Diagnostic Studies in Obstructive Sleep Apnea

Comparative study of anatomical features of primary and accessory maxillary ostia between patients with obstructive sleep apnea and healthy controls

PURPOSE

The purpose of this study was to examine how the size and shape of the maxillary sinus and its ostia (the primary maxillary ostium and accessory maxillary ostium) relate to each other in patients with OSA using computed tomography (CT) scans. Additionally, the study aimed to explore whether or not obstructive sleep apnea (OSA) had an effect on these structures.

METHODS

CT images of patients diagnosed with OSAS and healthy participants were evaluated to compare the patency, location, dimension, and presence of PMOs and AMOs using the Mann-Whitney U, Student t, and chi-square tests. Also, intragroup correlations were analyzed by Spearman's correlation test.

RESULTS

Among 139 patients with OSA and healthy controls, there were significant variations in the average length (p = 0.001) and width (p = 0.008) of PMOs among the study groups. The mean maxillary sinus volume was significantly decreased in the OSA group (p = 0.001). A significant decrease in the maxillary sinus volume was observed in the OSA group (p = 0.001). In the OSA group, a significant correlation was observed between PMO obstruction and the presence of AMO (p = 0.004). The healthy group had significant correlations (r = 0.755, p = 0.000) between the vertical height and the distance between PMO and the maxillary sinus floor. Correlation analyses revealed positive, strong correlations between study variables such as the mean length and width of AMO and the vertical height of the maxillary sinus (r = 0.566, p = 0.000) in the OSA group.

CONCLUSIONS

The current study indicated significant differences in sinus volume, PMO occlusion, and AMO-related dimensions between patients with OSA and healthy controls.

Identification of Patients at Risk of Obstructive Sleep Apnea in Dental Settings

Objectives This study aims to assess the risk of obstructive sleep apnea (OSA) in the Saudi Arabian population at a dental hospital using the Berlin Questionnaire (BQ) and investigate the association of gender, age, neck circumference, systolic blood pressure (SBP), diastolic blood pressure (DBP), and smoking habits with the risk of OSA. Methodology Participants were recruited through random selection from walk-in patients aged between 18 and 80 years. BQ was used to screen for OSA. In addition, age, gender, smoking habits, neck circumference, and blood pressure were collected. Data were analyzed using descriptive statistics, Student's t-test, and chi-square test. Results In this study, 55 participants were screened for OSA using BQ. Of the participants, 44 (80%) were considered to be at low risk of OSA. Age, neck circumference, BMI, SBP, and DBP were statistically significantly associated with high risk of OSA (P < 0.05). Age and neck circumference were found to be statistically significant predictors of OSA, even after controlling for gender and smoking status (P < 0.05). Conclusions BQ is a reliable tool for assessing the risk of OSA in the Saudi Arabian population. Age, neck circumference, BMI, SBP, and DBP are all significant factors of OSA, while age and neck circumference are significant predictors of OSA. Dental practitioners can play a valuable role in the early detection and referral of patients at high risk of OSA.

Decreased maxillary sinus volume is a potential predictor of obstructive sleep apnea

OBJECTIVES

To investigate the associations between nasal airway volume and the presence and severity of obstructive sleep apnea (OSA) in adults.

MATERIALS AND METHODS

The medical records of adult patients who visited the sleep clinic at University Hospital between June 2013 and April 2017 and underwent overnight polysomnography for the diagnosis of obstructive sleep apnea were reviewed retrospectively. Using computed tomography, the volumes of the nasal airways and maxillary sinuses were measured, and associations with the presence and severity of OSA were analyzed while controlling for the effects of possible confounders such as lateral cephalometric variables, maxillary widths, tongue/hyoid position, and soft palate dimensions.

RESULTS

Comparison between normal subjects and patients with OSA revealed that the latter had decreased ratios of maxillary sinus volume to whole nasal airway volume (P = .029) than normal subjects. OSA severity was greater in those with inferior positions of the hyoid (P = .010), in older patients (P = .011), and in those with high body mass index (P = .001). The volume of the total nasal airway or maxillary sinuses were not associated with OSA severity.

CONCLUSIONS

A decreased ratio of maxillary sinus volume to whole nasal airway volume is associated with adult OSA. However, OSA severity is not associated with either maxillary sinus volume or whole nasal airway volume.

Parapharyngeal fat pad area at the subglosso-supraglottic level is associated with corresponding lateral wall collapse and apnea-hypopnea index in patients with obstructive sleep apnea: a pilot study

The aim of this study was to assess associations between fat pad areas at various anatomic levels and the sites of lateral wall collapse and disease severity in adult patients with obstructive sleep apnea (OSA). Forty-one patients with OSA who prospectively underwent drug-induced sleep computed tomography were included. Areas of parapharyngeal fat pads and degrees of lateral wall collapse at three representative anatomic levels (nasopharynx, oropharynx, and subglosso-supraglottis), and apnea-hypopnea index (AHI) were measured. In the subglosso-supraglottic region, the parapharyngeal fat pad area in 17 (41%) patients with complete lateral wall collapse was significantly larger than that in 24 (59%) patients without complete collapse (median, 236.0 mm² vs 153.0 mm²; P = 0.02). In multivariate regression analysis, the parapharyngeal fat pad area at the subglosso-supraglottic level (β = 0.02; P = 0.01) and body mass index (β = 3.24; P = 0.01) were independently associated with AHI. Our preliminary results supported that parapharyngeal fat pads at the subglosso-supraglottic level may be involved in the development of lateral wall collapse and then determine the severity of OSA. Further studies are warranted to investigate the effect of reducing parapharyngeal fat pads in the treatment of OSA.

Submental Ultrasonographic Parameters among Patients with Obstructive Sleep Apnea

Objective

This study aimed to determine the value of submental ultrasonography (US) parameters for diagnostic workup among patients with obstructive sleep apnea (OSA) and to determine whether there is a correlation between US findings and the severity of OSA.

Study Design

Cross-sectional analysis.

Setting

Tertiary education hospital.

Subjects and Methods

The study included 147 patients with suspected OSA who underwent submental US to evaluate various parameters following overnight polysomnography. US findings were compared with the apnea-hypopnea index and other parameters.

Results

All US parameters, except for subcutaneous tissue thickness, were significantly different among patients with OSA. Of note, distance between lingual arteries (DLA), geniohyoid muscle thickness (GMT), and lateral parapharyngeal wall thickness (LPWT) were significantly greater in the patients with severe OSA than those with mild and moderate OSA ( P < .001). GMT had the strongest correlation with OSA ( r = 0.419, P < .001); LPWT and DLA also had high correlation coefficient values ( r = 0.343, P < .001, and r = 0.342, P < .001, respectively). Stepwise regression analysis showed that GMT (beta = 0.243, P = 0.004), LPWT (beta = 0.236, P = 0.004), and DLA (beta = 0.204, P = 0.008) were the most significant factors for predicting the severity of OSA according to the apnea-hypopnea index.

Conclusion

Submental US can be used to determine whether there is a correlation between US findings and severity of OSA. GMT could be considered a novel parameter for determining the severity of OSA.

Safety and efficacy of drug-induced sleep endoscopy using a probability ramp propofol infusion system in patients with severe obstructive sleep apnea

BACKGROUND

Drug-induced sleep endoscopy (DISE) uses sedative-hypnotics to induce moderate obstruction in sleep apnea patients, thereby facilitating anatomic assessment of obstructive physiology. Implementation of DISE with propofol requires a dosing strategy that reliably and efficiently produces obstruction while minimizing oxygen desaturation.

METHODS

The surgeon in a prospective study of transoral robotic resection of the tongue base enrolled 97 patients with obstructive sleep apnea confirmed by polysomnography who failed continuous positive airway pressure. All patients were screened by DISE. Propofol dose was determined using custom software written in MATLAB, which has been previously described. Studies were performed in an operating room with standard monitors and resuscitation equipment. No topical anesthesia was used, and no IV drugs other than propofol were used. All patients received 2 L/min supplemental oxygen via a nasal cannula placed in the mouth. After initiation of propofol sedation, a pediatric bronchoscope was positioned via the naris to observe the velopharynx. The sedation sequence was continued until the clinical end point of obstruction onset was noted. Observation of the pharynx was performed for a sufficient period to obtain images of the anatomic site(s) of obstruction. The infusion was then terminated. Statistical analysis was performed with MATLAB (MathWorks, version 2012b). Comparison of saturation nadirs between DISE and subject sleep studies was performed with both the paired and unpaired Student t test.

RESULTS

The subject population was characterized by a median body mass index of 32.1 (interquartile range [IQR] 6.8) kg/m and apnea-hypopnea index of 48 (IQR 32). All patients demonstrated obstruction within the design variables. Obstruction was observed after 236 (±57.9) seconds at an estimated effect-site concentration of 4.2 ± 1.3 mcg/mL. The median saturation nadir during DISE was significantly higher (91.4% (IQR 5.1)) than that during standard sleep studies (81.0% [IQR 11.2], P < 0.0001). Ninety-five percent confidence intervals for correlations between DISE saturation nadir and body mass index, age, apnea-hypopnea index, or administered propofol dose included zero in all cases.

CONCLUSIONS

A propofol infusion strategy that requires limited experience with propofol dose selection and only 1 pump dosing change reliably produced airway obstruction in patients with severe sleep apnea. Clinical obstruction was achieved faster than target-controlled infusion-based systems for similar procedures reported in the literature. The observed degree of oxygen desaturation in the model system was within a clinically acceptable range.

Dynamics of upper airways during the Müller maneuver in healthy subjects: a cine MRI study

The Müller maneuver has been widely applied to mimic the pathophysiological condition of obstructive sleep apnea (OSA) during wakefulness. We applied cine MRI to elucidate dynamics of the upper airway during the Müller maneuver in healthy subjects (n = 7). Three sets of images (during quiet nose breathing, quiet mouth breathing, and Müller maneuver) were recorded on sagittal midline plane together with impedance pneumography. The position of the tongue root changed during a respiratory cycle when subjects breathed quietly. At the early inspiratory phase the tongue root moved forward and upward, the retroglossal airway size increased toward the middle of inspiration, and the airway size became smaller again toward the end of inspiration. During expiration the airway size became further smaller. When the subject performed the Müller maneuver, the movement of the oropharynx and its narrowing were greater than those of the velopharynx. However, the airway was not completely obstructed. A relatively large morphological change was observed in the retropalatal and retroglossal regions with the backward and downward motion of the tongue root and flattening of the tongue shape during the Müller maneuver. Although patterns of upper airway narrowing and tongue shape alterations were variable among subjects, upper airway narrowing was commonly prominent in the retroglossal area. Cine MRI with the Müller maneuver enables to visualize the upper airway dynamics and could be easily applied to evaluate upper airway collapsibility during wakefulness.

The use of sub-mental ultrasonography for identifying patients with severe obstructive sleep apnea

OBJECTIVE

This study aimed to explore the association between obstructive sleep apnea (OSA) severity and pharyngeal parameters using sub-mental ultrasonography (US), and investigate the accuracy of US for identifying severe OSA patients.

METHODS

One hundred and five consecutive referrals for suspected OSA were enrolled. The diameters of the retro-glossal (RG) and retro-palatal (RP) regions were measured via sub-mental US upon expiration during tidal breathing, forced inspiration, and Müller maneuver (MM). Independent factors associated with severe OSA identified from two-thirds of randomly-selected patients (model-development group) were used to construct a model for predicting severe OSA. The accuracy of the model was validated in the remaining one-third of patients (validation group).

RESULTS

Fifty severe OSA patients, 30 with mild-moderate OSA, and 25 without OSA were enrolled. Compared to non-OSA and mild-moderate OSA patients, those with severe OSA had narrower RP diameter in all three maneuvers. Using the prediction model constructed with changes of RP diameters at MM and neck circumference, the independent predictors of severe OSA in the model-development group had 100% sensitivity and 65% specificity.

CONCLUSION

Sub-mental US can accurately discriminate the severity of OSA and be used to identify patients with severe OSA.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00674076.

Surgical therapy of obstructive sleep apnea: a review

Obstructive sleep apnea (OSA) is a disease characterized by intermittent and repetitive narrowing of the airway during sleep. Surgical therapies for the treatment of OSA aim to improve airway patency by addressing selected site(s) of obstruction. Because several areas may each be responsible for the narrowing, different surgical modalities have also been developed. In this review, we give an overview of surgery for each of potential obstruction site(s). As a consequence of the multi-factorial and heterogeneous etiology of OSA, surgical therapies need to be selected and performed specifically for each patient, as there is no perfect surgery that will fit all patients. As with any other treatment modalities for OSA, surgical therapies have variable efficacy, but are a very important tool on OSA management in selected patients and have been shown effectiveness in decreasing the morbidity and mortality associated with the disease.

Evaluation and management of pediatric obstructive sleep apnea beyond tonsillectomy and adenoidectomy

PURPOSE OF REVIEW

There is an increasing percentage of children with persistent obstructive sleep apnea (OSA) after removal of the tonsils and adenoids (T&A). Although sleep apnea has been an active area of research and treatment in the adult population, our awareness of this problem in children is still in its initial stages. In addition, therapies to successfully treat this residual OSA are still not fully established. It is important to develop evaluation and management protocols for these children.

RECENT FINDINGS

This review will discuss risk factors associated with persistent OSA after T&A and techniques to evaluate the pediatric airway in order to identify the site, or sites, of obstruction. Various medical and surgical options are presented.

SUMMARY

Clinicians need to be aware of the potential for persistent sleep disordered breathing and OSA in children, despite previous T&A. Evaluation protocols and techniques will differ in children, due to limitations in their cooperation during the physical examination. Alternative methods, such as airway endoscopy and cine MRI, are presented. Medical and surgical options are presented. Outcomes data for pediatric populations are rare. Multilevel, single stage surgery has a higher risk for oropharyngeal stenosis in children compared with adults and conservative, multistage approaches may be more appropriate.

Quantification of retropalatal region in obstructive sleep apnea

OBJECTIVE

Flexible optic laryngoscopy (FOL) allows us to visualize the obstructive sleep apnea (OSA)-related airway passages. However, objective data presenting evidence of OSA through this perspective are lacking. The aim of this study was to quantify the surface area of the retropalatal region in control subjects and OSA patients utilizing FOL images. This was a prospective, case-control study. The study was performed at the otolaryngology department of a university hospital.

SUBJECTS AND METHODS

Sixty-seven OSA patients in group 1 and 87 patients with no complaints of OSA in group 2 were evaluated. Retropalatal region photographs were captured at the base of uvula through endoscopic images. The retropalatal surface area (RPSA) was measured using AutoCAD. Groups 1 and 2 RPSA measurements were analyzed. The RPSA measurements of subgroups in group 1 were analyzed to document severity of OSA.

RESULTS

Mean RPSA measurements in group 1 was 73.21 (SD, 31.99), and that in group 2 was 129.31 (SD, 26.54), respectively. Retropalatal surface area is significantly larger in group 2 when compared with group 1 (P = 0.0001). Twenty-four patients had mild (mean respiratory disturbance index [RDI], 10.83 [SD, 3.63], 26 had moderate (mean RDI, 20.9 [SD, 4.14]), and 17 had severe OSA (mean RDI, 52.13 [SD, 17.24]) in group 1. The mean RPSA measurements are 72.48 (SD, 28.9) in mild subgroup, 73.88 (SD, 30.5) in moderate subgroup, and 73.22 (SD, 39.59) in severe subgroup, showing no evidence of correlation between the severity OSA and RPSA measurements.

CONCLUSIONS

The RPSA measurements are significantly larger in control subjects (group 2) when compared with OSA patients (group 1). This might implicate that RPSA measurements through FOL examination can be a predictor of OSA when screening patients.

The role of polysomnography in diagnosing and treating obstructive sleep apnea in pediatric patients

Obstructive sleep apnea in children is associated with serious neurocognitive and cardiovascular morbidity, systemic inflammation, and increased health care use, yet remains underdiagnosed. Although the prevalence of obstructive sleep apnea is 1-3% in the pediatric population, the prevalence of primary snoring (PS) is estimated to be 3-12%. The challenge for pediatricians is to differentiate PS from obstructive sleep apnea in a cost-effective, reliable, and accurate manner before recommending invasive or intrusive therapies, such as surgery or continuous positive airway pressure. The validity of polysomnography as the gold standard for diagnosing obstructive sleep apnea has been challenged, primarily related to concerns that abnormalities on polysomnography do not correlate well with adverse outcomes, that those abnormalities have statistical more than clinical significance, and that performing polysomnograms on all children who snore is a practical impossibility. The aim of this article is to review the clinical utility of diagnostic tests other than polysomnography to diagnose obstructive sleep apnea, to highlight the limitations and strengths of polysomnography, to underscore the threshold levels of abnormalities detected on polysomnography that correlate with morbidity, and to discuss what the practical implications are for treatment.

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.

Age-Specific Size of the Upper Airway Structures in Children during Development

Objectives:

The purpose of this study was to establish the largest magnetic resonance imaging study so far, by including 292 cases in a prospective fashion, to investigate the normative values of the upper airway and surrounding tissues during development.

Methods:

We enrolled in the study 448 children who underwent cranial magnetic resonance imaging. We included 292 patients who had no sleep disorders or any associated symptom that could be related to breathing disorders. Using midsagittal and axial images, we evaluated the variations in size of the upper airway tissues.

Results:

On images from the midsagittal plane, the normative values of the length and the thickness of the soft palate, the length and height of the tongue, the distance between the mental spine and the clivus, the thickness of the adenoid pad and the nasopharyngeal area, the adenoid pad oblique width, the soft palate oblique width, and the tongue oblique width were obtained for several age groups. Using images from the axial plane at the level of maximal tonsillar cross-sectional area, we measured the normative values of the mean tonsillar width and intertonsillar space.

Conclusions:

Magnetic resonance imaging is an excellent method of assessing upper airway structures. Knowledge of variations in size of the upper airway and surrounding tissues is essential in determining the significance of incidental findings in this area.

Diagnostic imaging and sleep medicine

Obstructive sleep apnea syndrome (OSAS) is a relatively common disorder characterized by recurrent episodes of upper airway collapse and obstruction during sleep. It results in apneic events (or in the case of partial obstruction, hypopneic events) that lead to loud snoring, hypoxia, and arousals that interrupt the normal sleep cycle. Typically, these nocturnal arousals cause patients to complain of excessive daytime sleepiness, which may interfere with routine daily activities. More importantly, when moderate to severe, OSAS can lead to a wide variety of medical complications, some of which can result in severe consequences or even death.