Piezoelectric rubber sheet sensor: a promising tool for home sleep apnea testing

PURPOSE

This study aimed to develop an unobtrusive method for home sleep apnea testing (HSAT) utilizing micromotion signals obtained by a piezoelectric rubber sheet sensor.

METHODS

Algorithms were designated to extract respiratory and ballistocardiogram components from micromotion signals and to detect respiratory events as the characteristic separation of the fast envelope of the respiration component from the slow envelope. In 78 adults with diagnosed or suspected sleep apnea, micromotion signal was recorded with a piezoelectric rubber sheet sensor placed beneath the bedsheet during polysomnography. In a half of the subjects, the algorithms were optimized to calculate respiratory event index (REI), estimating apnea-hypopnea index (AHI). In the other half of subjects, the performance of REI in classifying sleep apnea severity was evaluated. Additionally, the predictive value of the frequency of cyclic variation in heart rate (Fcv) obtained from the ballistocardiogram was assessed.

RESULTS

In the training group, the optimized REI showed a strong correlation with the AHI (r = 0.93). Using the optimal cutoff of REI ≥ 14/h, subjects with an AHI ≥ 15 were identified with 77.8% sensitivity and 90.5% specificity. When applying this REI to the test group, it correlated closely with the AHI (r = 0.92) and identified subjects with an AHI ≥ 15 with 87.5% sensitivity and 91.3% specificity. While Fcv showed a modest correlation with AHI (r = 0.46 and 0.66 in the training and test groups), it lacked independent predictive power for AHI.

CONCLUSION

The analysis of respiratory component of micromotion using piezoelectric rubber sheet sensors presents a promising approach for HSAT, providing a practical and effective means of estimating sleep apnea severity.

Determinants of apnea-hypopnea index variability during home sleep testing

BACKGROUND

A single-night attended in-laboratory polysomnography or home sleep testing are common approaches for obstructive sleep apnea (OSA) diagnosis. However, internight variability in apnea-hypopnea index value is common, and may result in misclassification of OSA severity and inapropriate treatment decisions.

OBJECTIVE

To investigate factors determining short-term apnea-hypopnea index variability using multi-night automated home sleep testing, and to determine how this variability impacts clinical decisions.

PATIENTS/METHODS

Adults with suspected OSA who successfully performed three home sleep tests using measurements of mandibular jaw movements (Sunrise, Namur, Belgium) combined with automated machine learning analysis were enrolled. Data analysis included principal component analysis, generalized estimating equation regression and qualitative agreement analysis.

RESULTS

160 individuals who performed three sleep tests over a mean of 8.78 ± 8.48 days were included. The apnea-hypopnea index varied by -0.88 events/h (5th-95th percentile range: -14.33 to 9.72 events/h). Based on a single-night recording, rates of overtreatment and undertreatment would have been of 13.5% and 6.0%, respectively. Regression analysis adjusted for age, sex, body mass index, total sleep time, and time between home sleep tests showed that time spent in deep non-rapid eye movement sleep and with head in supine position were independent significant predictors of the apnea-hypopnea index variability.

CONCLUSIONS

At the individual level, short-term internight variability in the apnea-hypopnea index was significantly associated with time spent in deep non-rapid eye movement sleep and head in supine position. Clinical decisions based on a single-night testing may lead to errors in OSA severity classification and incorrect therapeutic decisions.

Long term adherence to continuous positive Airway pressure in mild obstructive sleep apnea

BACKGROUND

Studies have shown that a significant percentage of patients with obstructive sleep apnea (OSA) do not tolerate continuous positive airway pressure (CPAP) therapy and long-term use may be as low as 30%. Given the lower levels of symptoms and health-related risks, patients with mild sleep apnea may be at even higher risk for non-adherence to long term CPAP. The purpose of our study was to investigate the prevalence and associations of long-term CPAP adherence in first time users with mild sleep apnea diagnosed by home sleep apnea testing (HSAT).

METHODS

We identified all the patients who were diagnosed with mild sleep apnea (5 = < AHI < 15) by home sleep apnea testing from 01/2013 to 06/2019 at a large, combined community and hospital-based sleep practice. Only first time CPAP users were included. Compliance was defined as CPAP usage ≥ 4 h per night on ≥ 70% of nights over 30 consecutive days. We defined long term adherence as compliance on the 12th month following CPAP set up. Patient demographics, comorbidities, and CPAP compliance at 1st, 3rd, 6th, 9th and 12th month after therapy initiation were collected. We compared and identified the factors that had significant difference (P < 0.1) between compliant and non-compliant groups at the 12th month.

RESULTS

222 patients were included in the analysis. 57 (25.7%) patients were adherent with long term CPAP treatment. The following factors were associated with a greater likelihood for long-term CPAP adherence: older age, lower body mass index (BMI), presence of a bed partner, non-smoker, presence of Diabetes Mellitus (DM), presence of Heart Failure (CHF), lack of depression, and compliance at 1st, 3rd, 6th and 9th month.

CONCLUSIONS

Long term CPAP compliance in mild sleep apnea patients is low. Long term adherence to CPAP can be predicted based on CPAP adherence during the first three months.

Creating an Optimal Approach for Diagnosing Sleep Apnea

Sleep apnea is nowadays recognized as a treatable chronic disease and awareness of it has increased, leading to an upsurge in demand for diagnostic testing. Conventionally, diagnosis depends on overnight polysomnography in a sleep clinic, which is highly human-resource intensive and ignores the night-to-night variability in classical sleep apnea markers, such as the apnea-hypopnea index. In this review, the authors summarize the main improvements that could be made in the sleep apnea diagnosis strategy; how technological innovations and multi-night home testing could be used to simplify, increase access, and reduce costs of diagnostic testing while avoiding misclassification of severity.

Belun Ring (Belun Sleep System BLS-100): Deep learning-facilitated wearable enables obstructive sleep apnea detection, apnea severity categorization, and sleep stage classification in patients suspected of obstructive sleep apnea

GOAL AND AIMS

Our objective was to evaluate the performance of Belun Ring with second-generation deep learning algorithms in obstructive sleep apnea (OSA) detection, OSA severity categorization, and sleep stage classification.

FOCUS TECHNOLOGY

Belun Ring with second-generation deep learning algorithms REFERENCE TECHNOLOGY: In-lab polysomnography (PSG) SAMPLE: Eighty-four subjects (M: F = 1:1) referred for an overnight sleep study were eligible. Of these, 26% had PSG-AHI<5; 24% had PSG-AHI 5-15; 23% had PSG-AHI 15-30; 27% had PSG-AHI ≥ 30.

DESIGN

Rigorous performance evaluation by comparing Belun Ring to concurrent in-lab PSG using the 4% rule.

CORE ANALYTICS

Pearson's correlation coefficient, Student's paired t-test, diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, Cohen's kappa coefficient (kappa), Bland-Altman plots with bias and limits of agreement, receiver operating characteristics curves with area under the curve, and confusion matrix.

CORE OUTCOMES

The accuracy, sensitivity, specificity, and kappa in categorizing AHI ≥ 5 were 0.85, 0.92, 0.64, and 0.58, respectively. The accuracy, sensitivity, specificity, and Kappa in categorizing AHI ≥ 15 were 0.89, 0.91, 0.88, and 0.79, respectively. The accuracy, sensitivity, specificity, and Kappa in categorizing AHI ≥ 30 were 0.91, 0.83, 0.93, and 0.76, respectively. BSP2 also achieved an accuracy of 0.88 in detecting wake, 0.82 in detecting NREM, and 0.90 in detecting REM sleep.

CORE CONCLUSION

Belun Ring with second-generation algorithms detected OSA with good accuracy and demonstrated a moderate-to-substantial agreement in categorizing OSA severity and classifying sleep stages.

Clinical impact of manual scoring of peripheral arterial tonometry in patients with sleep apnea

PURPOSE

The objective was to analyze the clinical implications of manual scoring of sleep studies using peripheral arterial tonometry (PAT) and to compare the manual and automated scoring algorithms.

METHODS

Patients with suspected sleep-disordered breathing underwent sleep studies using PAT. The recordings were analyzed using a validated automated computer-based scoring and a novel manual scoring algorithm. The two methods were compared regarding sleep stages and respiratory events.

RESULTS

Recordings of 130 patients were compared. The sleep stages and time were not significantly different between the scoring methods. PAT-derived apnea-hypopnea index (pAHI) was on average 8.4 events/h lower in the manually scored data (27.5±17.4/h vs.19.1±15.2/h, p<0.001). The OSA severity classification decreased in 66 (51%) of 130 recordings. A similar effect was found for the PAT-derived respiratory disturbance index with a reduction from 31.2±16.5/h to 21.7±14.4/h (p<0.001), for automated and manual scoring, respectively. A lower pAHI for manual scoring was found in all body positions and sleep stages and was independent of gender and body mass index. The absolute difference of pAHI increased with sleep apnea severity, while the relative difference decreased. Pearson's correlation coefficient between pAHI and oxygen desaturation index (ODI) significantly improved from 0.89 to 0.94 with manual scoring (p<0.001).

CONCLUSIONS

Manual scoring results in a lower pAHI while improving the correlation to ODI. With manual scoring, the OSA category decreases in a clinically relevant proportion of patients. Sleep stages and time do not change significantly with manual scoring. In the authors' opinion, manual oversight is recommended if clinical decisions are likely to change.

Supine sleep patterns as a part of phenotyping patients with sleep apnea-a pilot study

Purpose

Polysomnography (PSG) is considered the best objective study to diagnose and quantify sleep disorders. However, PSG involves multiple electrodes and is usually performed in a sleep laboratory that in itself may change the physiology of sleep. One of the parameters that can change during PSG is the sleep position, leading to more supine sleep. The aim of this study was to quantify the amount of supine sleep during PSG and compare it to consecutive nights of a home sleep apnea test (HSAT) in the same patients.

Methods

This prospective study evaluated 22 consecutive patients undergoing PSG followed by HSAT. Sleep position was analyzed during PSG and subsequently on 2 to 6 nights (mean 3.7 nights) at home, and the amount of supine sleep was recorded during each night.

Results

Of 22 patients, there were 12 men (55%). The median age was 60.0 years for women and 45.5 years for men. Median proportion of supine sleep during PSG and HSAT was 61% and 26% (p < 0.001), respectively. Four “phenotypes” were identified according to their sleep position during PSG and HSAT, with 5 patients sleeping mainly supine during all nights, 7 patients sleeping mainly non-supine during all nights, 3 patients sleeping in different positions during each night, and 7 patients sleeping supine during PSG but non-supine at home, during HSAT.

Conclusions

There is a higher proportion of supine sleep during PSG compared to home sleep. We identified a subgroup of patients who slept mainly supine during PSG and mainly non-supine during HSAT. PSG may overestimate OSA severity in a specific phenotype of patients.

Sleep Measurement in Children-Are We on the Right Track?

Sleep plays a critical role in the development of healthy children. Detecting sleep and sleep disorders and the effectiveness of interventions for improving sleep in children require valid sleep measures. Assessment of sleep in children, in particular infants and young children, can be a quite challenging task. Many subjective and objective methods are available to evaluate various aspects of sleep in childhood, each with their strengths and limitations. None can, however, replace the importance of thorough clinical interview with detailed history and clinical examination by a sleep specialist.

Evaluation of a non-contact ultra-wideband bio-radar sleep monitoring device for screening of sleep breathing disease

PURPOSE

Ultra-wideband bio-radar (UWB) is a new non-contact technology that can be used to screen for obstructive sleep apnea (OSA). However, little information is available regarding its reliability. This study aimed to evaluate the effectiveness of UWB and to determine if UWB could provide a novel and reliable method for the primary screening of sleep-related breathing disorders.

METHOD

Subjects with suspected OSA from the sleep center of the First Hospital of the China Medical University were assessed over the period of September 2018 to April 2019 for enrollment in the study. Three detection methods were simultaneously used, including the STOP-Bang questionnaire (SBQ), UWB, and standard polysomnography (PSG). The data were analyzed using a fourfold table, receiver operating characteristic curves, Spearman rank correlation coefficients, Bland-Altman plots, and epoch-by-epoch analysis.

RESULT

Of 67 patients, 56 were men, mean age was 43 ± 11 years, mean body mass index was 27.8 ± 4.8 kg/m², and mean SBQ score was 4.8 ± 1.6. The apnea-hypopnea index (AHI) (r = 0.82, p < 0.01) and minimum arterial oxygen saturation (r = 0.80, p < 0.01) of the UWB were positively correlated with those obtained from the PSG. UWB performed better than SBQ, as indicated by the larger area under the curve (0.85 vs. 0.632). The sensitivity and specificity of the UWB-AHI were good (100%, 70%, respectively).

CONCLUSIONS

UWB performs well in the screening of OSA and can provide reliable outcomes for the screening of OSA at the primary level.

A validation study of an esophageal probe-based polygraph against polysomnography in obstructive sleep apnea

STUDY OBJECTIVES

The aim of this study was to validate the automatically scored results of an esophageal probe-based polygraph system (ApneaGraph® Spiro) against manually scored polysomnography (Nox A1, PSG) results. We compared the apnea-hypopnea index, oxygen saturation index, and respiratory disturbance index of the devices.

METHODS

Consenting patients, referred for obstructive sleep apnea workup, were tested simultaneously with the ApneaGraph® Spiro and Nox A1® polysomnograph. Each participant made one set of simultaneous registrations for one night. PSG results were scored independently. Apnea-hypopnea index, oxygen desaturation index, and respiratory disturbance index were compared using Pearson's correlation and scatter plots. Sensitivity, specificity, and positive likelihood ratio of all indices at 5, 15, and 30 were calculated.

RESULTS

A total of 83 participants had successful registrations. The apnea-hypopnea index showed sensitivity of 0.83, specificity of 0.95, and a positive likelihood ratio of 5.11 at an index cutoff of 15. At a cutoff of 30, the positive likelihood ratio rose to 31.43. The respiratory disturbance index showed high sensitivity (> 0.9) at all cutoffs, but specificity was below 0.5 at all cutoffs. Scatterplots revealed overestimation in mild OSA and underestimation in severe OSA for all three indices.

CONCLUSIONS

The ApneaGraph® Spiro performed acceptably when OSA was defined by an AHI of 15. The equipment overestimated mild OSA and underestimated severe OSA, compared to the PSG.

Asian accreditation of sleep medicine physicians and technologists: practice guidelines by the Asian Society of Sleep Medicine

Due to the rapid growth in sleep medicine's professional content, several countries have recognized sleep medicine as an independent specialty. The practice of sleep medicine and the demand for this service in Asian countries are expanding. At this point of growth, the accreditation of sleep medicine specialists is paramount to patient care and the training of physicians and technologists. The Asian Society of Sleep Medicine (ASSM) mandated a taskforce committee for the accreditation of sleep medicine practice. This taskforce developed Asian accreditation practice guidelines for sleep medicine physicians and technologists. This paper presents the newly approved Asian accreditation practice guidelines for sleep medicine physicians and technologists by the ASSM.

Clinician-Focused Overview and Developments in Polysomnography

Purpose of Review

Polysomnography (PSG) represents a fundamental diagnostic tool used in the evaluation of sleep disorders. It represents a simultaneous recording of sleep staging, eye movements, electromyographic tone, respiratory parameters, and electrocardiogram. It is particularly helpful in the assessment of sleep-disordered breathing and its management, propensity for excessive sleepiness, complex behaviors during sleep, including motor disturbances of sleep, sleep-related epilepsy, and parasomnias. This review is intended to summarize the indications for PSG, the limitations and challenges of this diagnostic tool, indications for home sleep apnea testing options, and new developments and trends in polysomnography.

Recent Findings

The polysomnogram is fundamentally important in the evaluation of sleep-disordered breathing in the setting of cardiovascular comorbidities and neurologic conditions such as neuromuscular disease, stroke, and epilepsy and in the evaluation of dream enactment behavior in the setting of REM sleep behavior disorder (RBD). Because RBD is predictive of neurodegenerative disorders, recent data highlights the importance of PSG in corroborating the diagnosis of RBD and identifying people who may be at risk. However, due to cost as well as limitations in access to care, further testing has been developed and implemented including the home sleep apnea test (HSAT). The evolution of consumer wearable devices has also been a growing trend in sleep medicine; however, few have received appropriate validation.

Summary

PSG has been used in both the clinical and research settings and remains the gold standard clinical diagnostic test for suspected obstructive sleep apnea (OSA) or central sleep apnea (CSA). Clinicians must be familiar with the basic indications for a PSG but also recognize when it is absolutely required. At this time, the PSG is essential in the evaluation of nocturnal hypoventilation disorders of sleep, periodic limb movements of sleep, and central nervous system hypersomnia (in the absence of CSF hypocretin) when combined with the multiple sleep latency test (MSLT) and is probably the only way to help differentiate among complex behaviors during sleep, especially in the setting of RBD. The capacity to establish an early diagnostic risk of potential dementia would be of critical importance once neuroprotective agents become available.

Reopening Sleep Medicine Services in the Conundrum of an Ongoing COVID-19 Pandemic: A Global View

The emergence of COVID-19 brought all healthcare services around the globe to immense strain; hospitals abandoned elective care for acute care. Like all other elective services, sleep medicine services suffered a partial deadlock due to the closing down of the sleep disorders diagnostic and therapeutic services, although clinical consultations and follow-ups, carried on remotely, allowed some mitigation. Since there is dire need to resume the services, we tried to formulate the principles and guidelines to work in this exigent healthcare setting. Principles and guidelines are based on epidemiological and infection control guidelines besides recommendations of various healthcare organizations and sleep societies, after a requisite web search to extract the data.

Prevalence and management of sleep disorders in the Veterans Health Administration

The prevalence of diagnosed sleep disorders among Veterans treated at Veterans Affairs (VA) medical facilities increased significantly during fiscal years (FY) 2012 through 2018. Specifically, the prevalence of sleep-related breathing disorders (SRBD) increased from 5.5% in FY2012 to 22.2% in FY2018, and the prevalence of insomnia diagnoses increased from 7.4% in FY2012 to 11.8% in FY2018. Consequently, Veterans' demand for sleep medicine services also increased significantly between FY2012-2018, with steady increases in the annual number of VA sleep clinic appointments during this period (<250,000 in FY 2012; >720,000 in FY2018). Common co-morbid conditions among Veterans diagnosed with sleep disorders include obesity, diabetes, congestive heart failure, depression, post-traumatic stress disorder (PTSD) and traumatic brain injury (TBI). To address this healthcare crisis, the Veterans Health Administration (VHA) developed and/or implemented numerous innovations to improve the quality and accessibility of sleep care services for Veterans. These innovations include a TeleSleep Enterprise-Wide Initiative to improve rural Veterans' access to sleep care; telehealth applications such as the Remote Veteran Apnea Management Platform (REVAMP), Clinical Video Telehealth, and CBT-i Coach; increased use of home sleep apnea testing (HSAT); and programs for Veterans who experience sleep disorders associated with obesity, PTSD, TBI and other conditions.

Successful home respiratory polygraphy to investigate sleep-disordered breathing in children

OBJECTIVE

Sleep-disordered breathing (SDB) in children is common. Interest in sleep tests, such as polygraphy (PG), which can be performed in a non-attended setting, are gaining is increasing. PG has, however, been little studied in children with co-morbidities other than obstructive sleep apnea (OSA), and in particular, if performed in a non-attended setting. We report on the feasibility and interpretability of implementing PGs at home versus in hospital.

METHODS

PGs were analyzed according to the setting (hospital or home) and sequence (initial or subsequent) in which they were performed. Non-interpretability was defined as absent or unreliable oxygen saturation by pulse oximetry (SpO₂), or airflow and respiratory inductance plethysmography flow trace signals during the time analyzed.

RESULTS

We retrospectively analyzed 400 PGs; 332/400 were initial PGs. Indications were: suspected OSA (65%), obesity (13%), craniofacial malformations (5%), neuromuscular disease (4%), and other (13%) which included prematurity. 16% were recorded in hospitals and 84% at home. The mean age was 5.7 ± 5.8 years and 7.3 ± 4.5 years for the hospital and home groups, respectively. Interpretability was similar in both settings (87%). In the 68 subsequent PGs, interpretability was 84% when performed for follow-up and 96% when repeated for non-interpretability. Non-interpretability was predominantly due to a failure of the SpO₂ channel.

CONCLUSIONS

PG performed at home is both feasible and interpretable for a variety of indications. Non-interpretability was not predictable in association with the setting, anthropometric data, or indication, independently of the sequence (initial or subsequent PG) in which the parameters were analyzed.

SIESTA - Home sleep study with BresoDx for obstructive sleep apnea: a randomized controlled trial

STUDY OBJECTIVES

The objectives of this study were to evaluate (1) the accuracy of the clinical diagnosis of obstructive sleep apnea (OSA) informed by the home sleep study with a Type 4 portable monitor BresoDx® versus Type 1 polysomnography (PSG); and (2) agreement of the apnea-hypopnea index (AHI) compared between BresoDx and PSG.

MATERIAL AND METHODS

This was a randomized, parallel, multicentre, single-blind, pragmatic controlled trial enrolling adults referred to three Ontario sleep clinics for suspected OSA. Participants were randomized to BresoDx followed by PSG (one-night apart) or PSG followed by BresoDx sleep testing sequence arms. The primary outcomes included the accuracy of clinical diagnosis and OSA severity measured by AHI between tests.

RESULTS

In sum, 233 participants completed both sleep studies and 206 completed physician consultation visits. The agreement between clinical diagnosis informed by PSG versus BresoDx was fair (Cohen's kappa coefficient = 0.28). The sensitivity of BresoDx-informed clinical diagnosis against PSG was between 0.86 and 0.89, and the specificity between 0.38 and 0.44. For AHI cut-off of ≥5 events/hour the sensitivity, specificity and positive and negative predictive values were 0.85, 0.48, 0.81 and 0.54.

CONCLUSIONS

Home sleep apnea testing with BresoDx can be used in a referral population with a high pretest probability of OSA similar to other Type IV devices. This study complements the existing body of evidence suggesting that home testing with portable devices plays a valuable role for diagnosing of OSA in a variety of settings. SIESTA TRIAL REGISTRATION: www.clinicaltrials.gov (Identifier: NCT02003729).

Using a modified version of the "STOP-BANG" questionnaire and nocturnal oxygen desaturation to predict obstructive sleep apnea after stroke or TIA

PURPOSE

Obstructive sleep apnea (OSA) is a risk factor and common morbidity for stroke and transient ischemic attack (TIA). However, screening for OSA in patients with stroke or TIA is uncommonly performed, due in part to difficulties associated with conducting polysomnography (PSG) and Home Sleep Apnea Tests (HSATs). The 8-point "STOP-BANG" questionnaire has been shown to have high methodological quality in screening for OSA. This study examined the clinical utility of a modified version of the "STOP-BANG" questionnaire, which removed neck circumference and included nocturnal oxygen desaturation in diagnosing OSA (ie, the "STOP-BAG-O" tool), with the goal of improving uptake and accuracy in diagnosing OSA.

METHODS

In total, 231 participants completed both the STOP-BAG questionnaire and PSG or HSAT within 12 months of stroke/TIA. Using receiver-operating curves, scores on the "STOP-BAG-O" and "STOP-BAG" questionnaires were assessed for their ability to predict a diagnosis of OSA and classify at least 50% of the study population.

RESULTS

Compared to an OSA diagnosis of AHI≥10, the STOP-BAG (using cut-offs of ≤3 and ≥4) had a sensitivity and specificity of 83.5% and 67.2%, respectively. The STOP-BAG-O (using cut-offs of ≤3 and ≥5) had a sensitivity and specificity of 95.9% and 78.4%, respectively. For all AHI cut-offs used, the area under the curve for the STOP-BAG-O was greater and statistically different (p < 0.001) than that for the STOP-BAG.

CONCLUSIONS

The STOP-BAG-O is a valid tool for identifying risk of OSA post-stroke/TIA. The simplicity of this tool and ease of assessing nocturnal oxygen desaturation makes it a feasible option for widespread use.

Flow limitation/obstruction with recovery breath (FLOW) event for improved scoring of mild obstructive sleep apnea without electroencephalography

OBJECTIVE

Apnea/hypopnea index (AHI), especially without arousal criteria, does not adequately risk stratify patients with mild obstructive sleep apnea (OSA). We describe and test scoring reliability of an event, Flow Limitation/Obstruction With recovery breath (FLOW), representing obstructive airflow disruptions using only pressure transducer and snore signals available without electroencephalography.

METHODS

The following process was used (i) Development of FLOW event definition, (ii) Training period and definition refinement, and (iii) Reliability testing on 10 100-epoch polysomnography (PSG) samples and two 100-sample tests. Twenty full-night in-laboratory baseline PSGs in OSA patients with AHI with ≥4% desaturations <15 were rescored for FLOW events, traditional hypopneas with desaturations, respiratory-related arousal (RRA) events (hypopneas with arousals and respiratory-effort related arousals) and non-respiratory arousals (NRA).

RESULTS

Scoring of FLOW events in 100-epoch samples had good reliability with intraclass correlation (ICC) of 0.91. The overall kappa for presence of events on two sets of 100 sample events was 0.84 and 0.87 demonstrating good agreement. Moreover, 80% of RRA and 8% of NRA were concurrent with FLOW events. Furthermore, 56% of FLOW events were independent of RRA events. FLOW stratifies patients in traditional AHI categories with 50%/8% of AHI with ≥3% desaturations (AHI3) <5 and 12%/63% of AHI3 >5 in lowest/highest tertiles of AHI3 plus FLOW index.

CONCLUSIONS

Scoring of FLOW after training is reliable. FLOW scores a high proportion of RRA and many currently unrepresented obstructive airflow disruptions. FLOW allows for stratification within the current normal-mild OSA category, which may better identify patients who will benefit from treatment.

Addition of frontal EEG to adult home sleep apnea testing: does a more accurate determination of sleep time make a difference?

RATIONALE

Home sleep apnea testing (HSAT) typically does not include electroencephalogram (EEG) monitoring for sleep assessment. In patients with insomnia and low sleep efficiency, overestimation of the sleep period can result from absence of EEG, which will reduce sleep disordered breathing (SDB) indices and may lead to a false-negative result.

OBJECTIVE

To validate a single channel frontal EEG for scoring sleep versus wake against full EEG during polysomnography, and then to examine the utility of adding this single channel EEG to standard HSAT to prevent false-negative results.

METHODS

Epoch-by-epoch validation for sleep scoring of single channel EEG versus full PSG was first performed in 21 subjects. This was followed by a separate retrospective analysis of 207 consecutive HSATs in adults performed in a university-affiliated sleep center using the Somte (Compumedics) HSAT with one frontal EEG as well as chin EMG, nasal airflow, oxyhemoglobin saturation, respiratory effort, pulse rate, and body position. Each study was scored twice, with (HSAT_EEG) and without the EEG signal visible (HSAT_Polygraphy), to calculate AHI4 and RDI and the effect on OSA diagnosis and severity. Analyses were repeated in 69 patients with poor sleep suggesting insomnia plus Epworth Sleepiness Scale < 7 as well as in 38 patients ultimately shown to have sleep efficiency < 70% on HSAT with EEG.

MEASUREMENTS AND MAIN RESULTS

Single channel and full EEG during polysomnography agreed on sleep versus wake in 92-95% of all epochs. HSAT without EEG overestimated the sleep period by 20% (VST = 440 ± 76 min vs TST = 356 ± 82 min), had a false-negative rate of 8% by AHI4 criteria, and underestimated disease severity in 11% of all patients. Sub-group analysis of patients with subjective poor sleep suggesting insomnia did not change the results. Patients later shown to have low sleep efficiency had lower SDB indices and a 20.8% false negative rate of sleep apnea diagnosis.

CONCLUSIONS

Although overall false negative rates using HSAT_Polygraphy were moderate, suggesting utility for ruling out OSA, there was a specific subgroup in whom there were significant missed diagnoses. However, we were unable to identify this subgroup a priori.

Diagnostic accuracy of level IV portable sleep monitors versus polysomnography for obstructive sleep apnea: a systematic review and meta-analysis

PURPOSE

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder. In-laboratory, overnight type I polysomnography (PSG) is the current "gold standard" for diagnosing OSA. Home sleep apnea testing (HSAT) using portable monitors (PMs) is an alternative testing method offering better comfort and lower costs. We aimed to systematically review the evidence on diagnostic ability of type IV PMs compared to PSG in diagnosing OSA.

METHODS

Participants: patients ≥16 years old with symptoms suggestive of OSA;intervention: type IV PMs (devices with < 2 respiratory channels); comparator: in-laboratory PSG; outcomes: diagnostic accuracy measures;studies: cross-sectional, prospective observational/experimental/quasi-experimental studies; information sources: MEDLINE and Cochrane Library from January 1, 2010 to May 10, 2016. All stages of review were conducted independently by two investigators.

RESULTS

We screened 6054 abstracts and 117 full-text articles to select 24 full-text articles for final review. These 24 studies enrolled a total of 2068 patients with suspected OSA and evaluated 10 different PMs with one to six channels. Only seven (29%) studies tested PMs in the home setting. The mean difference (bias) between PSG-measured and PM-measured apnea-hypopnea index (AHI) ranged from - 14.8 to 10.6 events/h. At AHI ≥ 5 events/h, the sensitivity of type IV PMs ranged from 67.5-100% and specificity ranged from 25 to 100%.

CONCLUSION

While current evidence is not very strong for the stand-alone use of level IV PMs in clinical practice, they can potentially widen access to diagnosis and treatment of OSA. Policy recommendations regarding HSAT use should also consider the health and broader social implications of false positive and false negative diagnoses.

Methodological strategies in using home sleep apnea testing in research and practice

PURPOSE

Home sleep apnea testing (HSAT) has increased due to improvements in technology, accessibility, and changes in third party reimbursement requirements. Research studies using HSAT have not consistently reported procedures and methodological challenges. This paper had two objectives: (1) summarize the literature on use of HSAT in research of adults and (2) identify methodological strategies to use in research and practice to standardize HSAT procedures and information.

METHODS

Search strategy included studies of participants undergoing sleep testing for OSA using HSAT. MEDLINE via PubMed, CINAHL, and Embase with the following search terms: "polysomnography," "home," "level III," "obstructive sleep apnea," and "out of center testing."

RESULTS

Research articles that met inclusion criteria (n = 34) inconsistently reported methods and methodological challenges in terms of: (a) participant sampling; (b) instrumentation issues; (c) clinical variables; (d) data processing; and (e) patient acceptability. Ten methodological strategies were identified for adoption when using HSAT in research and practice.

CONCLUSIONS

Future studies need to address the methodological challenges summarized in this paper as well as identify and report consistent HSAT procedures and information.

Comparison of home sleep apnea testing versus laboratory polysomnography for the diagnosis of obstructive sleep apnea in children

INTRODUCTION

Obstructive sleep apnea (OSA) affects 1-5% of pediatric patients. Laboratory polysomnography is expensive, not always available, and is inconvenient for patients. Our study investigates the diagnostic ability of an unattended ambulatory monitor for the diagnosis of pediatric OSA.

METHODS

A prospective study was conducted in children, ages 2-17. Subjects completed in-lab polysomnography simultaneously with ambulatory monitoring. Caregivers attempted home studies on two subsequent nights to compare the home monitor and the laboratory polysomnogram (PSG).

RESULTS

Thirty-three subjects completed simultaneous laboratory polysomnogram with portable monitoring. Twenty patients completed home studies, with 16 completing 2 nights of monitoring. The measurement of AHI by the portable monitor was different than that obtained by the PSG with statistical significance for the comparisons of PSG vs. In-Lab (p = 0.0026), PSG vs. Home 1 (p = 0.033), and PSG vs. Home 2 (p = 0.033). The sensitivity of the portable monitor for diagnosing OSA was best for the In-lab use at 81%, but only 69% and 70% for the uses at home on the 2 nights respectively. Interestingly, the comparison of AHI and lowest oxygen saturation measurements from the home sleep test in children age 6 and older did not differ significantly from the PSG.

CONCLUSIONS

This pilot study demonstrated differences between home sleep testing and in-lab polysomnography for the diagnosis of pediatric sleep apnea. These differences were predominantly found to exist in younger children. Larger prospective studies are needed prior to widespread use, but home studies may alleviate issues of access to care and higher costs of laboratory polysomnography.

Unattended Hospital and Home Sleep Apnea Testing Following Cerebrovascular Events

BACKGROUND

Home sleep apnea testing (HSAT) is an alternative to polysomnography for the detection of obstructive sleep apnea (OSA). We assessed the feasibility of HSAT as an unattended screening tool for patients with a stroke or transient ischemic attack (TIA).

AIMS

The primary outcome was the feasibility of unattended HSAT, as defined by analyzability of the data. Secondary outcomes included determining (1) predictors of obtaining nonanalyzable sleep data and (2) time to OSA detection and continuous positive airway pressure (CPAP) initiation.

METHODS

In this single-center prospective observational study, inpatients or outpatients who had sustained a stroke or TIA were screened for OSA using the ApneaLink Plus ambulatory sleep monitor in their home or hospital room.

RESULTS

There were 102 patients who completed unattended sleep monitoring. Mean age was 68.7 ± 13.7 years, 55.9% were male, 57.8% were outpatients, and 77.5% had a stroke (22.5% with TIA). Eighty-two (80.4%) patients obtained four or more hours of analyzable sleep data. Functional dependence (defined as a modified Rankin Scale of >2) and elevated body mass index were independently associated with obtaining nonanalyzable data. OSA was detected in 63.4% (52 of 82) of patients and, of those, 34 of 52 (65.4%) initiated CPAP therapy. The mean time from study recruitment to HSAT was 1.7 days (median: 1, interquartile range [IQR]: 2) and CPAP was initiated on average within 62.7 days of recruitment (median: 53, IQR: 30).

CONCLUSIONS

Unattended HSAT can be feasibly implemented after stroke or TIA. This method facilitates rapid diagnosis and management of OSA in both the outpatient and inpatient settings.