bluuebunny/crossref_metadata_2025 huggingface dataset:
O026 Within-subject variation in circadian timing in shift workers repeating the same shift patternn
Authors: Ji Y , Shen L , Postnova S , Knock S , Zhong Y , Howard M , Stone J , Facer-Childs E , Rajaratnam S , Sletten T
Published: December 2024

Introduction

While inter-individual variation in circadian response to shift work has been demonstrated, the within-individual variation across repeated roster patterns is unknown. This study aims to examine the consistency in circadian timing during repeated occasions of the same shift pattern.

Methods

In an ongoing study, shift workers (n=24, age 36.79±8.83 years, 8 females) from multiple industries were monitored during two replications of their usual shift patterns, separated by at least 6 weeks. Shifts included consecutive night shifts, consecutive early morning shifts, and early-morning-to-night rotations. Participants completed daily sleep diaries and wore an activity monitor to measure sleep, and a light sensor to measure light exposure. Circadian phase was assessed at the end of each shift pattern via 6-sulphatoxymelatonin (aMT6s) acrophase (peak) in urine.

Results

Preliminary analyses (n=15) showed considerable within-subject variability in aMT6s acrophase at the end of each shift patterns. Mean difference in acrophase was 2.06±1.36 h (range 0.15-5.22 h). Individuals working consecutive night shifts demonstrate larger variation in acrophase (3.43±1.58 h; range 1.50-5.22 h), compared to those working consecutive morning (2.01±0.69 h, range 1.18-2.86 h) or early morning-to-night shifts (1.30±0.95 h, range 0.15-2.95 h). The mediating role of individual light exposure patterns in the variation in aMT6s acrophase will be presented.

Discussion

Preliminary findings highlight inconsistency in circadian phase within individual shift workers, possibly associated with variation in socially-driven behaviours. Further factors influencing variability in circadian timing, i.e., individual light exposure, will be examined, to support prediction of circadian timing for informing personalised interventions for shift workers.
O027 Integrating digital behavioural therapy for insomnia into primary care: a feasibility mixed-methods study
Authors: Rahimi M , Gordon C , Cheung J , Menczel Schrire Z , Aji M , Salomon H , Doggett I , Glozier N , Wong K , Marshall N , Bartlett D , Grunstein R
Published: December 2024

Introduction

Digital cognitive behavioural therapy (dCBT) programs have been developed for insomnia to increase access to treatment. However, these digital programs are not widely used in primary care settings. This study evaluated whether a digital insomnia therapy (SleepFix mobile application) could be integrated into routine primary care for patients suffering from insomnia.

Method

A single-arm feasibility trial of SleepFix was conducted involving a digital behavioural therapy for insomnia patients. SleepFix delivered sleep restriction therapy over six weeks to improve sleep efficiency. Health care professionals (HCPs) including general practitioners, pharmacists, and nurses participated in prescribing SleepFix to appropriate insomnia patients (i.e. having at least one item from a 3-item DSM-5 checklist). The main outcome measured was the number of SleepFix downloads. Interviews explored the responses of HCPs and patients on using digital insomnia treatments.

Results

30 HCPs (21 GPs, 6 pharmacists and 3 nurses) and 105 patients participated in the study between November 2021 and March 2022. 14 HCPs prescribed the digital therapy at least once and 50 patients (47.6%) downloaded and used SleepFix. Post-study interviews found HCPs were willing to incorporate digital sleep programs into practice, and patients found SleepFix acceptable. Significant improvements in insomnia, mood, and sleep quality were seen after 6 weeks of using SleepFix.

Discussion

This trial demonstrated the successful integration of a digital insomnia therapy program into primary care, offering a potential model for prescribing digital sleep interventions.
O029 The Impact of Adherence to Specific Components of CBT for Insomnia on Treatment Outcomes
Authors: Drummond S , Bei B
Published: December 2024

Introduction

CBT-I requires significant behavioural change. A recent systematic review found there are surprisingly few associations between adherence to that behaviour change and outcomes. Prior studies examined adherence over the entire course of treatment, however, the role of adherence may change throughout therapy. We examined the effect of adherence to Sleep Restriction (SR) and Stimulus Control (SC) using the recently proposed two-stage Build-Maintain Model of CBT-I.

Methods

83 participants underwent 7 weeks of therapist-led CBT-I. 78 initiated SR (age: 48.0±14.3, 57.7%F). Treatment was divided into “Build” (initial phase of SR, building sleep debt) and “Maintain” (starting the first week sleep opportunity increased) stages of therapy. Analyses examined the impact of adherence to SR (deviation from bed/wake times, naps) and SC (wake time-in-bed during daytime, overnight, and after final awakening) and stage of treatment on diary-based sleep efficiency (SE) and Insomnia Severity Index (ISI).

Results

Adherence to morning SC predicted both greater SE (regardless of the stage) and lower ISI (specifically during Maintain stage). Fewer average minutes napping predicted lower ISI scores, regardless of stage.

Discussion

Adherence to morning SC (i.e., getting out of bed right away after final awakening) and adherence to the no-nap rule of SR were associated with better CBT-I treatment outcomes. Surprisingly, adherence to neither the prescribed bed time nor wake time in SR were associated with treatment outcomes. While adherence to some aspects of CBT-I appear related to outcomes, more work needs to be conducted to determine the measure(s) of adherence most predictive of treatment outcomes.
O032 Is a fear of death keeping you awake at night? Examining the relationship between death anxiety and insomnia
Authors: Menzies R , Brown J , Turner M , Cunnington D , Burge M , Dunican I , Meaklim H
Published: December 2024

Introduction

The fear of death (death anxiety) is a risk factor for psychopathology, including anxiety and depressive disorders. There is little research on the role of death anxiety in sleep disorders like insomnia. We examined the relationship between death anxiety and insomnia and investigated whether distressing dreams/nightmares play a mediating role in this relationship.

Methods

The study consisted of 515 adult participants (360 females; M age=44.15 years) who completed an online survey via REDCAP. The survey assessed insomnia symptoms (ISI), death anxiety (DABBS), and nightmare severity (DDNSI). Correlations and hierarchical regression analyses were conducted to explore the relationship between insomnia symptoms and death anxiety, with an additional mediation analysis (Hayes PROCESS macro) examining the role of nightmare severity.

Results

Death anxiety was positively correlated with insomnia (r=.27; p<.001). In the hierarchical regression analysis, death anxiety remained a significant predictor of insomnia, even after controlling for general anxiety (p=.037). Notably, nightmare severity mediated the relationship between death anxiety and insomnia, with higher levels of death anxiety associated with more severe nightmares and, subsequently, more severe insomnia symptoms (all p’s<.001). As the direct effect of death anxiety on insomnia remained significant (p<.001) in the mediation model, our results suggest that nightmares are a partial mediator of the relationship.

Discussion

Death anxiety is associated with insomnia symptoms, with nightmares partially mediating the relationship. Fears of death may, therefore, play a greater role in insomnia symptomatology than previously thought. Targeting death anxiety in insomnia treatment may be an important avenue for future research.
O034 Development and Evaluation of Two Non-Invasive Approaches for Estimating Breath-by-Breath Ventilatory Drive in Obstructive Sleep Apnea Patients
Authors: Zhang J , Mann D , Leppänen T , Sands S , Terrill P
Published: December 2024

Introduction

Estimation of breath-by-breath ventilatory drive is an important step in quantifying key obstructive sleep apnea (OSA) endotypes. However, the gold-standard for measuring ventilatory drive requires invasive instrumentation. Here, we extend two published methods for estimating breath-by-breath ventilatory drive non-invasively from polysomnography.

Methods

We retrospectively analysed sleep studies of 33 OSA patients (apnea-hypopnea index>5) who underwent a clinical in-lab polysomnography with the addition of intraoesophageal diaphragmatic electromyography (Edi). The ventilatory drive was estimated on a breath-by-breath basis using two independent methods: (a) a flow-shape-based machine learning approach (Flow-Drive method), Mann et al 2019 ERJ; and (b) a chemoreflex model-based approach (Loop-gain method), Terrill et al 2014 ERJ. The Spearman’s rank correlation (ρ) between the two estimated breath-by-breath ventilatory drive signals and Edi (gold-standard) was calculated: (i) for 7-min overlapping windows throughout the night for each individual; and (ii) an overnight ensemble average of obstructive respiratory events at onset and termination periods (three breaths before and after event onset and termination respectively).

Results

The Spearman’s ρ in the 7-minute window was similar between the Flow-Drive and Loop-gain methods, and Edi [0.40(0.10)vs.0.27(0.13), mean(SD)]. Flow-Drive and Loop-gain methods both showed similar Spearman’s ρ with Edi at event onset [0.69(0.34)vs.0.69(0.25) respectively]. At event termination, the Loop-gain method [0.85(0.13)] was more strongly correlated with Edi than the Flow-Drive method [0.78(0.30)].

Conclusions

These promising results set a foundation for integrating the advantages of a machine learning approach and a physiological model-based approach in a unified method to improve the non-invasive estimation of breath-by-breath ventilatory drive.
O035 Refining the desaturation area-based parameters by investigating different baseline methods
Authors: de Chazal P , He S , Cistulli P
Published: December 2024

Introduction

Repetitive hypoxia serves as the principal mechanistic bridge between Obstructive Sleep Apnoea and cardiovascular disease (CVD). Desaturation area-based parameters, like Hypoxic Burden (HB) and the Respiratory Event Desaturation Transient Area (REDTA), are promising metrics for predicting CVD mortality. These metrics are not without limitations. HB calculation is complex and noise sensitive, while REDTA may be overly simplistic. We investigated six area-based methods, each with a different choice of sampling window and baseline.

Methods

The oximetry signals from the Sleep Heart Health Study (SHHS) with CVD mortality outcomes and covariate information was used. The HB method was implemented and denoted as ARE. It uses a record-specific sampling window and event-specific baseline. We extended the experiment to include two additional baseline methods: a record-specific baseline (ARR) and a fixed baseline (ARF). Similarly, REDTA which uses a fixed sampling window and baseline (AFF), was extended to an event-specific baseline (AFE) and a record-specific baseline (AFR). Six desaturation area-based methods were performed in this study. The performance of each parameter in predicting CVD mortality was assessed using an adjusted Cox proportional hazard ratio(HR) analysis.

Results

ARR and AFR outperformed other methods The HRs were ARR:1.79 (95% CI: 1.00-3.19, p<0.05), and AFR:1.64 (95% CI: 1.16-2.32, p<0.01).

Discussion

Computational complexity was also considered. AFR was easier to calculate than ARR as it used a fixed sampling window. We believe AFR provides a step towards a novel parameter with easy calculation providing early risk stratification in cardiovascular patients.
O039 Agreement between MotionWatch8 and Polysomnography sleep outcomes in Menopausal Women
Authors: Li X , Chow C , Halaki M
Published: December 2024

Introduction

Polysomnography (PSG) is the gold standard for sleep measurement but is costly and can disrupt sleep. Actigraphy offers a non-invasive alternative for longer-term monitoring. This study aims to validate the MotionWatch8 device against PSG for sleep outcomes among menopausal women.

Methods

Sixteen healthy women aged 45-65 years with menopausal symptoms underwent four in-lab overnight PSG studies while wearing the MotionWatch8. Sleep parameters including time in bed (TIB), total sleep time (TST), sleep efficiency (SE), sleep onset latency (SOL), and wake after sleep onset (WASO) were measured. Agreements between MotionWatch8 and PSG was assessed using Bland-Altman plots.

Results

MotionWatch8 tended to overestimate: TIB by 1.2 minutes with limits of agreement (LOA): 6.7 to 9.2 minutes; SE by 3.5%, LOA: -11.7% and 18.7%, and significant proportional error especially for nights with SE<92%; and TST by 18.6 minutes, LOA: -56.8 to 94.0 minutes. MotionWatch8 underestimated: SOL by 11.2 minutes, LOA: -53.6 to 31.3 minutes, and a significant proportional error especially for a longer sleep latency (SOL>20minutes); and WASO by 7.4 minutes, LOA: 40.5 to 25.7 minutes.

Discussion

The results indicate that the MotionWatch8 provides acceptable agreement and LOA with PSG for TIB, TST and WASO; and for SOL and SE for people without significant sleep problem. The device is not recommended to be used for people with longer sleep latency and poorer sleep efficiency. While the MotionWatch is a feasible tool for large-scale sleep studies in menopausal women, it should be used with caution for these specific situations.
O041 Prevalence, patterns and clinical associations of sleep disordered breathing in children with neuromuscular disorders
Authors: Withers A , Lam J , Pettigrew G , Downs J , Spano J , Deegan S , Filmer K , Gauld L , Milla C , Buu M , Wilson A
Published: December 2024

Objectives

to determine prevalence, patterns and clinical associations of sleep disordered breathing in a cohort of children with neuromuscular disorders.

Methods

children from three sites had a laboratory polysomnogram and clinical data collection. Sleep disordered breathing (SDB) was defined as the presence of obstructive sleep apnoea (OSA), hypoventilation and/or central sleep apnoea (CSA).

Results

64 children aged 6.0-16.7 years (median 11.5) were included, 72% were male and diagnoses were Duchenne Muscular Dystrophy (DMD) (40%), spinal muscular atrophy (SMA) (28%), congenital muscular dystrophy (CMD) (13%) and congenital myopathy (CM) (19%). Scoliosis was present in 50%, 51% could ambulate and median BMI z-score was -0.23. Of the 13 (20%) who used non-invasive ventilation (NIV), 6 (46%) had SMA and 10 (77%) used NIV during the entire polysomnogram. Sleep disordered breathing was present in 48%, OSA in 31%, CSA in 14%, hypoventilation in 16% and mixed SDB in 23%. SDB was present in 50% of children with DMD, SMA and CM, most often OSA in DMD (70%) and SMA (78%). Hypoventilation was most common in children with CM (83%) and CMD (100%). SDB and OSA were associated with older age and OSA with inability to ambulate (OR 4.45). Hypoventilation was significantly more common in CM, CMD and those with lower BMI z-scores.

Conclusions

The prevalence of SDB was high and likely under-estimated due to use of NIV, particularly in those with SMA. The findings reflect the heterogeneity of the cohort and suggest individual risk factors for each type of SDB.
O043 Performance of a machine-learning based automated oximetry algorithm for detection of sleep apnoea in children
Authors: Kevat A , Hartnett C , Suresh S , Terrill P , Iyer K
Published: December 2024

Background

In-laboratory polysomnography (PSG) remains the gold-standard method for the detection of significant paediatric sleep-disordered breathing, although it is resource-intensive. We therefore trained, using data from 2380 diagnostic PSGs, a support vector regression (SVR) algorithm to predict apnoea hypopnea index (AHI) using oximetry data alone, for potential use as a pre-PSG screening/triage tool. This study aimed to test the algorithm’s performance in detecting potentially significant sleep apnoea, defined as AHI ≥5.

Methods

We extracted oximetry data (oxygen saturation and heart rate, down-sampled to 1Hz) from 300 PSGs performed in 2018 in a single Australian paediatric centre. De-identified demographic and clinical information was extracted from medical records. Oximetry data was then evaluated by the SVR algorithm, which utilised 19 heart rate and oxygen saturation-derived features to predict AHI. The SVR-predicted AHI was compared to gold-standard AHI determined by original PSG, with AHIs undergoing binary classification into AHI <5 or ≥5.

Results

Of 297 patients (median age 7.4 years), 26% had a significant neuromuscular, neurologic or genetic disorder diagnosed, 15% had undergone previous adenoidectomy+/-tonsillectomy and 14% were obese. On PSG 102 (34%) had AHI ≥5. Sensitivity and specificity of the SVR algorithm for detecting this was 0.75 and 0.76 respectively; positive predictive value was 0.62 and negative predictive value was 0.85.

Conclusion

This demonstration of a machine learning algorithm classifying oximetry traces from a real-world cohort of a diverse group of children undergoing evaluation for possible sleep apnoea demonstrates the automated tool may be useful in helping with PSG waitlist prioritisation.
O048 Ultrasound evaluation of the pterygomandibular raphe in Obstructive Sleep Apnoea
Authors: Necati E , Jugé L , Bilston L , Brown E
Published: December 2024

Introduction

The pterygomandibular raphe (PMR) is an aponeurotic junction in the lateral upper airway soft tissue that may be an anatomical marker to predict mandibular advancement splint (MAS) treatment success (Brown et al. 2021). We evaluated the feasibility of a novel ultrasound (US) protocol to assess these lateral soft tissues, particularly PMR.

Methods

31 participants (n=19(61.3%) female) with and without obstructive sleep apnoea (OSA) underwent lateral upper airway ultrasound. Inclusion criteria were age 18-75 years and previous polysomnogram. Eight participants also underwent MRI. The anatomical landmarks of PMR were measured.

Results

Participants were middle aged (56.5±15.9 years), overweight or obese (BMI 29.4±6.4 kg/m2) and had moderate OSA (mean AHI 24.4±21.7 events/hour). PMR was detected in all subjects. Submandibular gland depth (4.8±1.2 mm), US-PMR depth (18.1±3.0 mm) and US-PMR width (2.4±0.4 mm) were measured (n=31), and tonsil depth was recorded (n=24, 19.5±3.8 mm). US-PMR width measurements of OSA (n=24, 2.5±0.3 mm) and non-OSA (n=7, 2.5±0.6 mm) subjects were not different (p>0.05). MRI-PMR width values were similar (OSA 3.1±0.9 vs. non-OSA 2.5±1.5 mm, p>0.05). The width of MRI-PMR (2.7±1.2 mm) compared to and US-PMR (2.8±0.5 mm) was not significantly different (p>0.05).

Discussion

This research highlights the potential of US as a useful tool to study lateral upper airway tissues, particularly the PMR. We plan to correlate these findings in a larger number of participants who have undergone both MRI and US to demonstrate the sensitivity, specificity and clinical utility of US.
O053 Relationship between cardiovascular risk and pulse wave amplitude characteristics in a sleep clinic cohort
Authors: Stewart G , Tong B , Flood J , Cistulli P
Published: December 2024

Introduction

Novel pulse oximetry-derived measures of autonomic vasoreactivity have recently been developed as a biomarker of cardiovascular outcomes in patients with obstructive sleep apnoea (OSA). It is currently unclear if these measures relate to general cardiovascular risk in an unselected population undergoing polysomnography.

Methods

This study examined pulse wave amplitude characteristics (from photoplethysmography) in 547 individuals who underwent a diagnostic in-laboratory polysomnogram and had sufficient clinical data to calculate a modified Framingham cardiovascular risk score. Individuals were categorised as either having an established cardiovascular disease (CVDest, n=47) or a calculated Framingham 10-year CVD risk score that was low (CVDlow-risk, n=177) or intermediate-to-high (CVDelevated-risk, n=323). Standard polysomnography variables and the pulse-wave amplitude drops index (defined by the number of drops in pulse wave amplitude of >30% per hour of sleep, PWADIn) were derived and compared between the 3 groups.

Results

The PWADIn was significantly different between each of the CVD risk groups (CVDest: 37.8±19.1; CVDelevated-risk: 42.2±22.3; CVDlow-risk: 50.6±19.3, p<0.01). Similar findings were observed for PWADIn during REM and non-REM sleep, and group differences in PWADIn remained significant (p<0.01) after adjusting for apnoea-hypopnea index, age, sex, and body mass index.

Conclusions

These data indicate that pulse oximetry-derived measures of autonomic vasoreactivity may provide a marker of cardiovascular disease risk in a general sleep clinic population undergoing polysomnography. The mechanistic link between recurrent nocturnal pulse wave amplitude drops and cardiovascular disease risk requires further study.
O056 Workplace fatigue in the New Zealand healthcare workforce: A snapshot survey
Authors: O’Keeffe K , Frampton C
Published: December 2024

Introduction

A growing body of research has highlighted that workplace fatigue is associated with decreased patient safety, increased healthcare costs and adverse health and safety consequences for healthcare workers.

Methods

All workers in the New Zealand District Health Board (DHB) workforce were invited to complete an anonymous online questionnaire evaluating personal and work demographics, work patterns in the last week, sleep, life outside work, and two fatigue-related outcomes. Workers were categorised into nine groups: Senior Medical Officer/Senior Dental Officer, Resident Medical Officer (RMO), Nurse, Midwife, Allied and Scientific, Care and Support, Corporate, Administration and Clerical, and Other.

Results

Fatigue-related outcomes were commonly experienced by the DHB workforce. The highest proportion of workers reporting making a fatigue-related error in the last 6 months was observed among RMOs (82.5%), and the highest proportion of workers experiencing feeling sleepy at the wheel in the last 12 months was observed among midwives (70.5%). The odds of reporting a fatigue-related error were generally higher in workers who had a higher frequency of shift extensions and fewer days when they could take breaks within their shifts. The odds of reporting drowsy driving were generally increased in workers who were younger, had fewer days when they could take breaks within their shifts, got fewer hours of sleep, worked more night shifts and had regular additional work responsibilities outside the home.

Discussion

Given the high safety risk, it is recommended that future work focus on the development of a more comprehensive approach to managing fatigue among healthcare workers.
O059 Examining the efficacy of the “SleepSync” app in improving sleep and performance in healthcare shift workers
Authors: Varma P , Postnova S , Knock S , Howard M , Rajaratnam S , Sletten T
Published: December 2024

Introduction

Two-thirds of shift workers experience inadequate sleep. Disruption of sleep and circadian rhythms is linked to decrements in performance and negative consequences for overall health. This study examined the efficacy of SleepSync in improving sleep in and performance in shift working nurses. SleepSync is a personalised sleep-wake management app, codesigned with nurses that delivers circadian-based optimal times for sleep using biomathematical models of sleep-wake and alertness regulation (the Model of Arousal Dynamics). The app includes educational toolkits, recovery metrics and visualisations for health management and engagement.

Methods

In this open-label trial, 32 nurses (41.4±7.1y; 27f) used the SleepSync app for a six-week period, including two-weeks of baseline where the app provided no recommendations. Following baseline, participants received daily recommendations for their sleep, education regarding light exposure, caffeine consumption and alertness management. Measures reported here: Insomnia Severity Index (ISI), Sleep Hygiene Index (SHI), PROMIS-Sleep Related Impairment (PROMIS-SRI), 3-min Psychomotor Vigilance Task (PVT; completed at multiple shifts).

Results

Preliminary analyses revealed improvements in ISI (Pre App Use=16.4±5.3; Post App Use=10.2±4.0; p<.001) and SHI (Pre App Use=27.6±8.3; Post App Use=20.5±5.1; p<.001), but not PROMIS-SRI. Median Reaction Time recorded improvement following the intervention and after controlling for shift type, start/end of shift and age (t-value = 4.2; p<.01). 75.0% reported the app satisfactory, 65.6% suggested they would recommend it to a friend.

Conclusion

The study provides initial evidence for efficacy of SleepSync app in improving sleep and performance in shift workers, with participant feedback being incorporated into further development and implementation of the app.
O060 “I wish someone would’ve taught me how to sleep”: qualitative development of co-designed sleep resources for young shiftworkers
Authors: Shriane A , Ferguson S , Gupta C , Hilditch C , Kolbe-Alexander T , Marino J , Paterson J , Rigney G , Sprajcer M , Stanton R , Thomas M , Vincent G
Published: December 2024

Shiftwork – employment outside traditional waking hours – impacts sleep, contributing to circadian disruption and increased risk for numerous poor health outcomes. Young adults are increasingly engaging in shiftwork, therefore requiring tailored, evidence-based sleep resources early in their careers to mitigate sleep and health risks. Despite this need, such resources aren’t readily available for young shiftworkers.

A participatory, co-design approach recruited individuals with lived and/or professional experience in shiftworker sleep to develop resources by participating in two online workshops. Reflexive thematic analysis was applied to workshop transcripts to identify data codes, which were then grouped into themes and populated with information from the current scientific evidence base, allowing for the construction of sleep resources for young shiftworkers.

Co-designers (n=48) stressed the need to support young shiftworkers in prioritising their sleep, as “not doing so comes at a cost, and you often don’t realise that cost until much later”. In addition to prioritisation, analysis identified 33 unique codes, categorised into five overarching themes: sleep science (sleep disorders, circadian rhythms, chronotypes), impacts of poor sleep (health, wellbeing, safety), habits impacting sleep (environment, substances), strategies (fatigue management, napping, stimulus control), and workplace recommendations (education, rostering). Themes were populated with evidence-based content to develop a website, housing comprehensive sleep information; a pictorial infographic, detailing behaviours supportive or detrimental to sleep; and an animated video for resource promotion.

Tailored, evidence-based sleep resources can provide a point of early intervention for young shiftworkers, now requiring formal evaluation to ascertain their impact on knowledge and behaviour change.
O062 Relationship between pulse oximetry derived markers of obstructive sleep apnoea severity and cardiac function in heart failure with preserved ejection fraction
Authors: Stewart G , Tong B , McClintock S , deChazal P , Lal S , O’Sullivan J , Cistulli P
Published: December 2024

Introduction

The pathophysiological implications of Obstructive Sleep Apnoea (OSA) in patients with Heart Failure with Preserved Ejection Fraction (HFpEF) remains unclear. While novel pulse oximetry-derived measures of OSA-related cardiovascular risk have recently been described, these have not been comprehensively assessed in HFpEF.

Methods

Clinical, cardiovascular and polysomnography assessments have been conducted in thirty-five HFpEF patients to date. Pulse oximetry-derived measures of hypoxic burden (HB, cumulative area of respiratory event related SpO2 dips, %min/h) and pulse-wave amplitude drops index (PWADIn, drops in pulse wave amplitude of >30% per hour, events/h) were compared in HFpEF patients with and without moderate to severe OSA (Apnoea-Hypopnoea Index ≥15 events/h). Associations between HB, PWADIn and cardiovascular function were explored.

Results

Twenty-two HFpEF patients had moderate to severe OSA (Age 66±12y; BMI 35.4±7.7kg/m2; BNP 367±554ng/L) and thirteen had no or mild OSA (Age 65±13y; BMI 32.7±8.0kg/m2; BNP 159±142ng/L). Age, BMI, BNP and PWADIn (40.6±20.2 vs 37.4±25.6 events/h, p=0.699) were comparable between groups, while HB (99.4±70.0 vs 29.0±23.5 %min/h, p<0.001) and right ventricular end-diastolic volume (RVEDV, 150±21ml vs 122±22, p=0.016) were higher in moderate to severe OSA. PWADIn correlated with left ventricular (LV) volume (R=0.621, p=0.006), while HB correlated with RVEDV (R=0.463, p=0.014) and aortic augmentation index (R=0.506, p=0.002).

Conclusions

These findings indicate that pulse oximetry-derived measures of hypoxic burden and pulse wave amplitude characteristics may provide additional insight into the severity and pathophysiology of OSA in HFpEF. The impact of nocturnal pulse wave amplitude drops and oxygen desaturations on LV and RV remodelling requires further investigation.
O066 Generalized linear model for characterisation of nocturnal arrhythmia
Authors: Salari Shahrbabaki S , Dharmaprani D , Strong C , Tonchev I , Chapman D , Baumert M , Ganesan A
Published: December 2024

Background

Generalised linear models (GLM) based on point processes have been previously shown helpful for characterising dynamics of sleep-disordered breathing (SDB) events using sleep stages, body position and history of SDB events, and characterising period limb movements. Episodes of non-sustained arrhythmias may occur during sleep in patients with underlying cardiac conditions, and the point process theory may help model their occurrence over time.

Objective

This study aims to develop a (GLM) to analyse the temporal patterns of nocturnal arrhythmia (NA) and their relationship with sleep disturbances and architecture.

Methods

This study analysed 7341 polysomnography-derived ECG recordings from the MESA and SHHS datasets to detect non-sustained arrhythmias. NAs were defined as any instance where ECG R-R intervals dropped by 30% of the baseline and then returned to 90% of the baseline. we developed our GLM framework to characterise NA events as a function of SDB and sleep arousal events, sleep stages, as well as previously occurring NA episodes.

Results

The likelihood of NA occurrence during light NREM sleep was, on average, 10% higher than during REM sleep (p=0.022), and 16% and 40% higher than during deep sleep and wakefulness, respectively (p<0.001). The influence of SDB on NA occurrence in men was 4% higher than in women (p=0.032). Participants older than 75 years showed nearly an 8% higher impact of sleep arousal compared to those younger than 65 years.

Conclusion

A GLM-framework characterises NAs dynamics and their association with sleep disruptions and architecture.
O075 Update in the management of Pierre Robin Sequence
Authors: Lieu N , Theis L , Yeung C , Jones C , Widmer R , Mehta B , Water K
Published: December 2024

Background

Pierre Robin sequence (PRS) is a congenital triad of micrognathia, glossoptosis and airway obstruction. Current treatment approaches in Australia include nasopharyngeal airway, continuous positive airway pressure, and surgery including mandibular distraction osteogenesis. The Tübingen Palatal Plate (TPP) offers an orthodontic method for jaw distraction that has hitherto not been available in Australia. Since October 2023, we have assembled the team required to implement this treatment. This study evaluates the outcomes of patients managed with TPP at our centre, to date.

Methods

Retrospective analysis comparing treatment outcomes for patients diagnosed with PRS managed at a tertiary paediatric centre from October 2023 to October 2024.

Progress to date

Of ten patients with PRS treated at our centre since October 2023, seven (70%) were treated with TPP. Eight (80%) patients underwent polysomnography (PSG) prior to intervention. The mean apnoea hypopnea index (AHI) was 49.6 events/hr (±24.1; 16.4-88.5) and obstructive apnoea hypopnea index (OAHI) was 43.2 events/hr (±24.4; 15.5-88.5). A repeat PSG within 3 weeks post intervention demonstrated improvement in AHI by 24 events/hr (±24.9; -3.8-66; p=0.06) and OAHI by 18 events/hr (±9.2; 4.9-31.4; p=0.09). At the time of submission, 2 patients have completed TPP treatment with final PSG AHI/OAHI values of 4.5/3.4 and 9.4/3 respectively. This demonstrates mean reduction in AHI scores of 28.8 events/hr (±21.6; 11.9-45.7; p=0.33) and OAHI 22.7 events/hr (±15.5; 12.5-32.9; p=0.27).

Intended outcome and impact

We have successfully implemented TPP therapy for PRS in Australia, confirming its effectiveness as an orthodontic method of jaw distraction.
O078 Sleep quality in children and adolescents with Cystic Fibrosis and non-Cystic Fibrosis Bronchiectasis in Hospital and Hospital in the Home (HiTH)
Authors: Cook J , Adams A , Vandeleur M
Published: December 2024

Purpose

We aimed to investigate and compare the sleep quality (SQ) of children and adolescents with cystic fibrosis (CF) and non-CF bronchiectasis who were admitted to a tertiary paediatric hospital and those receiving hospital-in-the-home (HITH) care.

Design

Children aged 0-18 years diagnosed with CF or a non-CF bronchiectasis underwent seven days of light, sound, and actigraphy measurement and completed five paediatric questionnaires alongside their parent(s). These questionnaires evaluated baseline sleep and sleepiness levels (Sleep Disturbance Scale for Children, Paediatric Daytime Sleepiness Scale), mood (Children’s Depression Inventory), health-related quality of life (Obstructive Sleep Apnoea-18), and in-hospital SQ (Potential Hospital Sleep Disruption and Noises Questionnaire, PHSDNQ). Sleep patterns were documented daily during admission via a sleep diary (SD). Parent and patient demographic data was collected.

Results

Four children with CF have been recruited to date; three completed the study in-hospital and one patient in both hospital and HITH settings, with recruitment ongoing. Hitherto, subjective questionnaire data (PHSDNQ and SD) reveal sleep disturbance due to bedside equipment noise, overnight staff interventions, and general background noise on the wards.

Conclusion

In this small cohort, children with CF experience reduced SQ within the hospital setting. Subjective and objective SQ data will be presented for a larger population of hospitalised children with chronic respiratory disease to further evaluate the factors contributing to sleep disturbance.
P134 Effectiveness of home non-invasive ventilation for persistently hypercapnic COPD patients
Authors: Bird D , Curtin D , Tay G
Published: December 2024

Introduction/Aim

Approximately 25% of patients with GOLD stage 3 or 4 COPD have chronic hypercapnia with a daytime/awake PaCO2 >45mmHg. Persistent hypercapnia is associated with worse quality of life, increased frequency and severity of exacerbations, increased frequency and length of hospital presentations, increased need for invasive and non-invasive acute non-invasive ventilation (NIV) and increased mortality. Acute NIV is very effective at treating decompensated hypercapnic respiratory failure, but the role domiciliary NIV is less clear in those that remain persistently hypercapnic beyond their exacerbation. The aim of this study is to evaluate an existing cohort of severe COPD patients with chronic hypercapnia who were commenced on home NIV over a 5 year period and assess their outcomes.

Methods

We conducted a five-year retrospective audit of medical records of all patients commenced on home NIV in our institution between January 2017 to January 2023. Only patients who received a home NIV device with confirmed COPD, hypoventilation and chronic hypercapnia were considered for the study. Mortality was assessed at 12 months following NIV initiation. Rehospitalisation rates were assessed 12 month prior and following home NIV initiation. Additional analysis of demographical data, device settings and pressures used will be included for discussion.

Results

During the study period there were 189 patients identified that met the inclusion criteria. Ongoing data analysis is in progress…

Conclusion

The expected conclusions are that our cohort will include a significant proportion of OSA overlap patients, which is a higher risk demographic. This may largely be due to the funding available for subsided devices through the Queensland sleep disorders program. We anticipate a decrease in hospitalisation presentations. We also anticipate much lower pressures than those used in the literature.
O082 A new model of care for perioperative OSA management
Authors: Roberts J , Mansfield D
Published: December 2024

Background

Obstructive Sleep Apnoea (OSA) is a common condition that is associated with poorer perioperative outcomes including higher rates of cardiac complications, an increased risk of intensive care admissions and a longer hospital length of stay. While there is growing evidence in support of a perioperative sleep service, there is limited published data on an effective model of care. Monash Health has established a perioperative sleep clinic with the goal to identify patients with high probability of moderate/severe OSA to improve perioperative OSA workup and management without causing surgical delays.

Methods

This retrospective study includes all patients reviewed in the perioperative sleep clinic over 8 months (60 patients). We reviewed patient characteristics, scores from screening tools and severity of OSA. Time from referral to initial clinic review, evaluation with polysomnography and subsequent surgery was measured.

Progress to date

Data collection to date shows a patient population with a median age of 63 years and BMI of 37kg/m2. Over 90% of new referrals were for patients awaiting category 2 (90 days) or 3 surgeries. The median time from clinic referral to polysomnography was 45 days. A new diagnosis of moderate/severe OSA was made in 52% of patients tested.

Intended outcome and impact

Despite growing evidence in support of perioperative OSA services, there is limited published data in support of a specific model of care. This study aims to provide a detailed overview of a newly established service in an Australian setting that will examine screening and diagnostic rates, treatment effectiveness and postoperative outcomes.
P004 Gender differences in heart rate during respiratory events and arousals in patients with obstructive sleep apnea and chronic obstructive pulmonary disease overlap syndrome
Authors: Behbahani S , Terrill P
Published: December 2024

Introduction

Obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are associated with increased sympathetic nervous activity, and patients affected by both disorders have a higher risk of mortality than patients with COPD or OSA alone. This preliminary study compared HR during respiratory events and respiratory arousals in men and women with OSA-COPD overlap syndrome.

Methods

121 individuals with both OSA (AHI>=5) and COPD (86 male, 65.4±7.5 years; 35 female, 62.7±10.0 years) were identified from a retrospective clinical dataset of 989 individuals who were studied with clinical diagnostic polysomnography. Continuous electrocardiography was extracted, and the mean HR was calculated during respiratory events terminated with arousals, respiratory arousals, and non-event baseline. The duration of respiratory arousals was calculated.

Results

The mean HR during respiratory-arousals was higher in women compared to men (72.4±5.0 vs 69.3±5.3; p<0.05 Wilcoxon rank-sum test). The duration of respiratory arousals was also greater in women (10.1±1.0 vs 9.3±0.7; p<0.05). The difference in HR in respiratory arousal compared with baseline was greater in females (5.2±1.3 vs. 2.3±0.9, p<0.05) The mean HR during respiratory events did not significantly differ between males and females.

Discussion

Literature has previously speculated that women with OSA-COPD overlap have greater sympathetic modulation of heart rate. This is consistent with our results showing higher HR during respiratory-arousals (and greater HR increase relative to baseline) in women. However, substantial further work is required to distinguish the relative effects of gender, OSA-COPD overlap, and numerous other confounding factors (i.e., OSA severity and endotype/phenotype, age, and sleep state).
P007 A Comparison of Sleep Study Parameters between COPD+OSA (Overlap Syndrome) and Obstructive Sleep Apnoea
Authors: Moman A , Hukins C , Duce B
Published: December 2024

Background

Comorbid Chronic Obstructive Pulmonary Disease (COPD) and Obstructive Sleep Apnoea (OSA)—Overlap Syndrome (OVS) is associated with worse sleep study parameters than OSA alone. The patient demographics and severity of OSA often confound these sleep study parameters. Aim: In this study, we aim to compare OVS to OSA PSG parameters in a case-control study.

Methods

We matched OVS and OSA patients for age, sex, BMI, and AHI, then compared the PSG data. We also compared additional measures of hypoxic burden, including desaturation severity, desaturation slope, and desaturation recovery.

Results

We suitably matched a total of 83 patients in each group. There were no differences in sleepiness (Epworth Sleepiness Scale; OVS 10±5 vs. OSA 10±5, P = 0.978), PVT lapses (OVS 30±30 vs. OSA 25±30, P = 0.260), or comorbidity. The OVS group has poorer quality of life (SF36 Physical Component Score (OVS 37±11 vs. OSA 41±11, P = 0.001). There were no differences in sleep duration (OVS 274±82 min vs. OSA 284±78 min, P = 0.383) or sleep efficiency (OVS 63% vs. OSA 66%, P = 0.204). There were no differences in the number of ≥3% desaturations scored (OVS 149±117 vs. OSA 125±126, P = 0.072). The OVS had greater desaturation severity (0.40% vs. 0.25%; P<0.035) and greater sleep time below SpO2 90% (11% vs. 1%; P<0.001). There were no differences in desaturation duration, desaturation slope, or recovery slope.

Discussion/Conclusion

When controlling for demographics and AHI, OVS shows no differences in sleep study parameters except for oxygen saturation.
P008 Ventilatory burden predicts change in self‑reported sleepiness following continuous positive airway pressure treatment in obstructive sleep apnoea
Authors: Staykov E , Mann D , Duce B , Kainulainen S , Leppänen T , Töyräs J , Azarbarzin A , Sands S , Terrill P
Published: December 2024

Introduction

Excessive daytime sleepiness is an important symptom of obstructive sleep apnoea (OSA) and commonly quantified using the Epworth Sleepiness Scale (ESS). Measures of ventilatory burden, flow limitation, and hypoxaemia could be used to predict sleepiness change (i.e. ΔESS) following continuous positive airway pressure (CPAP) treatment. We hypothesised that ΔESS can be predicted from baseline polysomnography.

Methods

Associations between OSA severity measures and ESS were evaluated in three cross‑sectional cohorts (n=3117), adjusting for age, sex, BMI, total sleep time, and depression. ΔESS prediction was evaluated using CPAP treatment studies (HomePAP, BestAIR, and ABC) in three steps: severity measures were compared (adjusted regression predicting ΔESS, n=64), a prediction model was developed using baseline ventilatory burden and baseline ESS (n=139), then evaluated in holdout participants (n=74).

Results

In cross‑sectional analyses, increased ESS was associated with increased ventilatory burden (0.27 points/SD; 95% CI 0.07−0.48), the apnoea‑hypopnoea index (AHI) (0.25; 0.05−0.45), flow limitation severity (0.24; 0.05−0.43), and hypoxic burden (0.21; 0.00−0.42). Comparison analysis revealed that ΔESS was most strongly associated with baseline ventilatory burden (‑1.07 points/SD; ‑2.12 to ‑0.05) and baseline ESS (‑2.75; ‑3.83 to ‑1.69); the AHI association was weaker (‑0.97; ‑2.01−0.05). Predicted and actual ΔESS were associated in holdout participants (adjusted R²=0.315); median [IQR] actual ΔESS of predicted responders (≥2 ESS reduction) was ‑5.0 [‑10.0 to ‑2.0] and non‑responders was 0.0 [‑1.0−1.0] (p<0.001).

Discussion

Baseline ventilatory burden and baseline ESS were independently associated with ΔESS and could be used together to inform clinicians whether CPAP treatment will likely improve a patient’s sleepiness.
P009 Sharper Minds Better Sleep: Results from a pilot brief intervention for improving sleep health in young adults
Authors: Rossa K , Edmed S , Lorimer N , Smith S
Published: December 2024

Introduction

The transition to university can be associated with increased stress, poorer mental health and increased risk of sleep problems. This pilot study assessed the effectiveness of a brief, skills building sleep education program (Sharper Minds Better Sleep) designed to increase knowledge about healthy sleep and its relationship to mental health, and to promote healthy sleep behaviours.

Method

Using a single arm pre-post design, participants completed an electronic sleep diary, a range of standardised sleep related questionnaires and wore an actigraph for 7 days pre-and post- program. The intervention consisted of 4x45 minute online group (6-8 people) learning sessions delivered via Zoom by trained Provisional Psychologists to first year university students in 2022/3.

Results

81 students participated in the program (71% female; Mage =21.1, SD = 4.6). Preliminary paired t-tests conducted on available actigraphy data indicate no significant change in sleep duration from pre- to post- program, however sleep regularity [Mpre=75.65, Mpost=82.66, Cohen’s d=-.75], and intradaily variability [Mpre=.81, Mpost=.71, Cohen’s Cohen’s d=.37) significantly improved. Preliminary assessment of questionnaire data revealed significant improvements in scores on the Insomnia Severity Index (Mpre=11.70, Mpost=9.74, Cohen’s d=0.40) and Bedtime Procrastination (Mpre=13, Mpost=11, Cohen’s d=0.38) from pre- to post- program.

Discussion

The Sharper Minds Better Sleep program has demonstrated benefits in improving sleep health behaviours in young adults. Since sleep is intrinsically linked to a range of wellbeing functions, further analyses of these data will seek to understand the utility of the program as part of a stepped care model.