P064 The Impact of Artefact-free Recording Time on the Diagnosis of Sleep Disordered Breathing

Background Overnight studies are used to diagnose sleep disordered breathing (SDB), however the minimum artefact-free recording time (AFRT) has not been established in children. Aim To determine the impact of AFRT on SDB diagnoses. Methods Patients attended overnight cardiorespiratory polygraphy/polysomnography, alongside pulse oximetry sleep studies. Respiratory parameter reports were generated using the first 4, 5, 6 and 7 hours of AFRT. Predetermined clinically relevant cut-off (CRCO) values were defined: Obstructive AHI (OAHI; CRCO≥2); Central Apnoea-Hypopnoea Index (CAHI; CRCO≥5); 3% Oxygen Desaturation Index (ODI3%; CRCO≥6); 4% Oxygen Desaturation Index (ODI4%; CRCO≥4). Studies crossing CRCO across different AFRTs were described as ‘Cases of Change’ (COC). Receiver operating characteristic (ROC) curves determined ranges at 4 hours which predicted COC across subsequent AFRTs. Results 137 children (0.39–17.98 years) were consecutively recruited. Mean OAHI, CAHI, ODI3% and ODI4% were 1.54 (σ=2.66), 1.56 (σ=3.43), 5.21 (σ=6.53) and 2.77 (σ=4.42) respectively. For children achieving 7 hours AFRT (n=103), COC from 4 hours were: OAHI≥2 =9.7% (10/103); CAHI≥5 =2.9% (3/103); ODI3%≥6 =3.7% (4/109); ODI4%≥4 =1.8% (2/109). For OAHI≥2, optimal points on ROC curves for predicting COC provided a range of 0.875 (AUC= 0.733; 50% sensitivity; 93% specificity) - 3.125 (AUC= 0.968; 100% sensitivity; 81% specificity). Conclusion Four hours AFRT yields diagnostic results in > 90% cases when commonly used cut-off criteria are applied. For OSA, ranges at 4 hours within which diagnostic change is most likely with longer periods of AFRT are provided. Consideration should be given to repeating short studies where values lie within these ranges.

O041 The impact of including oxygen desaturations occurring during awake epochs on the oxygen desaturation index

Introduction The oxygen desaturation index (ODI) is an important measure of sleep disordered breathing during polysomnography (PSG) however there is no accepted standard for its calculation. The AASM Manual for the Scoring of Sleep and Associated events (V2.6) does not specify whether oxygen desaturations occurring during awake epochs should be included. More generally, epoch-based scoring is potentially problematic for accurate ODI calculation. This study aims to compare the calculation of ODI including and excluding oxygen desaturations occurring during awake epochs and to determine the impact of sleep efficiency (SE) on any discrepancy. Methods Using twenty-one consecutive unattended PSG’s for investigation of OSA, two oxygen desaturation indices were calculated from each PSG; one excluding (ODIsleep) and one including (ODIall) oxygen desaturations marked in awake epochs. Results The median (IQR) ODIall was 19.3/h (10.3, 27.0) and ODIsleep was 13.0/h (6.6, 16.7). The median (IQR) difference (ODIall - ODIsleep) was 5.2/h (2.7, 10.4). This difference was greater with decreasing SE (r = -.63, p = .002). Patients with SE ≤ 75% (n=10) had a median ODI difference of 11.5/h (4.0, 17.6), and those with SE > 75% (n=11) had a difference of 2.8/h (2.0, 5.5) (p = .02). Discussion ODI was greater when including oxygen desaturations during awake epochs, with this discrepancy being greatest when SE is ≤ 75%. We plan to confirm these findings in a larger sample. This investigation informs clinical practice, highlights the difficulties of epoch scoring, and informs future standards for the scoring of sleep and associated events.

Simple screening model for identifying the risk of sleep apnea in patients on opioids for chronic pain

BackgroundThere is an increased risk of sleep apnea in patients using opioids for chronic pain. We hypothesized that a simple model comprizing of: (1) STOP-Bang questionnaire and resting daytime oxyhemoglobin saturation (SpO2); and (2) overnight oximetry will identify those at risk of moderate-to-severe sleep apnea in patients with chronic pain.MethodAdults on opioids for chronic pain were recruited from pain clinics. Participants completed the STOP-Bang questionnaire, resting daytime SpO2, and in-laboratory polysomnography. Overnight oximetry was performed at home to derive the Oxygen Desaturation Index. A STOP-Bang score ≥3 or resting daytime SpO2 ≤95% were used as thresholds for the first step, and for those identified at risk, overnight oximetry was used for further screening. The Oxygen Desaturation Index from overnight oximetry was validated against the Apnea-Hypopnea Index (≥15 events/hour) from polysomnography.ResultsOf 199 participants (52.5±12.8 years, 58% women), 159 (79.9%) had a STOP-Bang score ≥3 or resting SpO2 ≤95% and entered the second step (overnight oximetry). Using an Oxygen Desaturation Index ≥5 events/hour, the model had a sensitivity of 86.4% and specificity of 52% for identifying moderate-to-severe sleep apnea. The number of participants who would require diagnostic sleep studies was decreased by 38% from Step 1 to Step 2 of the model.ConclusionA simple model using STOP-Bang questionnaire and resting daytime SpO2, followed by overnight oximetry, can identify those at high risk of moderate-to-severe sleep apnea in patients using opioids for chronic pain.Trial registration numberNCT02513836.

Oxygen Desaturation Index calculation: impact of different methodologies

Obstructive Sleep Apnea (OSA) is a syndrome characterized by episodes of airway obstruction, which causes oxygen desaturation events. These events can be identified by oximetry analysis and are used as one of the parameters to diagnose OSA. However, desaturation events have an inaccurate definition in manuals and in most of the literature. Thus, this work aims to evaluate whether different methodologies for the calculation of desaturation events impact the Oxygen Desaturation Index (ODI) and the diagnosis of OSA. The results indicated that the ODI values are significantly different from each other (p <0.001) and the methodologies provided variable performance for the diagnosis of OSA.

Different Associations between Tonsil Microbiome, Chronic Tonsillitis, and Intermittent Hypoxemia among Obstructive Sleep Apnea Children of Different Weight Status: A Pilot Case-Control Study

The tonsil microbiome is associated with chronic tonsillitis and obstructive sleep apnea (OSA) in children, and the gut microbiome is associated with host weight status. In this study, we hypothesized that weight status may be associated with clinical profiles and the tonsil microbiome in children with OSA. We prospectively enrolled 33 non-healthy-weight (cases) and 33 healthy-weight (controls) pediatric OSA patients matched by the proportion of chronic tonsillitis. Differences in the tonsil microbiome between the non-healthy-weight and healthy-weight subgroups and relationships between the tonsil microbiome and clinical variables were investigated. Non-healthy weight was associated with significant intermittent hypoxemia (oxygen desaturation index, mean blood saturation (SpO2), and minimal SpO2) and higher systolic blood pressure percentile, but was not related to the tonsil microbiome. However, chronic tonsillitis was related to Acidobacteria in the non-healthy-weight subgroup, and oxygen desaturation index was associated with Bacteroidetes in the healthy-weight subgroup. In post hoc analysis, the children with mean SpO2 ≤ 97% had reduced α and β diversities and a higher abundance of Bacteroidetes than those with mean SpO2 > 97%. These preliminary findings are novel and provide insights into future research to understand the pathogenesis of the disease and develop personalized treatments for pediatric OSA.

566 Persistent Sleep Apnea and Desaturation in Preterm Children at 18 Months of Age at High Altitude (2640 M)

Introduction Children born at term who live at high altitude (HA) (≥ 2500 m) have different respiratory patterns from those that live at sea level. It is essential to determine these patterns in preterm children due to their high risk of Sleep Apnea-Hypopnea Syndrome (SAHS). The evolution of the apnea hypopnea index (AHI), desaturation index (ODI), and oxygen saturation (SpO2) is unknown in this group at HA. The objective was to characterize the respiratory patterns during sleep of preterm children living at HA and compare it with those of healthy children born at term. Methods We conducted a cross-sectional study in Bogotá, Colombia (altitude: 2640 m). We included 302 children, 127 were preterm with an average of gestational age of 31weeks (SD: 2.9) and an average weight at birth of 1600 g (SD: 594) and 175 healthy full-term infants. Three groups were defined according to age: Group I: 3–4 months, Group II: 6–7 months,, Group III: 10–18 months. All children underwent nocturnal polysomnogram to evaluate their respiratory variables: AHI, average and minimum SpO2, ODI, and T90 during sleep and analyzed the data according to the parameters of the American Academy of Sleep Medicine Results 302 polysomnograms were performed, 54.3% were girls and were distributed by groups as follows: Group I:105 patients (34.8%), 16 preterm, Group II: 107 patients (35.4%), 46 preterm and Group III: 90 patients (29.8%), 65 preterm. We observed higher respiratory parameters within each age strata in premature infants compared to children born at term. Preterm infants had higher ODI, AHI, obstructive apnea hypopnea index (O-AHI), and Central Apnea hypopnea index (C-AHI). Although the effect decreases over time, we found a significant difference in the first age group. There was a high persistence index in children with a history of preterm birth living at high altitude. We also found a significant decrease in AHI, ODI across time in healthy and preterm children p&lt;0.01 Conclusion Premature children living at HA persist with higher ODI and AHI compared to children of similar ages born at term. The high desaturation index indicates the presence of intermittent hypoxia that persists in these children over time Support (if any):

053 REM Sleep Apnea Severity Contributes to Poor Verbal Memory in Cognitively Asymptomatic Older Adults

Introduction The prevalence of obstructive sleep apnea (OSA) rises with age, leading to increased dementia risk and memory decline. However, it remains unclear which OSA features drive this relationship. Here, we examine associations between verbal memory and multiple OSA features in healthy older adults. Methods 58 cognitively asymptomatic adults (61.4±6.3 years; 38 females) underwent polysomnography (PSG) and the Rey Auditory Verbal Learning Test (RAVLT; 0.2±0.5 years between assessments). OSA measures included apnea-hypopnea index (AHI), respiratory disturbance index (RDI), and desaturation index in both NREM and REM sleep. RAVLT measures included total learning (sum of trials 1–5), short-delayed recall, and long-delayed recall. Pearson correlations with FDR correction were calculated between OSA-related measures and RAVLT. Multiple regression was then used to adjust for OSA features in other sleep stages (i.e., REM versus NREM), age, sex, time between PSG and neuropsychological assessments, years of education, and APOE4 status. We also explored whether age moderated these relationships. Results REM RDI is negatively associated with RAVLT total learning (r=-0.31, p&lt;0.01 with age moderating the effect at 1SD above mean: B=-0.22, t(49)=-2.88, p=0.01) and RAVLT long-delayed recall (r=-0.36, p&lt;0.001; with age moderating the effect at mean: B=-0.05, t(49)=-2.38, p=0.02; and moderating at 1SD above mean: B=-0.09, t(49)=-3.91, p&lt;0.01). REM desaturation index was also associated with RAVLT total learning (r=-0.21, p&lt;0.01) and RAVLT long-delayed recall (r=-0.34, p&lt;0.01). REM AHI was negatively correlated to RAVLT long-delayed recall (r=-0.34, p&lt;0.01; with age significantly moderating the effect at the mean: B=-0.06, t(49)=-2.87, p=0.01; and moderating at 1SD above the mean: B=-0.11, t(49)=-4.23, p&lt;0.01). Of note, NREM OSA features were not significantly correlated to RAVLT measures when REM OSA features were included in the model. Conclusion These findings demonstrate that REM OSA features in particular contribute to poor verbal memory encoding and retrieval, especially at older ages. Verbal memory decline has been predictive of conversion to Alzheimer’s disease (AD). Future studies including brain imaging, AD biomarkers, REM sleep oscillations, and comprehensive neuropsychological testing may elucidate the underlying mechanisms linking REM OSA features to memory decline and dementia risk. Support (if any) This research was supported by R56 AG052698 and P50AG033514.