory event index (REI: events/hour of monitoring) was 5.4 ± 6.7 (6.7 ± 7.5 in male participants, 2.6 ± 2.1 in female participants). There were 170 participants (36.6%) with an REI≥5, including 158 male participants (46.9%) and 12 female participants (9.1%). SDB or undefined OSA with low REI (15 > REI≥5) was observed in 141 participants (30.4%), defined OSA with moderate REI (30 > REI≥15) in 19 participants (4.1%), and defined OSA with high REI (REI≥30) in 10 participants (2.2%). Among the male students, 129 had low REI (38.3%), 19 had moderate REI (5.6%), and 10 had high REI (3.0%). All female participants with OSA events (9.4%) had a low REI.

CONCLUSIONS

The prevalence of OSA in Japanese young adults, especially males under 30 years old, is similar or even higher than that in older age groups described previously. Thus, an aggressive sleep study for SDB might be necessary for the younger generation in the Asian population.

Application of Personalized, Predictive, Preventative, and Participatory (P4) Medicine to Obstructive Sleep Apnea. A Roadmap for Improving Care?

Dr. Leroy Hood promotes a paradigm to advance medical care that he calls P4 medicine. The four Ps are: personalized, predictive, preventative, and participatory. P4 medicine encourages a convergence of systems medicine, the digital revolution, and consumer-driven healthcare. Might P4 medicine be applicable to obstructive sleep apnea (OSA)? OSA should be personalized in that there are different structural and physiological pathways to disease. Obesity is a major risk factor. The link between obesity and OSA is likely to be fat deposits in the tongue compromising the upper airway. Clinical features at presentation also vary between patients. There are three distinct subgroups: (1) patients with a primary complaint of insomnia, (2) relatively asymptomatic patients with a high prevalence of cardiovascular comorbidities, and (3) excessively sleepy patients. Currently, there have been limited efforts to identify subgroups of patients on the basis of measures obtained by polysomnography. Yet, these diagnostic studies likely contain considerable predictive information. Likewise, there has currently been limited application of -omic approaches. Determining the relative role of obesity and OSA for particular consequences is challenging, because they both affect the same molecular pathways. There is evidence that the effects of OSA are modified by the level of obesity. These insights may lead to improvements in predicting outcomes to personalized therapies. The final P-participatory-is ideally suited to OSA, with technology to obtain extensive data remotely from continuous positive airway pressure machines. Providing adherence data directly to patients increases their use of continuous positive airway pressure. Thus, the concept of P4 medicine is very applicable to obstructive sleep apnea and can be the basis for future research efforts.

Obstructive sleep apnea: current perspectives

The prevalence of obstructive sleep apnea (OSA) continues to rise. So too do the health, safety, and economic consequences. On an individual level, the causes and consequences of OSA can vary substantially between patients. In recent years, four key contributors to OSA pathogenesis or "phenotypes" have been characterized. These include a narrow, crowded, or collapsible upper airway "anatomical compromise" and "non-anatomical" contributors such as ineffective pharyngeal dilator muscle function during sleep, a low threshold for arousal to airway narrowing during sleep, and unstable control of breathing (high loop gain). Each of these phenotypes is a target for therapy. This review summarizes the latest knowledge on the different contributors to OSA with a focus on measurement techniques including emerging clinical tools designed to facilitate translation of new cause-driven targeted approaches to treat OSA. The potential for some of the specific pathophysiological causes of OSA to drive some of the key symptoms and consequences of OSA is also highlighted.

Obstructive sleep apnoea and the role of tongue reduction surgery in children with Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome (BWS) is a rare paediatric overgrowth disorder. Associated macroglossia is a feature of many children with BWS and is felt to be a risk factor for obstructive sleep apnoea (OSA). Sleep-disordered breathing is highly variable in this population. The relationship between degree of macroglossia or other genotypic or phenotypic factors and OSA severity has not been established. The natural history of OSA in this population is unknown; a variety of conservative and surgical therapies have been used to treat OSA in children with BWS but none have been studied systematically. Tongue reduction is the mainstay of surgical therapy for macroglossia associated with BWS, but limited data are available regarding its efficacy in treating OSA or its effect on speech and swallowing. More research is needed to better identify which children with BWS are at risk for OSA and the most effective treatment for these patients.

Obstructive Sleep Apnea in Women: Study of Speech and Craniofacial Characteristics

Background

Obstructive sleep apnea (OSA) is a common sleep disorder characterized by frequent cessation of breathing lasting 10 seconds or longer. The diagnosis of OSA is performed through an expensive procedure, which requires an overnight stay at the hospital. This has led to several proposals based on the analysis of patients’ facial images and speech recordings as an attempt to develop simpler and cheaper methods to diagnose OSA.

Objective

The objective of this study was to analyze possible relationships between OSA and speech and facial features on a female population and whether these possible connections may be affected by the specific clinical characteristics in OSA population and, more specifically, to explore how the connection between OSA and speech and facial features can be affected by gender.

Methods

All the subjects are Spanish subjects suspected to suffer from OSA and referred to a sleep disorders unit. Voice recordings and photographs were collected in a supervised but not highly controlled way, trying to test a scenario close to a realistic clinical practice scenario where OSA is assessed using an app running on a mobile device. Furthermore, clinical variables such as weight, height, age, and cervical perimeter, which are usually reported as predictors of OSA, were also gathered.

Acoustic analysis is centered in sustained vowels. Facial analysis consists of a set of local craniofacial features related to OSA, which were extracted from images after detecting facial landmarks by using the active appearance models. To study the probable OSA connection with speech and craniofacial features, correlations among apnea-hypopnea index (AHI), clinical variables, and acoustic and facial measurements were analyzed.

Results

The results obtained for female population indicate mainly weak correlations (r values between .20 and .39). Correlations between AHI, clinical variables, and speech features show the prevalence of formant frequencies over bandwidths, with F2/i/ being the most appropriate formant frequency for OSA prediction in women. Results obtained for male population indicate mainly very weak correlations (r values between .01 and .19). In this case, bandwidths prevail over formant frequencies. Correlations between AHI, clinical variables, and craniofacial measurements are very weak.

Conclusions

In accordance with previous studies, some clinical variables are found to be good predictors of OSA. Besides, strong correlations are found between AHI and some clinical variables with speech and facial features. Regarding speech feature, the results show the prevalence of formant frequency F2/i/ over the rest of features for the female population as OSA predictive feature. Although the correlation reported is weak, this study aims to find some traces that could explain the possible connection between OSA and speech in women. In the case of craniofacial measurements, results evidence that some features that can be used for predicting OSA in male patients are not suitable for testing female population.

Magnetic resonance imaging of the upper airway in patients with quadriplegia and obstructive sleep apnea

The aim of this study was to investigate upper airway anatomy in quadriplegics with obstructive sleep apnea. Fifty subjects were recruited from three hospitals in Australia: people with quadriplegia due to spinal cord injury and obstructive sleep apnea (n = 11), able-bodied people with obstructive sleep apnea (n = 18), and healthy, able-bodied controls (n = 19). All underwent 3-Tesla magnetic resonance imaging of their upper airway. A subgroup (n = 34) received a topical vasoconstrictor, phenylephrine and post-phenylephrine magnetic resonance imaging. Mixed-model analysis indicated no significant differences in total airway lumen volume between the three groups (P = 0.086). Spinal cord injury-obstructive sleep apnea subjects had a significantly larger volume of soft palate (P = 0.020) and retroglossal lateral pharyngeal walls (P = 0.043) than able-bodied controls. Able-bodied-obstructive sleep apnea subjects had a smaller mandible volume than spinal cord injury-obstructive sleep apnea subjects and able-bodied control subjects (P = 0.036). No differences were seen in airway length between groups when controlling for height (P = 0.055). There was a marginal increase in velopharyngeal volume across groups post-phenylephrine (P = 0.050), and post hoc testing indicated the difference was confined to the able-bodied-obstructive sleep apnea group (P < 0.001). No other upper airway structures showed significant changes with phenylephrine administration. In conclusion, people with obstructive sleep apnea and quadriplegia do not have a structurally smaller airway than able-bodied subjects. They did, however, have greater volumes of soft palate and lateral pharyngeal walls, possibly due to greater neck fat deposition. The acute response to upper airway topical vasoconstriction was not enhanced in those with obstructive sleep apnea and quadriplegia. Changes in upper airway anatomy likely contribute to the high incidence in obstructive sleep apnea in quadriplegic subjects.

Identification of significant obstructive sleep apnoea in the obese patient: development of the novel DX-OSA score

BACKGROUND AND OBJECTIVES

There is a high prevalence of undiagnosed obstructive sleep apnoea (OSA) in obese surgical patients. We investigated the extent to which anthropometric measurements can be used to identify the presence of significant OSA (Apnoea/Hypopnoea Index (AHI) ≥ 20) in adult patients.

MATERIALS AND METHODS

We prospectively studied 1357 adult patients scheduled for elective laparoscopic bariatric surgery. Prior to surgery, body mass index (BMI), gender, neck circumference, STOP-Bang score, SpO₂, neck and trunk fat (by dual X-ray absorptiometry) were recorded. All patients with a STOP-Bang score ≥ 5 underwent polysomnography. Auto-titrated Positive Airway Pressure (APAP) therapy was instituted when AHI ≥ 20/h. Predictors of OSA were identified and their cut-off values determined.

RESULTS

In total, 1357 patients were screened; 345 patients underwent preoperative polysomnography; 190 had AHI ≥ 20/h and received APAP treatment. The novel Dual X-Ray-Obstructive Sleep Apnoea (DX-OSA) score was derived from the data. The score included 6 items: the STOP-Bang score, BMI, neck fat, trunk fat, baseline SpO₂, and Expiratory Reserve Volume (ERV), and its sensitivity, specificity, positive-predictive values, negative-predictive values, likelihood ratios, and post-test probabilities determined. At a cut-off of 3, the DX-OSA score had the same sensitivity as the STOP-bang score, but better specificity. The lowest likelihood ratio was found for STOP-Bang and the highest for the DX-OSA score (OSA probability > 83%).

CONCLUSION

The DX-OSA score may be useful for identifying obese patients with significant OSA who require CPAP (continuous positive airway pressure) treatment, and CPAP could be commenced without the need for polysomnography, therefore, without delaying surgery.

Obstructive sleep apnea: in search of precision

Introduction

Obstructive sleep apnea (OSA) is a highly prevalent condition that is viewed as a major global health concern, while affecting approximately 10% of the middle-aged population. OSA is a chronic disease that has been conclusively associated with poor quality of life, cognitive impairments and mood alterations, enhanced cardiovascular and metabolic morbidity, thereby leading to marked increments in healthcare costs.

Areas covered

The authors have reviewed the current evidence on the pathophysiology of OSA and its consequences, the heterogeneity of its phenotypic expression, the current therapeutic applications and their efficacy, and the implications for diagnosis, treatment and follow-up strategies in the context of the clinical management of OSA.

Expert commentary

Personalized medicine in OSA identifies different needs and approaches: i) phenotyping and defining the different and segregated clusters of OSA patients whose recognition may improve prognostic predictions and guide therapeutic strategies; ii) to further characterize and predict the impact of OSA and its treatment, particularly revolving around mortality and the processes closely related to ageing (cardiovascular diseases, cancer and neurocognitive diseases); iii) the introduction of new technologies including telemedicine that have shown promise in the implementation of personalized medicine approaches.

Historia del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS)

La historia de la apnea obstructiva del sueño es larga y complicada desde sus primeras descripciones en el siglo XIX con el relato de Pickwick en la primera novela de Charles Dickens. La definición de este término por parte de diferentes investigadores resalta la importancia de comprender las entidades asociadas al síndrome, como la hipoventilación alveolar y la somnolencia diurna excesiva. De esta forma, los estudios neurofisiológicos adelantados desde entonces, el desarrollo de la conferencia de la sociedad europea de neurología de 1964, la descripción del síndrome en pacientes pediátricos, la confirmación de la comorbilidad cardiovascular asociada a la enfermedad, la traqueostomía como tratamiento y la creación de implantes de estimuladores del nervio hipogloso —pasando por el descubrimiento de Sullivan de la presión positiva como tratamiento en casa— han sido esenciales para la comprensión de este síndrome.

Electrical stimulation for the treatment of obstructive sleep apnoea: a review of the evidence

INTRODUCTION

Obstructive sleep apnoea is an increasingly prevalent clinical condition with significant impact on individuals and public health. Continuous positive airway pressure therapy is the standard treatment, but adherence is limited and alternative treatments are needed. In this context, non-invasive and invasive methods for the electrical stimulation of upper airway dilator muscles have been demonstrated to be effective in selected patients. Areas covered: This review will cover investigations on the clinical effects, safety, and tolerability of non-invasive and invasive electrical stimulation of the upper airway for the management of obstructive sleep apnoea. Following a search of the relevant literature published on PubMed this review is focused mainly on data obtained from randomized clinical trials and clinical studies. Expert commentary: The available evidence provides a rationale to consider upper airway electrical stimulation as treatment for selected patients with obstructive sleep apnoea, who have poor adherence or experience difficulties with continuous positive airway pressure therapy. Non-invasive stimulation using transcutaneous electrodes and implantable hypoglossal nerve stimulator technologies may provide an alternative to continuous positive airway pressure for the treatment of obstructive sleep apnoea via restoration of neuromuscular tone and improved upper airway patency.

Sleep-disordered breathing in heart failure: facts and numbers

Sleep‐disordered breathing has a high prevalence in the general population, but is especially prominent in patients with heart failure (HF). HF and sleep‐disordered breathing share a bidirectional relationship, with sleep‐disordered breathing being both cause and effect of poor cardiac functioning. The high inter‐individual variability of symptom presentation can impede the clinical diagnostic process. Polysomnography is the gold‐standard method of diagnosing sleep‐disordered breathing. Therapy of sleep‐disordered breathing should always consist of optimizing the treatment of the underlying disorder of HF. Additional therapeutic measures include continuous positive airway pressure ventilation therapy. New therapeutic options using neurostimulation are yielding promising results; however, long‐term benefits still need to be confirmed.

Understanding Phenotypes of Obstructive Sleep Apnea: Applications in Anesthesia, Surgery, and Perioperative Medicine

Obstructive sleep apnea (OSA) is a prevalent sleep-disordered breathing with potential long-term major neurocognitive and cardiovascular sequelae. The pathophysiology of OSA varies between individuals and is composed of different underlying mechanisms. Several components including the upper airway anatomy, effectiveness of the upper airway dilator muscles such as the genioglossus, arousal threshold of the individual, and inherent stability of the respiratory control system determine the pathogenesis of OSA. Their recognition may have implications for the perioperative health care team. For example, OSA patients with a high arousal threshold are likely to be sensitive to sedatives and narcotics with a higher risk of respiratory arrest in the perioperative period. Supplemental oxygen therapy can help to stabilize breathing in OSA patients with inherent respiratory instability. Avoidance of supine position can minimize airway obstruction in patients with a predisposition to upper airway collapse in this posture. In this review, the clinically relevant endotypes and phenotypes of OSA are described. Continuous positive airway pressure (CPAP) therapy is the treatment of choice for most patients with OSA but tolerance and adherence can be a problem. Patient-centered individualized approaches to OSA management will be the focus of future research into developing potential treatment options that will help decrease the disease burden and improve treatment effectiveness.

From oral facial dysfunction to dysmorphism and the onset of pediatric OSA

The upper airway is a collapsible tube, and its collapsibility increases during sleep. Extrinsic factors such as atypical craniofacial features may increase the risks of airway collapse. We review early development of oral-facial structures and the anatomical variants that may be present at birth and can impact nasal breathing. After birth, there is a continuous interaction between orofacial functions and growth of anatomic features. We review the dysfunctions identified to date that may impact orofacial development leading to sleep-disordered-breathing through changes in the orofacial growth. The identification of risk-factors, ultimately leading to full-blown obstructive sleep apnea, may allow early recognition of these factors and the development of treatments to eliminate early problems or at least decrease their impact.

The efficacy of continuous positive airway pressure therapy in reducing cardiovascular events in obstructive sleep apnea: a systematic review

Prospective studies show an association between obstructive sleep apnea and cardiovascular disease. Continuous positive airway pressure (CPAP) is the treatment of choice and effectively reduces subjective sleepiness and apneic and hypopneic events. However, randomized trials have not shown a reduction in cardiovascular outcomes with CPAP therapy. We review the past 10 years of randomized trial evidence regarding the therapeutic efficacy of CPAP on cardiovascular outcomes and mortality in adults with obstructive sleep apnea. The majority of studies found no significant improvement in cardiovascular outcomes with CPAP, although many noted nonsignificant benefits. Adjusted analysis in several trials showed significant cardiovascular benefit in those patients with higher CPAP compliance. Existing trials may lack sufficient follow-up and CPAP compliance, among other limitations.

Soluble (Pro)renin Receptor and Obstructive Sleep Apnea Syndrome: Oxidative Stress in Brain?

(Pro)renin receptor ((P)RR) is a multi-functional molecule that is related to both the renin-angiotensin system (RAS) and vacuolar H⁺-ATPase (v-ATPase), an ATP-dependent multi-subunit proton pump. Soluble (P)RR (s(P)RR), which consists of the extracellular domain of (P)RR, is present in blood and urine. Elevated plasma s(P)RR concentrations are reported in patients with chronic kidney disease and pregnant women with hypertension or diabetes mellitus. In addition, we have shown that plasma s(P)RR concentrations are elevated in patients with obstructive sleep apnea syndrome (OSAS). Interestingly, the levels are elevated in parallel with the severity of OSAS, but are not related to the presence of hypertension or the status of the circulating RAS in OSAS. It is known that v-ATPase activity protects cells from endogenous oxidative stress, and loss of v-ATPase activity results in chronic oxidative stress. We hypothesize that hypoxia and subsequent oxidative stress, perhaps in the brain, may be one of the factors that elevate plasma s(P)RR levels in OSAS.

Digital Morphometrics: A New Upper Airway Phenotyping Paradigm in OSA

BACKGROUND

OSA is associated with changes in pharyngeal anatomy. The goal of this study was to objectively and reproducibly quantify pharyngeal anatomy by using digital morphometrics based on a laser ruler and to assess differences between subjects with OSA and control subjects and associations with the apnea-hypopnea index (AHI). To the best of our knowledge, this study is the first to use digital morphometrics to quantify intraoral risk factors for OSA.

METHODS

Digital photographs were obtained by using an intraoral laser ruler and digital camera in 318 control subjects (mean AHI, 4.2 events/hour) and 542 subjects with OSA (mean AHI, 39.2 events/hour).

RESULTS

The digital morphometric paradigm was validated and reproducible over time and camera distances. A larger modified Mallampati score and having a nonvisible airway were associated with a higher AHI, both unadjusted (P < .001) and controlling for age, sex, race, and BMI (P = .015 and P = .018, respectively). Measures of tongue size were larger in subjects with OSA vs control subjects in unadjusted models and controlling for age, sex, and race but nonsignificant controlling for BMI; similar results were observed with AHI severity. Multivariate regression suggests photography-based variables capture independent associations with OSA.

CONCLUSIONS

Measures of tongue size, airway visibility, and Mallampati scores were associated with increased OSA risk and severity. This study shows that digital morphometrics is an accurate, high-throughput, and noninvasive technique to identify anatomic OSA risk factors. Morphometrics may also provide a more reproducible and standardized measurement of the Mallampati score. Digital morphometrics represent an efficient and cost-effective method of examining intraoral crowding and tongue size when examining large populations, genetics, or screening for OSA.

Test-retest repeatability of human speech biomarkers from static and real-time dynamic magnetic resonance imaging

Static anatomical and real-time dynamic magnetic resonance imaging (RT-MRI) of the upper airway is a valuable method for studying speech production in research and clinical settings. The test-retest repeatability of quantitative imaging biomarkers is an important parameter, since it limits the effect sizes and intragroup differences that can be studied. Therefore, this study aims to present a framework for determining the test-retest repeatability of quantitative speech biomarkers from static MRI and RT-MRI, and apply the framework to healthy volunteers. Subjects (n = 8, 4 females, 4 males) are imaged in two scans on the same day, including static images and dynamic RT-MRI of speech tasks. The inter-study agreement is quantified using intraclass correlation coefficient (ICC) and mean within-subject standard deviation (σ_e). Inter-study agreement is strong to very strong for static measures (ICC: min/median/max 0.71/0.89/0.98, σ_e: 0.90/2.20/6.72 mm), poor to strong for dynamic RT-MRI measures of articulator motion range (ICC: 0.26/0.75/0.90, σ_e: 1.6/2.5/3.6 mm), and poor to very strong for velocities (ICC: 0.21/0.56/0.93, σ_e: 2.2/4.4/16.7 cm/s). In conclusion, this study characterizes repeatability of static and dynamic MRI-derived speech biomarkers using state-of-the-art imaging. The introduced framework can be used to guide future development of speech biomarkers. Test-retest MRI data are provided free for research use.

Tracheostomy for Severe Pediatric Obstructive Sleep Apnea: Indications and Outcomes

Objectives (1) To describe characteristics of pediatric patients undergoing tracheostomy for obstructive sleep apnea (OSA). (2) To highlight perioperative events and outcomes of the procedure. Study Design Case series with chart review. Setting Four tertiary care academic children's hospitals. Subjects and Methods Twenty-nine children aged <18 years from January 1, 2010, to December 31, 2015, who underwent tracheostomy for severe OSA, defined as an apnea-hypopnea index (AHI) >10, were included in the study. Data on patient characteristics, polysomnographic findings, comorbidities, and perioperative events and outcomes were collected and analyzed. Results Twenty-nine patients were included. Mean age at tracheostomy was 2.0 years (95% CI, -2.2 to 6.2). Mean body mass index z score was -1.2 (95% CI, -4.9 to -2.5). Mean preoperative AHI was 60.2 (95% CI, -15.7 to 136.1). Mean postoperative intensive care unit stay was 23.2 days (95% CI, 1.44-45.0). One procedure was complicated by bronchospasm. Thirteen patients had craniofacial abnormalities; 10 had a neurologic disorder resulting in hypotonia; and 5 had a diagnosis of laryngomalacia. Mean follow-up was 30.6 months (95% CI, -10.4 to 71.6). Six patients were decannulated, with a mean time to decannulation of 40.8 months (95% CI, 7.9-73.7). Five patients underwent capped sleep study prior to decannulation with a mean AHI of 6.6 (95% CI, -9.9 to 23.1) and a mean oxygen nadir of 90.0% (95% CI, 80%-100%). Conclusion OSA is an uncommon indication for tracheostomy in children. Patients who require the procedure usually have an associated syndromic diagnosis resulting in upper airway obstruction. The majority of children who undergo tracheostomy for OSA will remain dependent at 24 months.

Drug-Induced Sleep Endoscopy as a Selection Tool for Surgical Management of Obstructive Sleep Apnoea Syndrome: Our Personal Experience

The role of Drug-induced sleep endoscopy as a selection tool for surgical management of obstructive sleep apnoea syndrome.

SOURCE OF DATA

Polysomnography proved OSA patients, who are planned for surgery in dept. of ENT AND HEAD& NECK, JSS Hospital, Mysore.

STUDY DESIGN

A prospective clinical study.

METHOD

30 Polysomnography proved OSA patients, age between 20 and 60 years have been selected for Drug Induced Sleep Endoscopy (DISE) after taking informed consent for proposed surgery. Inj propofol infusion given throughout the DISE procedure and upper airway nasal endoscopy performed for assessment of site of collapse (Retropalatal, Retrolingual, Hypopharyngral), type of collapse (circumferential, lateral) and severity of obstruction, Lowest SpO₂, apnoeic episodes and DISE findings were recorded. Out of these thirty patients 90% were male and 10% were female, observed that 66.7% of males and 40.7% of females belonged to 31-40 age group, and BMI of 63.3% of patient population were overweight, 20% were obese and 5% were normal. Mean fall in SpO₂ was 90.20 ± 2.77 in normal subjects, 83.05 ± 5.14 in overweight subjects and 68.83 ± 9.11 in obese subjects. Normal subjects had 0.4 ± 0.9 apnoeic episodes, overweight subjects had 0.9 ± 1.6 episodes and obese subjects had 4.0 ± 2 apnoeic episodes. We observed that 40% had retropalatal airway collapse, 23.3% had airway obstruction at the base of the tongue, 20% had airway obstruction with floppy epiglottis, 12% multiple level collapse, 6.7% of patient population had grade 4 enlarged tonsils, 3.3% had lateral pharyngeal wall collapse, and 0% hypopharyngeal collapse. Out of 30, 29 Patients underwent surgery (Expansion sphincter pharyngo plasty-14, Hyoid advancement-4, Uuvulopalatoplasty-10, Epiglottic surgery-6, Zeta pharyngoplasty-2, midline glossectomy-3, Endoscopic septoplasty-5, Inferio turbinoplasty-2, LASSER Assisted lingual tonsillectomy-1), All these 29 patient were followed for 3 months, at the end of 3rd month again Each subject was evaluated with a baseline Epworth Sleepiness Scale and LEVEL-3 PSG, the results were impressive with statistically significant. DISE is a dynamic, safe, and easy-to-perform technique that visualizes, the anatomical sites of snoring or apneas for assessment site of collapse (Retropalatal, Retrolingual, Hypopharyngral), type of collapse (Circumferential, Lateral) and severity of obstruction and guides the design of a tailor-made treatment plan for a OSA SURGEON in individual cases, which will improves perioperative outcome.

Ultrasonographic Detection of Airway Obstruction in a Model of Obstructive Sleep Apnea

Purpose Obstructive sleep apnea (OSA) is a common clinical disorder characterized by repetitive airway obstruction during sleep. The gold standard for diagnosis of OSA, polysomnogram (PSG), cannot anatomically localize obstruction. Precise identification of obstruction has potential to improve outcomes following surgery. Current diagnostic modalities that provide this information require anesthesia, involve ionizing radiation or disrupt sleep. To mitigate these problems, we conceived that ultrasound (US) technology may be adapted (i) to detect, quantify and localize airway obstruction and (ii) for translational application to home-based testing for OSA. Materials and Methods Segmental airway collapse was induced in 4 fresh cadavers by application of negative pressure. Following visualization of airway obstruction, a rotary US probe was used to acquire transcervical images of the airway before and after induction of obstruction. These images (n=800) were analyzed offline using image processing algorithms. Results Our results show that the non-obstructed airway consistently demonstrated the presence of a US air-tissue interface. Importantly, automated detection of the air-tissue interface strongly correlated with manual measurements. The algorithm correctly detected an air-tissue interface in 90% of the US images while incorrectly detecting it in 20% (area under the curve=0.91). Conclusion The non-invasive detection of airway obstruction using US represents a major step in expanding OSA diagnostics beyond PSG. The preliminary data obtained from our model could spur further research in non-invasive localization of obstruction. US offers the benefit of precise localization of the site of obstruction, with potential for improving outcomes in surgical management.

A Practical Approach to the Identification and Management of Sleep-Disordered Breathing in Heart Failure Patients

Sleep-disordered breathing (SDB) is a major health problem affecting much of the general population. Although SDB is responsible for rapid progression of heart failure (HF) and the worsening morbidity and mortality, advanced HF state is associated with accelerated development of SDB. In the face of recent developments in SDB treatment and availability of effective therapeutic options known to improve quality of life, exercise tolerance, and heart function, most HF patients with SDB are left unrecognized and untreated. This article provides an overview of SDB in HF with focus on practical approaches intended to facilitate screening and treatment.

Velopharyngeal mucosal surface topography in healthy subjects and subjects with obstructive sleep apnea

Macroscopic pharyngeal anatomical abnormalities are thought to contribute to the pathogenesis of upper airway (UA) obstruction in obstructive sleep apnea (OSA). Microscopic changes in the UA mucosal lining of OSA subjects are reported; however, the impact of these changes on UA mucosal surface topography is unknown. This study aimed to 1) develop methodology to measure UA mucosal surface topography, and 2) compare findings from healthy and OSA subjects. Ten healthy and eleven OSA subjects were studied. Awake, gated (end expiration), head and neck position controlled magnetic resonance images (MRIs) of the velopharynx (VP) were obtained. VP mucosal surfaces were segmented from axial images, and three-dimensional VP mucosal surface models were constructed. Curvature analysis of the models was used to study the VP mucosal surface topography. Principal, mean, and Gaussian curvatures were used to define surface shape composition and surface roughness of the VP mucosal surface models. Significant differences were found in the surface shape composition, with more saddle/spherical and less flat/cylindrical shapes in OSA than healthy VP mucosal surface models (P < 0.01). OSA VP mucosal surface models were also found to have more mucosal surface roughness (P < 0.0001) than healthy VP mucosal surface models. Our novel methodology was utilized to model the VP mucosal surface of OSA and healthy subjects. OSA subjects were found to have different VP mucosal surface topography, composed of increased irregular shapes and increased roughness. We speculate increased irregularity in VP mucosal surface may increase pharyngeal collapsibility as a consequence of friction-related pressure loss.NEW & NOTEWORTHY A new methodology was used to model the upper airway mucosal surface topography from magnetic resonance images of patients with obstructive sleep apnea and healthy adults. Curvature analysis was used to analyze the topography of the models, and a new metric was derived to describe the mucosal surface roughness. Increased roughness was found in the obstructive sleep apnea vs. healthy group, but further research is required to determine the functional effects of the measured difference on upper airway airflow mechanics.

Real-time multislice MRI during continuous positive airway pressure reveals upper airway response to pressure change

PURPOSE

To determine if a real-time magnetic resonance imaging (RT-MRI) method during continuous positive airway pressure (CPAP) can be used to measure neuromuscular reflex and/or passive collapsibility of the upper airway in individual obstructive sleep apnea (OSA) subjects.

MATERIALS AND METHODS

We conducted experiments on four adolescents with OSA and three healthy controls, during natural sleep and during wakefulness. Data were acquired on a clinical 3T scanner using simultaneous multislice (SMS) RT-MRI during CPAP. CPAP pressure level was alternated between therapeutic and subtherapeutic levels. Segmented airway area changes in response to rapid CPAP pressure drop and restoration were used to estimate 1) upper airway loop gain (UALG), and 2) anatomical risk factors, including fluctuation of airway area (FAA).

RESULTS

FAA significantly differed between OSA patients (2-4× larger) and healthy controls (Student's t-test, P < 0.05). UALG and FAA measurements indicate that neuromuscular reflex and passive collapsibility varied among the OSA patients, suggesting the presence of different OSA phenotypes. Measurements had high intrasubject reproducibility (intraclass correlation coefficient r > 0.7).

CONCLUSION

SMS RT-MRI during CPAP can reproducibly identify physiological traits and anatomical risk factors that are valuable in the assessment of OSA. This technique can potentially locate the most collapsible airway sites. Both UALG and FAA possess large variation among OSA patients.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1400-1408.