Sites of Obstruction in Obstructive Sleep Apnea

doi:10.1378/chest.122.4.1139

Chest

Volume 122, Issue 4, October 2002, Pages 1139-1147

https://doi.org/10.1378/chest.122.4.1139 Get rights and content

Study objective

The aim of this article was to identify the most common sites of obstruction in patients with obstructive sleep apnea (OSA) by a systematic review of published studies.

Design

The review was conducted by a MEDLINE search of the English literature published during the years 1980 to 2002. The inclusion criteria were experiments involving five or more adult subjects, total rather than partial obstruction or narrowing of the upper airway, and techniques that were performed on the subjects while they were asleep.

Conclusion

Although there was considerable variability in the techniques and the results, the most common site of obstruction detected by these studies was at the level of the oropharynx, with extension to the laryngopharynx commonly observed.

Section snippets

Materials and Methods

Preliminary article searches were performed for the years 1980 to 2002 using the key words sites of obstruction, obstructive sleep apnea, CT, and MRI. Articles from the search were collected and screened based on the following selection criteria: studies consisted entirely of adults > 18 years of age; studies recorded complete rather than partial obstruction or narrowing of the UA; studies employed techniques that were performed during sleep, induced with or without sedation; and studies that

Endoscopy

Endoscopy represents one of the earliest techniques that was used to detect the sites of obstruction in OSA patients and involves using a nasopharyngoscope. Rojewski et al² studied 11 patients using simultaneous polysomnography and video recordings from a 4.4-mm diameter nasopharyngoscope. Detailed data were not provided, but the investigators found the level of obstruction in the area of the hypopharynx. The length of the collapsing segment was variable and was observed to extend as high as

Fluoroscopy

Fluoroscopy is a technique used to observe the internal structure of the UA using x-rays. Suratt et al³ studied 11 patients using videofluoroscopy with or without barium and obtained data in 6 patients who fell asleep and had UA obstruction. All six patients had obstructions during inspiration when the soft palate touched the posterior pharyngeal wall and tongue, with extension of the obstruction in the caudal direction. Hillarp et al⁴ studied 57 patients using video recordings of the UA after

Catheters

Catheters positioned in the UA can measure pressure differences during an apnea to localize the sites of obstruction. UA pressure measurements have been attempted using a variety of techniques, including fluid-filled catheters,⁹ movable catheters,¹⁰¹¹ bias-flow catheters,¹¹² and micropressure sensors.¹³¹⁴¹⁵¹⁶¹⁷¹⁸ The techniques have varied from the use of only one movable catheter, one to several stationary catheters, or a combination of stationary and movable catheters, all containing variable

CT Scanning

CT scanning is a noninvasive imaging technique that can provide a quantitative assessment of the UA. Stein et al²⁰ evaluated eight patients using cine CT scans (scanner capable of multiple-level, rapid-sequence scans) and found that all eight patients had obstructions at the uvula and oropharynx, but that the length of obstruction varied from one patient to another. In three of the eight patients, the obstruction extended caudally to the hypopharynx. Furthermore, in three of eight patients, as

MRI

MRI has been used to investigate the dynamic changes of the UA in OSA patients. Suto et al²² studied 15 patients using ultrafast MRI, and obstruction was noted in 13 patients. Six patients had a single obstruction at the velum palatinum, while seven patients had multiple levels of obstruction (obstructions at the velum palatinum and oropharynx, five patients; obstruction at the velum palatinum, oropharynx, and hypopharynx, one patient; and obstruction at the velopharynx and hypopharynx, one

Conclusion

Diverse methods have been used to identify sites of obstruction in OSA patients. No technique is without methodological problems, ranging from the invasiveness of the procedures with concomitant sleep disruption (eg, endoscopy and catheters) to viewing time limitations secondary to radiation exposure (eg, fluoroscopy and CT scanning). Given these limitations, the precise localization of the sites of obstruction in patients with OSA may not be possible using current techniques. Nevertheless, the

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Studies pertaining to the objective assessments of the efficacy of mandibular advancement device in patients with obstructive sleep apnea are scarce.
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Twenty-nine consenting participants satisfying predetermined inclusion and exclusion criteria were enrolled and an adjustable two-piece MAD was fabricated at 50% maximum mandibular protrusion and after 4 weeks was adjusted to 70% protrusion. CT scans were obtained at baseline, 4 weeks after delivering MAD with 50% mandibular protrusion, and then after 4 weeks with 70% mandibular protrusion. Cross sectional area with diameters (lateral and anteroposterior) of upper airway was measured at three specific anatomic levels (retropalatal-RP, retroglossal-RG, and epiglottal-EG). Data were analyzed using the Student t-test for parametric analysis.
Intragroup comparison revealed a statistically significant increase in lateral & anteroposterior dimensions as well as cross sectional area at all three anatomical levels at 4 weeks after MAD with 50% mandibular protrusion compared with baseline and 4 weeks after MAD with 70% mandibular protrusion compared with baseline. However, the difference between lateral and anteroposterior dimensions with MAD at 70% protrusion compared with MAD at 50% protrusion was not statistically significant. The difference between cross-sectional area was found to be statistically significant.
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This study aimed to evaluate a 3-dimensional (3D) U-Net-based convolutional neural networks model for the fully automatic segmentation of regional pharyngeal volume of interests (VOIs) in cone-beam computed tomography scans to compare the accuracy of the model performance across different skeletal patterns presenting with various pharyngeal dimensions.
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The proposed model achieved highly accurate performance, showing a mean dice similarity coefficient of 0.928 ± 0.023, the volumetric similarity of 0.928 ± 0.023, precision of 0.925 ± 0.030, and recall of 0.921 ± 0.029 for total PAS segmentation. The performance showed region-specific differences, revealing lower accuracy in the glossopharyngeal and hypopharyngeal sections than in the upper sections (P <0.001). However, the accuracy of model performance at each pharyngeal VOI showed no significant difference according to sagittal or vertical skeletal patterns.
The 3D-convolutional neural network performance for region-specific PAS analysis is promising to substitute for laborious and time-consuming manual analysis in every skeletal and pharyngeal pattern.
Dynamic tongue base thickness measured by drug-induced sleep ultrasonography in patients with obstructive sleep apnea
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From May 2017 to May 2018, thirty patients with OSA were prospectively recruited. Sleep was induced with propofol via use of a target-controlled infusion (TCI) system. The depth of sedation was monitored by the bispectral (BIS) index with BIS levels ranging from 50 to 70. The dynamic change in the tongue base from the awake state to drug-induced sleep was recorded. The correlation between TBT in the awake state and in drug-induced sleep with OSA severity was analysed.
The mean TBT in drug-induced sleep was significantly greater than that in the awake state (66.2 ± 4.8 mm vs 61.6 ± 4.6 mm, P < 0.001). TBT in drug-induced sleep was more correlated with AHI compared to TBT in the awake state (r = 0.50 vs r = 0.40). This study showed that TBT in drug-induced sleep had the largest AUC (Area Under the Curve) in the ROC (Receiver Operating Characteristics) analysis (0.875), providing a cut-off point of 63.20 mm with 95% sensitivity for diagnosis of moderate versus severe OSA.
Our findings validate the use of DISU in objectively assessing the tongue base collapse in OSA patients. It provides a convenient and non-invasive way to evaluate the upper airway changes in OSA patients in the future.
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Citation Excerpt :
The site of obstruction of the airway during apnea events differs with intra- and inter-subject variations and with a change in the obstruction site between sitting and supine positions. However, most of the studies, irrespective of the technique to localize the occlusion, indicate that the primary site of occlusion is the oropharynx, with extension to the laryngopharynx [3,4,16,37,44]. Table 2 summarizes anatomical structure dimension of the neck and airway in controls and OSAHS patients as reported in the literature [29,45–47].
Obstructive sleep apnea/hypopnea syndrome (OSAHS) is characterized by repetitive narrowing or full collapse of the upper airway concomitant with continued respiratory effort during sleep lasting 10s or more. OSAHS is the most prevalent form of sleep-disordered breathing, affecting more than 17% of the middle-aged U.S. population. Hence, many individuals need to be tested for having OSAHS. Currently, detection of airway occlusion due to OSAHS is achieved by indirect measurements, often requiring multiple sensor types, such as a flow transducer combined with chest and abdomen plethysmography. The need for the use of multiple sensors in the current OSAHS detection systems adds to the cost and complexity of the current systems and associated procedures. Development of a simple sensor system that allows direct detection of airway occlusion is advantageous, as it simplifies detection of OSAHS and paves the way for home diagnosis of OSAHS. The utilization of ultrasonic transducers is attractive, as it is non-invasive and non-ionizing. We present a new ultrasound sensing system for direct detection of the occlusion in the upper airway in OSAHS patients during sleep. The system takes into consideration the constraints arising from the location of probing and the acoustic requirements for transducers. The physiological and theoretical backgrounds are presented for using ultrasonic pulses to detect the presence and degree of occlusion in the airway. The proposed methodology for creating an anthropomorphically-correct neck and airway phantoms to test the hypothesis and the results of the tests are presented.
An ultrasonic signal transmitted through or reflected from an open airway will have different features compared to those associated with a partially or fully occluded airway.
A system, comprising a phantom model of the airway and neck with the approximate anatomical-correct dimensions and acoustic properties of the airway, is designed and built. It allows simulating fully open airway as well as hypopnea and apnea events. Further, it facilitates probing using multiple ultrasonic frequencies and transducer configurations for use with different neck sizes. Ultrasound waves are generated using a piezoelectric source to the model of the airway and received by piezoelectric receivers on the opposite side. Energy, the area under the curve, and the peak value of the received signal, are used to detect the airway occlusion.
The amount of reflected ultrasonic energy from the phantom model of the airway back to the transmitting transducer reduces as the airway model occlusion increases. Also, transmitted signal through the airway model increases as the amount occlusion of the airway model increases.
The results of this study support the hypothesis that it is feasible to use ultrasonic pulses to detect partial and full upper airway occlusion.

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Chest

Clinical InvestigationsSites of Obstruction in Obstructive Sleep Apnea

Study objective

Design

Conclusion

Section snippets

Materials and Methods

Endoscopy

Fluoroscopy

Catheters

CT Scanning

MRI

Conclusion

Sleep Med

Uvulopalatopharyngoplasty in obstructive apnea: value of preoperative localization of site of upper airway narrowing during sleep

Am Rev Respir Dis

Synchronous video recording of the pharyngeal airway and polysomnograph in patients with obstructive sleep apnea

Laryngoscope

Fluoroscopic and computed tomographic features of the pharyngeal airway in obstructive sleep apnea

Am Rev Respir Dis

Videoradiography of patients with habitual snoring and/or sleep apnea: technical description and presentation of videoradiographic results during sleep concerning occurrence of apnea, type of apnea, and site of obstruction

Acta Radiol

Somnofluoroscopy: cineradiographic observation of obstructive sleep apnea

Sleep

Somnofluoroscopy, computed tomography, and cephalometry in the assessment of the airway in obstructive sleep apnoea

Thorax

Inspiratory activation of the masseter

Prog Clin Biol Res

Effect of upper airway anesthesia on obstructive sleep apnea

Am J Respir Crit Care Med

Localization of upper airway collapse during sleep in patients with obstructive sleep apnea

Am Rev Respir Dis

Site of airway obstruction in patients with obstructive sleep apnea before and after uvulopalatopharyngoplasty

Laryngoscope

Site of upper airway obstruction in patients with idiopathic obstructive sleep apnea

Laryngoscope

Variable site of airway narrowing among obstructive sleep apnea patients

J Appl Physiol

Pressure recordings: a method for detecting site of upper airway obstruction in obstructive sleep apnea syndrome

Acta Otolaryngol Suppl

A multisensor solid-state pressure manometer to identify the level of collapse in obstructive sleep apnea

Otolaryngol Head Neck Surg

Determining the site of airway collapse in obstructive sleep apnea with airway pressure monitoring

Laryngoscope

Localization of site of obstruction in snorers and patients with obstructive sleep apnea syndrome: a comparison of fiberoptic nasopharyngoscopy and pressure measurements

Acta Otolaryngol

Site of upper airway obstruction in obstructive sleep apnoea and influence of sleep stage

Eur Respir J

The sites of obstruction in OSA, identified by continuous measurements of airway pressure and flow during sleep: ambulatory vs in-hospital recordings

Clin Otolaryngol

Obstructive sleep apnea following topical oropharyngeal anesthesia in loud snorers

Am Rev Respir Dis

Clinical Investigations
Sites of Obstruction in Obstructive Sleep Apnea