Change In Apnea-hypopnea Index Research Articles

Gender differences in oral appliance treatment of obstructive sleep apnea.

Although overall success rates for treating obstructive sleep apnea (OSA) with an oral appliance (OA) are high, they are significantly higher among females. To verify published data, the study's purpose was to evaluate a participant sample after one year of OA use. The primary outcome was treatment response, with responders defined as having an apnea-hypopnea index (AHI) < 10 at follow-up and/or reduced by ≥50% of baseline. Secondary measures were from standardized questionnaires. A sample of 314 participants, predominately with moderate-to-severe OSA, were enrolled and instructed to use an OA every night. At baseline and one-year follow-up, polygraphic recordings and questionnaires, including sleepiness (measured using the Epworth sleepiness scale) and quality-of-life (measured using the Functional Outcomes of Sleep Questionnaire), were collected. Among the 314 participants, 192 completed the one-year evaluation: 51 females (27%) and 141 males (73%). Overall, OA treatment resulted in 78% and 77% responders among females and males, respectively. Neither the difference in improvement nor the absolute change in AHI differed significantly based on gender, at any OSA severity level. There were no significant gender differences in sleepiness or quality of life. Treatment-related adverse reactions were more common among females. Both females and males with OSA respond well to OA therapy, with nonsignificant gender differences in outcomes. Thus, the hypothesis that females respond better to OA treatment is rejected.

Adenotonsillectomy Versus Watchful Waiting for Children with Obstructive Sleep Apnea Syndrome: A Systematic Review with Meta-Analysis

AbstractThe treatment of children with Obstructive Sleep Apnea Syndrome (OSAS) remains a point of debate among otorhinolaryngologists worldwide. This study aims to comparatively assess the clinical outcomes of adenotonsillectomy (ATE) and watchful waiting in children with OSAS. We searched the databases of PubMed, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL), until the 1st of October 2023. Comparative trials assessing the efficacy of adenotonsillectomy and watchful waiting in children with OSAS were considered. The primary outcome measure was the apnea-hypopnea index (AHI), and secondary outcomes included quality of life as measured by OSA-18 score, and mean SpO2 levels. A subgroup analysis evaluating the changes in AHI depending on the severity of the initial disease was also executed. We conducted a random-effects pairwise meta-analysis of change scores to include randomized and non-randomized controlled trials. The quality assessment was carried out by using the Cochrane risk of bias tool for randomized and the ROBINS-I tool for non-randomized trials, respectively. Two randomized and five non-randomized trials were included. There was a statistically significant difference regarding AHI in favor of the ATE group compared to the watchful waiting group (Standardized mean difference [SMD] was − 0.60, 95%CI −0.79 to −0.41, p &lt; 0.001). Likewise, a statistically significant decrease in change scores for OSA-18 between ATE and watchful waiting was noted (SMD was − 0.79, 95%CI −0.97 to −0.61, p &lt; 0.001). On the other hand, there was no significant difference when ATE and watchful waiting groups were compared for SpO2 levels between each other (SMD was 0.52, 95%CI −1.53 to 2.56, p &lt; 0.62). In the subgroup analysis assessing mild OSAS, there was a significant difference in favor of ATE compared to watchful waiting (SMD was −0.91, 95%CI −1.35 to −0.47, p &lt; 0.0001). For mild to moderate OSAS, similar results were noted favoring ATE as well (SMD was − 0.53, 95%CI −0.87 to −0.19, p &lt; 0.003). This study provides evidence of moderate strength supporting the superiority of ATE over the watchful waiting approach in terms of AHI and OSA-18. This also appears to be the case for AHI in children with mild and mild to moderate OSAS.

The association of weight loss from anti-obesity medications or bariatric surgery and apnea-hypopnea index in obstructive sleep apnea.

Weight loss is recommended for individuals with obstructive sleep apnea (OSA) and overweight or obesity, but there is limited evidence to guide the selection of weight management strategies for patients who do not lose sufficient weight with diet and lifestyle changes. We evaluated the relationship between weight loss caused by pharmacologic or surgical interventions and subsequent improvement in OSA by the apnea-hypopnea index (AHI). PubMed, Cochrane CENTRAL, and EMBASE were searched for randomized trials comparing pharmacologic or surgical obesity interventions to usual care, placebo, or no treatment in adults with OSA. The association between percentage weight loss and AHI change between randomization and last follow-up was evaluated using meta-regression. CRD42022378853. Ten eligible trials (n= 854 patients) were included. Four (n= 211) assessed bariatric surgery, and 6 (n= 643) assessed pharmacologic interventions over a median follow-up of 13 months (interquartile range 6-26 months). The linear best estimate of the change in AHI is 0.45 events per hour (95% Confidence Interval 0.18 to 0.73 events per hour) for every 1% body weight lost. Weight loss caused by medication or surgery caused a proportionate improvement of the AHI. Providers could consider extrapolating from this relationship when advising patients of the expected effects of other pharmacologic or surgical interventions without direct evidence in OSA.

A novel TASK channel antagonist nasal spray reduces sleep apnea severity in physiological responders: a randomized, blinded, trial.

Preclinical and human physiological studies indicate that topical, selective TASK 1/3 K+ channel antagonism increases upper airway dilator muscle activity and reduces pharyngeal collapsibility during anesthesia and nasal breathing during sleep. The primary aim of this study was to determine the effects of BAY2586116 nasal spray on obstructive sleep apnea (OSA) severity and whether individual responses vary according to differences in physiological responses and route of breathing. Ten people (5 females) with OSA [apnea-hypopnea index (AHI) = 47 ± 26 events/h (means ± SD)] who completed previous sleep physiology studies with BAY2586116 were invited to return for three polysomnography studies to quantify OSA severity. In random order, participants received either placebo nasal spray (saline), BAY2586116 nasal spray (160 µg), or BAY2586116 nasal spray (160 µg) restricted to nasal breathing (chinstrap or mouth tape). Physiological responders were defined a priori as those who had improved upper airway collapsibility (critical closing pressure ≥2 cmH2O) with BAY2586116 nasal spray (NCT04236440). There was no systematic change in apnea-hypopnea index (AHI3) from placebo versus BAY2586116 with either unrestricted or nasal-only breathing versus placebo (47 ± 26 vs. 43 ± 27 vs. 53 ± 33 events/h, P = 0.15). However, BAY2586116 (unrestricted breathing) reduced OSA severity in physiological responders compared with placebo (e.g., AHI3 = 28 ± 11 vs. 36 ± 12 events/h, P = 0.03 and ODI3 = 18 ± 10 vs. 28 ± 12 events/h, P = 0.02). Morning blood pressure was also lower in physiological responders after BAY2586116 versus placebo (e.g., systolic blood pressure = 137 ± 24 vs. 147 ± 21 mmHg, P < 0.01). In conclusion, BAY2586116 reduces OSA severity during sleep in people who demonstrate physiological improvement in upper airway collapsibility. These findings highlight the therapeutic potential of this novel pharmacotherapy target in selected individuals.NEW & NOTEWORTHY Preclinical findings in pigs and humans indicate that blocking potassium channels in the upper airway with topical nasal application increases pharyngeal dilator muscle activity and reduces upper airway collapsibility. In this study, BAY2586116 nasal spray (potassium channel blocker) reduced sleep apnea severity in those who had physiological improvement in upper airway collapsibility. BAY2586116 lowered the next morning's blood pressure. These findings highlight the potential for this novel therapeutic approach to improve sleep apnea in certain people.

Effects of Tongue Strength Training on Patients with Mild to Moderate Sleep-disordered Breathing: A Randomized Controlled Trial.

: Several studies have reported that oropharyngeal myofunctional therapy (OMT) reduces the severity of obstructive sleep apnea (OSA). However, because OMT protocols are often complicated, they take time and effort to implement. The aim of this study was to determine the therapeutic effect of 8 weeks of simple tongue strength training with a training device. : Twenty patients with mild to moderate sleep-disordered breathing were randomized to the control group (n=10) or intervention group (n=10). The patients in the intervention group completed 8 weeks of daily tongue strength training using a training device. After 8 weeks, we evaluated each patient for sleep-disordered breathing by portable monitoring. We also evaluated each patient's body mass index (BMI), neck circumference, Epworth Sleepiness Scale (ESS) score, and tongue pressure. No significant difference was found in the change in apnea hypopnea index (AHI) from baseline to 8 weeks between the control and intervention groups (P=0.44). However, the changes in neck circumference (P=0.02) and maximum tongue pressure (P=0.03) from baseline to 8 weeks were significantly different between the two groups. No significant difference was found for changes in BMI and ESS scores from baseline to 8 weeks between the two groups. : Tongue strength training in patients with sleep-disordered breathing did not significantly improve AHI as measured by portable monitoring, although significant changes were observed for increased tongue pressure and reduced neck circumference.

Effect of Weight Loss on the Apnea Hypopnea Index is Related to Waist Circumference in Chinese Adults with Overweight and Obesity.

The present study aimed to evaluate the efficiency of traditional anthropometric and body composition parameters in predicting apnea hypopnea index (AHI) change after weight loss. Chinese adults with overweight and obesity were included into this study containing two parts. A cross-sectional study was conducted in 137 individuals using the baseline data from two weight loss intervention trials. The second part was the weight-loss intervention study conducted in 60 overweight and obese patients with obstructive sleep apnea (OSA). All participants underwent physical examination, bioelectrical impedance analysis and overnight polysomnography. Multivariate linear regression models were used to identify the most accurate parameters to predict AHI and the mediation analysis to evaluate the mediators between weight loss and AHI reduction. Waist circumference (WC), body mass index and fat mass were positively associated with AHI after adjusting multiple collinearities in the cross-sectional study. After weight-loss intervention, body weight decreased from 94.6 ± 15.3 to 88.0 ± 13.9 kg, and AHI decreased from 41.9 (13.0,66.9) to 20.7 (8.7,51.2) events/h. Among these parameters, only percentage changes in WC and AHI across the intervention were positively intercorrelated after controlling for covariates (adjusted r = 0.271, P = 0.041). The mediation analysis supported WC as a mediator between weight loss and AHI reduction (standardized indirect effect [95% CI] = 4.272[0.936,7.999]). Both general and abdominal obesity are of high prognostic value for OSA. WC as an easily accessible parameter mediates the effects of weight loss in decreasing OSA severity.

Successful Virtual CPAP Set up in Obstructive Sleep Apnoea: A positive innovation during the pandemic

BackgroundTraditionally continuous positive airways pressure (CPAP) trials for obstructive sleep apnoea (OSA) are through face to face (F2F) set up. During Covid-19 pandemic CPAP was classed as aerosol-generating hence Leeds sleep service moved to a virtual service. Patients received equipment by post followed by virtual reviews (VR). We evaluated the adherence and symptomatic benefit of postal compared to F2F method. MethodsObservational data were collected from databases monitoring CPAP loans. F2F patients met a sleep technician for hands on setup in 2019, and in 2020 postal patients received equipment, written guides, and links to custom made YouTube videos. All (F2F and postal) patients had a telephone and VR appointment to discuss symptoms, and CPAP machine (AirSense 10, ResMed Inc., San Diego, USA) data including data on usage and treatment apnoea-hypopnoea index (AHI). Data was analysed using unpaired T-tests, Mann-Whitney U tests, and chi-square tests to examine differences in means, medians, and proportions, respectively of the F2F and postal groups. ResultsBoth groups (n = 1,221, 656 F2F, 53.7%) were similar in all categories except length of CPAP trial (postal 33 vs F2F 84 days,p < 0.0001), change in AHI (postal 22.4/Hr vs F2F 25.1/Hr,p = 0.04), and trial average use (postal 4.9 vs F2F 5.2 h,p = 0.04). There was no significant difference in the proportion of patients continuing with CPAP (postal 64%, F2F 66%, p = 0.71), the improvement in Epworth Sleepiness Score (ESS) (postal 6.9/24, F2F 7.1/24, p = 0.31) or the patient's subjective rating on whether they felt much better, better, the same or worse on CPAP (p = 0.27). Logistic regression showed factors which affected odds ratios of continuing CPAP were diagnostic AHI, treatment AHI, treatment ESS and how they felt on CPAP. Trial type did not affect the odds ratios of continuing CPAP. ConclusionsPostal CPAP trial patients had similar odds of continuing CPAP therapy compared to patients with F2F trials and achieved similar levels of ESS improvement and reporting feeling better on CPAP. This provides support for postal trials as a viable option post-pandemic.

Progression of obstructive sleep apnoea after renal denervation is not associated with hypertension exaggeration

PurposeIn a cohort, observational prospective trial, we assessed the long-term dynamics of sleep-disordered breathing in patients with resistant hypertension after renal denervation and their association with blood pressure change at remote follow-up.Materials and methodsTwenty-eight patients with stable hypertension who were recruited for endovascular radiofrequency renal denervation in 2012–2019 and had valid both baseline and follow-up sleep study, were included in the analysis. All patients underwent physical examination, anthropometry, office and ambulatory blood pressure measurements, blood and urine tests, kidney visualization, and full polysomnography before and within 12–36 months after renal denervation.ResultsThe average follow-up comprised 30.1 ± 8.4 months. At long-term follow-up, no significant changes in creatinine level, estimated glomerular filtration rate, body mass index were registered. There was a significant increase in sleep apnea severity indices: the mean change in apnea-hypopnea index comprised 9.0(-21.1;25.2) episodes/h, in oxygen desaturation index 6.5(-16.8;35.9) episodes/h, in the average SpO2 -1.7(-5.6;1.9)%. Over 12-month follow-up, there were no significant differences in blood pressure response in patients with and without sleep apnea. The baseline apnea-hypopnea and oxygen desaturation indices and the mean SpO2 were associated with the circadian blood pressure profile at follow-up, but did not correlate with the blood pressure response.ConclusionsAlthough the severity of sleep apnea worsens at > 12 months follow-up after renal denervation, this is not associated with hypertension exaggeration.

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

To evaluate the efficacy and safety of modified coblation endoscopic lingual lightening to address retrolingual obstruction in multilevel surgery for obstructive sleep apneae (OSA). Patients with OSA due to retropalatal and retrolingual obstructions were enrolled. Group 1 consisted of patients who underwent modified coblation endoscopic lingual lightening combined with H-uvulopalatopharyngoplasty, while group 2 comprised patients treated by H-uvulopalatopharyngoplasty alone. Objective parameters and subjective evaluations were recorded preoperatively and at 6months postoperatively. The mean (standard deviation) apnea-hypopnea index (AHI) declined from 51.5 (18.9) to 14.3 (7.2) in group 1, and from 51.7 (15.8) to 28.5 (16.9) in group 2. The mean (standard deviation) percentage change in AHI was higher in group 1 than in group 2 (73.2 [10.9] vs. 48.9 [22.4], P < 0.01). The surgical response rate differed significantly between groups 1 and 2 (88.5 [23/26] vs. 46.7 [14/30], P < 0.01). Other outcomes, including the lowest oxygen saturation, Epworth Sleepiness Scale score, snoring visual analog scale score, and subjective improvement rate, were also significantly better in group 1 than in group 2. Without increasing complications, modified coblation endoscopic lingual lightening significantly improved surgical outcomes as part of multilevel surgery in patients with OSA due to multilevel obstruction.

Fluoroscopic-Assisted Tongue Suspension: Advancement and Innovation in the Management of Complex Pediatric Obstructive Sleep Apnea.

The primary aim of this study is to describe a novel surgical technique developed for tongue base suspension (TBS). The second aim of this study is to assess the efficacy of the developed procedure by quantifying preoperative and postoperative polysomnographic outcomes for pediatric patients undergoing fluoroscopic-assisted tongue suspension (FATS) with the Encore System. Our hypothesis is that our FATS technique will provide at least a 50% reduction in the Apnea/Hypopnea Index (AHI), including in the medically complex pediatric population. Retrospective case series. An electronic medical record review was conducted of patients who underwent FATS by a single surgeon at a tertiary care medical center between December 2019 and June 2022. Inclusion criteria included all patients <18 years old with evidence of OSA or sleep-disordered breathing and who had glossoptosis on sleep endoscopy. Data extracted from the medical record included age, gender, medical comorbidity history, reason for referral, history of airway surgeries, length of hospital stay, surgical complications data, and preoperative and postoperative polysomnographic data. Surgical success was defined by at least a 50% reduction in AHI. Thirty patients (53.3% male) with a mean age of 6.3 (±5.3, 0.16-17) years underwent FATS over the study period. Most patients (93%) had an underlying comorbidity: cerebral palsy (37%), chromosomal abnormalities (23%), Down syndrome (13%), Pierre-Robin sequence (10%), and obesity (10%). The majority of patients (77%) were explicitly referred for tracheostomy placement secondary to failed management of OSA. 21 patients completed both preoperative and postoperative polysomnograms. The mean preoperative AHI, obstructive AHI (oAHI), and respiratory disturbance index (RDI) were 28.8 (±19.8), 30.8 (±19.6), and 30.5 (±19.3), respectively. The mean postoperative AHI, oAHI, and RDI were 7.3 (±9.2), 7.5 (±9.1), and 7.9 (±9.3), respectively. The mean change in AHI was -21.5 (±21.4) events/h (p < 0.01, 95% CI -29.0 to -11.4 events/h). The mean percentage decrease in AHI was 74.7%. The mean change in oAHI and RDI were -23.3 (±21.9) events/h (p < 0.01 95% CI- 39.9 to -21.4 events/h) and -22.5 (±21.5) events/h (p < 0.01, 95% CI- 31.5 to -12.4 events/h), respectively. The mean percentage decrease in oAHI and RDI was 75.6% and 73.8%, respectively. Surgical success occurred in 16 of the 21 (76%) patients. Of the 23 patients referred explicitly for tracheostomy placement, 21 (91%) were able to avoid tracheostomy placement secondary to improvements in OSA. Patients undergoing fluoroscopic-assisted TBS revealed statistically significant improvements in AHI, oAHI, and RDI, with an overall surgical success rate of 76%. Complication rates were minimal, despite the complex nature of the study population. FATS should be considered a viable surgical approach in pediatric patients with an identified base of tongue obstruction and OSA. 4 Laryngoscope, 134:S1-S9, 2024.

Mean disease alleviation between surgery and CPAP in matched adults with obstructive sleep apnea.

Polysomnography parameters measure treatment efficacy for obstructive sleep apnea, such as reduction in apnea hypopnea index. However, for continuous positive airway pressure (CPAP) therapy, polysomnography measures do not factor in adherence and thus do not measure effectiveness. Mean disease alleviation (MDA) corrects polysomnography measures for CPAP adherence and was used to compare treatment effectiveness between CPAP and multilevel upper airway surgery. This retrospective cohort study consisted of a consecutive sample of 331 patients with obstructive sleep apnea managed with multilevel airway surgery as second line treatment (N=97) or CPAP (N=234). Therapeutic effectiveness (MDA as % change or as corrected change in apnea hypopnea index) was calculated as the product of therapeutic efficacy (% or absolute change in apnea hypopnea index) and adherence (% time on CPAP of average nightly sleep). Cardinality and propensity score matching was utilised to manage confounding variables. Surgery patients achieved greater MDA % than CPAP users (67 ± 30% vs. 60 ± 28%, p=0.04, difference 7 ± 3%, 95% confidence interval 4% to 14%) in an unmatched comparison, despite a lower therapeutic efficacy seen with surgery. Cardinality matching demonstrated comparable MDA % in surgery (64%) and CPAP (57%) groups (p=0.14, difference 8 ± 5%, 95% confidence interval -18% to 3%). MDA measured as corrected change in apnea hypopnea index showed similar results. In adult patients with obstructive sleep apnea, multilevel upper airway surgery and CPAP provide comparable therapeutic effectiveness on polysomnography. For patients with inadequate CPAP use, surgery should be considered.

OSA-Onset: An algorithm for predicting the age of OSA onset

Study objectivesThere is currently no way to estimate the period of time a person has had obstructive sleep apnoea (OSA). Such information would allow identification of people who have had an extended exposure period and are therefore at greater risk of other medical disorders; and enable consideration of disease chronicity in the study of OSA pathogenesis/treatment. MethodThe ‘age of OSA Onset’ algorithm was developed in the Wisconsin Sleep Cohort (WSC), in participants who had ≥2 sleep studies and not using continuous positive airway pressure (n = 696). The algorithm was tested in a participant subset from the WSC (n = 154) and the Sleep Heart Health Study (SHHS; n = 705), those with an initial sleep study showing no significant OSA (apnea-hypopnea index (AHI) < 15 events/hr) and later sleep study showing moderate to severe OSA (AHI≥15 events/hr). ResultsRegression analyses were performed to identify variables that predicted change in AHI over time (BMI, sex, and AHI; beta weights and intercept used in the algorithm). In the WSC and SHHS subsamples, the observed years with OSA was 3.6 ± 2.6 and 2.7 ± 0.6 years, the algorithm estimated years with OSA was 10.6 ± 8.2 and 9.0 ± 6.2 years. ConclusionsThe OSA-Onset algorithm estimated years of exposure to OSA with an accuracy of between 6.6 and 7.8 years (mean absolute error). Future studies are needed to determine whether the years of exposure derived from the OSA-Onset algorithm is related to worse prognosis, poorer cognitive outcomes, and/or poorer response to treatment.

0530 Efficacy of obstructive sleep apnea treatment by a unique oral appliance and effect of concurrent myofunctional and CPAP therapy

Abstract Introduction Current treatment options for obstructive sleep apnea (OSA) include positive airway pressure, oral appliances, and upper airway surgery. The Day and Night Appliance (DNA) is a component of a dentist-guided system (Complete Airway Repositioning and Expansion [CARE], Vivos Therapeutics) that leads to gradual increases in upper airway volume. This study examines the effects of DNA treatment on OSA in patients before and after use of the device; we also examined how DNA treatment was impacted by concurrent myofunctional and CPAP therapy. Methods Data from a prospectively-collected clinical database (Vivos Airway Intelligence Service [AIS]) were reviewed, and 94 adult OSA patients who met DNA use criteria and had pre- and post-treatment sleep studies without the device in place were included. We compared the apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) pre- and post-treatment using a paired t-test and fit linear regression models with change in AHI and ODI as dependent variables. Results Mean patient age was 47.8±14.7 years and 44.7% were men. Pre- and post-treatment sleep studies were conducted 15.2±7.0 months apart. 24.5% of patients were treated with DNA and myofunctional therapy (14.1% exclusively myofunctional, 10.4% myofunctional plus another treatment, e.g., tonsillectomy, frenectomy). 17.0% of patients were treated with CPAP (12.8% exclusively CPAP, 4.2% CPAP plus another treatment). For both pre-treatment and post-treatment, mean AHIs were 22.3±19.4 and 12.7±11.2 respectively (p&amp;lt; 0.0001) and mean ODIs were 11.6±13.7 and 7.8±9.1 respectively (p&amp;lt; 0.0001). Excluding patients who had undergone myofunctional therapy and another treatment modality and adjusting for patient age, BMI, and gender, we found myofunctional therapy was associated with a -10.4 change in AHI (p=0.038). However, myofunctional therapy was not associated with a significant change in ODI (p=0.905). Concurrent CPAP use did not have a significant association with change in either AHI (p=0.47) or ODI (p=0.61). Conclusion This study shows that DNA use significantly improved post-treatment OSA severity, and that concurrent myofunctional but not CPAP therapy may result in further OSA improvement. An oral appliance system that provides palatal expansion with consequent improvement in OSA severity but does not require permanent nightly use has advantages over conventional oral appliances; however, further investigation is warranted. Support (if any)

0572 Weight reduction and the impact on apnea-hypopnea index: a meta-analysis

Abstract Introduction The occurrence of obstructive sleep apnea (OSA) is strongly associated with obesity. Behavioral, pharmacological, and surgical interventions that promote weight reduction can reduce OSA severity and improve other common obesity related complications and quality of life. While the relationship between weight reduction and apnea-hypopnea index (AHI) improvement has been documented, it does not seem to have been quantified adequately. The objective of this analysis was to quantify the association between percent change in body weight and percent change in AHI using results from the literature. Methods A literature search identified 13 studies with AHI and weight measurements before and after weight intervention in people living with obesity and OSA; 6 studies from bariatric surgery, 4 studies from diet and exercise intervention, and 3 studies from anti-obesity medications (including 2 placebo-controlled randomized clinical trials). A polynomial and a linear meta regression model as well as 95% prediction intervals were used to assess the relationship between % weight change from baseline and % change in AHI from baseline. Results Both the polynomial and linear models show, on average, weight reduction in patients living with obesity and OSA has a clinical benefit in reducing AHI. The linear meta-regression model that we developed suggests a mean AHI decrease of 2.6% per 1% weight reduction. As the prediction intervals are relatively wide, a precise relationship could not be established. For example, based on the linear model for a patient with 20% weight reduction we expect to see a mean 52.8% reduction in AHI with a 95% prediction interval (89.8%, 15.8%) AHI reduction. Conclusion Evidence shows that intentional weight reduction in people living with obesity and OSA results in improvements in OSA severity, and this was confirmed by our meta-analysis and modeling. The model shows that the degree of AHI improvement is dependent on the magnitude of weight reduction. However, establishing a precise relationship between percent change in AHI and percent weight reduction is challenging given the sparsity of data, variability in populations studied, and variability in AHI change following weight reduction. Support (if any) Eli Lilly and Company

0492 Variability in High Altitude Sleep Disordered Breathing and Impact of Acclimatization

Abstract Introduction Individuals who travel to high altitude experience variable levels of poor sleep quality and sleep disordered breathing, which can have neurocognitive and other systemic impacts. Past studies by our group and others have shown that the apnea hypopnea index (AHI) increases, and nocturnal oxygen saturation decreases at higher altitude. This may change over time with acclimatization to environmental hypoxemia. The aim of this study was to examine the trajectory and variability in high altitude sleep disordered breathing effects in healthy young adult volunteers. Methods Twenty healthy volunteers were recruited from a local university (35% women), mean age 23.5(20.0, 32.2) years and BMI of 30.0(28.0, 35.9) kg/m2. Peripheral Arterial tonometry based home sleep apnea tests (HSAT; WatchPat One) was performed on all subjects at sea level up to three days prior to transportation via car to high altitude (3800m White Mountain Research Center - Barcroft Station, CA). Participants continued HSAT testing for three consecutive nights at high altitude sleeping in any position, without oxygen, acetazolamide, or use of any other medications impacting sleep or breathing. Mixed effects modeling was used to compare sleep parameters across nights. Results Subjects' characteristics: median (IQR)[range] age 23(20,32)[19,39] years, BMI 30(28, 36)[23,48] kg/m2, 35% women. AHI at altitude night 1 (67±4 events/hour) was significantly higher than sea level (7±4 events/hour; P&amp;lt; 0.001). Mean sleep SpO2 at altitude night 1 (79±1%) was significantly lower than sea level (95±1%; P&amp;lt; 0.0001). There was no statistically significant change in AHI or mean sleep SpO2 on nights 1-3; however substantial variability was noted between individual trajectories. Conclusion Healthy young adults exhibit severe Sleep Disordered Breathing when traveling to high altitude. Despite acclimatization, the severity of Sleep Disordered Breathing remained relatively unchanged overall. However substantial differences in individual trajectories were apparent. Larger studies are needed to understand how differences in genetics, sex, and other factors might impact Sleep Disordered Breathing at altitude. In addition, the impacts of (or tolerances to) altitude are likely to be broadly informative towards Sleep Disordered Breathing, hypoxemia, and other areas. Support (if any) N/A

0535 Impact of hypoglossal nerve stimulation surgery alone on sleep disordered breathing and sleepiness

Abstract Introduction Hypoglossal Nerve Stimulation (HNS) is an established option for CPAP -intolerant obstructive sleep apnea (OSA) patients, with multiple studies demonstrating safety and effectiveness. There are known nightly variations in OSA severity. We aimed to determine if device implant alone (with therapy off) compared to baseline influenced sleep disordered breathing and daytime sleepiness. Methods This was a retrospective analysis of the STAR (Stimulation Therapy for Apnea Reduction) Trial, conducted from 2010-2016, that led to FDA approval HNS. Data was collected at a pre-implant screening, and post-implant prior to device activation (therapy off). Each visit included an attended polysomnography (PSG) and Epworth Sleepiness Scale (ESS). PSGs were scored by a central core lab. Results There were 126 participants (83% male), age 55 ± 10 years. The time between pre-implant baseline screening and device activation visit averaged 88 ± 29 days. BMI was 28 ± 3 at baseline and 28 ± 3 post-implant with therapy off. The pre and post-implant Apnea Hypopnea Index (AHI)s were similar (32 ± 9 vs 32 ± 9 events/hour, p=0.82). The two-night AHI ranged from 13 to 65. The average AHI change between pre-implant and post-implant (therapy off) was -0.3 ± 17 events/hour. The Sher 20 response rate between pre-implant and post-implant therapy off was 13%. By comparison, previously published mean AHI with therapy activated was approximately 10-15 events/hour, and Sher 20 response rates ranged between 65%-75%. ESS pre and post-implant (therapy off) were similar (12 ± 5 vs 11 ± 5, p=0.09), compared to ESS previously reported with HNS therapy activated (typically 6-7). Conclusion The STAR two-night baseline AHIs ranged between 13-65. While there were nightly differences in AHI in some patients, surgical implant of HNS with therapy off, did not result in meaningfully improvement in the AHI, Sher 20 response rate, or ESS. Support (if any) Inspire Medical Systems

Adenotonsillectomy-related changes in systemic inflammation among children with obstructive sleep apnea.

Adenotonsillar hypertrophy is the most common cause of pediatric obstructive sleep apnea (OSA). Although adenotonsillectomy considerably reduces OSA and systemic inflammation, whether and how systemic inflammation influences the effects of adenotonsillectomy on OSA has yet to be determined. This study investigated the associations between changes in anatomical variables, % changes in subjective OSA-18 questionnaire scores, % changes in 11 polysomnographic parameters, and % changes in 27 systemic inflammatory biomarkers in 74 children with OSA. Fifty-six (75.6%) boys and 18 (24.4%) girls with the mean age of 7.4 ± 2.2 years and apnea-hypopnea index (AHI) of 14.2 ± 15.9 events/h were included in the statistical analysis. The mean period between before and after adenotonsillectomy was 5.6 ± 2.6 months. After adenotonsillectomy, the OSA-18 score, eight of 11 polysomnographic parameters, and 20 of 27 inflammatory biomarkers significantly improved (all p < 0.005). Notably, there were significant associations between change in tonsil size and % change in AHI ( r = 0.23), change in tonsil size and % changes in interleukin-8 (IL-8) ( r = 0.34), change in tonsil size and % change in and IL-10 ( r = -0.36), % change in IL-8 and % change in C-C chemokine ligand 5 (CCL5) ( r = 0.30), and % change in CCL5 and % change in AHI ( r = 0.38) (all p < 0.005). Interestingly, % change in IL-8 and % change in CCL5 serially mediated the relationship between change in tonsil size and % change in AHI (total effect: β = 16.672, standard error = 8.274, p = 0.048). These preliminary findings suggest that systemic inflammation is not only a complication of OSA but also that it mediates the surgical effects, which may open avenues for potential interventions to reduce tonsil size and OSA severity through the regulation of IL-8 and CCL5.

Effects of continuous positive airway pressure on very short-term blood pressure variability associated with sleep-disordered breathing by pulse transit time-based blood pressure measurements.

Blood pressure (BP) variability (BPV) is a predictor of cardiovascular outcomes independently of BP absolute values. We previously reported that pulse transit time (PTT) enables monitoring beat-to-beat BP, identifying a strong relationship between the extent of very short-term BPV and the severity of sleep-disordered breathing (SDB). Here, we investigated the effects of continuous positive airway pressure (CPAP) on very short-term BPV. We studied 66 patients (mean age 62 years old, 73% male) with newly diagnosed SDB who underwent full polysomnography on two consecutive days for diagnosis (baseline) and CPAP, together with PTT-driven BP continuous recording. PTT index was defined as the average number of acute transient rises in BP (≥12 mmHg) within 30 s/h. CPAP treatment effectively improved SDB parameters, and attenuated PTT-based BP absolute values during the night-time. Very short-term BPV that includes PTT index and standard deviation (SD) of systolic PTT-BP was significantly reduced by CPAP therapy. The changes in PTT index from baseline to CPAP were positively correlated with the changes in apnea-hypopnea index, obstructive apnea index (OAI), oxygen desaturation index, minimal SpO 2 , and mean SpO 2 . Multivariate regression analysis revealed that changes in OAI and minimal SpO 2 , as well as heart failure, were the independent factors in determining the reduction of PTT index following CPAP. PTT-driven BP monitoring discovered the favorable effects of CPAP on very short-term BPV associated with SDB events. Targeting very short-term BPV may be a novel approach to identifying individuals who experience greater benefits from CPAP.

The effect of head rotation on OSA is associated with disease severity: a cross-sectional study.

Head rotation is an effective positional therapy for obstructive sleep apnea (OSA). However, not all OSA patients benefit from head rotation. This study aimed to explore the clinical phenotype of OSA patients who can benefit from head rotation. We performed a retrospective review of 184 consecutive OSA patients who underwent polysomnography. Head rotation in supine position was determined by high-quality video recording. According to the changes in apnea-hypopnea index (AHI) after head rotation, OSA patients were divided into two groups: patients with response to head rotation(HR) and patients without response to head rotation(NHR). Demographic factors and overnight polysomnography were analyzed. Compared with NHR group, HR group showed significantly lower AHI (51.8 vs 31.5, p < 0.01), time spent with oxygen saturation below 90%(5.3% vs 0.51%, p < 0.01), and higher lowest oxygen saturation(80% vs 86%, p < 0.05). Logistic regression showed that AHI was an independent factor to predict the decrease of AHI in head rotation (OR 0.985, 95% CI 0.970-0.979, p < 0.05). Among mild to moderate group (AHI < 30/h), severe group (30/h ≤ AHI < 60/h), and extremely severe group (AHI ≥ 60/h), the percentage decrease of AHI in head rotation was 18.5%, 9.5%, and 2.6%, respectively. Surprisingly, the percentage decrease of AHI of 6 responders in mild to moderate group was more than 50%. OSA patients who respond well to head rotation have less severe disease, and patients with mild to moderate OSA are more likely to improve and benefit from this position. Our research provides potential strategies and insights into the individual treatment of OSA patients.

Obstructive sleep apnea in aboriginal Australians: polysomnographic outcomes and symptom perception post-continuous positive airway pressure implementation.

Obstructive sleep apnea (OSA) is reported to be highly prevalent among Aboriginal Australians. However, no studies have assessed the implementation and efficacy of continuous positive airway pressure (CPAP) therapy in this population. Hence, we compared the clinical, self-reported perception of sleep quality and polysomnographic (PSG) characteristics among Aboriginal patients with OSA. Adult Aboriginal Australians who underwent both diagnostic (Type 1 and 2) and in-lab CPAP implementation studies were included. Total of 149 patients were identified (46% female, median age 49 years, body mass index 35 kg/m2). The OSA severity was 6% mild, 26% moderate, and 68% severe on the diagnostic PSG. On application of CPAP, there were significant improvements in; total arousal index (diagnostic 29 to 17/h on CPAP), total apnea-hypopnea index (AHI) (diagnostic 48 to 9/h on CPAP), non-rapid eye movement AHI (diagnostic 47 to 8/h on CPAP), rapid eye movement (REM) AHI (diagnostic 56 to 8/h on CPAP) and oxygen saturation (SpO2) nadir (diagnostic 77% to 85% on CPAP) (p < 0.001 for each). Following a single night of CPAP, 54% of patients reported sleeping "better than normal" compared to 12% following the diagnostic study (p = 0.003). In multivariate regression models, males had a significantly lesser change in REM AHI than females (5.7 events/hour less change (IQR 0.4, 11.1), p = 0.029). There is substantial improvement in several sleep-related domains on the application of CPAP among Aboriginal patients with a good initial acceptance of treatment. Whether the positive impact observed in this study translates to better sleep health outcomes with long-term adherence to CPAP therapy is yet to be assessed.