[Update on upper airway evaluation in obstructive sleep apnea]

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

OBJECTIVES

To determine the most relevant aerodynamic characteristic of the oropharynx related to the collapse of the upper airway in obstructive sleep apnea (OSA) patients; and to determine the correlation between the most relevant aerodynamic characteristic(s) of the oropharynx and anatomical characteristics of the oropharynx in OSA patients.

METHODS

31 mild to moderate OSA patients (mean ± SD age = 43.5 ± 9.7 years) and 13 control subjects (mean ± SD age = 48.5 ± 16.2 years) were included in this prospective study. The diagnosis of OSA patients was based on an overnight polysomnographic recording. To exclude the presence of OSA in the control subjects, they were asked to fill out a validated questionnaire to determine the risk of OSA. NewTom5G cone beam CT (CBCT) scans were obtained from both OSA patients and control subjects. Computational models of the oropharynx were reconstructed based on CBCT images. The aerodynamic characteristics of the oropharynx were calculated based on these computational models. Pearson correlation analysis was used to analyse the correlation between the most relevant aerodynamic characteristic(s) and anatomical characteristics of the oropharynx in OSA patients.

RESULTS

Compared with controls, the airway resistance during expiration (R_ex) of the OSA patients was significantly higher (p = 0.04). There was a significant negative correlation between R_ex and the minimum cross-sectional area (CSA_min) of the oropharynx (r = -0.41, p = 0.02), and between R_ex and the volume of the oropharynx (r = -0.48, p = 0.01) in OSA patients. After excluding an outlier, there is only significant correlation between R_ex and the CSA_min of the oropharynx (r = -0.45, p = 0.01).

CONCLUSIONS

Within the limitations of this study, we concluded that the most relevant aerodynamic characteristic of the oropharynx in the collapse of the upper airway in OSA patients is R_ex. Therefore, the repetitive collapse of the upper airway in OSA patients may be explained by a high R_ex, which is related to the CSA_min of the oropharynx.

Assessment and treatment of obstructive sleep-disordered breathing

Obstructive sleep-disordered breathing (OSDB) is a condition that affects 1% to 3% of the pediatric population. These disorders are difficult to diagnosis and left untreated may be serious, including not only medical comorbidities but also cognitive, academic, behavioral, and emotional sequelae. This article is designed to bring awareness of the severity and prevalence to family physicians and pediatricians. It reviews detailed information concerning OSDB, including the predisposing factors, assessment of presenting features, and treatment.

The surgical treatment of sleep-related upper airway obstruction

BACKGROUND

Obstructive sleep apnea (OSA) is a very common disorder among adults: the prevalence of mild OSA is 20%, and that of moderate or severe OSA is 6% to 7%. Simple snoring is even more common. Conservative treatments such as nocturnal ventilation therapy and oral appliances are successful as long as the patient actually uses them, but they do not eliminate the underlying obstruction of the upper airway.

METHOD

The relevant literature up to 2008 on the surgical treatment of OSA was selectively reviewed.

RESULTS

Five types of surgical treatment for OSA are available, each for its own indications: optimization of the nasal airway to support nasal ventilation therapy, (adeno-)tonsillectomy as first-line treatment for OSA in children, minimally invasive surgery for simple snoring and mild OSA, invasive surgery as first- and second-line treatment for mild OSA, and invasive multilevel surgery as second-line treatment of moderate to severe OSA that remains refractory to ventilation therapy.

CONCLUSION

Surgical treatment for OSA is appropriate for specific indications as a complement to the established conservative treatment methods.

Surgical treatment of obstructive sleep apnea: standard and emerging techniques

PURPOSE OF REVIEW

Patients with obstructive sleep apnea (OSA), as well as their physicians, seek alternative therapies to continuous positive airway pressure (CPAP) due to problems with CPAP adherence. A large variety of surgical options exist, and each intervention must be individually evaluated. The author performed a literature search concerning surgery for sleep apnea until May 2010. The studies were evaluated according to evidence-based medicine criteria.

RECENT FINDINGS

An increasing number of controlled and even randomized controlled trials are available. Minimally invasive surgery remains under debate due to the very limited efficacy versus very low morbidity. Uvulopalatopharyngoplasty is still the standard procedure for many patients with moderate OSA, whereas maxillomandibular advancement is as effective as CPAP in severe OSA. Multilevel surgery is reserved to secondary treatment after CPAP failure. Tonsillectomy and maxillomandibular advancement may be offered as a first-line treatment in certain patients. There is increasing evidence that upper airway surgery has a positive impact on arterial hypertension, markers of cardiovascular disease, insomnia, daytime symptoms, quality of life, and CPAP adherence.

SUMMARY

Patients who are nonadherent to CPAP must be thoroughly evaluated before choosing any of the available surgical options. Upper airway surgery may improve disease markers of OSA, if appropriately chosen and properly indicated and performed.

[Tongue fixation system for therapy of sleeping disorders. A feasibility study]

INTRODUCTION

Forward displacement of the tongue is a verified principle in the therapy of sleep disorders which prevents the tongue from sinking backwards thus avoiding obstruction of the upper respiratory tract during sleep. In this feasibility study a novel oral appliance which connects to a pin implanted within the tongue was investigated.

METHODS

A new tongue positioning system using previously implanted tongue piercings as a pivot was developed. By pulling the tongue forward the oral device prevents airway obstruction. In our study we fitted 10 subjects who already had the tongue pierced with the developed oral device. The subjects underwent two nights of polysomnography with and without using the tongue positioning system. Wearing comfort and side effects were evaluated using a questionnaire. Moderate alcohol consumption was used to provoke snoring or apnea in the subjects. Tongue positioning with and without the device was visualized with oropharyngeal MRI.

RESULTS

Subjects did not report any discomfort or side effects wearing the device. Subjects showed only moderate snoring or apnea after alcohol consumption and snoring after alcohol consumption was reduced with the device. The average apnea/hypopnea index (AHI) was 0.8/h without the device. Using the device led to an increase of apnea in the subjects. MRI visualization showed that the device did not keep the upper airway space opened by fixing the tongue.

CONCLUSION

The effectiveness of the tongue positioning system should be improved by a modification which should be investigated in patients with preexisting sleep disorders.