Wavelet-Based Biphase Analysis of Brain Rhythms in Automated Wake–Sleep Classification

Many studies in the field of sleep have focused on connectivity and coherence. Still, the nonstationary nature of electroencephalography (EEG) makes many of the previous methods unsuitable for automatic sleep detection. Time-frequency representations and high-order spectra are applied to nonstationary signal analysis and nonlinearity investigation, respectively. Therefore, combining wavelet and bispectrum, wavelet-based bi-phase (Wbiph) was proposed and used as a novel feature for sleep–wake classification. The results of the statistical analysis with emphasis on the importance of the gamma rhythm in sleep detection show that the Wbiph is more potent than coherence in the wake–sleep classification. The Wbiph has not been used in sleep studies before. However, the results and inherent advantages, such as the use of wavelet and bispectrum in its definition, suggest it as an excellent alternative to coherence. In the next part of this paper, a convolutional neural network (CNN) classifier was applied for the sleep–wake classification by Wbiph. The classification accuracy was 97.17% in nonLOSO and 95.48% in LOSO cross-validation, which is the best among previous studies on sleep–wake classification.

Passive longitudinal weight and cardiopulmonary monitoring in the home bed

Home health monitoring has the potential to improve outpatient management of chronic cardiopulmonary diseases such as heart failure. However, it is often limited by the need for adherence to self-measurement, charging and self-application of wearables, or usage of apps. Here, we describe a non-contact, adherence-independent sensor, that when placed beneath the legs of a patient’s home bed, longitudinally monitors total body weight, detailed respiratory signals, and ballistocardiograms for months, without requiring any active patient participation. Accompanying algorithms separate weight and respiratory signals when the bed is shared by a partner or a pet. Validation studies demonstrate quantitative equivalence to commercial sensors during overnight sleep studies. The feasibility of detecting obstructive and central apneas, cardiopulmonary coupling, and the hemodynamic consequences of non-sustained ventricular tachycardia is also established. Real-world durability is demonstrated by 3 months of in-home monitoring in an example patient with heart failure and ischemic cardiomyopathy as he recovers from coronary artery bypass grafting surgery. BedScales is the first sensor to measure adherence-independent total body weight as well as longitudinal cardiopulmonary physiology. As such, it has the potential to create a multidimensional picture of chronic disease, learn signatures of impending hospitalization, and enable optimization of care in the home.

Rationalising requests for preoperative sleep studies and postoperative HDU beds: a quality improvement project in paediatric ENT patients undergoing elective surgery

BackgroundSleep disordered breathing represents a spectrum of upper airway obstruction including snoring, increased respiratory effort and obstructive sleep apnoea. An increasing demand for paediatric preoperative sleep studies and postoperative high dependency unit (HDU) beds was having a significant impact on service delivery at this ear, nose and throat (ENT) unit.MethodsRetrospective and prospective review of all paediatric sleep study requests over a 30-month period in a single tertiary ENT department. Data were collected on indication for and result of sleep study, patient outcome, operative details and HDU bed occupancy. During the study period, a ‘Sleep Study’ proforma was introduced which incorporated the ‘I’m Sleepy Score’ (ISS) and ENT-UK national guidelines.ResultsRetrospective review included 198 sleep studies, of which 62% (n=118) showed no evidence of obstructive sleep apnoea (OSA). There was little consistency in patients’ sleep study results and need for monitoring on HDU following adenotonsillectomy. Prospective review following intervention included 60 patients, of which 62% (n=37) showed evidence of OSA. The mean ISS in this cohort was 4.7. Only those with moderate-to-severe OSA or with relevant risk factors underwent overnight HDU observation. The number of sleep study requests fell by >50%; from 11 per month to 5 per month. The total HDU bed occupancy was reduced by 50% following intervention (from n=18 to n=9).ConclusionThe use of the ISS and incorporation of ENTUK’s recommendations has reduced the number of negative sleep studies being requested and has rationalised the number of paediatric HDU bed requests being made. This has helped provide a prudent elective paediatric ENT service in this unit with corresponding cost benefits.

Obstructive Apnea and Hypopnea Length in Normal Children and Adolescents

(1) Background: Breathing is an essential function that requires both metabolic (or au-tomatic) and voluntary (behavioral) control during wakefulness but during sleep depends on metabolic control via peripheral and central chemoreceptors. Breathing during sleep disordered breathing also depends on the maturity of the neural centers and the strength of the respiratory muscles. We do not know if the response to apnea varies with age. (2) Methods: We measured the obstructive apneas and hypopneas during REM and NREM in polysomnography studies from children referred for snoring. Exclusion criteria: younger than 1 year of age, neuromuscular or syndrome comorbidity, oxygen or positive airway pressure, central apnea, and studies with loss of airflow sensors. (3) Results: Two-hundred-and-sixty-eight sleep studies were included. Mean age was 8.7 years (4.68 SD), range 1–18 years, 160 were male, and 108 were female. The 5th centile of apnea duration during NREM is above 8 s at all ages, with a tendency to increase in the oldest groups up to 10 s. During REM sleep, it shows a gradual increase from 6 s in the youngest children to 10 s in the oldest. (4) Conclusions: Apnea/hypopnea length increases with age in children and adolescents independently from sex or severity of OSA. Using adult criteria in teens seems to be accurate.

Screening Sleep Abnormalities in Children with Prader–Willi Syndrome: Challenges in the Indian Scenario

There is a high prevalence of sleep-related breathing disorders in the form of obstructive and central sleep apnea as well as spontaneous oxygen desaturation in children with Prader–Willi syndrome (PWS). Most cases are asymptomatic and if untreated go on to develop unfavorable neurodevelopmental, cardiovascular, and cerebrovascular outcomes. Hence, sleep study or polysomnography (PSG) is recommended in all children at the time of diagnosis as well as with the development of certain risk factors including symptoms of sleep apnea, before and after initiation of recombinant growth hormone (rGH) therapy. The use of rGH in children with PWS has been shown to improve central sleep apnea but also shown to be associated with worsening of OSA. PSG is ideally performed in a sleep laboratory. Various types of PSG devices are available depending on the biological parameters that are desired to be monitored. Sleep disorders in children are distinct from those seen in adults and have different diagnostic scoring criteria necessitating a trained pediatric sleep specialist to analyze the PSG recording. Through the clinical case vignette of a 14-year-old girl with PWS, severe obesity, and sleep disordered breathing, this review aims to highlight the need, timing, types, analysis, and interpretation of sleep studies in infants and older children with PWS, particularly in relation to rGH therapy. There is a paucity of literature on sleep studies in children with PWS in the local setting. Thus this review also suggests the need for adapting the existing Western guidelines for PSG in Indian children with PWS.

P042 Five-year review of a tertiary paediatric sleep service for complex patients

Introduction Our paediatric sleep unit commenced service for children with complex medical problems in July 2015. Service capacity includes 12 inpatient level 1 studies (two neonates) and one home study per week. FTE includes senior scientists 2.6, sleep technologists 1.7, administration 1.0, nursing 0.7 and medical 1.2. The primary aim of this study was to evaluate activity during the first 5-years. The secondary aim was to document the impact of the COVID-19 pandemic. Methods Sleep unit operational & diagnostic data were collected from sleep booking sheets, sleep study reports, electronic medical records. Descriptive statistics are presented. Results A total of 2186 sleep studies were performed (July 2015 to June 2020) with a range of 368–472 studies per annum. Overall, 61.7% were diagnostic studies, 20.8% titration studies (CPAP, oxygen, bi-level or invasive ventilation), 10% neonatal and 7.5% home studies. Between 2016–2020, the average waiting time (days) for a neonatal study was 16, a titration study was 106, a diagnostic study was 110 and a home study was 76. Further delays were caused by the COVID19 pandemic. Mean waiting time rose 229% from 108 days (Feb 2020) to 355 days (Feb 2021). Referrals for sleep studies have exceeded bed capacity since the beginning of the pandemic. Discussion This audit describes activity in a tertiary complex paediatric sleep service during the first 5 years. The service has struggled on current FTE and bed capacity to manage waiting times, exacerbated further by the COVID-19 pandemic. A new business and clinical model are warranted.

P022 Unattended home sleep studies have a high recording failure rate in a preoperative anaesthetic clinic cohort when done as a routine screening procedure for Obstructive Sleep Apnoea (OSA)

Introduction Preoperative screening for OSA is strongly advised but attended laboratory sleep studies have limited availability. Portable unattended sleep monitors, such as ApneaLink, may provide a practical solution for large scale preoperative OSA screening. However, these unattended monitors may be prone to data recording failure. Methods We performed a prospective, uncontrolled, before-after study from March 2017 to December 2018 where patients from a pre-operative anaesthetic clinic were screened for OSA with an ApneaLink home sleep study (AHSS). 24 initial patients were provided with version 1 (v.1) recording instructions, while the next 24 patients received version 2 (v.2) which included colour, more detail and larger pictures compared to v.1. Recording failure was defined as an absence of recorded ApneaLink data. We analysed predictors of recording failure including instruction version and patient factors using logistic regression. Results Thirty-three of 48 (69%) patients successfully completed an AHSS. Failure rate was 31%. Median duration of recorded data was 480 minutes. The successful recording group was more likely to have used v.2 instructions than the failure group (61% vs. 27%; p=0.029). The odds ratio for successful recording using v.2 was 4.2 (95% CI: 1.1–16.2). Age, gender, country of birth, and number of days prior to surgery were not associated with recording failure. Discussion There was a high failure rate of AHSS for OSA screening from a preoperative anaesthetic clinic. Clear written instructions with greater use of colours and pictures may improve the recording success rate in this cohort.

P015 Home (Level 2) sleep studies are feasible in children

Introduction In-hospital polysomnography (PSG or Level 1 study) is the “gold-standard” for investigating sleep disorders in children. There are long waiting lists for sleep studies in Australian tertiary centres. Level 2 home-PSG has been proposed as an alternate option. However, there are limited data regarding the feasibility in a clinical population. The aim of this study is to assess the feasibility and patient experience of home-PSG in a clinical cohort. Methods The signal quality and outcomes of a home-PSG in young people undergoing sleep investigation in a single centre were reviewed. A successful home-PSG was defined as a study with ≥ 6hrs of sleep and all channels present for ≥90% of sleep time. Feedback from the guardian/young person was collected using a questionnaire. Results Fifty-five patients (4m-18yrs) were included. Successful home-PSG, on the first attempt, was achieved for 48/55 (87%) patients. There were no differences in success when accounting for neurodevelopmental conditions, OSA severity or age. A clinical diagnosis was confidently made in 53 (96%) patients. The majority (76%) rated their sleep as the same or better than normal and only 12% found having the study conducted at home difficult. Following the study, only 8% would have preferred a hospital sleep study. Discussion Home-PSG produced technically adequate recordings for most subjects and families found the experience of having a home sleep study to be positive. These data support, in appropriate circumstances, home-PSG as a viable alternative to an in-patient sleep study.