Evaluation of Therapeutic Positive Airway Pressure as a Hypoglossal Nerve Stimulation Predictor in Patients With Obstructive Sleep Apnea

Physiologic and anatomic determinants of hyoid motion during drug-induced sleep endoscopy

PURPOSE

To examine factors accounting for differences in hyoid motion during obstructive breathing events amongst obstructive sleep apnea (OSA) patients.

METHODS

This was a prospective cohort study from June 2022 to October 2022. Patients with OSA undergoing evaluation for PAP alternative therapies with drug-induced sleep endoscopy with positive airway pressure titration (DISE-PAP). All patients underwent DISE-PAP and concurrent hyoid-focused ultrasound. DISE-PAP enabled measurement of airway physiology (flow, respiratory effort) and airway collapsibility (pharyngeal opening pressure, PhOP). Hyoid-ultrasound enabled hyoid bone movement during obstructive breathing. Respiratory effort was measured using a retro-epiglottic pressure-sensitive catheter. Hyoid position was measured using a standardized, awake, CT protocol. Regression analyses adjusted for age, race, sex, and BMI were performed to associate indices of respiratory effort and CT data with hyoid motion.

RESULTS

On average, the 26 patients in this cohort were older (63.9 ± 10.5 years), male (69%), overweight (29.6 ± 3.99 kg/m2), and with moderate-to-severe OSA (26.8 ± 10.4 events/hour). Greater respiratory effort was associated with increased hyoid motion (β [95% CI] = 0.034 [0.016,0.052], standardized β = 0.261,p = 0.0003). Higher hyoid position was associated with greater hyoid displacement (β [95% CI] = -0.20 [-0.38,-0.01], Standardized β = -0.57, p = 0.036).

CONCLUSION

Our data demonstrate that greater respiratory effort, higher hyoid position, and higher airway collapsibility, but not airflow, are associated with greater hyoid motion during obstructive breathing in DISE. These findings suggest that downward hyoid movement represents a compensatory response to upper airway obstruction. Further studies should investigate the vectors of hyoid motion to better understand its role in sleep-related airway collapse.

Baseline Characteristics Associated with Hypoglossal Nerve Stimulation Treatment Outcomes in Patients with Obstructive Sleep Apnea: A Systematic Review

Hypoglossal nerve stimulation (HGNS) has emerged as an effective treatment for obstructive sleep apnea (OSA). Identifying baseline characteristics that prospectively could predict treatment outcomes even better is crucial for optimizing patient selection and improving therapeutic success in the future. A systematic review was conducted following PRISMA guidelines. Literature searches in Medline, Web of Science, and Cochrane databases identified studies assessing baseline characteristics associated with HGNS treatment outcomes. Inclusion criteria focused on studies with adult patients diagnosed with OSA, treated with HGNS, and assessed using full-night efficacy sleep studies. Risk of bias was evaluated using the NICE tool. Twenty-six studies met the inclusion criteria. Commonly reported baseline characteristics with predictive potential included BMI, site of collapse, and various pathophysiological endotypes. Most studies used the original Sher criteria to define treatment response, though variations were noted. Results suggested that lower BMI, absence of complete concentric collapse at the palatal level, and specific pathophysiological traits were associated with better HGNS outcomes. This review identified several baseline characteristics associated with HGNS outcomes, which may guide future patient selection. Importantly, patients were already preselected for HGNS. Standardizing response criteria is recommended to enhance the evaluation and effectiveness of HGNS therapy in OSA patients.

Differences in Positive Airway Pressure Requirements in Obstructive Sleep Apnea Between Black and White Patients

OBJECTIVE

There are disparities between Black and White patients in the utilization of positive airway pressure (PAP) alternatives for obstructive sleep apnea (OSA). Given low utilization rates among Black patients, there is limited knowledge of PAP alternative outcomes in this group. Therapeutic PAP levels are clinically accessible measures that have been shown to predict PAP alternative outcomes. Herein, we examined differences in PAP requirements between Black and White patients in a large clinical sample.

STUDY DESIGN

Cross-sectional.

SETTING

Academic sleep center.

METHODS

We included OSA patients prescribed autoadjusting PAP between January 2018 and 2020 with baseline apnea-hypopnea index (AHI) ≥ 10. Mean and 90th percentile PAP levels were compared between White and Black patients who used PAP for ≥1 hour daily using linear regression controlling for age, sex, body mass index (BMI), AHI, oxygen saturation nadir, and mask type.

RESULTS

There were 157 Black and 234 White patients who were generally obese (BMI, 37.3 ± 8.7) with severe OSA (AHI, 36.9 ± 25.6). Black patients had a 0.68 cm higher (95% confidence interval [CI]: 0.36, 1.35) mean PAP level and 0.85 cm H2O higher (95% CI: 0.36, 1.35) 90th percentile PAP level than white patients. Although statistically significant, differences were small and not clinically meaningful.

CONCLUSION

Black and White OSA patients had clinically insignificant differences in PAP requirements, suggesting comparable upper airway collapsibility. Considering the predictive value of therapeutic PAP levels, our findings suggest Black and White patients may have comparable PAP alternative responses from a collapsibility standpoint. Future studies should explore reasons for low utilization of PAP alternatives among Black patients.

Association Between Soft Tissue Measures From Computed Tomography and Upper Airway Collapsibility on Drug-Induced Sleep Endoscopy

OBJECTIVE

Positive airway pressure (PAP) titration during drug-induced sleep endoscopy (DISE) provides objective measures of upper airway collapsibility. While skeletal measurements relate to collapsibility measures on DISE, the influence of soft tissue dimensions on upper airway collapsibility is not known. We analyzed the relationship of measures of upper airway soft tissue volumes, specifically soft palate, pharyngeal lateral walls, and tongue, with metrics of collapsibility.

STUDY DESIGN

Cross-sectional analysis from a prospective cohort.

SETTING

Academic medical center.

METHODS

Patients seeking PAP alternative therapies for obstructive sleep apnea (OSA) underwent standardized supine computed tomography (CT) acquisition and DISE protocols. The CT analysis primarily focused on soft tissue volumes and, secondarily, on airway and skeletal volumetric measures. DISE with PAP administration (DISE-PAP) enabled the determination of the pressure at which inspiratory airflow first commenced (pharyngeal critical pressure, PcritA) and the pressure at which inspiratory flow limitation was abolished (pharyngeal opening pressure, PhOP). Both unadjusted and adjusted correlation analyses were performed to understand the relationship between upper airway anatomy and either PcritA or PhOP.

RESULTS

One hundred thirty-nine subjects completed both CT and DISE-PAP. On average, patients were male (70.5%), white (84.2%), middle-aged (56.6 ± 13.5 years), and overweight (29.6 ± 4.7 kg/m2), with moderate-severe apnea-hypopnea index (29.7 ± 21.3 events/h). Adjusted for age, sex, body mass index, and skeletal volumes, soft palate, and lateral pharyngeal wall volumes were not associated with PhOP or PcritA, but a larger tongue was associated with more positive PhOP (⍴ = 0.20, P = .02), and more positive PcritA (⍴ = 0.16, P = .07). Exploratory analyses revealed smaller minimum cross-sectional retropalatal area and intramandibular volume were also associated with increased collapsibility measures.

CONCLUSION

After controlling for clinical factors and skeletal volume, greater tongue volume was associated with more severe collapsibility during DISE. These results, in concert with previous work, suggest that greater tongue volume in a smaller skeletal dimensions contribute to the severity of airway collapsibility, a key driver of OSA pathogenesis.

DISE with CPAP: a useful procedure to evaluate upper airway collapsibility

PURPOSE

Drug-induced sleep endoscopy (DISE) is commonly performed in patients suffering obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) intolerance. We aimed to evaluate the effects of adding CPAP to DISE to provide understanding of the reason of its failure and better guidance in future therapeutic decisions.

METHODS

A retrospective observational descriptive study was conducted on CPAP-intolerant patients with moderate-severe OSA. DISE was used to evaluate upper airway collapsibility, and CPAP was tested to better describe anatomical sites of obstruction and to measure the opening pharyngeal pressure.

RESULTS

Sample size consisted of 38 patients with a mean age of 49 ± 9 years. Mean BMI was 28.4 ± 2.4 kg/m2, mean apnea-hypopnea index (AHI) was 35.4 events per hour ± 20.1, and mean saturation under 90% (TSat90) was 14.5%. In DISE we found a collapse at Velum in 92% of patients, at Oropharyngeal level in 89%, at tongue in 42%, and at epiglottis in 36%. In the subgroup of patients with clinical failure with CPAP, we observed 100% of epiglottic collapse and 50% of tongue obstruction. In this specific population, we recommended personalized surgery and myofunctional therapy.

CONCLUSION

DISE-CPAP is a useful tool to select the treatment that better fits to each patient taking care all information available. It improves our ability to prescribe a multilevel treatment with an exhaustive topographic evaluation of upper airway collapsibility that complements CPAP classic titration, and it can be helpful to distinguish better candidates for surgery, myofunctional therapy or CPAP.

The Repeatability of Pharyngeal Opening Pressure Under Drug-Induced Sleep Endoscopy

OBJECTIVE

Pharyngeal opening pressure (PhOP) is a measure of upper airway collapsibility that can be obtained during drug-induced sleep endoscopy (DISE) using a continuous positive airway pressure (CPAP) titration. However, the stability of PhOP over the course of sedation during DISE remains unclear. This study aims to compare repeat measures of PhOP over the course of DISE.

STUDY DESIGN

Single arm prospective study.

SETTING

Single tertiary care institution.

METHODS

Patients had 2 CPAP titrations while undergoing DISE. Collected data included patient demographics, PhOP, patient sedation index (PSI), and duration of and between CPAP titrations. t Tests, test-retest coefficient analysis, and repeated measures correlation were performed.

RESULTS

Twenty-five patients completed the study between 2022 and 2023 with 22 patients having sedation depth (PSI) recording. Most were male (76%), obese (average body mass index: 30.24 kg/m2), with severe obstructive sleep apnea (average apnea-hypopnea index: 39.8 events/hr). Test-retest analysis showed good-excellent correlation between PhOP values (intraclass correlation coefficient = 0.892, P < .0001, n = 25). Average time between CPAP titrations was 15 minutes to 6 seconds. Over that time, PhOP increased by an average of 0.72 cmH2O (P = .06, n = 25) and PSI decreased by 9.5 units (P = .01, n = 22). Repeated measures correlation showed a weak negative correlation between PhOP and PSI (r = -.45, P = .03, n = 22).

CONCLUSION

The results showed repeatability of PhOP values over the course of DISE. When adjusted for sedation depth (PSI), deeper sedation was weakly associated with greater PHOP. However, the magnitude of this change was small and we conclude that PhOP remains relatively stable over the course of DISE (Effects of Lung Volume on Upper Airway Patency During DISE [DISE-Pulm], NCT05350332, clinicaltrials.gov).

The Prevalence of Sentinel Central Events (SCent) During Drug-Induced Sleep Endoscopy

OBJECTIVE

With the recent addition of airflow and respiratory effort channels, our group has observed central and mixed apnea events during drug-induced sleep endoscopy (DISE). We measured the frequency and timing of sentinel central and/or mixed events (SCents), as well as assessed for differences in velum, oropharynx, tongue, and epiglottis (VOTE) classification compared to obstructive events.

STUDY DESIGN

Prospective single-cohort study.

SETTING

Tertiary Care Academic Medical Center.

METHODS

Patients underwent DISE between June 2020 and November 2022. Nasal airflow, thoracoabdominal effort belt signals, and videoendoscopy were simultaneously captured. Demographics, sleep study, and DISE data were compared among patients with and without SCents using Student's T tests or χ2 tests.

RESULTS

On average, the cohort (n = 103) was middle-aged (53.5 ± 12.1 years), overweight (body mass index of 29.7 ± 5.3 kg/m2), and had severe obstructive sleep apnea (apnea-hypopnea index of 30.7 ± 18.7 events/h). Forty-seven patients (46%) were found to have at least 1 SCent. Among those with SCent, 45 (95.7%) transitioned to obstructive pathology after an average of 7.91 ± 2.74 minutes, with at least 95% of patients expected to do so within 12.57 minutes. Twenty-nine out of 47 patients (61.2% [95% confidence interval: 46.4.9%, 75.5%]) with SCent had meaningful differences between central/mixed and obstructive VOTE scores.

CONCLUSION

Central events were present in almost half of our cohort. At least 95% of patients were expected to transition to obstructive events within 12 to 13 minutes of propofol initiation. In addition, over half of patients demonstrate significantly different VOTE scores between central and obstructive events. These factors should raise awareness of central events and scoring passive apneas during DISE and consider delaying VOTE scoring.

Airway Collapsibility during Drug-Induced Sleep Endoscopy Relates with Clinical Features of Obstructive Sleep Apnea

INTRODUCTION

Increased pharyngeal collapsibility leads to obstructive sleep apnea (OSA). Positive airway pressure titration during drug-induced sleep endoscopy (DISE-PAP) provides objective collapsibility metrics, the pharyngeal opening pressure (PhOP), and active pharyngeal critical pressure (PcritA ). We examined the interrelationships between risk factors of OSA, airway collapsibility measures, and clinical manifestations of the disease.

METHODS

This is a cross-sectional analysis of consecutive OSA patients undergoing DISE-PAP. Nasal PAP was increased stepwise until inspiratory flow limitation was abolished, signifying PhOP. PcritA was derived from the resulting titration pressure-flow relationships. Clinical data including demographics, anthropometrics, sleep studies, and patient-symptom questionnaires were obtained from the electronic medical record. Multivariate regression was used to evaluate the relationship between risk factors, airway collapsibility, and clinical data.

RESULTS

On average, the 164 patients meeting inclusion criteria were middle-aged (54.2 ± 14.7 years), overweight/obese (BMI 29.9 ± 4.5 kg/m2 ), male (72.6%), White (79.3%) and had severe OSA (AHI 32.0 ± 20.5 events/hour). Mean PhOP was 7.5 ± 3.3 cm H2 O and mean PcritA was 0.80 ± 3.70 cm H2 O. Younger age (Standardized β = -0.191, p = 0.015) and higher BMI (Standardized β = 0.176, p = 0.028) were associated with higher PhOP, but not PcritA . PhOP and PcritA were both associated with AHI, supine AHI, and SpO2 nadir. Higher PhOP was associated with higher snoring scores (Standardized β = 0.246, p = 0.008), but not other patient-reported outcomes.

CONCLUSION

Objective assessment of passive and active airway mechanics during DISE relates with clinical risk factors for OSA. Quantitative measures of collapsibility provide accessible and meaningful data, enhancing the standard sleep surgery evaluation.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:1978-1985, 2024.

The effect of head of bed elevation on upper airway collapsibility during drug-induced sleep endoscopy

STUDY OBJECTIVES

Drug-induced sleep endoscopy with positive airway pressure evaluates the collapsibility of the upper airway. It is currently unknown whether body position affects this assessment. We sought to determine whether the collapsibility of the airway may change with head of bed elevation.

METHODS

A prospective, consecutive cohort study was performed by 2 sleep surgeons at a tertiary care center. Inclusion criteria included adults 18 years of age and older with obstructive sleep apnea who were intolerant to continuous positive airway pressure therapy. Patients underwent drug-induced sleep endoscopy with positive airway pressure to evaluate them for alternative treatment options. Patients were evaluated in supine position with the head of bed both level and elevated to 30°. The airway was evaluated using the standardized VOTE scoring system in both positions.

RESULTS

The 61 patients included in the study were predominantly male (70.5%), middle-aged (51.2 years), and obese (body mass index, 30.2 kg/m2) with moderate-to-severe obstructive sleep apnea (apnea-hypopnea index, 34.1 events/h). The cohort consisted of predominantly positional obstructive sleep apnea (mean supine apnea-hypopnea index 48.7 events/h, nonsupine apnea-hypopnea index 20.8 events/h). All 4 sites of the upper airway demonstrated a significant decrease in airway opening pressures with the head of bed elevated compared to level (P < .01 for all sites). There was no significant difference in VOTE scoring between level and upright positions.

CONCLUSIONS

Patients with the head of bed elevated to 30° have a significantly lower degree of airway collapsibility compared to patients in the level position but no significant change in VOTE scoring was observed.

CITATION

Owen GS, Talati VM, Zhang Y, LoSavio PS, Hutz MJ. The effect of head of bed elevation on upper airway collapsibility during drug-induced sleep endoscopy. J Clin Sleep Med. 2024;20(1):93-99.

Minimally Invasive Hypoglossal Nerve Stimulator Enabled by ECG Sensor and WPT to Manage Obstructive Sleep Apnea

A hypoglossal nerve stimulator (HGNS) is an invasive device that is used to treat obstructive sleep apnea (OSA) through electrical stimulation. The conventional implantable HGNS device consists of a stimuli generator, a breathing sensor, and electrodes connected to the hypoglossal nerve via leads. However, this implant is bulky and causes significant trauma. In this paper, we propose a minimally invasive HGNS based on an electrocardiogram (ECG) sensor and wireless power transfer (WPT), consisting of a wearable breathing monitor and an implantable stimulator. The breathing external monitor utilizes an ECG sensor to identify abnormal breathing patterns associated with OSA with 88.68% accuracy, achieved through the utilization of a convolutional neural network (CNN) algorithm. With a skin thickness of 5 mm and a receiving coil diameter of 9 mm, the power conversion efficiency was measured as 31.8%. The implantable device, on the other hand, is composed of a front-end CMOS power management module (PMM), a binary-phase-shift-keying (BPSK)-based data demodulator, and a bipolar biphasic current stimuli generator. The PMM, with a silicon area of 0.06 mm2 (excluding PADs), demonstrated a power conversion efficiency of 77.5% when operating at a receiving frequency of 2 MHz. Furthermore, it offers three-voltage options (1.2 V, 1.8 V, and 3.1 V). Within the data receiver component, a low-power BPSK demodulator was ingeniously incorporated, consuming only 42 μW when supplied with a voltage of 0.7 V. The performance was achieved through the implementation of the self-biased phase-locked-loop (PLL) technique. The stimuli generator delivers biphasic constant currents, providing a 5 bit programmable range spanning from 0 to 2.4 mA. The functionality of the proposed ECG- and WPT-based HGNS was validated, representing a highly promising solution for the effective management of OSA, all while minimizing the trauma and space requirements.

The Application of Ultrasound to Quantify Hyoid Motion During Drug-Induced Sleep Endoscopy

INTRODUCTION

The significance of hyoid dynamics in OSA pathophysiology remains unclear. Drug-induced sleep endoscopy (DISE) is often used for evaluating patients intolerant to positive airway pressure (PAP) therapy. We performed DISE with concurrent hyoid-focused ultrasonography to quantify hyoid dynamics during obstructive and non-obstructive breathing.

METHODS

A cross-sectional analysis from a prospective cohort of patients undergoing DISE with PAP titration (DISE-PAP) and hyoid-focused ultrasound was conducted. Hyoid ultrasound was performed during obstructive breathing, and non-obstructive breathing after PAP administration. Motion was quantified by generating displacement curves based on echo-tracking hyoid movement. The image analysis protocol for quantifying hyoid displacement was performed independently by two researchers, and reliability of measures was assessed. Univariate and multivariate regressions were performed for various clinical data and hyoid displacement during obstructive breathing.

RESULTS

Twenty patients met inclusion criteria. On average, the cohort was male (75%), elderly (65.9 ± 10 years), overweight (29.3 ± 3.99 kg/m2 ), and with moderate-to-severe OSA (29.3 ± 12.5 events/h). Mean hyoid displacement during obstructive breathing was 5.81 mm (±3.48). In all patients, hyoid displacement decreased after PAP administration (-3.94 mm [95% CI: -5.10, -2.78]; p < 0.0001). Inter-rater reliability for measures of hyoid displacement was excellent. After multivariate regression, hyoid displacement at baseline was associated with higher AHI (β [95% CI] = 0.18 [0.03, 0.33], p = 0.020).

CONCLUSION

During DISE, hyoid displacement is greater during obstructive breathing with significant variability amongst patients. Further, these ultrasonographic measurements had excellent intra- and inter-rater reliability. Additional, larger studies are needed to understand contributors to hyoid mobility.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:3221-3227, 2023.

Current state of the art and future directions for implantable sensors in medical technology: Clinical needs and engineering challenges

Implantable sensors have revolutionized the way we monitor biophysical and biochemical parameters by enabling real-time closed-loop intervention or therapy. These technologies align with the new era of healthcare known as healthcare 5.0, which encompasses smart disease control and detection, virtual care, intelligent health management, smart monitoring, and decision-making. This review explores the diverse biomedical applications of implantable temperature, mechanical, electrophysiological, optical, and electrochemical sensors. We delve into the engineering principles that serve as the foundation for their development. We also address the challenges faced by researchers and designers in bridging the gap between implantable sensor research and their clinical adoption by emphasizing the importance of careful consideration of clinical requirements and engineering challenges. We highlight the need for future research to explore issues such as long-term performance, biocompatibility, and power sources, as well as the potential for implantable sensors to transform healthcare across multiple disciplines. It is evident that implantable sensors have immense potential in the field of medical technology. However, the gap between research and clinical adoption remains wide, and there are still major obstacles to overcome before they can become a widely adopted part of medical practice.

Transverse Maxillary Deficiency Predicts Increased Upper Airway Collapsibility during Drug-Induced Sleep Endoscopy

OBJECTIVE

To examine the relationship between craniofacial skeletal anatomy and objective measures of pharyngeal collapse obtained during drug-induced sleep endoscopy. We hypothesized that transverse maxillary deficiency and an increased pharyngeal length will be associated with higher levels of pharyngeal collapsibility.

STUDY DESIGN

Cross-sectional analysis in a prospective cohort.

SETTING

University Hospital.

METHODS

A cross-sectional analysis was conducted in a cohort of consecutive patients from the positive airway pressure (PAP) alternatives clinic who underwent computed tomography (CT) analysis and drug-induced sleep endoscopy for characterization of upper airway collapsibility. PAP titration was used to determine pharyngeal critical pressure (PCRIT ) and pharyngeal opening pressure (PhOP). CT metrics included: Transverse maxillary dimensions (interpremolar and intermolar distances) and pharyngeal length (posterior nasal spine to hyoid distance).

RESULTS

The cohort (n = 103) of severe obstructive sleep apnea (Apnea and Hipopnea Index 32.1 ± 21.3 events/h) was predominantly male (71.8%), Caucasian (81.6%), middle-aged (54.4 ± 14.3 years), and obese (body mass index [BMI] = 30.0 ± 4.9 kg/m2 ). Reduced transverse maxillary dimensions were associated with higher PCRIT (intermolar distance: β [95% confidence interval, CI] = -.25 [-0.14, -0.36] cmH2 O/mm; p = .03) and PhOP (Interpremolar distance: β = -.25 [-0.14, -0.36] cmH2 O/mm; p = .02). Longer pharyngeal length was also associated with higher PCRIT (β = .11 [0.08, 0.14] cmH2 O/mm, p = .04) and PhOP (β [95% CI] = .06 [0.03, 0.09] cmH2 O/mm, p = .04). These associations persisted after adjustments for sex, age, height, and BMI.

CONCLUSION

Our results further the concept that skeletal restriction in the transverse dimension and hyoid descent are associated with elevations in pharyngeal collapsibility during sleep, suggesting a role of transverse deficiency in the pathogenesis of airway obstruction.

The Accuracy and Reliability of Visually Assessed Pharyngeal Opening Pressures During Drug-Induced Sleep Endoscopy

OBJECTIVE

To examine the accuracy and interrater reliability of a visually assessed vs airflow-based measure of pharyngeal collapsibility obtained in patients with obstructive sleep apnea undergoing drug-induced sleep endoscopy (DISE).

STUDY DESIGN

Prospective observational study.

SETTING

Academic tertiary care practice.

METHODS

Patients underwent DISE with airflow monitoring and nasal positive airway pressure titration to determine visual and airflow-based levels of pharyngeal opening pressure (PhOP). Visual DISE-PhOP was assessed by 2 blinded independent raters and defined as the pressure at which visual confirmation of airway collapse, including snoring, was abolished. Airflow-based DISE-PhOP was defined as the minimally effective positive airway pressure that abolished inspiratory flow limitation. Equivalence testing between visual and airflow DISE-PhOP of each rater was performed with the two one sided T-test (TOST) with an a priori equivalence bound of ±1 cm H2 O. Interrater reliability was evaluated with the intraclass correlation coefficient.

RESULTS

One hundred patients were enrolled in the study and 77 completed the full evaluation. The population was predominantly male (74%) with an average age of 54.8 years, body mass index of 30.1 kg/m2 , and apnea-hypopnea index of 30.7 events/h. Equivalence testing showed that both raters were within ±1 cm H2 O of airflow-based DISE-PhOP (-0.43 to 0.09 cm H2 O and -0.32 to 0.48 cm H2 O). Interrater reliability of visual DISE-PhOP between the raters was also good to excellent with an intraclass correlation coefficient of 0.895 (95% CI, 0.84-0.932).

CONCLUSION

DISE-PhOP, a measure of upper airway collapsibility, was equivalent between airflow-based and visual assessments with strong interrater reliability, supporting its adoption as a standardized objective parameter in clinical DISE.

Drug-Induced Sleep Endoscopy Findings and Hypoglossal Nerve Stimulation Therapy Outcomes

Hypoglossal-nerve stimulation (HGNS) is an established second-line therapy for patients with obstructive sleep apnea (OSA). Existing studies investigating the effect of preoperative drug-induced sleep endoscopic (DISE) findings on HGNS outcomes have mainly focused on the apnea/hypopnea index (AHI) among polysomnography (PSG) parameters, and have less frequently tested other PSG parameters such as the apnea index (AI), hypopnea index (HI), oxygen desaturation index (ODI), snoring index, and arousal index, or patient-reported excessive daytime sleepiness. The aim of this study was to investigate the correlation between DISE findings and the above-mentioned metrics after HGNS therapy. We only included patients with DISE findings providing detailed information about the degree of the anteroposterior velar (APV), oropharyngeal lateral wall (OPLW), or tongue-base (BT) obstruction based on the velum, oropharynx, base of tongue, and epiglottis (VOTE) classification. The data of 25 patients (9 female (36%)) were retrospectively evaluated. The mean age at the date of implantation was 54.52 ± 9.61 years, and the mean BMI was 29.99 ± 3.97 kg/m2. Spearman’s rho correlation coefficients were calculated. Significant correlations were found between the degree of APV obstruction and postoperative HI (r = −0.5, p < 0.05), and between the degree of OPLW obstruction and postoperative snoring index (r = 0.42, p < 0.05). BT obstruction was strongly correlated with postoperative metrics such as AHI (r = −0.57, p < 0.01), AI (r = −0.5, p < 0.05), ODI (r = −0.57, p < 0.01), ∆ AHI (r = 0.58, p < 0.01), ∆ AI (r = 0.54, p < 0.01) and ∆ ODI (r = 0.54, p < 0.01). No significant correlation was found between DISE findings and postoperative Epworth Sleepiness Scale values. These findings suggest that preoperative DISE findings, especially the degree of BT obstruction, are important for predicting an HGNS therapy outcome.

Enhanced drug-induced sleep endoscopy: Distinguishing central from obstructive apnea

This case report describes a patient originally diagnosed with obstructive sleep apnea (OSA) who was later found to have central sleep apnea (CSA) during drug-induced sleep endoscopy, which was subsequently confirmed on an in-laboratory sleep study. The revised diagnosis resulted in a change in recommended therapy from hypoglossal nerve stimulation to phrenic nerve stimulation. This case report is a reminder that the sleep surgeon must be cognizant of the possibility of CSA being misclassified as OSA especially as home sleep studies become increasingly routine, and discusses ways to more easily distinguish between CSA and OSA. Laryngoscope, 133:706-708, 2023.

Practical Implementation of Sleep Endoscopy with Positive Airway Pressure in Clinical Practice

Drug-induced sleep endoscopy with positive airway pressure (DISE-PAP) is a new technique that allows for both the visualization of upper airway collapse as well as to evaluate the degree of airway collapsibility. This DISE-PAP protocol provides an affordable and clinically efficient manner in which to immediately implement this technique in clinical practice. Laryngoscope, 2022.

Association of hypoglossal nerve stimulator response with machine learning identified negative effort dependence patterns

Background

Hypoglossal nerve stimulator (HGNS) is a therapeutic option for moderate to severe obstructive sleep apnea (OSA). Improved patient selection criteria are needed to target those most likely to benefit. We hypothesized that the pattern of negative effort dependence (NED) on inspiratory flow limited waveforms recorded during sleep, which has been correlated with the site of upper airway collapse, would contribute to the prediction of HGNS outcome. We developed a machine learning (ML) algorithm to identify NED patterns in pre-treatment sleep studies. We hypothesized that the predominant NED pattern would differ between HGNS responders and non-responders.

Methods

An ML algorithm to identify NED patterns on the inspiratory portion of the nasal pressure waveform was derived from 5 development set polysomnograms. The algorithm was applied to pre-treatment sleep studies of subjects who underwent HGNS implantation to determine the percentage of each NED pattern. HGNS response was defined by STAR trial criteria for success (apnea–hypopnea index (AHI) reduced by > 50% and < 20/h) as well as by a change in AHI and oxygenation metrics. The predominant NED pattern in HGNS responders and non-responders was determined. Other variables including demographics and oxygenation metrics were also assessed between responders and non-responders.

Results

Of 45 subjects, 4 were excluded due to technically inadequate polysomnograms. In the remaining 41 subjects, ML accurately distinguished three NED patterns (minimal, non-discontinuous, and discontinuous). The percentage of NED minimal breaths was significantly greater in responders compared with non-responders (p = 0.01) when the response was defined based on STAR trial criteria, change in AHI, and oxygenation metrics.

Conclusion

ML can accurately identify NED patterns in pre-treatment sleep studies. There was a statistically significant difference in the predominant NED pattern between HGNS responders and non-responders with a greater NED minimal pattern in responders. Prospective studies incorporating NED patterns into predictive modeling of factors determining HGNS outcomes are needed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11325-022-02641-y.

Novel avenues to approach non-CPAP therapy and implement comprehensive OSA care

Recent advances in obstructive sleep apnoea (OSA) pathophysiology and translational research have opened new lines of investigation for OSA treatment and management. Key goals of such investigations are to provide efficacious, alternative treatment and management pathways that are better tailored to individual risk profiles to move beyond the traditional, continuous positive airway pressure (CPAP)-focused, "one size fits all", trial and error approach which is too frequently inadequate for many patients. Identification of different clinical manifestations of OSA (clinical phenotypes) and underlying pathophysiological phenotypes (endotypes), that contribute to OSA have provided novel insights into underlying mechanisms and have underpinned these efforts. Indeed, this new knowledge has provided the framework for precision medicine for OSA to improve treatment success rates with existing non-CPAP therapies such as mandibular advancement devices and upper airway surgery, and newly developed therapies such as hypoglossal nerve stimulation and emerging therapies such as pharmacotherapies and combination therapy. These concepts have also provided insight into potential physiological barriers to CPAP adherence for certain patients. This review summarises the recent advances in OSA pathogenesis, non-CPAP treatment, clinical management approaches and highlights knowledge gaps for future research. OSA endotyping and clinical phenotyping, risk stratification and personalised treatment allocation approaches are rapidly evolving and will further benefit from the support of recent advances in e-health and artificial intelligence.

A Missing Voice: The Lingual Complex and Osteopathic Manual Medicine in the Context of Five Osteopathic Models

The five osteopathic models recognized by the American Association of Colleges of Osteopathic Medicine guide clinicians in the evaluation and therapeutic choice which must be the most appropriate concerning the patient's needs. Skeletal muscles represent an important interpretation, such as screening and treatment, on which these models are based. A muscle district that is not considered by the usual osteopathic practice is the tongue. The lingual complex has numerous functions, both local and systemic; it can adapt negatively in the presence of pathology, just as it can influence the body system in a non-physiological manner if it is a source of dysfunctions. This paper, the first of its kind in the panorama of scientific literature, briefly reviews the anatomy and neurophysiology of the tongue, trying to highlight the logic and the need to insert this muscle in the context of the five osteopathic models. The clinician's goal is to restore the patient's homeostasis, and we believe that this task is more concrete if the patient is approached after understanding all the contractile districts, including the tongue.

Concentric vs Anteroposterior-Laterolateral Collapse of the Soft Palate in Patients With Obstructive Sleep Apnea

The presence of complete concentric collapse of the soft palate (CCCp) during drug-induced sleep endoscopy (DISE) has important therapeutic consequences. However, CCCp may present in various, sometimes doubtful, ways due to the complex anatomy of the upper airway. Herein, we aimed to characterize these doubtful variants by reviewing the DISE recordings of patients with obstructive sleep apnea (n = 332). We observed in some individuals that the soft palate collapsed in an anteroposterior-laterolateral (AP-LL) way, producing a polygonal shape that was distinct from CCCp. Patients with this collapse pattern (n = 29) had a smaller neck circumference and less severe obstructive sleep apnea than patients with CCCp (n = 68). The majority of patients with AP-LL collapse (n = 19) were originally diagnosed with CCCp. Based on these findings, AP-LL collapse of the soft palate might represent a distinct DISE phenotype that is easily confounded with CCCp.

Advances in Treatment of Sleep-Disordered Breathing

BACKGROUND

Sleep-disordered breathing, composed of obstructive sleep apnea (OSA) and central sleep apnea (CSA), affects millions of people worldwide carrying with it significant morbidity and mortality. Diagnosis is made by polysomnography, and severity of sleep apnea is determined by the apnea-hypopnea index (AHI). Positive airway pressure (PAP) therapy has been the gold standard in treating both OSA and CSA. PAP therapy can greatly reduce AHI burden as well as morbidity and mortality and improve quality of life.

AREAS OF UNCERTAINTY

However, patients report difficulties adhering to PAP therapy because of discomfort with mask interface, sensation of excessive pressure, and claustrophobia. Although other options exist to treat sleep apnea, such as mandibular advancement oral appliance devices, positional therapy, and surgery, these additional therapeutic modalities as current options have limitations. Emerging technology is now available to overcome hindrances to standard therapy.

DATA SOURCES

A literature search was performed from the following databases: PubMed, Cochrane Library (Cochrane Database of Systematic Reviews), and Cochrane Central Register of Controlled Trials, and FDA device database (clinicaltrial.gov).

THERAPEUTIC ADVANCES

Other modalities of treating sleep-disordered breathing now include the hypoglossal nerve stimulator, which stimulates the hypoglossal nerve during sleep to alleviate airflow obstruction by contracting the genioglossus muscle thus treating OSA. Similarly, the phrenic nerve stimulator restores a more stable breathing pattern during sleep by stimulating the phrenic nerve to activate the diaphragm during CSA. Both nerve stimulators have been shown to reduce AHI severity and improve quality of life for patients suffering from sleep-disordered breathing.

CONCLUSIONS

PAP therapy, although the gold standard, has limitations in the treatment of sleep apnea. New modalities such as hypoglossal nerve stimulator and phrenic nerve stimulator may help to overcome difficulties with adherence and offer new options for treatment of both obstructive and central sleep apnea.

Effect of body weight on upper airway findings and treatment outcome in children with obstructive sleep apnea

OBJECTIVE/BACKGROUND

Surgical interventions for obstructive sleep apnea (OSA) are less effective in obese than in normal-weight children. However, the mechanisms that underpin this relationship are not fully understood. Therefore, this study aimed to explore how body weight influences upper airway collapse and treatment outcome in children with OSA.

METHODS

We conducted a retrospective analysis of prospectively collected data on polysomnography, drug-induced sleep endoscopy (DISE), and treatment outcome in otherwise healthy children with OSA. Associations between body mass index (BMI) z-score and upper airway collapse during DISE were assessed using logistic regression modelling. Treatment success was defined as obstructive apnea-hypopnea index (oAHI) < 5 events/hour and cure as oAHI < 2 events/hour with obstructive apnea index < 1 event/hour.

RESULTS

A total of 139 children were included [median (Q1─Q3); age 4.5 (3.1─8.4) years; BMI z-score 0.3 (-0.8 to 1.4); oAHI 10.8 (6.8─18.0) events/hour]. Twenty-five of them were overweight and 21 were obese. After adjusting for age and history of upper airway surgery, BMI z-score was significantly correlated with circumferential upper airway collapse during DISE (odds ratio 1.67; 95% confidence interval 1.12─2.65; P = 0.011). Outcome of DISE-directed treatment was similar in normal-weight (success: 91.4%; cure: 78.5%), overweight (success: 88.0%; cure: 80.0%), and obese (success: 90.5%; cure: 76.5%) children. Children with circumferential collapse responded better to continuous positive airway pressure than to (adeno)tonsillectomy.

CONCLUSION

Increasing body weight is associated with circumferential upper airway collapse during DISE and, accordingly, may require treatment strategies other than (adeno)tonsillectomy.