Associations of polysomnographic measures of obstructive sleep apnea, and nocturnal oxygen saturation with incident type 2 diabetes mellitus in middle-aged and older men.

Obstructive sleep apnea (OSA) has been associated with incident type 2 diabetes mellitus (T2DM); however, few prospective epidemiological studies have accounted for important T2DM predictors including pre-diabetes status and testosterone. Participants in the longitudinal Men Androgens Inflammation Lifestyles Environment and Stress (MAILES) study, who underwent eight-channel home-based polysomnography (PSG) in 2010-2011 (n = 824) and were free of diabetes at baseline were included in the analysis (n = 682). From 2015 to 2021, 78.6% (n = 536) completed at least one follow-up assessment. Incident T2DM was determined by self-reported doctor diagnosis, diabetes medications, plasma glucose (fasting ≥7.0 mmol/L or random ≥11.0 mmol/L) or glycated haemoglobin ≥6.5%. Conservative hierarchical Poisson regression models adjusted associations of PSG metrics (categorical and continuous) for age, waist circumference, baseline fasting glucose and testosterone concentrations. In all, 52 men (9.7%) developed T2DM over a mean (range) of 8.3 (3.5-10.5) years. Significant age- and waist circumference-adjusted association of incident T2DM with rapid eye movement (REM) sleep apnea-hypopnea index (AHI) ≥20 events/h (incidence rate ratio [IRR] 1.5, 95% confidence interval [CI] 0.8-2.8; p = 0.23] and highest quartile of delta index (IRR 2.1, 95% CI 0.95-4.6; p = 0.066) were attenuated after adjustment for baseline glucose and testosterone, and the association with the lowest quartile of mean oxygen saturation persisted (IRR 4.2, 95% CI 1.7-10.3; p = 0.029). Categorical measures of AHI severity, oxygen desaturation index, and hypoxia burden index (HBI) were not independently associated with incident T2DM. Associations with T2DM were similar when continuous PSG variables were used; however, HBI was significant (IRR 1.015, 95% CI 1.006-1.024; p = 0.007). In a sub-sample with OSA treatment data (n = 479), these significant associations persisted after excluding adequately treated OSA (n = 32). Understanding underlying OSA endotypes generating hypoxaemia may identify opportunities for diabetes prevention.

Pre-morbid sleep disturbance and its association with stroke severity: results from the international INTERSTROKE study.

BACKGROUND AND PURPOSE: Whilst sleep disturbances are associated with stroke, their association with stroke severity is less certain. In the INTERSTROKE study, the association of pre-morbid sleep disturbance with stroke severity and functional outcome following stroke was evaluated. METHODS: INTERSTROKE is an international case-control study of first acute stroke. This analysis included cases who completed a standardized questionnaire concerning nine symptoms of sleep disturbance (sleep onset latency, duration, quality, nocturnal awakening, napping duration, whether a nap was planned, snoring, snorting and breathing cessation) in the month prior to stroke (n = 2361). Two indices were derived representing sleep disturbance (range 0-9) and obstructive sleep apnoea (range 0-3) symptoms. Logistic regression was used to estimate the magnitude of association between symptoms and stroke severity defined by the modified Rankin Score. RESULTS: The mean age of participants was 62.9 years, and 42% were female. On multivariable analysis, there was a graded association between increasing number of sleep disturbance symptoms and initially severe stroke (2-3, odds ratio [OR] 1.44, 95% confidence interval [CI] 1.07-1.94; 4-5, OR 1.66, 95% CI 1.23-2.25; >5, OR 2.58, 95% CI 1.83-3.66). Having >5 sleep disturbance symptoms was associated with significantly increased odds of functional deterioration at 1 month (OR 1.54, 95% CI 1.01-2.34). A higher obstructive sleep apnoea score was also associated with significantly increased odds of initially severe stroke (2-3, OR 1.48; 95% CI 1.20-1.83) but not functional deterioration at 1 month (OR 1.19, 95% CI 0.93-1.52). CONCLUSIONS: Sleep disturbance symptoms were common and associated with an increased odds of severe stroke and functional deterioration. Interventions to modify sleep disturbance may help prevent disabling stroke/improve functional outcomes and should be the subject of future research.

Mandibular advancement device in obstructive sleep apnea treatment: what happens to the condyle position and patient response?

BACKGROUND: This study aims primarily to assess the mandibular condyles and patient response to MAD therapy using cone-beam computed tomography (CBCT). Also, the study proposes to analyze whether variations in condylar position, OSA severity and mandibular protrusion influence patient response. METHODS: 23 patients diagnosed with mild/moderate OSA and treated with MAD comprised the sample. Clinical, CBCT, and PSG assessments were conducted at baseline and with MAD in therapeutic protrusion (4-6 months of MAD use). The condyle position was vertically and horizontally evaluated at baseline and at the therapeutic protrusion. RESULTS: The condyle position significantly changed with MAD, showing anterior (7.3 ± 2.8 mm; p < 0.001) and inferior (3.5 ± 1 mm; p < 0.001) displacement. Patients with mild OSA required more protrusion (p = 0.02) for improvement. Responders exhibited a significantly prominent (p = 0.04) anterior baseline condyle position. A negative modest correlation was found between treatment response and baseline condyle anterior position (p = 0.03; r=-0.4), as well as between OSA severity and the percentage of maximum protrusion needed for therapeutic protrusion (p = 0.02; r=-0.4). The patient protrusion amount did not predict condylar positional changes. Neither condyle position, OSA severity, nor therapeutic protrusion were predictors of MAD treatment response. CONCLUSION: MAD resulted in anterior and inferior condylar displacement, and the amount of protrusion did not predict condylar positional changes. Responders showed a more anterior baseline condyle position. OSA severity and mandibular protrusion did not predict treatment response.

Predictors of surgical outcomes for limited palatal muscle resection in patients with obstructive sleep apnea.

OBJECTIVE: Limited palatal muscle resection (LPMR) is a modified palatal surgical technique to correct retropalatal obstruction without complications. This study aims to determine the associated factors affecting the success and cure rate of LPMR in patients with obstructive sleep apnea (OSA), thus guiding patient selection and improving surgical outcome. METHODS: Thirty-five OSA patients underwent LPMR were enrolled. All patients received routine physical examination, preoperative drug-induced sleep endoscopy (DISE), and polysomnography (PSG). Clinical, polysomnographic, cephalometric variables, and DISE findings were evaluated. These measurements were compared between the surgical success and failure group based on the results of preoperative and postoperative PSG. Furthermore, we compared the cured and non-cured groups in the surgical success group. RESULTS: Among 35 patients, the overall success rate was 57 % with a cure rate of 31.4 %. Patients with Friedman stage II had a significantly higher success rate (p = 0.032). According to DISE results, tongue base obstruction affected the surgical outcome (p < 0.001). The success rate was 100 % in the no tongue base obstruction during DISE, 72.2 % in the partial obstruction, and 9.1 % in the total obstruction. Tonsil size is also helpful in predicting surgical success rate (p = 0.041). Furthermore, patients with mild AHI were more likely to be surgical cures. when compared with patients with severe AHI (p = 0.044). CONCLUSION: Patients with larger tonsil size and no tongue base obstruction during DISE may have a higher chance of surgical success with LPMR. The lower AHI may be predictors of surgical cure after LPMR.

Genetic variant in TNF-α gene and its plasma level in relation to obstructive sleep apnoea in the Pakistani population.

OBJECTIVE: To assess the link between tumour necrosis factor-alpha -308 guanine/adenine polymorphism and tumour necrosis factor-alpha plasma levels in relation to obstructive sleep apnoea. METHODS: The cross-sectional study was conducted from December 2018 to March 2021 at the sleep clinic of Dow University Hospital, Karachi, on obstructive sleep apnoea patients and healthy controls. Epworth Sleep Scale score was used to determine daytime sleepiness, while full-night polysomnography was carried out for obstructive sleep apnoea confirmation and categorisation according to severity. Blood sample collection was followed by deoxyribonucleic acid extraction and plasma tumour necrosis factor-alpha measurement using enzyme-linked immunosorbent assay. Genotype distribution and allelic frequency were assessed. Data was analysed using SPSS 20. RESULTS: Out of the 225 subjects, with a mean age of 47.68±9.88 years, 132 (58.7%) were males, and 93 (41.3%) were females. Among them, 150 (66.7%) were patients, and 75 (33.3%) were controls. Heterozygous tumour necrosis factor-alpha -308 guanine/adenine genotypes were significantly higher among the patients (p<0.05). Minor allele - 308 adenine showed an association with obstructive sleep apnoea, its severity, higher tumour necrosis factor-alpha levels, neck circumference, excessive daytime sleepiness and the presence of hypertension (p<0.05). CONCLUSIONS: Tumour necrosis factor-alpha -308 adenine allele and higher tumour necrosis factor-alpha levels were found to be linked with obstructive sleep apnoea. The polymorphism also showed an association with hypertension in obstructive sleep apnoea patients.

Positive airway pressure therapy adherence and outcomes in obstructive sleep apnea: An exploratory longitudinal retrospective randomized chart review.

Background: Positive airway pressure (PAP) therapy is prescribed to patients with obstructive sleep apnea (OSA). A commonly used definition for PAP therapy adherence is based upon the minimum requirements to receive Medicare coverage in the US, defined as PAP usage of four or more hours per night on 70 percent of nights for at least 30 consecutive days. However, little evidence exists to support this definition for PAP therapy adherence. Therefore, the present study sought to determine the efficacy of the present definition of PAP therapy adherence on longitudinal outcomes in patients with OSA, using objectively measured PAP device usage time. Methods: An exploratory longitudinal, retrospective, randomized chart review was done to assess clinical outcomes between patients with OSA who were defined as PAP therapy adherent (n=50) and non-adherent (n=50) during an eight-year observation period. Results: No significant differences were shown between groups for mortality, hospitalizations, or development of co-morbidities during the observation period. However, logistic regression showed significantly higher odds of adherence in male patients compared to female patients (OR=8.519; 95%CI=1.301-55.756; p=0.025) and significantly lower odds of adherence in patients with higher normal (OR=0.039; 95%CI=0.005-0.392; p=0.003), mild excessive (OR=0.039; 95%CI=0.003-0.517; p=0.014), and severe excessive (OR=0.088; 95%CI=0.012-0.635; p=0.016) daytime sleepiness compared to patients with lower normal daytime sleepiness. An increasing number of hospitalizations also corresponded with a significant decrease in odds of being adherent (OR=0.741; 95%CI=0.551-0.995; p=0.046). Conclusion: The present study supports a steadily growing body of literature calling for more consideration and evidence to support a definition of PAP therapy adherence that is clinically meaningful.

Methodological parameters for upper airway assessment by cone-beam computed tomography in adults with obstructive sleep apnea: a systematic review of the literature and meta-analysis.

BACKGROUND: A reliable method for analyzing the upper airway (UA) remains a challenge. This study aimed to report the methods for UA assessment using cone-beam computed tomography (CBCT) in adults with obstructive sleep apnea (OSA). METHODS: We performed a systematic review (PROSPERO #CRD42021237490 and PRISMA checklist) that applied a search strategy to seven databases and grey literature. RESULTS: In 29 studies with moderate-to-high risk of bias, investigators mostly reported the body position during CBCT (upright or supine) and hard tissue references, diverging in UA delimitation and terminologies. The meta-analysis showed two subgroups (upright and supine), and no statistical differences were identified (p = 0.18) considering the UA area. The volume in the OSA group was smaller than that in the control group (p < 0.003 and Cohen's d = - 0.81) in the upright position. Patients with OSA showed smaller anteroposterior dimensions than the control group and were not affected by the position during image acquisition (p = 0.02; Cohen's d = - 0.52). The lateral measurements were also lower in the OSA group (supine) (p = 0.002; Cohen's d = - 0.6). CONCLUSIONS: Patients with OSA showed smaller UA measurements in the upright (volume) and supine (lateral dimension) positions. The anteroposterior dimension was also reduced in patients with OSA compared to the control group, regardless of the position during CBCT acquisition.

Adherence to continuous positive airway pressure treatment in a cohort of elderly adults with newly diagnosed obstructive sleep apnea.

PURPOSE: To evaluate adherence to continuous positive airway pressure (CPAP) treatment in elderly patients newly diagnosed with obstructive sleep apnea syndrome (OSAS). METHODS: Consecutive patients ≥ 70 years attending one of the participating centers, requiring CPAP treatment and agreeing to participate, were included. Mean hours of CPAP during the first 5 months of treatment defined adherence as CPAP ≥ 4 h/day on 70% of nights over a 30-day period. RESULTS: From January 2014 to April 2019, 262 patients aged between 76.7 and 87.7 years (mean age, 82.6 years) were included and fully evaluated; 224 (85.5%) were adherent. Mean adherence time was 6.9 h in adherent patients, vs 2 h in non-adherent patients (p < 0.0001). Compared to non-adherent patients, adherent patients tended to have higher baseline AHI without reaching statistical significance (44.7 vs 39.5, p = 0.0913). They less frequently presented with dementia (3.7% vs 21.6%, p < 0.0001). The somnolence (ODSI and Epworth), nocturia, and depression (QD2A) scores of adherent patients improved significantly from baseline to the fifth month: ODSI decreased from 7 to 3.7 (p < 0.0001), Epworth from 8.7 to 6.2 (p < 0.0001), nocturia from 6.6 to 4.1 (p = 0.0015), and QD2A from 3.7 to 3 (p = 0.0025). Many more patients in the non-adherent group used nasal plugs than in the adherent group (14.7% vs 2.1%, p = 0.0006). CONCLUSION: The present real-world study showed the ability of newly diagnosed elderly adults (including the very old) to adhere to CPAP therapy and the benefit of 5 months' well-conducted CPAP treatment. REGISTRATION NUMBER: Not applicable.

Adherence to continuous positive airway pressure therapy in patients with spinal cord injury and obstructive sleep apnea: trajectories and predictors.

PURPOSE: To identify specific determinants of non-adherence or cessation of continuous positive airway pressure (CPAP) therapy in a population of patients with spinal cord injuries (SCI). METHODS: Retrospective analysis of data from patients with SCI who underwent a full night supervised polysomnography between 2015 and 2021 and presented with moderate to severe obstructive sleep apnea (OSA) and for whom CPAP was indicated. Adherence was studied at 1, 6, and 12 months. Univariate and multivariate analyses were performed to identify factors associated with non-adherence (< 4 h per night or CPAP cessation). Factors studied were demographic and disease-related data and both subjective and objective sleep parameters. RESULTS: A total of 60 patients were included (40% cervical SCI). In univariate analysis, the only predictive parameters of non-adherence observed at 1, 6, and 12 months were the average use of CPAP on the 1st night (p = 0.02) and over the 1st week (p ≤ 0.001). A complete lesion (AIS-A) was predictive of non-adherence at 1 and 6 months (p = 0.02 at 6 months), while mask leakage was associated with non-adherence at 12 months (p = 0.02). Upper limb autonomy and the presence of family caregivers did not appear to be protective. In multivariate analysis, only the average use in the first week remained predictive of adherence (> 4 h) in the short, medium and long term. CONCLUSION: In patients with SCI and OSA, the 1st week of CPAP treatment seems to be determinant of short-, medium-, and long-term CPAP adherence. Support for SCI patients from the start of treatment is essential and may help avoid treatment failures.

A Classifying Model of Obstructive Sleep Apnea Based on Heart Rate Variability in a Large Korean Population.

BACKGROUND: The majority of patients with obstructive sleep apnea do not receive timely diagnosis and treatment because of the complexity of a diagnostic test. We aimed to predict obstructive sleep apnea based on heart rate variability, body mass index, and demographic characteristics in a large Korean population. METHODS: Models of binary classification for predicting obstructive sleep apnea severity were constructed using 14 features including 11 heart rate variability variables, age, sex, and body mass index. Binary classification was conducted separately using apnea-hypopnea index thresholds of 5, 15, and 30. Sixty percent of the participants were randomly allocated to training and validation sets while the other forty percent were designated as the test set. Classifying models were developed and validated with 10-fold cross-validation using logistic regression, random forest, support vector machine, and multilayer perceptron algorithms. RESULTS: A total of 792 (651 men and 141 women) subjects were included. The mean age, body mass index, and apnea-hypopnea index score were 55.1 years, 25.9 kg/m², and 22.9, respectively. The sensitivity of the best performing algorithm was 73.6%, 70.7%, and 78.4% when the apnea-hypopnea index threshold criterion was 5, 10, and 15, respectively. The prediction performances of the best classifiers at apnea-hypopnea indices of 5, 15, and 30 were as follows: accuracy, 72.2%, 70.0%, and 70.3%; specificity, 64.6%, 69.2%, and 67.9%; area under the receiver operating characteristic curve, 77.2%, 73.5%, and 80.1%, respectively. Overall, the logistic regression model using the apnea-hypopnea index criterion of 30 showed the best classifying performance among all models. CONCLUSION: Obstructive sleep apnea was fairly predicted by using heart rate variability, body mass index, and demographic characteristics in a large Korean population. Prescreening and continuous treatment monitoring of obstructive sleep apnea may be possible simply by measuring heart rate variability.

ASSESSMENT OF STANDARD ANTHROPOMETRIC AIRWAY CHARACTERISTICS RELEVANT FOR AIRWAY MANAGEMENT OF PATIENTS WITH OBSTRUCTIVE SLEEP APNEA SYNDROME DURING SLEEP BREATHING DISORDER SURGERY: A RETROSPECTIVE, SINGLE CENTER STUDY.

The aim of this study was to explore standard anthropometric airway characteristics of patients with obstructive sleep apnea syndrome (OSAS) and determine the incidence and risk factors for difficult airway management. Final analysis included 91 patients with polysomnography-verified diagnosis of OSAS who underwent sleep breathing disorder surgery under general anesthesia with direct laryngoscopy oroendotracheal intubation. The incidence of difficult manual mask ventilation during anesthesia induction, difficult intubation and immediate postextubation respiratory complications was 17.6%, 7.7% and 7.7%, respectively. Compared to patients without difficult manual mask ventilation, the group of OSAS patients with difficult manual mask ventilation had a higher rate of body mass index (BMI) ≥25 kgm-2 (p=0.010), Mallampati score ≥3 (p=0.024) and Cormack-Lehane score ≥3 (p=0.002). The OSAS patients with difficult intubation had more Cormack-Lehane score ≥3 (p=0.002) in comparison to those without difficult intubation. Our study demonstrated that manual mask ventilation during anesthesia induction was the most troublesome airway management task in OSAS patients during sleep breathing disorder surgery. Cormack-Lehane score was a relevant determinator of difficult mask ventilation and difficult intubation, while Mallampati score and BMI were relevant determinators only for difficult manual mask ventilation.

SLEAP SMART (Sleep Apnea Screening Using Mobile Ambulatory Recorders After TIA/Stroke): A Randomized Controlled Trial.

BACKGROUND AND PURPOSE: Poststroke/transient ischemic attack obstructive sleep apnea (OSA) is prevalent, linked with numerous unfavorable health consequences, but remains underdiagnosed. Reasons include patient inconvenience and costs associated with use of in-laboratory polysomnography (iPSG), the current standard tool. Fortunately, home sleep apnea testing (HSAT) can accurately diagnose OSA and is potentially more convenient and cost-effective compared with iPSG. Our objective was to assess whether screening for OSA in patients with stroke/transient ischemic attack using HSAT, compared with standard of care using iPSG, increased diagnosis and treatment of OSA, improved clinical outcomes and patient experiences with sleep testing, and was a cost-effective approach. METHODS: We consecutively recruited 250 patients who had sustained a stroke/transient ischemic attack within the past 6 months. Patients were randomized (1:1) to use of (1) HSAT versus (2) iPSG. Patients completed assessments and questionnaires at baseline and 6-month follow-up appointments. Patients diagnosed with OSA were offered continuous positive airway pressure. The primary outcome was compared between study arms via an intention-to-treat analysis. RESULTS: At 6 months, 94 patients completed HSAT and 71 patients completed iPSG. A significantly greater proportion of patients in the HSAT arm were diagnosed with OSA (48.8% versus 35.2%, P=0.04) compared with the iPSG arm. Furthermore, patients assigned to HSAT, compared with iPSG, were more likely to be prescribed continuous positive airway pressure (40.0% versus 27.2%), report significantly reduced sleepiness, and a greater ability to perform daily activities. Moreover, a significantly greater proportion of patients reported a positive experience with sleep testing in the HSAT arm compared with the iPSG arm (89.4% versus 31.1%). Finally, a cost-effectiveness analysis revealed that HSAT was economically attractive for the detection of OSA compared with iPSG. CONCLUSIONS: In patients with stroke/transient ischemic attack, use of HSAT compared with iPSG increases the rate of OSA diagnosis and treatment, reduces daytime sleepiness, improves functional outcomes and experiences with sleep testing, and could be an economically attractive approach. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02454023.

Pediatric obstructive sleep-disordered breathing is associated with arterial stiffness.

The association between obstructive sleep-disordered breathing (oSDB) and arterial stiffness, an independent predictor of cardiovascular outcomes, is not well established in children. This study compared cardiovascular parameters between healthy and oSDB children and aimed to identify predictors of arterial stiffness indices in children with oSDB. Cross-sectional study realized in a tertiary hospital from June 2018 to January 2020. Forty-eight children (3 to 10 years old) with clinical diagnosis of oSDB and indication for adenotonsillectomy and 24 controls were evaluated. Cardiovascular parameters were measured non-invasively by brachial artery oscillometry with a portable device. The main arterial stiffness indices assessed were augmentation index and pulse wave velocity, both derived from the aortic pulse wave. In the oSDB group, the questionnaires Obstructive Sleep Apnea-18 (OSA-18) and Pediatric Quality of Life Inventory version 4.0 (PedsQL 4.0) were applied. The oSDB group had higher values of reflection coefficient (p = 0.044) and augmentation index (p = 0.003) than the control group. Stepwise multiple regression analysis revealed that age, female sex, reflection coefficient, and systolic volume were independent predictors of augmentation index. Higher pulse wave velocity values were associated with worse quality of life assessed by PedsQL 4.0 questionnaire. There was no association with OSA-18. The vascular and hemodynamic parameters were similar in both groups.Conclusion: Children with oSDB have increased augmentation index, an independent predictor of cardiovascular outcomes. The early identification of subclinical cardiovascular changes reinforces the importance of treating the disease, as well as changing lifestyle habits, to prevent complications in adulthood. What is Known: • The association between oSDB and cardiovascular risk in adults is well described in the literature. • Children with oSDB, regardless of their weight or sex, have higher PWV values when compared to non-snoring children. What is New: • Children with oSDB have augmented arterial stiffness, evidenced by the increase in AIx@75, measured non-invasively by brachial artery oscillometry with a portable device. • Low quality of life and therefore a high disease burden in children with oSDB may be a risk factor for arterial stiffness.

The utility of acoustic pharyngometry in treatment of obstructive sleep apnea patients with expansion sphincter pharyngoplasty surgery.

PURPOSE: Expansion sphincter pharyngoplasty (ESP) is a common surgery for patients with obstructive sleep apnea (OSA) which aims to correct the obstruction at the palatal level. The effectiveness of ESP has been widely shown in the literature using surgical success rates, but to our knowledge, there is no research which documents the changes in the upper airway anatomy objectively. We aimed to demonstrate the effectiveness of expansion sphincter pharyngoplasty using acoustic pharyngometry. We also aimed to study the possible utility of acoustic pharyngometry in predicting surgical outcomes. METHODS: Pre- and post-operative acoustic pharyngometry and polysomnography data of patients who underwent expansion sphincter pharyngoplasty were compared prospectively. Minimum cross-sectional area (MCA) and total volume of the pharynx (TPV), apnea-hypopnea index (AHI), and surgical success rates were evaluated. RESULTS: Fifty-two patients with OSA were invited to this study, and 35 patients who agreed to participate were enrolled. All patients underwent ESP surgery. Surgical success rate was 63% according to Sher's criteria. The mean AHI of the patients decreased from 29.6 ± 16.3 to 18.3 ± 18.1. MCA increased from 1.1 ± 0.4 to 2.3 ± 0.4 cm2, and TPV increased from 21.1 ± 6.9 to 31.7 ± 5.5 cm3. Comparative analysis of the successful and unsuccessful groups yielded no significant differences between the groups concerning pre- and post-operative MCA and TPV or in mean changes in MCA and TPV achieved with the surgery. CONCLUSION: Improvement in the upper airway anatomy by expansion sphincter pharyngoplasty can be clearly demonstrated using acoustic pharyngometry. Acoustic pharyngometry findings are quite similar in patients with successful and unsuccessful outcomes; therefore, pharyngometry findings cannot be used to predict surgical success; and surgical success cannot be solely attributed to the changes in MCA and TPV.

Point-of-care prediction model of loop gain in patients with obstructive sleep apnea: development and validation.

BACKGROUND: High loop gain (unstable ventilatory control) is an important-but difficult to measure-contributor to obstructive sleep apnea (OSA) pathogenesis, predicting OSA sequelae and/or treatment response. Our objective was to develop and validate a clinical prediction tool of loop gain. METHODS: A retrospective cohort of consecutive adults with OSA (apnea-hypopnea index, AHI > 5/hour) based on in-laboratory polysomnography 01/2017-12/2018 was randomly split into a training and test-set (3:1-ratio). Using a customized algorithm ("reference standard") loop gain was quantified from raw polysomnography signals on a continuous scale and additionally dichotomized (high > 0.7). Candidate predictors included general patient characteristics and routine polysomnography data. The model was developed (training-set) using linear regression with backward selection (tenfold cross-validated mean square errors); the predicted loop gain of the final linear regression model was used to predict loop gain class. More complex, alternative models including lasso regression or random forests were considered but did not meet pre-specified superiority-criteria. Final model performance was validated on the test-set. RESULTS: The total cohort included 1055 patients (33% high loop gain). Based on the final model, higher AHI (beta = 0.0016; P < .001) and lower hypopnea-percentage (beta = -0.0019; P < .001) predicted higher loop gain values. The predicted loop gain showed moderate-to-high correlation with the reference loop gain (r = 0.48; 95% CI 0.38-0.57) and moderate discrimination of patients with high versus low loop gain (area under the curve = 0.73; 95% CI 0.67-0.80). CONCLUSION: To our knowledge this is the first prediction model of loop gain based on readily-available clinical data, which may facilitate retrospective analyses of existing datasets, better patient selection for clinical trials and eventually clinical practice.

Overnight Rostral Fluid Shifts Exacerbate Obstructive Sleep Apnea After Stroke.

Background and Purpose: Overnight shifts of fluid from lower to upper compartments exacerbate obstructive sleep apnea (OSA) in some OSA populations. Given the high prevalence of OSA after stroke, decreased mobility and use of IV fluids among hospitalized patients with stroke, and improvement in OSA in the months after stroke, we hypothesized that overnight fluid shifts occur and are associated with OSA among patients with subacute ischemic stroke. Methods: Within a population-based project, we performed overnight sleep apnea tests (ApneaLink Plus) during ischemic stroke hospitalizations. Before sleep that evening, and the following morning before rising from bed, we assessed neck and calf circumference, and leg fluid volume (bioimpedance spectroscopy). The average per subject overnight change in the 3 fluid shift measurements was calculated and compared with zero. Linear regression was used to test the crude association between each of the 3 fluid shift measurements and the respiratory event index (REI). Results: Among the 292 participants, mean REI was 24 (SD=18). Within individuals, calf circumference decreased on average by 0.66 cm (SD=0.75 cm, P<0.001), leg fluid volume decreased by a mean of 135.6 mL (SD=132.8 mL, P<0.001), and neck circumference increased by 0.20 cm (SD=1.71 cm, P=0.07). In men, when the overnight change of calf circumference was negative, an interquartile range (0.8 cm) decrease in calf circumference overnight was significantly associated with a 25.1% increase in REI (P=0.02); the association was not significant in women. The relationship between overnight change in leg fluid volume and REI was U shaped. Conclusions: This population-based, multicenter, cross-sectional study showed that in hospitalized patients with ischemic stroke, nocturnal rostral fluid shifts occurred, and 2 of the 3 measures were associated with greater OSA severity. Interventions that limit overnight fluid shifts should be tested as potential treatments for OSA among patients with subacute ischemic stroke.

Risk of Atrial Fibrillation and Stroke After Bariatric Surgery in Patients With Morbid Obesity With or Without Obstructive Sleep Apnea.

Background and Purpose: Weight loss in morbidly obese patients reduces atrial fibrillation (AF); however, it is unknown whether similar benefits are maintained in patients with obstructive sleep apnea (OSA). We sought to determine whether incident AF and stroke rates are affected by OSA after weight loss and to identify predictors of AF and stroke. Methods: Differences in laparoscopic adjustable gastric banding­induced weight loss on incident AF and stroke events in those with and without OSA in the entire and in propensity-matched cohorts were determined longitudinally, and independent predictors of AF and stroke were identified. Results: Of 827 morbidly obese patients who underwent laparoscopic adjustable gastric banding (mean age, 44±11 years; mean body mass index, 49±8 kg/m2), incident AF was documented in 4.96% and stroke in 5.44% of patients during a mean 6.0±3.2-year follow-up. Despite a similar reduction in body weight (19.6% and 21% in 3 years), new-onset AF was significantly higher in patients with OSA than without OSA in the entire (1.7% versus 0.5% per year; P<0.001) and propensity-matched cohorts. Incident stroke was higher in the OSA than in the non-OSA group (2.10% versus 0.47% per year; P<0.001), but only 20% of patients with stroke had documented AF. On multivariate analysis, OSA (hazard ratio, 2.88 [95% CI, 1.45­5.73]), age, and hypertension were independent predictors of new-onset AF, and OSA (hazard ratio, 5.84 [95% CI, 3.02­11.30]), depression, and body mass index were for stroke events. Conclusions: In morbidly obese patients who underwent laparoscopic adjustable gastric banding, despite similar weight loss, patients with OSA had a higher incidence of AF and stroke than patients without OSA. Both non-AF and AF-related factors were involved in increasing stroke risk. Further investigation is warranted into whether OSA treatment helps reduce AF or stroke events in this population.

Standardized framework to report on the role of sleeping position in sleep apnea patients.

PURPOSE: Sleep apnea is a multifactorial illness which can be differentiated in various physiological phenotypes as a result of both anatomical and non-anatomical contributors (e.g., low respiratory arousal threshold, high loop gain). In addition, the frequency and duration of apneas, in the majority of patients with OSA, are influenced by sleeping position. Differences in characteristics between non-positional patients (NPP) and positional patients (PP) suggest another crucial phenotype distinction, a clinical phenotype focusing on the role of sleeping position on sleep apnea. Since this clinical phenotype distinction has therapeutic implications, further research is necessary to better understand the pathophysiology behind this phenotypic trait and to improve management of PP. Therefore, we suggest a standardized framework that emphasizes the role of sleeping position when reporting clinical and research data on sleep apnea. METHODS: We identified 5 key topics whereby a standardized framework to report on the role of sleeping position would be of added value: (1) sleep study data, (2) anatomical, morphological and physiological factors, (3) drug-induced sleep endoscopy (DISE) findings, (4) sleep apnea management, and (5) effectiveness versus efficacy of positional therapy in sleep apnea management. We performed a literature search to identify evidence to describe and support the rationale behind these 5 main recommendations. RESULTS: In this paper, we present the rationale behind this construct and present specific recommendations such as reporting sleep study indices (disease severity) and sleep time spent in various sleeping positions. The same is suggested for DISE findings and effect of treatment. Sleep study indices (disease severity), anatomical, morphological, and physiological factors in sleep apnea patients should be reported separately for PP and NPP. CONCLUSION: Applying these suggestions in future research will improve patient care, assist in better understanding of this dominant phenotype, and will enhance accurate comparisons across studies and future investigations.

Assessment, referral and management of obstructive sleep apnea by Australian general practitioners: a qualitative analysis.

BACKGROUND: The high and increasing demand for obstructive sleep apnea (OSA) care has exceeded the capacity of specialist sleep services prompting consideration of whether general practitioners could have an enhanced role in service delivery. However, little is known about the current involvement, experiences and attitudes of Australian general practitioners towards OSA. The purpose of this study was to provide an in-depth analysis of Australian general practitioners' experiences and opinions regarding their care of patients with OSA to inform the design and implementation of new general practice models of care. METHODS: Purposive sampling was used to recruit participants with maximum variation in age, experience and location. Semi-structured interviews were conducted and were analysed using Thematic Analysis. RESULTS: Three major themes were identified: (1) General practitioners are important in recognising symptoms of OSA and facilitating a diagnosis by others; (2) Inequities in access to the assessment and management of OSA; and (3) General practitioners currently have a limited role in the management of OSA. CONCLUSIONS: When consulting with patients with symptoms of OSA, general practitioners see their primary responsibility as providing a referral for diagnosis by others. General practitioners working with patients in areas of greater need, such as rural/remote areas and those of socio-economic disadvantage, demonstrated interest in being more involved in OSA management. Inequities in access to assessment and management are potential drivers for change in future models of care for OSA in general practice.

Relationship between allergic rhinitis and nasal surgery success in patients with obstructive sleep apnea.

OBJECTIVES: Nasal obstruction is common in patients with obstructive sleep apnea (OSA). Nonetheless, the effectiveness of isolated nasal surgery in treatment of OSA remains controversial. This study is to evaluate the subjective and objective outcome after isolated nasal surgery in patients with OSA and to determine the associated factors related to the success rate of isolated nasal surgery. METHODS: The study population consisted of 35 patients with nasal obstruction who had been diagnosed with OSA and were undergoing septoplasty and inferior turbinate reduction to correct nasal pathologies. Preoperative drug-induced sleep endoscopy was performed to evaluate the obstruction site. Patients were assessed before and after nasal surgery using subjective outcomes measures, including the Visual Analog Scale and Epworth Sleepiness Scale, as well as by overnight polysomnography. RESULTS: All patients experienced improved nasal breathing postoperatively. At 6 months postoperatively, patients exhibited significant symptomatic improvement in snoring, sleep apnea, morning headache, tiredness, and daytime sleepiness. Postoperative polysomnography revealed significant improvement in the apnea-hypopnea index, respiratory disturbance index, and percentage of time with oxygen saturation < 90%. Although the overall success rate of nasal surgery alone was 14.3%, the criteria for success were met in 50% of patients with allergic rhinitis. Furthermore, the success rate was significantly higher in patients with moderate to severe nasal obstruction than in patients with mild nasal obstruction. CONCLUSION: Among patients with OSA, those with allergic rhinitis and severe nasal obstruction are likely to have a better surgical outcome following isolated nasal surgery.