Quantitative airway analysis during drug-induced sleep endoscopy for evaluation of sleep apnea

The influence of different application patterns of propofol on the sedation courses during drug-induced sleep endoscopy

Objective

The course of sedation during drug-induced sleep endoscopy (DISE) depends on the application pattern of the sedative drug. The depth of sedation should imitate light and deep sleep as well. Moreover, there should be as many breathing cycles as possible available for observation during light and deep sedation. The aim of the study was to evaluate different rates of propofol application with respect to the achieved depth and length of the course of sedation.

Methods

Sixty-three consecutive patients with obstructive sleep apnea and/or snoring undergoing DISE were randomly sedated by propofol perfusion at seven different application patterns: 14, 16, 18, 19, 20, 22 mg/kg/h (0.233, 0.267, 0.3, 0.317, 0.333, 0.367 mg/kg/min) per perfusor and individual bolus application 10 mg each. Sedation depth was monitored by BiSpectral Index™ (BIS). The influence of baseline parameters and the courses of sedation were analyzed.

Results

The application rate was the only factor that influenced the depth of sedation. Basic parameters (gender, age, body mass index, apnea-hypopnea index) had no influence on the depth of sedation. The sedation depth was dependent on the rate of propofol application. Regimes at 14 and 16 mg/kg/h as well as bolus application did not reach BIS levels below 50 representing deep sleep. Propofol doses of more than 20 mg/kg/h led to rapid decreases of sedation levels below deep sleep niveau. Propofol rates between 18 and 20 mg/kg/h enable BIS levels below 50 representing deep sleep and providing enough breathing cycles for observation.

Conclusion

Lower application rates of propofol provide slower courses of sedation and shallower depths of sedation. A rate of 14 mg/kg/h might be appropriate to reach a sedation plateau at light sleep. A rate of 18 mg/kg/h leads to a sedation, corresponding to deep sleep. The combination of both rates might be a suitable pattern for performing sedation-controlled DISE.

Level of evidence

2: Randomized trial.

Evaluation of modified coblation endoscopic lingual lightening in multilevel surgery for obstructive sleep apnea hypopnea syndrome: an open intervention study

PURPOSE

To evaluate the efficacy and safety of modified coblation endoscopic lingual lightening to address retrolingual obstruction in multilevel surgery for obstructive sleep apneae (OSA).

METHODS

Patients with OSA due to retropalatal and retrolingual obstructions were enrolled. Group 1 consisted of patients who underwent modified coblation endoscopic lingual lightening combined with H-uvulopalatopharyngoplasty, while group 2 comprised patients treated by H-uvulopalatopharyngoplasty alone. Objective parameters and subjective evaluations were recorded preoperatively and at 6 months postoperatively.

RESULTS

The mean (standard deviation) apnea-hypopnea index (AHI) declined from 51.5 (18.9) to 14.3 (7.2) in group 1, and from 51.7 (15.8) to 28.5 (16.9) in group 2. The mean (standard deviation) percentage change in AHI was higher in group 1 than in group 2 (73.2 [10.9] vs. 48.9 [22.4], P < 0.01). The surgical response rate differed significantly between groups 1 and 2 (88.5 [23/26] vs. 46.7 [14/30], P < 0.01). Other outcomes, including the lowest oxygen saturation, Epworth Sleepiness Scale score, snoring visual analog scale score, and subjective improvement rate, were also significantly better in group 1 than in group 2.

CONCLUSION

Without increasing complications, modified coblation endoscopic lingual lightening significantly improved surgical outcomes as part of multilevel surgery in patients with OSA due to multilevel obstruction.

Prospective Evaluation of the Safety and Efficacy of THRIVE for Children Undergoing Airway Evaluation

Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) is a humidified high-flow nasal cannula capable of extending apneic time. Although THRIVE is assumed to stent upper airway soft tissues, this has not been objectively evaluated. Also, there are no prior studies providing safety and efficacy data for those patients undergoing upper airway evaluation using THRIVE.

The Quest for a DISE Protocol

OBJECTIVE

The objective of this quality initiative project was to modify our existing institutional drug-induced sleep endoscopy (DISE) protocol so that the surgeon could consistently determine obstructive breathing patterns while minimizing children's discomfort.

METHODS

A quality initiative study utilizing the well-described plan-do-study-act (PDSA) process was conducted at a tertiary hospital for children with polysomnogram-documented obstructive sleep apnea who were undergoing DISE. A 4-point Likert measurement tool was created. Change in each Likert rating with subsequent PDSA cycle was tested with the Wilcoxon rank sum test (Mann-Whitney), and change across all PDSA cycles was tested with the Kruskal-Wallis equality-of-populations rank test.

RESULTS

After a series of 4 PDSA cycles with 81 children, the DISE protocol was streamlined from 14 to 9 steps. There was significant improvement for all aspects of the DISE, with a final overall median rating of 1 (excellent) for intravenous (IV) placement, scope insertion, and anesthesiologist and surgeon satisfaction (P < .01).

DISCUSSION

For sleep surgeons, DISE is quickly becoming what bronchoscopy is to the airway surgeon. Utilizing inhalational agents to obtain IV access and insert the flexible scope in the rapid "on-off" fashion optimizes DISE success regardless of the primary sedation medication and allows ample time for these agents to dissipate.

IMPLICATIONS FOR PRACTICE

Adoption of a DISE protocol that includes nasal premedication and inhalational volatile gases for IV and scope insertion at the onset provides a more predictable level of sedation that is well tolerated by the patient, enabling the otolaryngologist to create an obstructive sleep apnea treatment plan.

Ansa cervicalis stimulation increases pharyngeal patency in patients with obstructive sleep apnea

Hypoglossal nerve stimulation (HNS) is an alternative treatment option for obstructive sleep apnea (OSA) that reduces pharyngeal collapsibility, but HNS nonresponders often demonstrate continued retropalatal and lateral pharyngeal wall collapse. Recent evidence suggests that caudal pharyngeal traction with sternothyroid muscle contraction via ansa cervicalis stimulation (ACS) can also stabilize the pharynx, but the underlying mechanisms have not been elucidated. Our objective was to evaluate the effect of ACS on pharyngeal patency during expiration when the airway is most hypotonic. Eight participants with OSA underwent sustained ultrasound-guided fine-wire stimulation of the medial branch of the right hypoglossal nerve with and without transient stimulation of the branch of the ansa cervicalis nerve plexus innervating the right sternothyroid muscle during drug-induced sleep endoscopy. Airway cross-sectional area and expiratory airflow (V̇e) were measured from endoscopy video with ImageJ and pneumotachometry, respectively. ACS significantly increased retropalatal cross-sectional area (CSA_RP) to 211% [159-263] of unstimulated CSA_RP (P < 0.05). Adding ACS to HNS increased CSA_RP from baseline by 341% [244-439] (P < 0.05), a 180% [133-227] increase over isolated HNS (P < 0.05). ACS increased V̇e from baseline by 177% [138-217] P < 0.05). Adding ACS to HNS increased V̇e by 254% [207-301], reflecting decreases in pharyngeal collapsibility. Combining ACS with HNS increased retropalatal cross-sectional area and increased expiratory airflow, suggesting decreases in pharyngeal collapsibility. Our findings suggest that ACS exerts caudal traction on the upper airway through sternothyroid muscle contraction and that it may augment HNS efficacy in patients with OSA.NEW & NOTEWORTHY Ansa cervicalis stimulation (ACS) is a recently proposed neurostimulation mechanism for generating caudal pharyngeal traction that may benefit patients with obstructive sleep apnea. Here, we document endoscopic findings with ACS during drug-induced sleep endoscopy and additionally detail the effects of ACS on expiratory airflow, when the pharynx is known to be most hypotonic.

Effect of Electrode Configuration and Impulse Strength on Airway Patency in Neurostimulation for Obstructive Sleep Apnea

OBJECTIVES/HYPOTHESIS

Hypoglossal nerve stimulation (HNS) has gained increasing interest for the treatment of patients with obstructive sleep apnea (OSA). Drug-induced sleep endoscopy (DISE) can both exclude improper airway collapse patterns and visualize airway changes under stimulation. Stimulation outcome effects depend on the impulse voltage and electric field resulting from the electrode configuration of the implanted device. The effects of various combinations of voltage and electric field on DISE airway patterns in contrast to awake endoscopy are unknown.

STUDY DESIGN

Cohort study.

METHODS

During therapy adjustment about 6 months after implantation, patients underwent a DISE and awake endoscopy with 100% and 125% of functional voltage in three typical electrode configurations (+ - +, o - o, - - -). All videos were analyzed by two separate persons for the opening of the airway at velum, tongue base, and epiglottis level.

RESULTS

Thirty patients showed typical demographic data. The opening effects were visible in all patients, but there were changes between different electrode configurations. Several demographic or therapeutic aspects such as obesity, OSA severity, or prior soft palate surgery were associated with changes arising from different electrode configurations, but none resulted in a consistently better airway opening.

CONCLUSIONS

In patients with poor results during the therapy adjustment, electric configuration changes can improve airway patency-an independent variable from increasing voltage. As these effects can only be seen in awake endoscopy or DISE, both endoscopies with live stimulation may be considered in cases with insufficient improvement in apnea-hypopnea index after initiation of HNS therapy.

LEVEL OF EVIDENCE

Prospective case series; level 4. Laryngoscope, 131:2148-2153, 2021.

Depth of sedation during drug induced sedation endoscopy monitored by BiSpectral Index® and Cerebral State Index®

PURPOSE

Drug induced sedation endoscopy (DISE) is performed to investigate patterns and sites of obstruction in patients with sleep-disordered breathing (SDB). During DISE the patients are sedated to obtain a muscular relaxation of the upper airway which mimics the relaxation during natural sleep. Different sleep stages are intended to be simulated by drug induced sedation, and it is helpful to measure the depth of sedation. The BiSpectral Index® (BIS) is often used for this procedure. Besides the BIS, other means of sedation depth monitoring exist in anaesthesiology but have not yet been investigated with respect to DISE. Monitoring of the Cerebral State Index® (CSI) is one of these methods. The aim of the study was to compare the BIS and CSI for sedation depth monitoring during DISE.

METHODS

Sixty patients underwent DISE monitored by the BIS and CSI in parallel. The BIS and CSI values were compared using the Bland-Altman analysis.

RESULTS

The BIS and CSI values differed during the course of sedation during DISE by a mean of - 6.07. At light sedation (BIS 60-80), lower values by 10 scale points of CSI compared with BIS were detectable. At deeper sedation levels (BIS 40-50), the CSI turned to present equal and even higher values compared with the BIS.

CONCLUSION

Sedation depth measurement during DISE can be performed by the BIS or CSI, but the differences should be interpreted carefully as comparable data for sleep stages in natural sleep are available only for BIS.

Computer-Assisted Quantitative Analysis of Drug-Induced Sleep Endoscopy for Obstructive Sleep Apnea/Hypopnea Syndrome

OBJECTIVES

To use computer-assisted quantitative measurements of upper airway changes during drug-induced sleep endoscopy (DISE) and to correlate these parameters with disease severities and physiologic changes in patients with obstructive sleep apnea/hypopnea syndrome (OSA).

DESIGN

A retrospective study.

SETTING

Tertiary academic medical center.

PATIENTS AND METHODS

A total of 170 patients who failed continuous positive airway pressure therapy and then underwent upper airway surgery were enrolled. All patients received polysomnography and DISE preoperatively. We used ImageJ 1.48v to obtain maximal and minimal measurements, including cross-sectional areas and anterior-posterior and lateral diameters at 4 anatomic levels (retropalatal, oropharyngeal, retroglossal, and retroepiglottic) under DISE, and then computed the percentage changes. We analyzed the clinical values of DISE changes by computer-assisted analysis in patients with OSA and any correlations between these changes and polysomnography parameters.

RESULTS

The percentage changes of upper airway showed significant collapses at all 4 anatomic levels (all P < .0001). We also found that the changes at retropalatal levels were significantly greater and that retroglossal levels were significantly smaller, while the changes of anterior-posterior diameters at retroglossal levels showed a significant positive association with apnea-hypopnea index and desaturation index. However, there were no statistically significant correlations between upper airway changes and obesity.

CONCLUSION

Computer-assisted quantitative analysis could evaluate upper airway changes of OSA in an objective way and may help identify the sites of obstruction during DISE more accurately. Upper airway showed multilevel collapse with independent significant changes in patients with OSA, with the retropalatal and retroglossal levels playing important roles in particular.

Prospective Determination of Airway Response to Upper Airway Stimulation: A New Opportunity for Advanced Device Titration

OBJECTIVES/HYPOTHESIS

Response to upper airway stimulation (UAS) is associated with the degree of airway opening during stimulation. UAS programming may affect this opening. The objective of this study was to examine airway changes in response to five different electrode configurations programmable within the Inspire UAS system.

STUDY DESIGN

Prospective single-arm cohort study.

METHODS

Subjects who underwent UAS implantation were recruited for a prospective single-arm cohort study during UAS device activation. Functional thresholds were recorded for all settings. Awake nasopharyngoscopy was performed to examine the retropalatal (RP) and retroglossal (RG) regions at rest and during activation with all settings at their functional thresholds. Cross-sectional measurements were made by two blinded reviewers and reported as percent change in airway size.

RESULTS

Sixteen patients were included. The standard setting (+-+) resulted in the greatest change in RP area in 43.8% of patients. An alternative setting resulted in greatest change in 56.2% of patients (--- and o-o in 18.8% each, -o- in 12.5%, and -+- in 6.3% of patients). Average response to all five settings was utilized to classify degree of palatoglossal coupling. Most patients had some enlargement (20%-70% change in RP area, 43.8%) or no enlargement (<20% change, 43.8%), whereas a minority of patients (12.5%) had marked enlargement (>70% change). RP and RG expansion were not correlated.

CONCLUSION

Degree of RP expansion varied among patients and settings. Although the standard setting resulted in greatest RP change in a plurality of patients, over half had a greater response to an alternative setting. Future studies should address whether choice of setting based on RP expansion results in improved outcomes.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:218-223, 2021.

Obstructive sleep apnoea as a late complication after tracheostomy

BACKGROUND

Obstructive sleep apnoea occurs consequent to partial or complete upper airway obstruction, caused mostly by the collapse of upper airway musculature. Drug-induced sleep endoscopy represents the 'gold standard' in identifying the obstruction site, from the palatal level to laryngeal entry. Breathing impairment in sleep caused by the collapse of cervical trachea after previous tracheostomy has not yet been described in the literature.

METHODS

This report presents two patients with severe obstructive sleep apnoea, in whom pre-operative drug-induced sleep endoscopy revealed upper airway and cervical trachea collapse at the level of previous tracheostomy.

RESULTS

The female patient was successfully treated with resection of hypertrophic tissue of the tongue base via lateral pharyngectomy, and resection of the collapsed segment of the trachea with primary reconstruction of the trachea by end-to-end anastomosis. The male patient was recommended continuous positive airway pressure therapy because of serious co-morbidities and high operative risk.

CONCLUSION

Drug-induced sleep endoscopy should always be used for visualisation of anatomical structures below the vocal folds in patients with a history of cervical trachea surgery. These two cases demonstrate the importance of drug-induced sleep endoscopy in planning conservative and surgical treatments, contributing significantly to operative success.

Retropalatal and retroglossal airway compliance in patients with obstructive sleep apnea

OBJECTIVES

We hypothesized that preferential retropalatal as compared to retroglossal collapse in patients with obstructive sleep apnea was due to a narrower retropalatal area and a higher retropalatal compliance. Patients with a greater retropalatal compliance would exhibit a recognizable increase in negative effort dependence (NED).

METHODS

Fourteen patients underwent upper airway endoscopy with simultaneous recordings of airflow and pharyngeal pressure during natural sleep. Airway areas were obtained by manually outlining the lumen. Compliance was calculated by the change of airway area from end-expiration to a pressure swing of -5 cm H₂O. NED was quantified for each breath as [peak inspiratory flow minus flow at -5 cm H₂O]/[peak flow] × 100.

RESULTS

Compared to the retroglossal airway, the retropalatal airway was smaller at end-expiration (p < 0.001), and had greater absolute and relative compliances (p < 0.001). NED was positively associated with retropalatal relative area change (r = 0.47; p < 0.001).

CONCLUSIONS

Retropalatal airway is narrower and more collapsible than retroglossal airway. Retropalatal compliance is reflected in the clinically-available NED value.

[Drug-induced sedation endoscopy-quo vadis? : Review and outlook]

BACKGROUND

Drug-induced sedation endoscopy (DISE) is a diagnostic procedure which allows evaluation of the collapsibility of the upper airway. According to expert opinion, it is possible to imitate nocturnal collapsibility and perform a realistic investigation of the site of obstruction and vibration. This should enable sufficient and precise therapeutic advice to be given solely on the basis of clinical assessment.

OBJECTIVE

The current publication critically evaluates the present state of development of DISE and its potential indications.

MATERIALS AND METHODS

A PubMed literature research was performed using "sleep" and "endoscopy" or "DISE" as keywords. Relevant publications were evaluated.

RESULTS

The present publication provides a historical summary of the available publications and relates these to other methods for examining obstructive sleep apnea. The present state of DISE in terms of drugs applied, grading systems, and validity is evaluated. Indications for DISE are described and critically discussed on the basis of literature data.

CONCLUSION

DISE provides deep insights into the genesis of obstructions of the upper airway and snoring. Although its value for diagnosis and treatment of sleep-disordered breathing could not yet be demonstrated for all non-CPAP (continuous positive airway pressure) therapies, DISE could identify predictive parameters some methods. Further potential indications for DISE might be predictive examinations for mandibular advancement devices and respiration-synchronous neurostimulation of the hypoglossal nerve. DISE will thus remain a valuable diagnostic tool for obstructive sleep apnea and rhonchopathy.

Reliability of drug-induced sedation endoscopy: interobserver agreement

PURPOSE

Several studies have demonstrated the validity, reliability, and safety of drug-induced sedation endoscopy (DISE) in assessing the collapse of the upper airway (UA) in patients with obstructive sleep apnea hypoapnea syndrome (OSAHS). The aim of this study was to assess the interobserver agreement on DISE and on therapeutic decision between an expert observer and an observer in training.

METHODS

This was a cross-sectional study. Thirty-one DISE videos performed in our service were randomly selected. Videos belonged to patients with OSAHS who wanted alternative treatments to CPAP. The videos were reviewed by an ENT experienced on DISE and a second observer in formation. Each observer independently assessed the presence of collapse of the UA according to a modified VOTE classification and proposed an alternative treatment to CPAP. Interobserver agreement kappa values were calculated.

RESULTS

In assessing the presence of collapse at different levels of the upper airway, the percentage of agreement was 80 % at the level of the soft palate (kappa = 0.1667), 89.29 % in the oropharynx (k = 0.7742), 80.65 % at the tongue base (k = 0.5571), and 74.17 % at the epiglottis (k = 0.4768). When degree and configuration of the collapse was evaluated, the interrater agreement was moderate to good, except at the level of the tongue base where the agreement was weak for both degree and configuration of collapse (k = 0.34 and 0.38, respectively). Interobserver agreement was moderate when the indication of alternative treatments to CPAP is valued based on the findings of DISE.

CONCLUSIONS

Overall, DISE is a reliable technique even when assessing interobserver agreement between an experienced observer and one in training; however, tongue base is the level of the upper airway that presents the greatest difficulties when assessing the collapse with DISE. Therefore, it is important to develop learning curves for this technique in order to obtain more reliable results.

MR Image Analytics to Characterize the Upper Airway Structure in Obese Children with Obstructive Sleep Apnea Syndrome

Purpose

Quantitative image analysis in previous research in obstructive sleep apnea syndrome (OSAS) has focused on the upper airway or several objects in its immediate vicinity and measures of object size. In this paper, we take a more general approach of considering all major objects in the upper airway region and measures pertaining to their individual morphological properties, their tissue characteristics revealed by image intensities, and the 3D architecture of the object assembly. We propose a novel methodology to select a small set of salient features from this large collection of measures and demonstrate the ability of these features to discriminate with very high prediction accuracy between obese OSAS and obese non-OSAS groups.

Materials and Methods

Thirty children were involved in this study with 15 in the obese OSAS group with an apnea-hypopnea index (AHI) = 14.4 ± 10.7) and 15 in the obese non-OSAS group with an AHI = 1.0 ± 1.0 (p<0.001). Subjects were between 8–17 years and underwent T1- and T2-weighted magnetic resonance imaging (MRI) of the upper airway during wakefulness. Fourteen objects in the vicinity of the upper airways were segmented in these images and a total of 159 measurements were derived from each subject image which included object size, surface area, volume, sphericity, standardized T2-weighted image intensity value, and inter-object distances. A small set of discriminating features was identified from this set in several steps. First, a subset of measures that have a low level of correlation among the measures was determined. A heat map visualization technique that allows grouping of parameters based on correlations among them was used for this purpose. Then, through T-tests, another subset of measures which are capable of separating the two groups was identified. The intersection of these subsets yielded the final feature set. The accuracy of these features to perform classification of unseen images into the two patient groups was tested by using logistic regression and multi-fold cross validation.

Results

A set of 16 features identified with low inter-feature correlation (< 0.36) yielded a high classification accuracy of 96% with sensitivity and specificity of 97.8% and 94.4%, respectively. In addition to the previously observed increase in linear size, surface area, and volume of adenoid, tonsils, and fat pad in OSAS, the following new markers have been found. Standardized T2-weighted image intensities differed between the two groups for the entire neck body region, pharynx, and nasopharynx, possibly indicating changes in object tissue characteristics. Fat pad and oropharynx become less round or more complex in shape in OSAS. Fat pad and tongue move closer in OSAS, and so also oropharynx and tonsils and fat pad and tonsils. In contrast, fat pad and oropharynx move farther apart from the skin object.

Conclusions

The study has found several new anatomic bio-markers of OSAS. Changes in standardized T2-weighted image intensities in objects may imply that intrinsic tissue composition undergoes changes in OSAS. The results on inter-object distances imply that treatment methods should respect the relationships that exist among objects and not just their size. The proposed method of analysis may lead to an improved understanding of the mechanisms underlying OSAS.

Awake examination versus DISE for surgical decision making in patients with OSA: A systematic review

OBJECTIVE

Traditionally, upper airway examination is performed while the patient is awake. However, in the past two decades, drug-induced sleep endoscopy (DISE) has been used as a method of tridimensional evaluation of the upper airway during pharmacologically induced sleep. This study aimed to systematically review the evidence regarding the usefulness of DISE compared with that of traditional awake examination for surgical decision making in patients with obstructive sleep apnea (OSA).

DATA SOURCES

Scopus, PubMed, and Cochrane Library databases were searched.

REVIEW METHODS

Only studies with a primary objective of evaluating the usefulness of DISE for surgical decision making in patients with OSA were selected. The included studies directly compared awake examination data with DISE outcome data in terms of possible influences on surgical decision making and operation success.

RESULTS

A total of eight studies with 535 patients were included in this review. Overall, the surgical treatment changed after DISE in 50.24% (standard deviation 8.4) cases. These changes were more frequently associated with structures contributing to hypopharyngeal or laryngeal obstruction. However, these differences do not automatically indicate a higher success rate.

CONCLUSION

This review emphasized the direct impact of DISE compared with that of awake examination on surgical decision making in OSA patients. However, it is also clear that the available published studies lack evidence on the association between this impact and surgical outcomes. Laryngoscope, 126:768-774, 2016.

Bispectral Index in Evaluating Effects of Sedation Depth on Drug-Induced Sleep Endoscopy

OBJECTIVE

To evaluate the effect of sedation depth on drug-induced sleep endoscopy (DISE).

METHODS

Ninety patients with obstructive sleep apnea (OSA) and 18 snorers underwent polysomnography and DISE under bispectral index (BIS)-guided propofol infusion at two different sedation levels: BIS 65-75 (light sedation) and 50-60 (deep sedation).

RESULTS

For the patients with OSA, the percentages of velopharynx, oropharynx, hypopharynx, and larynx obstructions under light sedation were 77.8%, 63.3%, 30%, and 33.3%, respectively. Sedation depth was associated with the severity of velopharynx and oropharynx obstruction, oropharynx obstruction pattern, tongue base obstruction, epiglottis anteroposterior prolapse and folding, and arytenoid prolapse. In comparison, OSA severity was associated with the severity of velopharynx obstruction, severity of oropharynx obstruction, and arytenoid prolapse (odds ratio (95% confidence interval); 14.3 (4.7-43.4), 11.7 (4.2-32.9), and 13.2 (2.8-62.3), respectively). A good agreement was noted between similar DISE findings at different times and different observers (kappa value 0.6 to 1, respectively). A high percentage of arytenoid prolapse (46.7% among the patients with OSA under light sedation) was noted.

CONCLUSIONS

Greater sedative depth increased upper airway collapsibility under DISE assessment. DISE under BIS-guided propofol infusion, and especially a level of 65-75, offers an objective and reproducible method to evaluate upper airway collapsibility. Some findings were induced by drug sedation and need careful interpretation. Specific arytenoid prolapse patterns were noted for which further investigations are warranted.

CLINICAL TRIALS REGISTRATION

http://www.clinicaltrials.gov, identifier: NCT01100554.

COMMENTARY

A commentary on this article appears in this issue on page 965.

The relationship between upper airway collapse and the severity of obstructive sleep apnea syndrome: a chart review

Background

We sought to determine the ability of the endoscopic Mueller maneuver (MM) to predict the severity of OSAS based on upper airway (UA) collapse.

Methods

This chart review retrospectively analyzed the results of endoscopic Mueller maneuvers examining the UA on 506 patients suspected of having OSAS. There were 3 areas of UA collapse that were evaluated: velopharynx (VP), base of tongue (BOT), and lateral pharyngeal walls (LPW). A sleep study was done after the examination to assess the severity of OSAS based on the apnea-hypopnea index (AHI).

Results

A total of 506 patients met criteria for OSAS, with 194 mild cases (5 ≤ AHI < 15), 163 moderate cases (15 ≤ AHI < 30) and 149 severe cases (30 ≤ AHI). At the VP, 30 patients had minimal collapse (mean AHI = 17); 41 patients had moderate VP collapse (mean AHI = 25); 392 patients had severe VP collapse (mean AHI = 27). At the BOT, 144 patients had minimal collapse (mean AHI = 19); 187 patients had moderate BOT collapse (mean AHI = 24); 175 patients had severe BOT collapse (mean AHI = 33). At the LPW, 158 patients had minimal collapse (mean AHI = 20); 109 patients had moderate LPW collapse (mean AHI = 25); 120 patients had severe LPW collapse (mean AHI =33). The correlations found between VP collapse, BOT collapse, and LPW collapse and OSAS severity were: r = 0.069 (95 % CI; −0.022, 0.16), r = 0.26 (95 % CI; 0.18, 0.34) and r = 0.22 (95 % CI; 0.12, 0.31), respectively.

Conclusions

In this study, the degree of collapse of the UA at all levels, especially at the BOT and LPW levels, correlate significantly with the severity of OSAS. The Mueller maneuver helped identify patients with severe sleep apnea based on UA collapse. The MM cannot be used to diagnose OSAS, but can be a valuable tool to help the physician estimate the severity of sleep apnea and the urgency to obtain a sleep study.

Volumetric MRI analysis pre- and post-Transoral robotic surgery for obstructive sleep apnea

OBJECTIVES/HYPOTHESIS

To quantitatively measure volumetric changes in upper airway soft tissue structures using magnetic resonance imaging (MRI) pre- and post transoral robotic surgery for obstructive sleep apnea (OSA-TORS).

STUDY DESIGN

Prospective, nonrandomized, institutional board-approved study.

METHODS

Apneics undergoing OSA-TORS, which included bilateral posterior hemiglossectomy with limited pharyngectomy and uvulopalatopharyngoplasty, had upper airway MRIs pre- and postoperatively. Changes (percent and absolute values) in upper airway and surrounding soft tissue volumes were calculated. We assessed whether there were significant volumetric changes and if changes correlated with apnea-hypopnea index (AHI) changes.

RESULTS

Nineteen MRIs and 18 polysomnograms were analyzed pre- and postoperation. Total airway volume increased by 19.4% (P = 0.030). Soft palate and tongue volumes decreased by 18.3% (P = 0.002) and 5.8% (P = 0.013), respectively. Retropalatal and total lateral wall volumes decreased by 49.8% (P = 0.0001) and 17.9% (P = 0.008), respectively. Changes in other structures were not significant. Eleven patients had surgical success, with a mean AHI decrease of 52.9; six were nonsuccesses with a mean AHI decrease of 4.5 (P =0.006). Decreased retropalatal lateral wall volume correlated with decreased AHI.

CONCLUSION

Airway, tongue, soft palate, and lateral wall volumes change significantly after OSA-TORS. Changes in the volume of the lateral walls correlated with changes in AHI. Volumetric upper airway MRI may be a helpful tool to better understand reasons for surgical success.

LEVEL OF EVIDENCE

4.

Evaluation of acoustic characteristics of snoring sounds obtained during drug-induced sleep endoscopy

INTRODUCTION

Snoring sounds are discussed to contain acoustic information about their geneses. Nocturnal snoring can easily be recorded acoustically but it is difficult to visually verify its genesis. Contrary, snoring patterns induced by drug-induced sleep endoscopy (DISE) can be visually differentiated. The aim of the study was to classify patterns of obstructions and vibration during DISE and to evaluate acoustic characteristics between these different patterns of snoring.

METHODS

DISE was performed in 41 male patients with sleep-disordered breathing. The recorded video sequences (n = 108) were classified visually at a mute mode in different patterns of snoring (velar, velar obstructive, tonsillar, post-apnoeic). The sound tracks of these subgroups were analysed and compared with regard to the parameters sound pressure level, loudness, sharpness, roughness, fluctuations strength and centre frequency.

RESULTS

Obstructive snoring patterns revealed a higher loudness than non-obstructive patterns (>25 sone). Velar snoring showed more roughness (>150 cAsper) than tonsillar and post-apnoeic snoring and revealed the lowest centre frequency (<3000 Hz) of all patterns. Tonsillar snoring presented the highest sharpness (>1.6 acum) whereas post-apnoeic snoring revealed the largest fluctuation strength (>50 cVacil).

CONCLUSION

Different snoring patterns induced by DISE can be classified visually, and an approach to differentiate them acoustically by means of psychoacoustic analyses is demonstrated. On the basis of these results, nocturnal snoring might also be differentiated by psychoacoustic algorithms which could be implemented in acoustic polygraphic screening devices in the future.

Effect of upper-airway stimulation for obstructive sleep apnoea on airway dimensions

Upper-airway stimulation (UAS) using a unilateral implantable neurostimulator for the hypoglossal nerve is an effective therapy for obstructive sleep apnoea patients with continuous positive airway pressure intolerance. This study evaluated stimulation effects on retropalatal and retrolingual dimensions during drug-induced sedation compared with wakefulness to assess mechanistic relationships in response to UAS. Patients with an implanted stimulator underwent nasal video endoscopy while awake and/or during drug-induced sedation in the supine position. The cross-sectional area, anterior-posterior and lateral dimensions of the retropalatal and retrolingual regions were measured during baseline and stimulation. 15 patients underwent endoscopy while awake and 12 underwent drug-induced sedation endoscopy. Increased levels of stimulation were associated with increased area of both the retropalatal and retrolingual regions. During wakefulness, a therapeutic level of stimulation increased the retropalatal area by 56.4% (p=0.002) and retrolingual area by 184.1% (p=0.006). During stimulation, the retropalatal area enlarged in the anterior-posterior dimension while retrolingual area enlarged in both anterior-posterior and lateral dimensions. During drug-induced sedation endoscopy, the same stimulation increased the retropalatal area by 180.0% (p=0.002) and retrolingual area by 130.1% (p=0.008). Therapy responders had larger retropalatal enlargement with stimulation than nonresponders. UAS increases both the retropalatal and retrolingual areas. This multilevel enlargement may explain reductions of the apnoea-hypopnoea index in selected patients receiving this therapy.

Examining the mechanism of action of a new device using oral pressure therapy for the treatment of obstructive sleep apnea

STUDY OBJECTIVES

The objective of this study was to explore the mechanism of action of the oral pressure therapy (OPT) device, a new treatment for sleep apnea.

DESIGN

Case series.

SETTING

Academic medical center.

PATIENTS

Fifteen subjects with sleep apnea who had been successfully treated (responders) with the OPT device and 4 subjects who were not successfully treated (non-responders) with the OPT device.

INTERVENTIONS

All subjects underwent a MRI (without the device, with the device in place without vacuum and with the device in place with vacuum) to examine the biomechanical changes associated with the OPT device.

MEASUREMENTS AND RESULTS

Oral pressure therapy significantly (P = 0.002) increased the size of the retropalatal airway in both the lateral and anterior-posterior dimensions by moving the soft palate anteriorly and superiorly and the anterior-superior segment of the tongue forward, toward the teeth. The percentage and absolute increase in the cross-sectional area of the retropalatal region, the superior movement of the soft palate, and the anterior displacement of the tongue were significantly greater in the responders than in the non-responders. In responders, there were significant increases in the mean (P = 0.002), maximum (P = 0.0002), and minimum (P = 0.04) cross-sectional areas of the retropalatal region with the OPT device. However, in the retroglossal region, airway caliber decreased with the OPT device.

CONCLUSIONS

In those who responded to oral pressure therapy, it increased airway caliber in the retropalatal region by moving the soft palate anteriorly and superiorly and the anterior-superior segment of the tongue forward.

CITATION

Schwab RJ, Kim C, Siegel L, Keenan BT, Black J, Farid-Moayer M, Podmore J, Vaska M. Examining the mechanism of action of a new device using oral pressure therapy for the treatment of obstructive sleep apnea.

Drug-induced sleep endoscopy in sleep-disordered breathing: report on 1,249 cases

OBJECTIVES/HYPOTHESIS

To describe upper airway (UA) collapse patterns during drug-induced sleep endoscopy (DISE) in a large cohort of patients with sleep-disordered breathing (SDB) and to assess associations with anthropometric and polysomnographic parameters.

STUDY DESIGN

Observational study.

METHODS

A total of 1,249 patients [age 47 ± 10 y; apnea-hypopnea index (AHI) 18.9 ± 15.3/h; body mass index (BMI) 27.2 ± 3.7 kg/m(2)] underwent polysomnography and DISE. DISE findings were categorized to the following UA levels: palate, oropharynx, tongue base, and hypopharynx. The degree of collapse was reported as complete, partial, or none. The pattern of the obstruction was described as anteroposterior, lateral, or concentric. Associations between DISE findings and anthropometric and polysomnographic parameters were analyzed.

RESULTS

Palatal collapse was seen most frequently (81%). Multilevel collapse was noted in 68.2% of all patients. The most frequently observed multilevel collapse pattern was a combination of palatal and tongue base collapse (25.5%). Palatal collapse was seen most frequently (81%). The prevalence of complete collapse, multilevel collapse, and hypopharyngeal collapse increased with increasing severity of obstructive sleep apnea (OSA). Multilevel and complete collapse were more prevalent in obese patients and in those with more severe OSA. Both higher BMI and AHI values were associated with a higher probability of complete concentric palatal collapse.

CONCLUSION

The current study provides an overview of UA collapse patterns in a large cohort of SDB patients who underwent DISE. The associations found in this study may indicate that UA collapse patterns observed during DISE cannot be fully explained by selected baseline polysomnographic and anthropometric characteristics.