Dynamic Drug-Induced Sleep Computed Tomography in Adults With Obstructive Sleep Apnea

Characteristics and Mechanism of Upper Airway Collapse Revealed by Dynamic MRI During Natural Sleep in Patients with Severe Obstructive Sleep Apnea

Purpose

Upper airway collapse during sleep in patients with obstructive sleep apnea (OSA) is a complex and dynamic phenomenon. By observing and analyzing the dynamic changes in the upper airway and its surrounding tissues during airway obstruction, we aim to reveal dynamic characteristics in different obstruction patterns, and the relationship between anatomical features during normal breathing and dynamic characteristics of airway obstruction.

Patients and Methods

Dynamic MRI was performed in 23 male patients (age range 26-63) with severe OSA diagnosed by overnight polysomnography, and obstruction events were identified from their images. Dynamic changes in parameters of the upper airway and surrounding tissues were measured to assess the key characteristics in different obstruction patterns.

Results

We categorized airway obstruction into four types based on the obstruction location and motion characteristics of tissues during collapse, and detailed the alterations in the airway and surrounding tissues under each obstruction pattern. In all 112 obstruction events extracted from the dynamic images of 23 patients, type A (retropalatal obstruction caused by the soft palate separated from the tongue), BI, BII (both retropalatal obstructions caused by the soft palate attached to the tongue, and C (retropalatal and retroglossal obstruction caused by the soft palate and the tongue), accounted for 28.6%, 44.6%, 12.5%, and 14.3% respectively. In severe OSA patients with tongue and palatal obstruction related to type B or C, the more posterior hyoid position, shorter distance between tongue and uvula, and wider retropalatal space, the larger the tongue displacement and deformation during collapse, and the greater the reduction in airway space.

Conclusion

There are multiple airway obstruction patterns, each with its own anatomical characteristics and behaviors during collapse. Hyoid position, tongue and uvula distance, and retropalatal space play an important role in airway collapse and should be paid more attention in the treatment of OSA.

Development of a Deep Learning-Based Epiglottis Obstruction Ratio Calculation System

Surgeons determine the treatment method for patients with epiglottis obstruction based on its severity, often by estimating the obstruction severity (using three obstruction degrees) from the examination of drug-induced sleep endoscopy images. However, the use of obstruction degrees is inadequate and fails to correspond to changes in respiratory airflow. Current artificial intelligence image technologies can effectively address this issue. To enhance the accuracy of epiglottis obstruction assessment and replace obstruction degrees with obstruction ratios, this study developed a computer vision system with a deep learning-based method for calculating epiglottis obstruction ratios. The system employs a convolutional neural network, the YOLOv4 model, for epiglottis cartilage localization, a color quantization method to transform pixels into regions, and a region puzzle algorithm to calculate the range of a patient's epiglottis airway. This information is then utilized to compute the obstruction ratio of the patient's epiglottis site. Additionally, this system integrates web-based and PC-based programming technologies to realize its functionalities. Through experimental validation, this system was found to autonomously calculate obstruction ratios with a precision of 0.1% (ranging from 0% to 100%). It presents epiglottis obstruction levels as continuous data, providing crucial diagnostic insight for surgeons to assess the severity of epiglottis obstruction in patients.

Comparing Diagnostic Efficacy of Imaging During Muller's Maneuver Versus Drug Induced Sleep Endoscopy in Obstructive Sleep Apnoea

The aim of the study was to compare the diagnostic efficacy of quantitative computed tomography (CT) based upper airway analysis using the Muller's maneuver (MM) and compare the findings with drug induced sleep endoscopy (DISE). A prospective observational study was conducted on 50 adult patients with symptoms of OSA and having apnoea-hypopnea index more than 5. They further underwent CT during normal breathing and during MM; findings of which were compared with DISE. Collapse at velum had statistically significant correlation with collapse at retropalatal level in CT (in MM) (P value = 0.001; r = 0.536). Base of tongue in DISE correlates significantly with retroglossal collapse on CT (P value = 0.002; r = 0.423). Epiglottic and oropharyngeal collapse had no correlation with any CT parameter. Collapse in CT as measured during MM shows significant correlation with DISE findings at velum and tongue base but cannot solely predict all levels without the aid of DISE.

Depression with obstructive sleep apnea lead to high cardiovascular disease morbidity/all-cause mortality: Findings from the SHHS cohort

The aim of this study is to explore the association between depression and obstructive sleep apnea, and cardiovascular disease morbidity/all-cause mortality using Sleep Heart Health Study data. This post hoc analysis of a prospective study used patient data from the Sleep Heart Health Study conducted between 1995 and 1998. The association between depression and obstructive sleep apnea, and cardiovascular disease morbidity/all-cause mortality was explored using multivariable Cox proportional hazard models. A total of 4918 participants, 656 (13.3%) with obstructive sleep apnea (obstructive sleep apnea group), 1614 (32.8%) with depression (depression group), 482 (9.8%) with depression and obstructive sleep apnea (depression and obstructive sleep apnea group), and 2166 (44%) with neither obstructive sleep apnea nor depression (health group), were included. The incidence of cardiovascular disease was 24.5%, 31.0%, 31.6% and 41.7% for healthy, depression, obstructive sleep apnea, and depression and obstructive sleep apnea groups, respectively. The risk of cardiovascular disease in depression and obstructive sleep apnea participants was increased compared with that in healthy participants, which was consistent across various definitions of obstructive sleep apnea (hazard ratio [95% confidence interval]: 1.24 [1.06-1.47]; 1.25 [1.05-1.49]; 1.28 [1.06-1.54]; 1.55 [1.22-1.96] for apnea-hypopnea index ≥ 10 per hr, 15 per hr, 20 per hr, 30 per hr, respectively). The risk of all-cause mortality was increased in the depression and obstructive sleep apnea participants (hazard ratio: 1.46; 95% confidence interval: 1.07-1.99) compared with that in healthy participants when the definition of obstructive sleep apnea was apnea-hypopnea index ≥ 30. Participants with depression and obstructive sleep apnea might be at a greater risk of cardiovascular disease, and those with higher apnea-hypopnea index might be at a greater risk of all-cause mortality.

Ramped versus sniffing position in the videolaryngoscopy-guided tracheal intubation of morbidly obese patients: a prospective randomized study

BACKGROUND

Ramped positioning is recommended for intubating obese patients undergoing direct laryngoscopy. However, whether the use of the ramped position can provide any benefit in videolaryngoscopy-guided intubation remains unclear. This study assessed intubation time using videolaryngoscopy in morbidly obese patients in the ramped versus sniffing positions.

METHODS

This is a prospective randomized study in patients with morbid obesity (n = 82; body mass index [BMI] ≥ 35 kg/m2). Patients were randomly allocated to either the ramped or the standard sniffing position groups. During the induction of general anesthesia, difficulty in mask ventilation was assessed using the Warters scale. Tracheal intubation was performed using a C-MAC® D-Blade videolaryngoscope, and intubation difficulty was assessed using the intubation difficulty scale (IDS). The primary endpoint was the total intubation time calculated as the sum of the laryngoscopy and tube insertion times.

RESULTS

The percentage of difficult mask ventilation (Warters scale ≥ 4) was significantly lower in the ramped (n = 40) than in the sniffing group (n = 41) (2.5% vs. 34.1%, P < 0.001). The percentage of easy intubation (IDS = 0) was significantly higher in the ramped than in the sniffing group (70.0% vs. 7.3%, P < 0.001). The total intubation time was significantly shorter in the ramped than in the sniffing group (22.5 ± 6.2 vs. 40.9 ± 9.0, P < 0.001).

CONCLUSIONS

Compared with the sniffing position, the ramped position reduced intubation time in morbidly obese patients and effectively facilitated both mask ventilation and tracheal intubation using videolaryngoscopy.

Holistic care for obstructive sleep apnea (OSA) with an emphasis on restoring nasal breathing: A review and perspective

Obstructive sleep apnea (OSA) is characterized by partial or complete airway blockage during sleep. Nocturnal nasal obstruction usually leads to mouth breathing while sleeping, which worsens sleep apnea by aggravating tongue base and lateral pharyngeal wall collapse. The pathogenesis of OSA is multifactorial, and the precipitating factors vary significantly among individuals. Although continuous positive airway pressure (CPAP) is considered the first-line therapy for OSA, its adherence rate remains a challenge. Oral appliances are more suitable for simple snorers or patients with mild OSA. Maxillomandibular advancement (MMA) is highly effective for treating those with mandibular retrognathia and moderate-to-severe OSA. Intrapharyngeal surgeries yield favorable outcomes in patients with large tonsils and low tongue resting position (Friedman Stage I); however, their efficacy declines with time. Each therapy has its own strength and weakness; thus, the principle of multimodality treatment should be adopted. Nasal surgery plays an indispensable role in the holistic care for OSA. In addition to alleviating nasal congestion, nasal surgery significantly reduces snoring intensity and daytime sleepiness, which improves the quality of life of patients with OSA. Although it significantly reduces the respiratory disturbance index, its effect on the apnea-hypopnea index remains controversial. A combination of nasal surgery and multilevel pharyngeal surgery may result in better prognosis. Nasal surgery can significantly reduce the therapeutic pressure and improve the CPAP compliance of patients undergoing CPAP therapy. In conclusion, multimodality treatment and holistic care for OSA should involve nasal surgery for optimizing treatment outcomes.

Dynamic sleep MRI in obstructive sleep apnea: a systematic review and meta-analysis

Purpose

The objective of this study is to systematically review the international literature for dynamic sleep magnetic resonance imaging (MRI) as a diagnostic tool in obstructive sleep apnea (OSA), to perform meta-analysis on the quantitative data from the review, and to discuss its implications in future research and potential clinical applications.

Study design

A comprehensive review of the literature was performed, followed by a detailed analysis of the relevant data that has been published on the topic.

Methods

Clinical key, Uptodate, Ovid, Ebscohost, Pubmed/MEDLINE, Scopus, Dynamed, Web of Science and The Cochrane Library were systematically searched. Once the search was completed, dynamic sleep MRI data were analyzed.

Results

Nineteen articles reported on 410 OSA patients and 79 controls that underwent dynamic sleep MRI and were included in this review. For meta-analysis of dynamic sleep MRI data, eight articles presented relevant data on 160 OSA patients. Obstruction was reported as follows: retropalatal (RP) 98%, retroglossal (RG) 41% and hypopharyngeal (HP) in 5%. Lateral pharyngeal wall (LPW) collapse was found in 35/73 (48%) patients. The combinations of RP + RG were observed in 24% and RP + RG + LPW in 16%. If sedation was used, 98% of study participants fell asleep compared to 66% of unsedated participants.

Conclusions

Dynamic sleep MRI has demonstrated that nearly all patients have retropalatal obstruction, retroglossal obstruction is common and hypopharyngeal obstruction is rare. Nearly all patients (98%) who are sedated are able to fall asleep during the MRI. There is significant heterogeneity in the literature and standardization is needed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00405-021-06942-y.

Post-Operative Sleep Endoscopy with Target-Controlled Infusion After Palatopharyngoplasty for Obstructive Sleep Apnea: Anatomical and Polysomnographic Outcomes

INTRODUCTION

The findings of drug-induced sleep endoscopy (DISE) are not always correlated with the outcome of upper airway surgery for obstructive sleep apnea (OSA), and whether multilevel surgery is truly required in treating multilevel obstruction identified in preoperative DISE remains an issue. We attempted to compare DISE findings before and after palatopharyngoplasty in patients with OSA because changes in DISE may be beneficial to better understand polysomnographic and anatomical outcomes.

METHODS

This was a prospective cohort study for 34 patients with moderate to severe OSA who underwent palatopharyngoplasty at a tertiary care center from 2016 to 2018. We recorded the patients' demographic characteristics, procedures, and surgical outcomes and compared the preoperative and postoperative DISE staging patterns.

RESULTS

The apnea-hypopnea index (AHI) values of 34 adults improved significantly after surgery (40.6 ± 23.3 versus 25.6 ± 20.6, P < 0.001). The majority of patients, 26/34, had preoperative complete concentric collapse at the velum, and for most (20/26, 77%) there was a change of the collapse pattern into anteroposterior collapse postoperatively. Patients with postoperative velar collapse had higher follow-up AHI values than those who without (27.8 ± 21.9 versus 15.2 ± 7.7, P = 0.023). Patients with preoperative complete tongue base collapse had higher follow-up AHI values than did those with no or partial collapse (40.6 ± 21.0 versus 21.0 ± 18.6, P = 0.017). Patients with postoperative complete tongue base collapse also had higher follow-up AHI values than the others (42.7 ± 22.1 versus 18.5 ± 15.4, P = 0.001).

CONCLUSION

Palatopharyngoplasty could change the collapse pattern at the velum in most patients. Preoperative and postoperative complete tongue base collapse and postoperative velar collapse identified in TCI-DISE were associated with relatively poor outcomes.

Prediction of Epiglottic Collapse in Obstructive Sleep Apnea Patients: Epiglottic Length

OBJECTIVE

This study aims to explore the factors that contribute to epiglottic collapse (EC) in patients with obstructive sleep apnea (OSA).

METHODS

This study enrolled 35 patients (34 males; median age, 39 years; median apnea-hypopnea index (AHI), 55.4 events/h; median body mass index (BMI), 26.9 kg/m²). EC (epiglottis attaching onto the posterior pharyngeal wall) was diagnosed by drug-induced sleep computed tomography (DI-SCT). Three dimensions were assessed for comparison between the EC and non-EC (NEC) groups that included anatomical measurement: epiglottic length and angle, endoscopic classification of epiglottis obstructing the glottis (Type I, none; Type II, partial; and Type III, total), and dynamic hyoid movement during DI-SCT (Δ hyoid = √(x² + y²), maximal displacement of hyoid in x and y axes during sleep breathing cycle).

RESULTS

EC was found in 12 patients (34%). No difference in age, gender, AHI, and BMI between the two groups was noted. The anatomical measurement revealed that epiglottis length was significantly different between the EC and NEC groups (21.2 vs 15.8 mm; p < 0.001), with a cutoff value of 16.6 mm (sensitivity, 100%; specificity, 65.2%). The EC group patients showed larger hyoid movement than the NEC group patients (Δ hyoid, 4.8 vs 3.0 mm; p = 0.027). By contrast, epiglottic angle and endoscopic classification revealed an insignificant difference between the two groups.

CONCLUSION

Epiglottis is a potential collapse site among multilevel obstruction in moderate to severe OSA patients. Epiglottic length is highly sensitive in predicting EC, with the cutoff value of 16.6 mm. Hyoid movement plays a role in contributing to EC in OSA patients.

Prevalence and patterns of tongue deformation in obstructive sleep apnea: A whole-night simultaneous ultrasonographic and polysomnographic study

Tongue deformation during whole-night natural sleep in adult patients with obstructive sleep apnea has not been well evaluated. Through simultaneous ultrasonography and polysomnography during whole-night sleep, we examined the prevalence and patterns of tongue depth changes and their relationship with the severity of obstructive sleep apnea. Sixty consecutive eligible adults presenting with symptoms suggesting obstructive sleep apnea were enrolled. We observed that 88.4% (38/43) of patients with obstructive sleep apnea exhibited a significant increase in the maximum ultrasonographic tongue depth when hypopnea or apnea occurred during sleep. A mixed-model analysis of variance demonstrated that compared with patients with primary snoring or mild obstructive sleep apnea, those with moderate to severe obstructive sleep apnea have significantly greater maximum ultrasonographic tongue depth during respiratory events (p = .0047). We identified three different ultrasonographic patterns of tongue deformation, namely en bloc, tongue body and tongue base. Approximately 82% (27/33) of patients with moderate to severe obstructive sleep apnea demonstrated an en bloc tongue deformation. By contrast, 70% (19/27) of primary snorers or patients with mild obstructive sleep apnea showed a tongue body obstruction. Recognizing the prevalence and patterns of tongue deformation during sleep may provide insights into pathogenesis and treatment decisions in patients with obstructive sleep apnea. Future studies are warranted to verify the treatment results of various tongue procedures by using this approach.

How to manage continuous positive airway pressure (CPAP) failure -hybrid surgery and integrated treatment

Obstructive sleep apnea (OSA) is a prevalent disease, which influences social relations and quality of life with major health impact. The etiology of OSA is multi-factorial involving both anatomical obstruction and physiological collapse of the upper airway during sleep with different proportion in individual patients. Continuous positive airway pressure (CPAP) is the gold standard and first-line treatment for OSA patients. The mechanism of CPAP is acting as air splint to avoid principal pharyngeal collapse during sleep. Consequently, extrapharyngeal collapse and significant pharyngeal obstructions can lower its compliance and lead to its failure. Adequate mask and pressure with thorough survey to eliminate side effects of CPAP from nasal, mask and flow-related problems are the prerequisite to improve CPAP compliance. For CPAP failure patients, multi-dimensional surgery is an alternative and salvage treatment that involves soft tissue surgery, skeletal surgery, and bariatric surgery. OSA patients with craniofacial anomaly are suggested to skeletal surgery. By contrast, OSA patients with pathological obesity are referred to bariatric surgery. Soft tissue surgery targets at the nose, soft palate, lateral pharyngeal wall, tongue and epiglottis that can be implemented by multi-level surgery with hybrid technique (mucosa-preservation, fat-ablation, muscle-suspension, tonsil-excision, cartilage-reconstruction) to maximize surgical outcomes and minimize complications. Some evolution in surgical concept and technique are noteworthy that include mini-invasive septoturbinoplasty, palatal suspension instead of excision, whole tongue treatment, and two-dimensional supraglottoplasty. Postoperative integrated treatment including myofunctional, positional therapy and body weight control reduces relapse of OSA and improves long-term treatment outcomes.

Risk of Alzheimer's Disease in Obstructive Sleep Apnea Patients With or Without Treatment: Real-World Evidence

OBJECTIVE

To assess the risk of Alzheimer's disease (AD) in patients with obstructive sleep apnea (OSA) with or without treatment based on real-world evidence.

STUDY DESIGN

Retrospective cohort study.

METHODS

Patients newly diagnosed with OSA during 1997-2012 were identified using the National Health Insurance Research Database of Taiwan. Patients without OSA were randomly selected and matched in a 1:4 ratio by age, sex, urbanization level, and income. All patients were followed up until death or the end of 2013. The primary outcome was AD occurrence.

RESULTS

This study included 3,978 OSA patients and 15,912 non-OSA patients. OSA was independently and significantly associated with a higher incidence of AD in an adjusted Cox proportional hazard model (adjusted hazard ratio: 2.12; 95% confidence interval [CI], 1.27-3.56). The average period of AD detection from the time of OSA occurrence was 5.44 years (standard deviation: 2.96). Subgroup analyses revealed that the effect of OSA remained significant in patients aged ≥60 years, male subgroups, patients without CPAP or surgical treatment, and patients without pharmacological therapies. Patients with OSA who received treatment (continuous positive airway pressure or surgery) exhibited a significantly reduced risk of AD compared with those without treatment (incidence rate ratio 0.23, 95% CI, 0.06-0.98).

CONCLUSION

OSA is independently associated with an increased risk of AD. Treatment for OSA reduces the AD risk in OSA patients. AD irreversibility renders OSA as a potential modifiable target for slowing or preventing the process of AD development.

LEVEL OF EVIDENCE

IV Laryngoscope, 130:2292-2298, 2020.

Parapharyngeal fat pad area at the subglosso-supraglottic level is associated with corresponding lateral wall collapse and apnea-hypopnea index in patients with obstructive sleep apnea: a pilot study

The aim of this study was to assess associations between fat pad areas at various anatomic levels and the sites of lateral wall collapse and disease severity in adult patients with obstructive sleep apnea (OSA). Forty-one patients with OSA who prospectively underwent drug-induced sleep computed tomography were included. Areas of parapharyngeal fat pads and degrees of lateral wall collapse at three representative anatomic levels (nasopharynx, oropharynx, and subglosso-supraglottis), and apnea-hypopnea index (AHI) were measured. In the subglosso-supraglottic region, the parapharyngeal fat pad area in 17 (41%) patients with complete lateral wall collapse was significantly larger than that in 24 (59%) patients without complete collapse (median, 236.0 mm² vs 153.0 mm²; P = 0.02). In multivariate regression analysis, the parapharyngeal fat pad area at the subglosso-supraglottic level (β = 0.02; P = 0.01) and body mass index (β = 3.24; P = 0.01) were independently associated with AHI. Our preliminary results supported that parapharyngeal fat pads at the subglosso-supraglottic level may be involved in the development of lateral wall collapse and then determine the severity of OSA. Further studies are warranted to investigate the effect of reducing parapharyngeal fat pads in the treatment of OSA.

The value of drug-induced sleep computed tomography in diagnosis of obstructive sleep apnea syndrome: a pilot study

Background: Obstructive sleep apnea syndrome (OSAS) is a public health problem that affects a large amount of people. Surgery sometimes is considered a better treatment modality that does not require the use of a device such as CPAP. Objectives: To explore the value of anesthetic-induced sleep computed tomography (DI-SCT) in the diagnosis of OSAS. Materials and methods: A total of 124 patients with OSAS aged between 18 and 65 years old were enrolled in this study. The upper airway was scanned by computed tomography (CT) while they were wake and went sleep. Sleep was induced by dexmedetomidine under electrocardiograph and oxyhemoglobin saturation monitoring. Parameters relevant to OSAS were then collected and counted. Results: CT scanning revealed that 119 occurred stenosis in oropharynx, in which 5 cases were accompanied with stenosis or occlusion at retroglossal area. About 38 (30.67%) cases existed deviation of nasal septum with retropalatal problems. About 61.33% of patients had multi-level obstructions and the most common obstructive site was oropharynx (90.67%). Conclusions and significance: DI-SCT is a safe and non-invasive modality for diagnosing the obstructive sites in OSAS patients.

Intrapharyngeal surgery with integrated treatment for obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common disease in adults, which influences human relations, quality of life and associates with major complications. Continuous positive airway pressure (CPAP) is the gold standard treatment modality in OSA patients. For patients incompliant or unwilling to CPAP therapy, surgery is an alternative treatment. Sleep surgery for OSA include intrapharyngeal surgery, extrapharyngeal surgery and bariatric surgery addressing upper airway soft tissue, maxillofacial bone, and obesity, respectively. Among sleep surgeries, intrapharyngeal surgery (soft tissue surgery) is widespread used and serves overwhelming majority in OSA surgical patients. Despite the popularity of intrapharyngeal surgery, its outcomes can be influenced by multiple factors and consequently need conjunctive remedy to enhance at the short-term and sustain in the long-term. In this article, we introduce updated indications for treating OSA, practical principle in decision-making between CPAP and surgery, hybrid procedures in treating obstruction at the nose, palate, tongue and epiglottis, and postoperative integrated treatment including oropharyngeal myofunctional therapy (local), positional therapy (regional), and body weight reduction (systemic), and circadian rhythm (central). In summary, intrapharyngeal surgery is a target-oriented procedure that needs to be performed precisely and combines with integrated treatment as a holistic care for OSA patients.

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.

Controversies in Obstructive Sleep Apnea Surgery

Obstructive sleep apnea (OSA) is a common chronic disease characterized by repetitive pharyngeal collapse during sleep. OSA is associated with cardiovascular disease and increased mortality, among other issues. Continuous positive airway pressure (CPAP) is considered first line therapy for OSA, but is not always tolerated. Both non-surgical and surgical alternative management strategies are available for the CPAP intolerant patient. This article explores controversies surrounding airway evaluation, definition of successful treatment, and surgical management of the CPAP intolerant patient with moderate to severe OSA. Controversies specific to maxillomandibular advancement (MMA) are also discussed.

Suspension Palatoplasty for Obstructive Sleep Apnea- A Preliminary Study

Suspension palatoplasty, a new surgical technique to treat obstructive sleep apnea (OSA), has been developed to correct the retropalatal obstruction in patients with small tonsils (grade I/II) and anterior-posterior palatal (A-P) obstruction. The objecteive of this preliminary study was to investigate the effectiveness and change in retropalatal airway dimensions after suspension palatoplasty. This retrospective case series study included 25 consecutive male adults with OSA. Unique technical features of suspension palatoplasty are exposure of pterygomandibular raphe and suspension of palatopharyngeus muscle to the raphe. Six months after suspension palatoplasty, apnea-hyponea index significantly reduced from 39.8 to 15.1 (effect size = 1.6). None experienced postoperative bleeding and velopharyngeal insufficiency 1 month following surgery. Subjective snoring severity (visual analogue scale) and daytime sleepiness (the Epworth Sleepiness Scale) significantly improved (8.7 vs 2.0 and 10.2 vs 4.9, respectively). A-P dimension of the retropalatal airspace widened significantly on perioperative endoscopy (23.0 units vs 184.6 unites) as well as posterior air space in cephalometry (7.6 mm vs 10.2 mm). Our preliminary findings show that suspension palatoplasty seems to be an effective OSA surgery in the specific patient population with minimal complications, however, further studies including a large number of patients are required to confirm the findings.

Airflow Shape Is Associated With the Pharyngeal Structure Causing OSA

BACKGROUND

OSA results from the collapse of different pharyngeal structures (soft palate, tongue, lateral walls, and epiglottis). The structure involved in collapse has been shown to impact non-CPAP OSA treatment. Different inspiratory airflow shapes are also observed among patients with OSA. We hypothesized that inspiratory flow shape reflects the underlying pharyngeal structure involved in airway collapse.

METHODS

Subjects with OSA were studied with a pediatric endoscope and simultaneous nasal flow and pharyngeal pressure recordings during natural sleep. The mechanism causing collapse was classified as tongue-related, isolated palatal, lateral walls, or epiglottis. Flow shape was classified according to the degree of negative effort dependence (NED), defined as the percent reduction in inspiratory flow from peak to plateau.

RESULTS

Thirty-one subjects with OSA (mean apnea-hypopnea index score ± SD, 54 ± 27 events/h) who were 50 ± 9 years of age were studied. NED was associated with the structure causing collapse (P < .001). Tongue-related obstruction (n = 13) was associated with a small amount of NED (median, 19; interquartile range [IQR], 14%-25%). Moderate NED was found among subjects with isolated palatal collapse (median, 45; IQR, 39%-52%; n = 8) and lateral wall collapse (median, 50; IQR, 44%-64%; n = 8). The epiglottis was associated with severe NED (median, 89; IQR, 78%-91%) and abrupt discontinuities in inspiratory flow (n = 9).

CONCLUSIONS

Inspiratory flow shape is influenced by the pharyngeal structure causing collapse. Flow shape analysis may be used as a noninvasive tool to help determine the pharyngeal structure causing collapse.