Obstructive site localization using multisensor manometry versus the Friedman staging system in obstructive sleep apnea

Obstruction level associated with outcome in hypoglossal nerve stimulation

Purpose

Selective hypoglossal nerve stimulation (sHNS) constitutes an effective surgical alternative for patients with obstructive sleep apnea (OSA). sHNS results in tongue protrusion and consecutive alleviation of obstructions at the tongue base level (lower obstructions). Furthermore, obstructions at the soft palate level (upper obstructions) may be prevented through palatoglossal coupling as seen on sleep endoscopy. However, it has not been studied if the distribution of obstruction level during a whole night measurement is a relevant factor for the treatment outcome.

Methods

Obstruction levels were measured with a manometry system during a whole night of sleep in 26 patients with OSA (f = 1, m = 25; age 59.4 ± 11.3; BMI = 29.6 ± 3.6) either before (n = 9) or after sHNS implantation (n = 12). Five patients received a measurement before and after implantation. Obstructions were categorized into velar (soft palate and above), infravelar (below soft palate), and multilevel obstructions. An association between obstruction level and treatment outcome was calculated.

Results

The mean distribution of preoperative obstruction level could be divided into the following: 38% velar, 46% multilevel, and 16% infravelar obstructions. Patients with a good treatment response (defined as AHI < 15/h and AHI reduction of 50%) had fewer preoperative velar obstructions compared to non-responder (17% vs. 54%, p-value = 0.006). In patients measured after sHNS implantation, a significantly higher rate of multilevel obstructions per hour was measured in non-responders (p-value = 0.012).

Conclusions

Selective hypoglossal nerve stimulation was more effective in patients with fewer obstructions at the soft palate level. Manometry may be a complementary diagnostic procedure for the selection of patients for HNS.

Correlation between short-time and whole-night obstruction level tests for patients with obstructive sleep apnea

Identification of obstructive level is crucial for successful surgical outcomes in patients with obstructive sleep apnea (OSA). Unfortunately, most of the dynamic airway evaluations are performed for a short duration under drug-induced sleep; therefore, it is uncertain whether they represent airway events that occur during a whole night of sleep. This study was aimed to evaluate the correlation between obstructive levels that were identified by a short-time and a whole-night test in patients with OSA. Total 101 patients with OSA underwent drug-induced sleep fluoroscopy (DISF) and pressure manometry (PM). For DISF, the obstructive pattern was classified into one of three groups: soft palate, tongue-based, and a combined obstruction. PM was used to measure the proportion of retroglossal events out of total whole-night obstructive events in each patient. The mean age of the patients was 43.8 years. The obstructive pattern was identified as soft palate in 56 patients, combined in 38 patients, and tongue-based in 7 patients following DISF. Results from PM showed that the mean percentage of retroglossal obstructive events was 31.2 ± 30.7%. The average proportion of retroglossal obstructive events that were identified by PM in patients with soft palate, combined, and tongue-based obstruction was 27.2%, 32.1%, and 59.0%, respectively (p = 0.033). There are limitations of evaluating obstructive events that occur during a whole night with short-time tests. Surgeons should be aware the possibility of disagreement in the obstructive level between short-time and whole-night tests.

Insights into Friedman stage II and III OSA patients through drug-induced sleep endoscopy

Background

The Friedman staging is a classic system to predict outcomes of obstructive sleep apnea (OSA) surgery. Increasing stage indicates more severe upper airway (UA) obstruction and worse surgical successful rate. In previous studies, the UA obstruction between stages were usually assessed based on awake examination. Drug-induced sleep endoscopy (DISE) is a new method that can evaluate airway collapse characteristics during sleep. Therefore, we planned to compare Friedman staging and DISE findings and fulfill the knowledge gap on the correlation between awake and sedated UA examination.

Methods

Retrospective case series study that assessed patients with OSA who underwent DISE. Subjects were classified to stage II and stage III groups based on Friedman staging system. UA collapse characteristics based on velum, oropharynx, tongue base, epiglottis (VOTE) classification, including single/multiple obstruction sites, single/combined upper and lower obstruction levels, collapse degree and patterns in different sites, and surgical results among the groups were analyzed.

Results

A total of 175 cases were analyzed. No significant differences were found in baseline measurements between groups. Stage III patients (n=102) had a higher proportion (74.5%) with 3 or 4 obstruction sites than stage II (57.5%, n=73). Velum (V) + oropharynx (O) + tongue base (T) was the most common multi-sites combined obstruction pattern with 33% in stage II and 37% in stage III, isolated lower level obstruction was the least with 6% and 4%, respectively. No significant differences were found in obstruction sites and levels. 106 patients underwent surgeries and 33 had post-surgical sleep study, 73.7% and 63.6% response rate were found in stage II and III with no significant difference.

Conclusions

Upper and lower combined obstruction was the main pattern of collapse in both, Friedman stage II and III patients. Patients with OSA and Friedman stage III had more than 2 sites of obstruction than stage II patients.

Hypoglossal nerve stimulation therapy does not alter tongue protrusion strength and fatigability in obstructive sleep apnea

STUDY OBJECTIVES

Hypoglossal nerve stimulation (HNS) is an effective surgical alternative for patients with obstructive sleep apnea (OSA). HNS therapy relies on the stimulation of the hypoglossal nerve to open the upper airways. This stimulation could lead to alterations in tongue strength and fatigability, which could alter treatment outcome over time. The aim of the study was to investigate whether HNS alters tongue strength and fatigability.

METHODS

Tongue protrusion strength (peak pressure in kPa) and fatigability (time to task failure during 50% of peak pressure contraction) were measured with a pressure transducer at least 2 months after HNS implantation (n = 30). These results were compared to a group of patients with OSA (n = 38) and a non-OSA control group (n = 35).

RESULTS

Median tongue protrusion strength was lower (54.7 [43.8, 63.0] versus 60.7 [53.7, 66.0] kPa, P = .013) and fatigue occurred more quickly (21.3 [17.4, 26.3] versus 26.0 [19.3, 31.3] seconds, P = .017) in the patients with OSA compared to the non-OSA control group. In multiple regression analysis, age was a significant factor for tongue strength and diagnosis of OSA for tongue fatigability. Tongue strength and fatigability did not differ between patients with OSA with conservative therapy or observation versus after HNS implantation (51.8 [41.3, 63.4] versus 56.3 [45.0, 62.3] kPa, P = .502; 20.8 [16.3, 26.2] versus 21.8 [18.3, 26.8] seconds, P = .418).

CONCLUSIONS

Tongue strength decreases with age. Tongue fatigability is more pronounced in people with OSA. However, approximately 1.5 years of HNS therapy on average does not alter tongue strength or fatigability compared to an OSA control group.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: Change in Tongue Strength and Fatigue After Upper Airway Stimulation Therapy; Identifier: NCT03980158.

Reduced upper obstructions in N3 and increased lower obstructions in REM sleep stage detected with manometry

In obstructive sleep apnea (OSA), airway obstruction occurs at different anatomic levels. The frequency and location of obstructions play a crucial role in the planning of surgical treatment. The aim of this study was to evaluate the pharyngeal obstruction levels in different sleep stages with manometry in OSA patients. In addition, the manometry results were compared with drug-induced sleep endoscopy (DISE). Forty-one patients with OSA received manometry measurements during one night of sleep. All patients were simultaneously evaluated with polysomnography. The frequency of obstructions in different sleep stages was assessed. Twenty patients were additionally studied with DISE. Obstruction levels detected with manometry were compared with DISE. The frequency of upper and to a lesser extent lower obstructions decreased in sleep stage N3. In rapid eye movement (REM) sleep, lower obstructions increased. The overall proportion of upper and lower obstructions detected with manometry corresponded with DISE in 13 of 20 cases. A significant change in the obstruction levels was detected with manometry in N3 and REM sleep. The reduction of both upper and to a lesser extent lower obstructions in N3 suggests more stable airways in slow-wave sleep. Relevant lower obstructions were not detected in DISE compared to manometry in 5 out of 20 examinations. This could be a potential reason for treatment failure of site-specific surgical OSA treatment when only performing DISE preoperatively. Therefore, manometry could be a useful complementary tool in the preoperative evaluation for OSA.

Friedman tongue position and cone beam computed tomography in patients with obstructive sleep apnea

Objective

Evaluate the correlation between Friedman Tongue Position (FTP) and airway cephalometrics in patients with obstructive sleep apnea (OSA).

Study Design

Retrospective review of adult patients with OSA undergoing Cone Beam Computed Tomography (CBCT).

Methods

Collected data included age, sex, body mass index, apnea hypopnea index, FTP, and airway cephalometric parameters. Data analyses were performed using ANOVA, dichotomous t‐testing, and linear regression.

Results

203 patients were included in the analysis. (M:F 132:71). The mean posterior airway space (PAS) was inversely correlated (p = 0.001, r =.119) with higher FTP grades with means of 12.3 mm, 7.9 mm, 6.6 mm, and 4.3 mm, I‐IV respectively. Minimal cross‐sectional area for patients with FTP I‐IV was 245.7, 179.8, 137.6, and 74.2 mm, 2 respectively (p = 0.002, r = .095). Mean hyoid‐mandibular plane (H‐MP) for FTP I‐IV was 20.6 mm, 20.4 mm, 24.7 mm, and 28.9 mm respectively. No statistically significant difference between H‐MP values when comparing patients with FTP I or II (p = 0.22). There were statistically significant differences when these two groups were individually compared to FTP III and IV (p = 0.002). Linear regression analysis confirmed an independent association between FTP and PAS (β = −2.06, p < 0.001), minimal cross‐sectional area (β = −45.07, p = 0.02), and H‐MP (β = 3.03, p = 0.01) controlling for BMI, age, AHI, and sex.

Conclusions

Use of FTP is supported by objective CBCT cephalometric results, in particular the PAS, minimal cross‐sectional area, and H‐MP. Understanding the correlation between objective measurements of retroglossal collapse should allow Otolaryngologists to more confidently select patients who may require surgery to address the retroglossal area, particularly when the ability to perform cephalometric analysis is not possible

Level of Evidence

4.

A Single Primary Site Obstruction May Lead to Sleep-Disordered Breathing in Multiple Sites: An Animal Model

OBJECTIVES

This study aimed to investigate the dynamic upper airway changes occurring in an obstructive sleep apnea (OSA) rabbit model using dynamic computerized tomography (CT).

METHODS

In this study, 2.5 U of botulinum toxin type A was injected into the genioglossus to paralyze the tongue in the OSA group (n = 7). The control group was injected with normal saline (n = 7). Apnea-hypopnea index was measured using ApneaLink at baseline and at 1, 2, 3, 4, 6, and 8 weeks post-injection. Anterior to posterior (AP) and transverse diameters at the levels of the palate and tongue base were measured using a dynamic CT at baseline and at 1 and 2 weeks post-injection.

RESULTS

The success rate of OSA induction was higher in the OSA group (P = .02). In the OSA group, transverse and AP diameters at the palate level and AP diameter at the tongue base level significantly decreased 2 weeks post-injection (P = .01).

CONCLUSIONS

A single obstruction site may constitute the primary pathogenesis in some OSA patients, even when the involvement of multiple sites is indicated. These findings may contribute to the identification of OSA pathogenesis and improve the planning of treatment based on the primary cause of OSA.

Correlation between the Friedman Staging System and the upper airway volume in patients with obstructive sleep apnea

PURPOSE

This study was designed to evaluate the correlation between computed tomography findings and data from the physical examination and the Friedman Staging System (FSS) in patients with obstructive sleep apnea (OSA).

PATIENTS AND METHODS

We performed a retrospective evaluation by reviewing the medical records of 33 patients (19 male and 14 female patients) with a mean body mass index of 30.38 kg/m(2) and mean age of 49.35 years. Among these patients, 14 presented with severe OSA, 7 had moderate OSA, 7 had mild OSA, and 5 were healthy.

RESULTS

The patients were divided into 2 groups according to the FSS: Group A comprised patients with FSS stage I or II, and group B comprised patients with FSS stage III. By use of the Fisher exact test, a positive relationship between the FSS stage and apnea-hypopnea index (P = .011) and between the FSS stage and body mass index (P = .012) was found. There was no correlation between age (P = .55) and gender (P = .53) with the FSS stage. The analysis of variance test comparing the upper airway volume between the 2 groups showed P = .018.

CONCLUSIONS

In this sample the FSS and upper airway volume showed an inverse correlation and were useful in analyzing the mechanisms of airway collapse in patients with OSA.

Localization of glossopharyngeal obstruction using nasopharyngeal tube versus Friedman tongue position classification in obstructive sleep apnea hypopnea syndrome

Assessing the severity of glossopharyngeal obstruction is important for the diagnosis and therapy of obstructive sleep apnea hypopnea syndrome (OSAHS). The polysomnography (PSG) with nasopharyngeal tube insertion (NPT-PSG) has shown good results in assessing glossopharyngeal obstruction. The objective of this study was to compare NPT-PSG with Friedman tongue position (FTP) classification which was also used to evaluate the glossopharyngeal obstruction. One hundred and five patients with OSAHS diagnosed by PSG were included in the study. All the patients were successfully examined by NPT-PSG. Based on the grade of FTP classification, 105 patients were divided into four groups. The differences of the general clinical data, PSG and NPT-PSG results were analyzed among the four groups. And the coincidence of diagnosing glossopharyngeal obstruction of two methods was calculated. There was no significant difference among the four groups in general clinical data and PSG results. However, NPT-PSG results were significantly different among the four groups. Following with the increasing FTP, apnea hypopnea index increased and lowest saturation of blood oxygen decreased. There were 38 patients with and other 38 patients without glossopharyngeal obstruction diagnosed by both methods. The coincidence of two methods was 72.4 %. NPT-PSG is an easy and effective method in assessing the severity of glossopharyngeal obstruction. The coincidence between the NPT-PSG and FTP classification is good. But in some special OSAHS patients such as glossoptosis, unsuccessful uvulopalatopharyngoplasty or suspicious pachyglossia, NPT-PSG is better than FTP classification.

Analysis of upper airway obstruction by sleep videofluoroscopy in obstructive sleep apnea: a large population-based study

OBJECTIVES/HYPOTHESIS

To analyze the pattern of the upper airway obstruction in a large cohort of obstructive sleep apnea (OSA) patients using sleep videofluoroscopy (SVF).

STUDY DESIGN

Retrospective analysis.

METHODS

This study included 922 OSA patients who underwent both polysomnography and SVF. Their mean age, apnea-hypopnea index, and body mass index were 46.8 years, 34.2 per hour, and 26.2 kg/m2, respectively. Sleep was induced by intravenous injection of midazolam, and the obstruction pattern was determined on SVF when oxygen saturation dropped by more than 4% in pulse oxymetry.

RESULTS

The anatomic structure and airway level, which were most commonly involved in obstruction, were the soft palate (77.9%) and the oropharynx (88.1%), respectively. The soft palate alone was the most common obstructed structure in mild OSA (43.2%), and the combination of the soft palate and the tongue base was more frequent in severe OSA (45.2%). The tongue base or the hypopharynx was progressively more involved in moderate/severe OSA cases (P<.001, respectively), and a multiplicity of obstruction pattern also increased according to OSA severity (P<.001). However, 32.4% of the patients with mild OSA also had multiple obstructive anatomic structures.

CONCLUSIONS

Even if multiplicity of obstruction pattern was most commonly associated with severe OSA, almost one third of mild OSA patients also showed multiple anatomic structures and levels of obstruction. Therefore, a precise evaluation for multiplicity of obstruction patterns should precede the decision of a treatment plan, regardless of disease severity.

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.

Comparison between tongue base and soft palate obstruction in obstructive sleep apnea

CONCLUSIONS

In obstructive sleep apnea syndrome (OSAS), respiratory disturbances are more serious in tongue base-associated obstructions (TBOs) than in soft palate-associated obstructions (SPOs), and the proportion of TBO was predicted by average duration of apnea and hypopnea, and inversely by percentage time of snoring.

OBJECTIVE

To compare the polysomnographic characteristics of two main obstruction sites of OSAS, the soft palate and tongue base, and to identify those variables correlated with tongue base obstructions in patients with OSAS.

PATIENTS AND METHODS

Thirty-one patients (28 men and 3 women) with OSAS were enrolled in this study. To identify airway obstruction levels upper airway pressure manometry was applied during polysomnography. Airway obstructions were categorized as SPO and TBO by observing pressure patterns. All analyses of events were performed in the supine position.

RESULTS

Average duration of apnea and hypopnea, percentage of apnea among apnea-hypopneas, average O(2) desaturation, and percentage of event-related arousals were significantly higher in TBOs compared with SPOs (all p<0.05). The percentage of TBO among total obstructions (TBO%) was independently associated with average duration of apnea and hypopnea (=0.38, p<0.05) and percentage time of snoring (=-0.44, p<0.01) (adjusted R(2)=30%, p<0.01).

Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.