OSA Patients Research Articles

Outcome of Continuous Positive Airway Pressure Adherence Based on Nasal Endoscopy and the Measurement of Nasal Patency-A Prospective Study.

The gold standard for treating obstructive sleep apnea in adults is continuous positive airway pressure (CPAP). However, it can be difficult to convince patients to adhere to this therapy. The aim of this study was to determine the relationship between nasal endoscopy findings/nose patency and CPAP adherence. Material and methods: A cohort of 450 consecutive patients suspected of having OSA were prospectively enrolled. For further analyses, 47 OSA patients undergoing CPAP treatment were selected (13 females and 34 males, average age, 65.3 years, BMI 34.1, apnea-hypopnea index. AHI 51.0). The patients were divided into two groups: patients with good CPAP adherence (n = 35) and patients who did not adhere to CPAP therapy (n = 12). The influence of nasal endoscopy and flow measurement on CPAP adherence was explored. Results: We found a statistical independence between adherence to CPAP and AHI (p = 0.124), T90 (p = 0.502), endoscopic findings (p = 0.588) and nasal patency measured by a flowmeter (p = 0.498). Conclusions: In our studied sample, endoscopic findings and nasal patency measured by a flowmeter were not predictors of CPAP non-adherence in the first year of the treatment. Our data show that while an endoscopic finding in the nasal cavity could indicate that a patient has a severe obstruction, compliance with CPAP therapy is not reduced in these patients and neither is it reduced with a decrease in nasal flow, according to our observation.

Obstructive Sleep Apnea - An Underestimated and Overlooked Condition

Obstructive Sleep Apnea OSA is one of the most over-looked and underestimated conditions by the general and dental practitioners. Being in dental profession we might be the first ones to diagnose OSA and make timely referrals for its management. Because of lack of knowledge of signs and symptoms of OSA among dentists and general practitioners irregularities in diagnosis and management of OSA patients are noted. Epidemiological studies have shown that detection of cases of OSA has risen considerably in the last decade and awareness among patients medical and dental fraternity can further help in better management and prognosis. This narrative review aimed to highlight the signs symptoms diagnosis and management of OSA for general and specialty medical and dental professionals which otherwise is easily overlooked.

Proteomic profiling for prediction of recurrent cardiovascular event in patients with acute coronary syndrome and obstructive sleep apnea: A post-hoc analysis from the ISAACC study

BackgroundObstructive sleep apnea (OSA) is associated with a recurrent cardiovascular event (CVE) risk in patients with a first acute coronary syndrome (ACS). However, the pathological pathways by which OSA promotes this deleterious role are unknown. We aim to explore the proteomic profile associated with OSA that promote the recurrent CVE risk in severe OSA patients with ACS without previous cardiovascular diseases. MethodsThis post-hoc analysis from the ISAACC study (NCT01335087) included 86 patients admitted for ACS. Patients underwent respiratory polygraphy for the first 24–72 h to OSA diagnosis. We analyzed of 276 cardiovascular and inflammatory related proteins in baseline fasting plasma samples using proximity expression assay technology (Olink®, Sweden). Protein levels were compared between severe OSA patients with/without recurrent CVEs during follow-up. Random forest was conducted to select relevant proteins and generate a predictive model of recurrent CVE. ResultsWe included 86 patients (median age: 61 years, median BMI: 29.4 kg/m2 and 86 % males) admitted for ACS with severe OSA (56 without recurrent CVE/30 with recurrent CVE). The plasma levels of 38 proteins were differentially expressed between groups. Additionally, 12 proteins had a significant association with respiratory polygraphy parameters. Three proteins discriminate with an AUC of 0.81 (95 % CI of 0.71–0.9) between severe OSA patients with and without recurrent CVE. These proteins were implicated in cell proliferation, communication and apoptosis, and regulation/response to the inflammatory and immune systems. ConclusionIn ACS patients with severe OSA, a proteomic profile was associated with recurrent CVEs. This proteomic profile was correlated with specific OSA parameters from respiratory polygraphy. Proteomic profiling may provide an new direction for patient risk stratification and clinical management.

Obstructive sleep apnea and pulmonary hypertension: the pendulum swings again.

Obstructive sleep apnea and pulmonary hypertension: the pendulum swings again.

An evaluation of the change in serum SCUBE-1 levels with CPAP treatment in patients with severe obstructive sleep apnea

ABSTRACT Objective Signal peptide CUB-EGF domain-containing protein 1 (SCUBE-1) is a cell surface protein, wherein inflammation causes an increase in serum. The aim of this study was to compare serum SCUBE-1 levels in OSA patients and to investigate the serum SCUBE-1 change with CPAP treatment. Methods Blood samples were obtained from 61 severe OSA patients and from 25 control subjects evaluated as simple snorers. The 61 patients with severe OSA were treated with CPAP therapy and were recalled for follow up after 1 year. Evaluation was made after 1 year of CPAP therapy. Results Serum SCUBE-1 values were significantly higher in patients with severe OSA. The SCUBE-1 values significantly decreased after treatment with CPAP. Conclusion Serum SCUBE-1 values in OSA patients showed a significant reduction in SCUBE-1 levels following 1 year of CPAP treatment.

Prediction model of obstructive sleep apnea-related hypertension: Machine learning-based development and interpretation study.

Obstructive sleep apnea (OSA) is a globally prevalent disease closely associated with hypertension. To date, no predictive model for OSA-related hypertension has been established. We aimed to use machine learning (ML) to construct a model to analyze risk factors and predict OSA-related hypertension. We retrospectively collected the clinical data of OSA patients diagnosed by polysomnography from October 2019 to December 2021 and randomly divided them into training and validation sets. A total of 1,493 OSA patients with 27 variables were included. Independent risk factors for the risk of OSA-related hypertension were screened by the multifactorial logistic regression models. Six ML algorithms, including the logistic regression (LR), the gradient boosting machine (GBM), the extreme gradient boosting (XGBoost), adaptive boosting (AdaBoost), bootstrapped aggregating (Bagging), and the multilayer perceptron (MLP), were used to develop the model on the training set. The validation set was used to tune the model hyperparameters to determine the final prediction model. We compared the accuracy and discrimination of the models to identify the best machine learning algorithm for predicting OSA-related hypertension. In addition, a web-based tool was developed to promote its clinical application. We used permutation importance and Shapley additive explanations (SHAP) to determine the importance of the selected features and interpret the ML models. A total of 18 variables were selected for the models. The GBM model achieved the most extraordinary discriminatory ability (area under the receiver operating characteristic curve = 0.873, accuracy = 0.885, sensitivity = 0.713), and on the basis of this model, an online tool was built to help clinicians optimize OSA-related hypertension patient diagnosis. Finally, age, family history of hypertension, minimum arterial oxygen saturation, body mass index, and percentage of time of SaO2 < 90% were revealed by the SHAP method as the top five critical variables contributing to the diagnosis of OSA-related hypertension. We established a risk prediction model for OSA-related hypertension patients using the ML method and demonstrated that among the six ML models, the gradient boosting machine model performs best. This prediction model could help to identify high-risk OSA-related hypertension patients, provide early and individualized diagnoses and treatment plans, protect patients from the serious consequences of OSA-related hypertension, and minimize the burden on society.

Daytime Sleepiness and Quality of Life in Obstructive Sleep Apnoea Patients before and after Long-Term Mandibular Advancement Device Treatment.

This study compared daytime sleepiness and quality of life in OSA patients with healthy controls and compared sleepiness and quality of life in OSA patients before and after long-term treatment with a mandibular advancement device (MAD). A total of 27 OSA patients (18 men, 9 women, mean age 52.3 years) and 32 healthy age- and sex-matched controls (20 men, 12 women, mean age 51.1 years) were included. At baseline and after MAD treatment, daytime sleepiness and quality of life were recorded by the Epworth Sleepiness Scale (ESS) and Short Form-36 questionnaires (SF-36). Daytime sleepiness occurred significantly more often in OSA patients compared to controls at baseline (p = 0.01). The quality of life domains Energy and vitality (p < 0.0001), General perception of health (p = 0.0002), Mental health (p = 0.0031), Social functioning (p = 0.0119), Role limitations due to emotional problems (p = 0.0173) and Physical functioning (p = 0.0226) were significantly poorer in OSA patients compared to controls at baseline. After long-term MAD treatment, daytime sleepiness decreased (p < 0.01) and the quality of life domain Energy and Vitality increased (p < 0.01) in OSA patients compared to baseline. The results of the present study support the relevance of MAD treatment as an effective tool for decreasing daytime sleepiness and increasing the quality of life in OSA patients—also in the long term.

OSA and Subsequent Risk of Hospitalization With Pneumonia, Respiratory Infection, and Total Infection: The Atherosclerosis Risk in Communities Study

OSA has been linked to microaspiration, systemic inflammation, and suboptimal immune function. Is OSA prospectively associated with risk of hospitalization for pneumonia, respiratory, and total infections? Prospective cohort. Participants in the Atherosclerosis Risk in Communities (ARIC) study (N= 1,586) underwent polysomnography in 1996-1998 and were followed up through 2018 for infection-related hospitalizations. The apnea-hypopnea index (AHI; events/h) was used to categorize participants as having severe OSA (≥ 30), moderate OSA (15-29), mild OSA (5-14), or a normal breathing pattern (< 5). Cox regression was used to calculate hazard ratios (HRs) and 95%CIs. ARIC participants were on average 62.7 (SD= 5.5) years of age, and 52.8%were female. Severe OSA was present in 6.0%, moderate OSA in 12.7%, mild OSA in 30.0%, and normal breathing in 51.3%. A total of 253 hospitalizations with pneumonia occurred over a median 20.4 (max, 22.9) years' follow-up. Participants with severe OSA were at 1.87 times (95%CI, 1.19-2.95) higher risk of hospitalization with pneumonia compared with those with a normal breathing pattern after adjustment for demographics and lifestyle behaviors. Results were attenuated modestly after adjustment for BMI (1.62 [0.99-2.63]), and prevalent asthma and COPD (1.62 [0.99-2.63]). A similar pattern existed for hospitalization with respiratory infection and composite infection (demographic and behavior-adjusted HRs: 1.47 [0.96-2.25] and 1.48 [1.07-2.04], respectively). Severe OSA was associated with increased risk of hospitalizations with pneumonia in this community-based cohort. OSA patients may benefit from more aggressive efforts to prevent pneumonia and other infectious conditions.

Impact of obstructive sleep apnea on platelet activation and development of silent brain infarctions

BackgroundObstructive sleep apnea (OSA) is a unique potent predictor for stroke compared to other predictors. By aiding in the adherence of leukocytes and platelets, soluble P-selectin (sP-selectin) contributes to the development of ischemic stroke. The objective of this study was to investigate the independent impact of OSA on platelet activation and development of silent brain infarction. Twenty-four OSA patients and 24 controls were studied in a case–control study, who underwent one-night polysomnography, magnetic resonance imaging for evaluation of silent brain infarctions (SBI), measurement of serum (sP-selectin) levels for assessment of increased platelet activation and C-reactive protein (CRP) serum levels.ResultsOut of 24 patients, 5 (20.8%) had mild OSA and 8 (33.3%) had moderate and 11 (45.8%) had severe OSA. Serum levels of sP-selectin were statistically significantly higher in moderate and severe groups (p < 0.001). Eleven (57.9%) patients in moderate and severe OSA had SBI. Fifty percent of patients with moderate OSA had elevated serum sP-selectin and 25.0% of them had SBI and 81.8% of severe OSA patients had elevated serum sP-selectin and 81.8% of them had SBI. Patients with mild OSA and controls had no SBI and normal serum sP-selectin level. CRP was statistically significantly higher in moderate and severe OSA groups (16.6% and 45.8%) than the mild and control groups (4.1% and 0%) (p < 0.001).ConclusionModerate and severe obstructive sleep apnea were associated independently with elevated serum sP-selectin reflecting increased platelet function, elevated inflammatory marker CRP and an increased risk of silent brain infarctions.

Identifying longitudinal patterns of CPAP treatment in OSA using growth mixture modeling: Disease characteristics and psychological determinants.

In this study, we aim to identify the distinct subtypes of continuous positive airway pressure (CPAP) user profiles based on the telemedicine management platform and to determine clinical and psychological predictors of various patterns of adherence. A total of 301 patients used auto-CPAP (Autoset 10, Resmed Inc.) during the treatment period. Four categories of potential predictors for CPAP adherence were examined: (1) demographic and clinical characteristics, (2) disease severity and comorbidities, (3) sleep-related health issues, and (4) psychological evaluation. Then, growth mixture modeling was conducted using Mplus 8.0 to identify the unique trajectories of adherence over time. Adherence data were collected from the telemedicine management platform (Airview, Resmed Inc.) during the treatment. Three novel subgroups were identified and labeled "adherers" (53.8% of samples, intercept = 385, slope = -51, high mean value, negative slope and moderate decline), "Improvers" (18.6%, intercept = 256, slope = 50, moderate mean value, positive slope and moderate growth) and "non-adherers" (27.6%, intercept = 176, slope = -31, low mean value, negative slope and slight decline). The comorbidities associated with OSA and the apnea-hypopnea index (AHI), which reflects the objective severity of the disease, did not differ significantly among the subgroups. However, "improvers" showed higher levels of daytime sleepiness (8.1 ± 6.0 vs. 12.1 ± 7.0 vs. 8.0 ± 6.1 in SWIFT, p = 0.01), reduced daytime function (4.6 ± 1.6 vs. 3.8 ± 1.6 vs. 4.2 ± 1.8 in QSQ daytime symptoms, p = 0.02), and characteristics of positive coping style (1.8 ± 0.5 vs. 1.9 ± 0.5 vs. 1.7 ± 0.5 in SCSQ positive coping index, p = 0.02). Negative emotion was more pronounced in patients with "non-adherers" (12.9 ± 3.8 vs. 13.7 ± 3.3 vs. 14.6 ± 3.5, p = 0.02 in the HADS depression dimension; 9.0 ± 6.1 vs. 9.8 ± 5.1 vs. 11.5 ± 6.3, p = 0.01 with Negative Affectivity in DS14, and 9.3 ± 6.1 vs. 10.3 ± 5.1 vs. 11.7 ± 6.5, p = 0.01 with Social Inhibition in DS14). Overall, our study demonstrated that CPAP therapy may present distinct trajectories of adherence over time in addition to the traditional binary classification. Self-reported sleep health issues (diurnal sleepiness and daytime dysfunction) as well as psychological characteristics (negative emotions and coping style) were predictors of different adherence subtypes in patients with OSA. Understanding CPAP use profiles and their predictors enable the identification of those who may require additional intervention to improve adherence and further enhance the therapeutic effect in OSA patients.

Carbonic Anhydrase IX as a Marker of Disease Severity in Obstructive Sleep Apnea.

Background and Objectives: Carbonic anhydrase (CA) enzymes are a family of metalloenzymes that contain a zinc ion in their active sites. CA enzymes have been implied in important situations such as CO2 transport, pH regulation, and oncogenesis. CA-IX is a transmembrane glycoprotein and stimulates the expression of hypoxia-inducible factor-1 (HIF-1) CA-IX. This study aimed to determine serum CA-IX levels in OSA patients in whom intermittent hypoxia is important and to investigate the relationship between serum CA-IX levels and disease severity. Materials and Methods: The study included 88 people who applied to Malatya Turgut Özal University Training and Research Hospital Sleep Disorders Center without a history of respiratory disease, malignancy, and smoking. Patients were divided into three groups: control (AHI &lt; 5, n = 31), mild-moderate OSA (AHI = 5-30, n = 27) and severe OSA (AHI &gt; 30, n = 30). The analysis of the data included in the research was carried out with the SPSS (IBM Statistics 25, NY, USA). The Shapiro-Wilk Test was used to check whether the data included in the study had a normal distribution. Comparisons were made with ANOVA in multivariate groups and the t-test in bivariate groups. ANCOVA was applied to determine the effect of the CA-IX parameter for OSA by controlling the effect of independent variables. The differentiation in CA-IX and OSA groups was analyzed regardless of BMI, age, gender, and laboratory variables. ROC analysis was applied to determine the parameter cut-off point. Sensitivity, specificity, and cut-off were calculated, and the area under the curve (AUC) value was calculated. Results: Serum CA-IX levels were 126.3 ± 24.5 pg/mL in the control group, 184.6 ± 59.1 pg/mL in the mild-moderate OSA group, and 332.0 ± 39.7 pg/mL in the severe OSA group. Serum CA-IX levels were found to be higher in the severe OSA group compared to the mild-moderate OSA group and control group and higher in the mild-moderate OSA group compared to the control group (p &lt; 0.001, p &lt; 0.001, p &lt; 0.001, respectively). In addition, a negative correlation between CA-IX and minimum SaO2 and mean SaO2 (r = -0.371, p = 0.004; r = -0.319, p = 0.017, respectively). A positive correlation between CA-IX and desaturation index (CT90) was found (r = 0.369, p = 0.005). A positive correlation was found between CA-IX and CRP (r = 0.340, p = 0.010). When evaluated by ROC curve analysis, the area under the curve (AUC) value was determined as 0.940 (95% CI 0.322-0.557; p &lt; 0.001). When the cut-off value for CA-IX was taken as 254.5 pg/mL, it was found to have 96.7% sensitivity and 94.8% specificity in demonstrating severe OSA. Conclusions: Our study found that serum CA-IX value was higher in OSA patients than in control patients, and this elevation was associated with hypoxemia and inflammation. CA-IX value can be a fast, precise, and useful biomarker to predict OSA.

Single-cell RNA-seq uncovers cellular heterogeneity and provides a signature for paediatric sleep apnoea.

Obstructive sleep apnoea (OSA) is a highly prevalent disease and a major cause of systemic inflammation leading to neurocognitive, behavioural, metabolic and cardiovascular dysfunction in children and adults. However, the impact of OSA on the heterogeneity of circulating immune cells remains to be determined. We applied single-cell transcriptomics analysis (scRNA-seq) to identify OSA-induced changes in transcriptional landscape in peripheral blood mononuclear cell (PBMC) composition, which uncovered severity-dependent differences in several cell lineages. Furthermore, a machine-learning approach was used to combine scRNAs-seq cell-specific markers with those differentially expressed in OSA. scRNA-seq demonstrated OSA-induced heterogeneity in cellular composition and enabled the identification of previously undescribed cell types in PBMCs. We identified a molecular signature consisting of 32 genes, which distinguished OSA patients from various controls with high precision (area under the curve 0.96) and accuracy (93% positive predictive value and 95% negative predictive value) in an independent PBMC bulk RNA expression dataset. OSA deregulates systemic immune function and displays a molecular signature that can be assessed in standard cellular RNA without the need for pre-analytical cell separation, thereby making the assay amenable to application in a molecular diagnostic setting.

P068 Computational fluid dynamic study in Obstructive Sleep Apnea patients

Abstract Introduction Obstructive sleep apnea (OSA) is a common disorder which may need surgery to widen the airway. However, the success rate of surgery is variable. Thus, it is necessary to predict the outcome of the surgery preoperatively. The purpose of this study is to evaluate the mechanical parameter of upper airway airflow in OSA patients using computational fluid dynamics (CFD) method. Method We conducted a study on the patients with snoring, underwent the full night polysomnograpny (PSG) and paranasal sinus computed tomography(CT). The patients with past history of previous trauma or surgery were excluded. Three-demensional reconstructions of the upper airway were created in the medical imaging software Mimics 16.0 using paranasal CT. The reconstructions extended from nasopharynx to hypopharynx. Steady-state, turbulent, inspiratory airflow simulations were conducted in Fluent 17.0 with following boundary conditions The mechanical parameters (wall shear stress, pressure, plane velocity) were calculated in the three levels of nasopharynx, retropalatal, retrolingual area. Results The maximum wall shear stress values were shown at the retropalatal plane in all patients. There is a tendency for the wall shear stress value of the retropalatal area to increase as the AHI increases. The maximum velocity values were shown at the retropalatal plane in all patients. The maximum pressure values were shown at the nasopharynx plane in all patients. Conclusion the maximum wall shear stress values were shown at the retropalatal plane and the wall shear stress value of the retropalatal area increased as the AHI increased. Thus, the palatal surgery might help the OSA patients.

O053 Obstructive sleep apnea is a distinct physiological phenotype in individuals with comorbid insomnia and sleep apnea (COMISA)

Abstract Introduction Obstructive sleep apnea (OSA) pathophysiology varies among individuals, though the influence of comorbid insomnia on this pathophysiology is unknown. We examined whether upper airway collapsibility, muscle compensation, loop gain, and the arousal threshold differ between OSA patients with and without comorbid insomnia disorder. Methods We noninvasively determined the four traits using the ventilatory flow pattern captured from standard polysomnography in 34 comorbid insomnia and obstructive sleep apnea (COMISA) and 34 OSA patients without insomnia (OSA-only). Participants had mild-to-severe OSA ( AHI 25.8±2.0 events/h) and were matched according to age (50.2±1.5 years) sex (42M:26F), and body mass index (29.3±0.6 kg/m²). Results COMISA patients had significantly lower respiratory arousal thresholds (128.9 [118.1–137.1] vs. 147.7 [132.3–165.0] %Veupnea, U=261, p&amp;lt;.001), less collapsible upper airways (i.e., higher Vpassive 88.2 [85.5–94.6] vs. 72.9 [64.7–79.2] %Veupnea, U=1081, p&amp;lt;.001) and more stable ventilatory control (i.e., lower loop gain: 0.51 [0.44–0.56] vs. 0.58 [0.49–0.70], U=402, p=.03) relative to OSA-only controls. Muscle compensation did not significantly differ between groups. Discussion OSA patients with comorbid insomnia appear to have OSA driven more by heightened nocturnal arousability than by the contribution of anatomical factors, compared to OSA patients without insomnia. Heightened nocturnal arousability as the driver of apneic events in COMISA suggests the conditioned arousal perpetuating insomnia may also increase risk or severity of OSA. Further research should investigate whether targeting increased arousal propensity (e.g., through CBT-I) provides therapeutic benefit to individuals with COMISA.

P027 Predictors of CPAP failure in severe obstructive sleep apnoea and obesity hypoventilation syndrome patients

Abstract There are mixed findings regarding predictors of failing continuous positive airway pressure in the obstructive sleep apnoea and obesity hypoventilation population, with duration of time under 90% oxygen saturation independently associated with treatment failure. Our study examined predictors of CPAP failure in severe OSA and OHS patients using baseline characteristics, diagnostic polysomnography, arterial blood gases and TcCO2 oximetry data. An observational review of patients in an accredited sleep laboratory from 2016 to 2021 was performed. Patients with treatment studies demonstrating CPAP failure were compared to patients controlled on CPAP therapy via pressure determination study. Independent t-test compared group characteristics and multivariate logistic regression was performed to assess predictors of CPAP failure. Data is presented as mean unless otherwise stated. Twenty patients who required bilevel support ventilation were compared to thirty-five patients controlled by CPAP. Total sleep time (266vs328minutes, p=0.007) and sleep efficiency (62% vs 75%, p=0.028) was lower in the BSV group. Patients who failed CPAP spent a greater percentage of T&amp;lt;88% on their diagnostic study (T&amp;lt;88%, 46.4%vs9.66%, p=0.001). Percentage of T&amp;lt;88% oxygen saturations were significant in being able to predict CPAP failure (p&amp;lt;0.001) using a model including arterial blood gas PaCO2 and TcCO2 data. TcCO2, blood gases and baseline demographic data were not significant in determining CPAP failure. Our study strengthens the duration of time spent hypoxic or T&amp;lt;88% as a significant predictor of CPAP failure. Surprisingly, TcCO2 data and paired arterial blood gas data was not able to predict who would require bilevel ventilation in our cohort.

P039 A novel mean disease alleviation outcome measure in the management of adult obstructive sleep apnoea

Abstract Introduction Current methods assessing device and surgical treatment efficacy for OSA, such as apnoea hypopnea index (AHI), do not factor in compliance. Clinical effectiveness may be better represented when long-term compliance is incorporated into a mean disease alleviation score (MDA). Here, MDA scores between surgery and device are compared in a high-volume adult OSA clinic. Methods Three hundred and forty-five patients seen over a 13-year period in a high-volume adult OSA clinic staffed by an experienced sleep-trained otolaryngologist and sleep physician were included. Patients were managed with device (Continuous Positive Airway Pressure (CPAP), Mandibular Advancement Splint (MAS) or underwent multilevel airway surgery. Mean disease alleviation was calculated as the product of therapeutic efficacy (change in AHI) and adjusted compliance. Surgical compliance was assumed as one hundred percent. Cardinality matching was utilised to account for differences in patient and disease factors between subgroups. Results Surgically treated patients demonstrated higher MDA than device users (67.3 ± 29.9% vs. 59.4 ± 31.1%, p=0.039), despite higher therapeutic efficacy seen in device users (85.0±24.4% vs. 67.0±29.9%, p&amp;lt;0.001). Surgical patients were younger, had lower comorbidity scores, lower BMI, and suffered worse daytime sleepiness than device users. Cardinality matching for these factors demonstrated similar mean MDA between groups (66% vs 58%, p=0.11). Device users had to utilise &amp;gt;8hrs per night of compliant use to reach a similar MDA to matched surgical patients. Discussion In Adult OSA patients with less-than-ideal CPAP compliance, multilevel airway surgery is an equivalent and effective alternative, based on novel MDA measures.

O056 The effect of acetazolamide and oxygen (ACZ+O2) combination therapy on loop gain and OSA severity

Abstract Introduction One third of patients with OSA have high loop gain. Acetazolamide (ACZ) and supplemental oxygen (O2) individually reduce loop gain (via different mechanisms) and the apnoea-hypopnoea-index (AHI). The current study aimed to explore the efficacy of combining both ACZ and O2 to maximally lower loop gain. Method Randomised single-blind cross-over trial. Participants took ACZ (500mg orally) or placebo for 7 days. Within each arm, participants completed two polysomnograms (PSGs) during which they slept with supplemental oxygen (3L/min) or sham-air. Sleep and respiratory events were scored by a (blinded) technologist. In addition to standard scoring, respiratory events were scored without SpO2 or arousal information to calculate a ‘flow-based AHI’ (fAHI). PSG data were then imported into Matlab for loop gain analysis. Results Nine participants (5 males, Age=52.4±9.1, BMI=32.0±4.9, AHI=39.9±22.0) have so far completed the trial. Loop gain was significantly reduced by ACZ (-22%, -0.15 CI95:-0.03 to -0.26, p=0.011), O2 (-25%, -0.19 CI95:-0.08 to -0.29, p=0.001) and combination ACZ+O2 (-33%, -0.23 CI95:-0.12 to -0.34, p&amp;lt;0.001) relative to placebo-sham-air condition. Similarly, fAHI was significantly reduced by ACZ (-34%, -15.7/hr CI95:-8.6 to -22.7, p&amp;lt;0.001), O2 (-21%, -10.2/hr CI95:-3.1 to -17.3, p&amp;lt;0.001) and ACZ+O2 (-45.2%, -21.3/hr CI95:-14.6 to -28.4, p&amp;lt;0.001). While fAHI was significantly lower on ACZ+O2 compared with O2 (p=0.003), the difference between ACZ+O2 and ACZ was not significant (-5.6/hr, p=0.12). ACZ+O2 induced a &amp;gt;50% reduction in fAHI in 4/9 participants. Discussion Our preliminary data demonstrate that ACZ+O2 may be an efficacious combination therapy for some OSA patients.

P109 Predicting major adverse cardiovascular events using symptom subtypes of severe obstructive sleep apnoea

Abstract Background Obstructive sleep apnoea (OSA) is a complex heterogeneous disorder, and patients with similar disease severity present with different symptom profiles and outcomes. It is unclear whether OSA symptom subtypes independently predict incident major adverse cardiovascular events (MACE). Method Consecutive patients attending a tertiary sleep clinic from 2006 to 2010 were prospectively investigated and linked to administrative health data. Data from 1,767 patients with severe OSA (apnoea-hypopnoea index ≥30 events/hour) were used in latent class analysis to identify symptom subtypes. Associations between symptom subtypes and incident MACE were assessed using Cox proportional hazards models, with adjustment for known cardiovascular risk factors. Results On average, patients were middle-aged (mean± SD 52.5±13.2 years), obese (BMI, 35.4±7.9 kg/m²), and male (71.7%). Four symptom subtypes were identified: high symptom burden: severe sleepiness (26.0%), high symptom burden: sleep onset insomnia (34.8%), moderate symptom burden (18.4%), and minimal symptoms (20.7%). Over a median follow-up of 7 years, 330 (18.7%) patients developed MACE. After adjustment for covariates, the high symptom burden: sleep onset insomnia subtype was associated with increased risk for MACE relative to those with moderate (HR, 1.59; 95%CI, 1.12–2.25; P=0.010) or minimal (HR, 1.47; 95%CI, 1.07–2.03; P=0.018) symptom burden. Discussion Distinct symptom subtypes can be identified among severe OSA patients. In symptomatic patients, those with a high prevalence of sleep onset insomnia were at increased risk of MACE, relative to those with moderate or minimal symptom burden. Our findings suggest that symptom subtypes may be clinically relevant in risk stratification for MACE in severe OSA.

P013 Continuous Positive Airways Pressure (CPAP) Adherence in Remote Patients using Telemedicine Model of Care

Abstract Background CPAP is an established first-line treatment for moderate-to-severe OSA. Adherence is universally low and is predicted by short-term adherence. Moderate-to-severe OSA is strongly associated with adverse cardiovascular outcomes. Evidence of CPAP benefit is limited to underpowered subgroups with arbitrarily defined "good adherence". Covid-19 has generated widespread acceptance and uptake of telemedicine. This study aims to determine if CPAP adherence is affected when health service is provided by telemedicine rather than in-person. Methods Single-centre, retrospective, cohort study of moderate-to-severe OSA patients identified between 1/6/21 and 30/6/22. Medical records were reviewed for residential address, referral pathway (face-to-face or telemedicine), age, gender, BMI, ESS, AHI and AI. Short-term adherence was determined from CPAP downloads. Progress to date 368 patients were identified, 40% had moderate-to-severe OSA. 31.5% were reviewed by telemedicine (64% remote, 36% local). Compared to in-person, remote telemedicine cohort was similar age (age ≥ 50, 64.9% vs 53.2%, p= 0.075) but more likely male (66.2% vs 50%, p= 0.014). ESS (9.7 ± 1.4 vs 9.1 ± 0.7, p= 0.38), BMI (36.1 ± 2.5 vs 33.5 ± 1.3, p= 0.08), AHI (27.5 ± 7.5 vs 21.7 ± 3.4, p= 0.12) and presence of moderate-to-severe OSA (48.6% vs 42.5%, p= 0.35) were similar. Patient subgroups including local, remote, telemedicine and face-to-face reviews were analysed. Adherence data is pending. Intended outcome and impact Pilot telemedicine programs (e.g. TeleSleep) are developing services designed to provide accessible and efficient care to remote patients. $800 per patient, environmental and transport savings can be anticipated.

High-density lipoprotein cholesterol efflux capacity in patients with obstructive sleep apnea and its relation with disease severity

BackgroundObstructive sleep apnea (OSA) is linked to an accelerated risk of cardiovascular disease (CVD). Some key CVD risk factors are present in patients suffering from OSA such as hypertension, inflammation, oxidative stress, and dyslipidemia. High-density lipoprotein (HDL) cholesterol efflux capacity (CEC) is proposed as a reliable biomarker of HDL function and the present study aimed to quantify this biomarker in patients with OSA.MethodsATP binding cassette subfamily A member 1 (ABCA1), non-ABCA1, and total CEC were determined in 69 polysomnographic-confirmed OSA patients and 23 controls. Moreover, paraoxonase (PON) activities, high-sensitivity C-reactive protein (hsCRP), apolipoprotein B (apo B), and apolipoprotein A-I (apo A-I) circulating levels were quantified in the studied population.Results: All CEC measures were reduced in the OSA group compared to the control group. Strikingly, ABCA1 CEC was diminished in severe OSA in comparison with mild OSA. Furthermore, PON activities and apo A-I showed lower levels, while hsCRP and apo B were elevated in OSA patients compared to controls. Moreover, ABCA1 CEC showed an inverse association with hsCRP and a positive association with apo A-I, while non-ABCA1 CEC presented an association with HDL-C.ConclusionThese results suggest the presence of an impaired HDL function in OSA. In particular, ABCA1 CEC was associated with disease severity and inflammation which could be a factor increasing the risk of CVD.