The utility of cephalometry with the Muller maneuver in evaluating the upper airway and its surrounding structures in Chinese patients with sleep-disordered breathing

Sleepiness Score-Specific Outcomes of a Novel Tongue Repositioning Procedure for the Treatment of Continuous Positive Airway Pressure-Resistant Obstructive Sleep Apnea

Background:

The gold standard of treatment for obstructive sleep apnea (OSA) is continuous positive airway pressure (CPAP). However, more than a third of patients have such difficulty with its chronic use such that they seek other options or choose to remain untreated. We evaluated sleepiness score-specific outcomes and the use of CPAP after tongue repositioning surgery for the treatment of OSA.

Patients and Methods:

A self-administered questionnaire was completed pre- and postoperatively by 10 patients who underwent tongue repositioning surgery for the treatment of OSA from October 2010 to December 2012. The questionnaire included the Epworth Sleepiness Scale (ESS) for the assessment of daytime somnolence and questions regarding CPAP use and overall satisfaction.

Results:

Preoperatively, 6 patients were “very sleepy” (ESS ≥16), 4 patients were “sleepy” (ESS = 10–16), and 0 patients were “not sleepy” (ESS ≤10). 30 days postoperatively, sleepiness scores decreased (10 patients were “not sleepy” (ESS ≤10) with 0 patients “very sleepy” or “sleepy;” P = 0.002). Thus, the median ESS score for the “very sleepy” and “sleepy,” decreased from 20 to 4 and 13 to 5, respectively, and the “nonsleepy” group increased from 0 to 4. After a 180-day review, the improved ESS scores remained unchanged (the median for “very sleepy” decreased to 3.5 that for “sleepy” remained at 5, and the median for “not sleepy” decreased to 3.5). Surgery decreased CPAP use by 100%. The surgery was judged to be worthwhile by all 10 of patients using a questionnaire, and all 10 patients said that they would recommend the treatment to other patients with OSA.

Conclusions:

These preliminary data indicate that tongue-repositioning surgery for the treatment of OSA may be effective in improving excessive daytime sleepiness. These proof-of-concept data require confirmation in an appropriately powered controlled study.

Prediction of tongue obstruction observed from drug induced sleep computed tomography by cephalometric parameters

OBJECTIVE

To elucidate potential role of cephalometric measurements to predict tongue base obstruction as observed on drug Induced Sleep Computed Tomography (DIS-CT).

METHODS

Study included 35 patients with moderate to severe sleep apnea who underwent DIS-CT & cephalometric examination to assess tongue base obstruction.

RESULTS

Statistically significant difference was noted for SNA angle & Mandibular posterior airway space (PAS) among groups with total tongue obstruction versus Non-total tongue obstruction identified on DIS-CT.

CONCLUSION

Lateral cephalogram can be used as a standard screening tool with commonly used skeletal and soft tissue parameters to predict the possibility of tongue collapse/obstruction during sleep in patient with moderate to severe OSAS.

Computational fluid dynamics simulation of the upper airway of obstructive sleep apnea syndrome by Muller maneuver

This study aimed to use computer simulation to describe the fluid dynamic characteristics in patients with obstructive sleep apnea syndrome (OSAS) and to evaluate the difference between during quiet respiration and the Muller maneuver (MM). Seven patients with OSAS were involved to perform computed tomographic (CT) scanning during quiet respiration and the MM. CT data in DICOM format were transformed into an anatomically three-dimensional computational fluid dynamics (CFD) model of the upper airway. The velocity magnitude, relative pressure, and flow distribution were obtained. Numerical simulation of airflow was performed to discuss how the MM affected airflow in the upper airway. To measure the discrepancy, the SPSS19.0 software package was utilized for statistic analysis. The results showed that the shape of the upper airway became narrower, and the pressure decreased during the MM. The minimal cross-sectional area (MCSA) of velopharynx was significantly decreased (P<0.05) and the airflow velocity in MCSAs of velopharynx and glossopharynx significantly accelerated (P<0.05) during the MM. This study demonstrated the possibility of CFD model combined with the MM for understanding pharyngeal aerodynamics in the pathophysiology of OSAS.

Nasal and oral snoring endoscopy: novel and promising diagnostic tools in OSAS patients

The aim of the present study was to investigate if any of the three awake procedures [fiberoptic nasopharyngoscopy with modified Müller Maneuver (FNMM), nasal snoring endoscopy (NSE), or oral snoring endoscopy (OSE)] could efficiently predict the grade or pattern of upper airway (UA) collapse found with drug-induced sleep endoscopy (DISE), which is considered by many authors as the current gold standard in optimizing obstructive sleep apnea syndrome (OSAS) patient selection for UA surgery. Twenty consecutive patients (simple snorers and OSAS patients) were studied with FNMM, NSE, OSE, and DISE. The inter-test agreement was evaluated with Cohen's kappa coefficient (κ). In the current series, we found that NSE and OSE were better than FNMM in predicting the pattern of collapse found with DISE. A significant pattern agreement between NSE and DISE was present in all sub-sites, and the agreement was measured with a scale proposed by Landis and Koch as: moderate in velo- and oropharynx (κ = 0.52, p = 0.001, and κ = 0.47, p = 0.003, respectively), and substantial in hypopharynx (κ = 0.63, p < 0.00001). Comparing OSE with DISE, the pattern agreement was almost perfect at oropharyngeal level (κ = 0.82, p < 0.00001), and moderate at hypopharyngeal level (κ = 0.55, p = 0.0002); while a trend towards significance was found at velopharyngeal level (κ = 0.20, p = 0.07). FNMM showed a fair pattern agreement with DISE only at oropharyngeal level (κ = 0.31, p = 0.009); while in the other sub-sites, no significant agreement was found. NSE and OSE are new promising diagnostic tools in OSAS patients. Further investigations are needed to see if they could predict the effectiveness of UA surgery.

Mandibular morphology and pharyngeal airway space: A cephalometric study

Introduction

Mandibular retrognathism is considered to be the most important risk factor for upper airway obstruction.

Aim

This cross-sectional study intended to examine the relationship between craniofacial morphology and the pharyngeal airway space (PAS) in patients with mandibular retrognathism and mandibular prognathism, when compared to normal subjects. The study also analyzed the influence of mandibular morphology on pharyngeal length (PL).

Materials and Methods

The PAS was assessed in 92 females (age 15-30 years) further divided into three groups - Group 1- normal mandible (76°≤ SNB ≤82°; n = 31); Group 2-mandibular retrognathism (SNB <76°; n = 31); Group 3-Mandibular prognathism (SNB >82°; n = 30). All subjects were examined by lateral cephalometry with head position standardized using an inclinometer. Craniocervical angulation, uvula length, thickness and angulation were compared among different groups.

Results

The results showed no statistically significant difference in the pharyngeal airway between the three groups. Measurements of PL showed statistically significant higher values for retrognathic mandible group than normal and prognathic mandible group.

Conclusion

There is no significant difference between PAS between patients with mandibular retrognathism, normal mandible and mandibular prognathism. Mandibular retrognathism patients show a significantly higher uvula angulation than patients with mandibular prognathism. Craniocervical angulation showed maximum value in retrognathic mandible group followed by normal and prognathic mandible group respectively. Mean PL for retrognathic mandible patients was significantly higher than prognathic mandible patients.

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.

Skeletal surgery in sleep apnea

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) is a common condition, increasing in incidence along with obesity in Americans. This review looks at skeletal surgery to treat sleep apnea and recent advancements.

RECENT FINDINGS

Skeletal surgery for OSA has improved with recent advancements in surgical genioplasty now able to advance the genioglossus as well as inferior mandible muscles without changing aesthetics. Some investigators have called for maxillomandibular advancement to be considered as a first-line therapy over continuous positive airway pressure.

SUMMARY

Maxillomandibular advancement appears safe and effective for consideration as a first-line therapy for select patients with OSA.

Sagittal mandibular development effects on the dimensions of the awake pharyngeal airway passage

OBJECTIVE

To test the hypothesis that sagittal mandibular development has no effects on the dimensions of the awake pharyngeal airway passage.

MATERIALS AND METHODS

Ninety-one subjects (age 15-25 years) with a normal vertical growth pattern of the mandible, normally positioned maxilla, and various sagittal mandibular developments were divided into three groups based on the sagittal mandibular development. Group I included 37 subjects who had a normally positioned mandible (76 degrees < or = angle between 'S,' 'N,' and 'B'; it represents the antero-posterior position of the maxilla in relation to the anterior cranial base [SNB] < or = 82 degrees ), Group II included 31 subjects in whom the mandible was retrognathic (SNB < 76 degrees ), and Group III included 23 subjects in whom the mandible was prognathic (SNB > 82 degrees ) in relation to the anterior cranial base. Lateral cephalograms were traced manually to evaluate the pharyngeal airway passage.

RESULTS

The length of the soft palate was significantly smaller in mandibular prognathism subjects than in subjects with mandibular retrognathism (P < .01). The thickness of the soft palate was significantly greater among subjects with mandibular prognathism than in subjects with normal (P < .01) and retrognathic (P < .001) mandibular development. The sagittal mandibular development had no effect on the dimensions of the nasopharyngeal and hypopharyngeal airway passage. The depth of the oropharynx was comparable among the subjects with normal and retrognathic mandibles but was greater (P < .001) among subjects with mandibular prognathism.

CONCLUSIONS

The hypothesis is rejected. Sagittal mandibular development had significant effects on the dimensions of the awake pharyngeal airway passage.

Predicting continuous positive airway pressure from a modified split-night protocol in moderate to severe obstructive sleep apnea-hypopnea syndrome

BACKGROUND

Most split-night sleep (SNS) studies have enrolled Caucasian patients with moderate-to-severe obstructive sleep apnea-hypopnea syndrome (OSAHS), with different apnea-hypopnea index (AHI) criteria for diagnosis and successful CPAP titration from the standard full-night study (FNS). This study aimed to describe a shortened diagnostic SNS in the Taiwanese population using diagnostic and CPAP therapeutic criteria identical to the standard FNS, and to generate a predictive equation for effective CPAP (Peff) titration.

METHODS

A total of 418 patients with moderate-to-severe OSAHS were enrolled in this study. The duration of the diagnostic SNS was shortened to approximately 1-2 hours. The diagnostic accuracy and the success rate of CPAP titration in SNS were evaluated and a statistical model for Peff was built. The accuracy of the predictive equation was validated in another 127 patients.

RESULTS

Eighty-nine percent of patients with moderate-to-severe OSAHS diagnosed in the preceding FNS yielded the same grade of OSAHS in SNS. These reproducible patients were more severe, with 88% attaining successful CPAP titration in SNS. The predictive Peff=1.98+0.184xBMI+0.01xAHISNS +0.016xDISNS (R2=0.28, p<0.0001) where BMI was the body mass index and DI the desaturation index. The | predictive Peff- Peff | was within 2 cm H(2)O in 84% of the study group and 73% of the validation group.

CONCLUSION

The modified split-night protocol and the predictive equation for CPAP can be useful in Taiwanese patients with moderate-to-severe OSAHS. Our findings may shorten the waiting time for polysomnography.

Current trends in the treatment of obstructive sleep apnea

Obstructive sleep apnea (OSA) is a condition of partial or complete upper airway obstruction leading to increased resistance to airflow and potential cessation of breathing during sleep. Effective treatment of OSA is challenging and there has been greater recognition by the medical and dental disciplines. By understanding the rationale, indications, benefits, risks and success of the various treatment options available, clinicians will be able to make more informed treatment recommendations in patient management.

Numerical investigation on the flow characteristics and aerodynamic force of the upper airway of patient with obstructive sleep apnea using computational fluid dynamics

Developing a mathematical model to predict the abnormal flow characteristics that are produced by obstructive sleep apnea is an important step in learning the pathophysiology of the obstructive sleep apnea (OSA) disease. The present study provides detailed calculations of flow in the pharyngeal airway of a patient with obstructive sleep apnea. To achieve this goal, a computational fluid dynamics model was constructed using raw data from three-dimensional computed tomogram (CT) images of an OSA patient. To reproduce the important transition from laminar to turbulent flow in the pharyngeal airway, the low Reynolds number k-epsilon model was adopted and successfully validated using previous open literature. The results show that the flow in the pharyngeal airway of patients with OSA comprises a turbulent jet formed by area restriction at the velopharynx. This turbulent jet causes higher shear and pressure forces in the vicinity of the velopharynx. From the results, It may be deduced that the most collapsible area in the pharyngeal airway of OSA patients is the velopharynx where minimum intraluminal pressure and maximum aerodynamic force lie.

Endoscopic evaluation of dynamic narrowing of the pharynx by the Bernouilli effect producing maneuver in patients with obstructive sleep apnea syndrome

OBJECTIVE

To evaluate the dynamic narrowing of the retropalatal pharynx by the Bernouilli effect producing maneuver (BEPM) in patients with obstructive sleep apnea syndrome (OSAS) with computer-assisted analysis of nasopharyngoscopic images.

METHODS

Endoscopic images of the retropalatal pharynx were obtained and their area was measured by NIH imaging. Because changes in distance between the CCD camera of the nasopharyngoscope and the site of pharyngeal narrowing decreased the measurement reliability, the area of the retropalatal pharynx was divided by the square of the uvula's lateral side length for normalization. We calculated both normalized areas: the pharyngeal narrowing during quiet nasal breathing and that during BEPM, which is a forced inspiration through the nose with the mouth closed. The narrowing rate was then calculated as an index of the pharyngeal dynamics.

RESULTS

Nasopharyngoscopy combined with BEPM showed a medial motion of the lateral walls of the pharynx due to the Bernoulli effect, which is an increase in speed and a reduction in pressure of a moving gas passing through a tube constriction. There was a significant correlation between the narrowing rate of the retropalatal pharynx and the apnea index. The decrease in intraluminal pressure at the narrowing combined with the higher atmospheric pressure exercised on the lateral pharyngeal walls would induce the pharyngeal collapse. There was also a significant correlation between the normalized retropalatal are and the apnea index.

CONCLUSION

Nasopharyngoscopy with BEPM suggest that in addition to the static narrowing, the dynamic narrowing of the retropalatal pharynx contributes to the pathophysiology of OSAS. The correlation between the apnea index and both the normalized retropalatal area and the narrowing rate of the retropalatal pharynx due to the Bernoulli effect constitute a quantitative and predictive alternative to the evaluation and understanding of the upper airways changes in OSAS.

Obesity, ethnicity, and sleep-disordered breathing: medical and health policy implications

The obesity epidemic in the United States is a major health problem, which poses im-mediate and long-term health risks with potential for significant reduction in life expectancy if not curtailed. Despite affecting all segments of the population, minorities carry a relatively larger burden of the obesity threat. Obesity is a major risk factor for develop-ing obstructive sleep apnea and the metabolic syndrome, which are associated with increased cardiovascular and cerebrovascular morbidity and mortality. This article discusses the implications of the obesity trend on the prevalence of obstructive sleep ap-nea and health, highlights ethnic differences, reviews the resultant economic implications, and suggests public health and health policy initiatives that may be beneficial in stemming the obesity scourge.

Relationship between the pharyngeal airway space and craniofacial morphology, taking into account head posture

This study assessed the relationship between craniofacial characteristics and the size of the pharyngeal airway space (PAS), taking into account head posture. Sixty dental students 25-30 years of age (30 men and 30 women) were examined by lateral cephalometry. The data were corrected with the use of appropriate regression equations for the PAS. The PAS significantly correlated with hyoid position, maxillary and mandibular size, maxillary and mandibular prognathism, and mandibular inclination. A large, anteriorly positioned mandible was associated with a large PAS-TP (the most proximal distance between the posterior pharyngeal wall and the tongue base). Uvula length and PNS-Ba (the distance between the most posterior point of the hard palate and the most inferior point of the anterior foramen magnum) correlated with PAS-UP (the most proximal distance between the posterior pharyngeal wall and uvula). Our results suggest that the anteroposterior dimension of the PAS is substantially affected by the size of the enclosure surrounding the PAS, including the maxilla, mandible and soft palate.

Quantitative Upper Airway Imaging with Anatomic Optical Coherence Tomography

BACKGROUND

Measurements of upper airway size and shape are important in investigating the pathophysiology of obstructive sleep apnea (OSA) and in devising, applying, and determining the effectiveness of treatment modalities. We describe an endoscopic optical technique (anatomic optical coherence tomography, aOCT) that provides quantitative real-time imaging of the internal anatomy of the human upper airway.

METHODS

Validation studies were performed by comparing aOCT- and computed tomography (CT)-derived measurements of cross-sectional area (CSA) in (1) conduits in a wax phantom and (2) the velo-, oro-, and hypopharynx during wakefulness in five volunteers. aOCT scanning was performed during sleep in one subject with OSA.

RESULTS

aOCT generated images of pharyngeal shape and measurements of CSA and internal dimensions that were comparable to radiographic CT images. The mean difference between aOCT- and CT-derived measurements of CSA in (1) the wax phantom was 2.1 mm(2) with limits of agreement (2 SD) from -13.2 to 17.4 mm(2) and intraclass correlation coefficient of 0.99 (p < 0.001) and (2) the pharyngeal airway was 14.1 mm(2) with limits of agreement from -43.7 to 57.8 mm(2) and intraclass correlation coefficient of 0.89 (p < 0.001). aOCT generated quantitative images of changes in upper airway size and shape before, during, and after an apneic event in an individual with OSA.

CONCLUSIONS

aOCT generates quantitative, real-time measurements of upper airway size and shape with minimal invasiveness, allowing study over lengthy periods during both sleep and wakefulness. These features should make it useful for study of upper airway behavior to investigate OSA pathophysiology and aid clinical management.

Ethnicity and obstructive sleep apnoea

There is a scarcity of adult prevalence studies of OSA outside the Caucasian populations of North America, Europe and Australia, and comparisons have been complicated by methodological differences in sleep study settings, respiratory events definition, measured risk factors and clinical outcomes, and the lack of objective parameters for the measurement of ethnicity itself. Comparing studies with the same methodological design and respiratory events definition, recent large-scale prevalence studies from Hong Kong, Korea and India show similar OSA rates to populations of mainly Caucasian composition. OSA is a very complex disorder determined by several phenotypes such as obesity, craniofacial structure and abnormalities in neuromuscular and ventilatory control. Genetics may partially explain some of the ethnic clustering of these phenotypes, modulated by cultural and environmental factors. The exact contribution of these component phenotypes to overall OSA risk will be determined by their varying prevalence and relative risk conferred across ethnic groups. For lesser degrees of obesity, Asians are at risk for a more severe degree of illness compared with Caucasians. Inter-ethnic studies suggests that African-American ethnicity may also be a significant risk factor for OSA. The increased prevalences of OSA among American Indians and Hispanic adults, and increased severity among Pacific Islanders and Maoris, were mainly explained by increased obesity parameters. Most cephalometric studies have largely been conducted without specific regard to ethnicity and comparisons of findings across studies have been mainly limited by differences in sampling methods and the varying selection and definition of measured cephalometric variables. The limited number of studies with inter-ethnic comparative data suggest cephalometric variables and their degree of contribution to OSA vary across ethnic groups.

Upper Airway and Its Surrounding Structures in Obese and Nonobese Patients With Sleep-Disordered Breathing

OBJECTIVES/HYPOTHESIS

The objective was to understand the pathophysiological relationship between obesity and sleep-disordered breathing by using cephalometry with the Muller maneuver.

STUDY DESIGN

A prospective study.

METHODS

One hundred habitually snoring men were evaluated for sleep-disordered breathing at the Sleep Center of Chang Gung Memorial Hospital (Taipei, Taiwan). Each subject received overnight polysomnography and two lateral cephalograms at the end-expiration phase (L1) and the Muller maneuver (L2), respectively, to evaluate the facial skeleton and the upper airway and its surrounding structures (soft palate, tongue, epiglottis, and hyoid bone). After excluding 14 patients from the study because of jaw opening during cephalometry, 86 (39 nonobese and 47 obese) patients with sleep-disordered breathing were enrolled.

RESULTS

Patients with varying degrees of obesity significantly differed in terms of the facial skeleton and the structure and function of the upper airway and its surrounding structures. The Muller maneuver caused dynamic changes in the hypopharyngeal airway and position of the tongue, and these dynamic changes were related to the pathogenesis of sleep-disordered breathing for the two groups (nonobese and obese patients). The regression model generated for the nonobese group revealed that the apnea hypopnea index was significantly related to the pharyngeal length (L2) and the soft palate thickness (L1). In contrast, the regression model generated for the obese group revealed that the apnea hypopnea index was significantly related to the soft palate (length [L1] and dynamic position change), the hyoid position (vertical [L1] and horizontal [L2]), the tongue (dynamic position change), and body mass index.

CONCLUSION

Cephalometry with the Muller maneuver may provide further insight into the pathogenesis of sleep-disordered breathing for the two groups of patients (nonobese and obese patients).