Comparison of the NovaSom QSG™, a new sleep apnea home-diagnostic system, and polysomnography

In-Laboratory Polysomnography Worsens Obstructive Sleep Apnea by Changing Body Position Compared to Home Testing

(1) Background: Home sleep apnea testing, known as polysomnography type 3 (PSG3), underestimates respiratory events in comparison with in-laboratory polysomnography type 1 (PSG1). Without head electrodes for scoring sleep and arousal, in a home environment, patients feel unfettered and move their bodies more naturally. Adopting a natural position may decrease obstructive sleep apnea (OSA) severity in PSG3, independently of missing hypopneas associated with arousals. (2) Methods: Patients with suspected OSA performed PSG1 and PSG3 in a randomized sequence. We performed an additional analysis, called reduced polysomnography, in which we blindly reassessed all PSG1 tests to remove electroencephalographic electrodes, electrooculogram, and surface electromyography data to estimate the impact of not scoring sleep and arousal-based hypopneas on the test results. A difference of 15 or more in the apnea-hypopnea index (AHI) between tests was deemed clinically relevant. We compared the group of patients with and without clinically relevant differences between lab and home tests (3) Results: As expected, by not scoring sleep, there was a decrease in OSA severity in the lab test, similar to the home test results. The group of patients with clinically relevant differences between lab and home tests presented more severe OSA in the lab compared to the other group (mean AHI, 42.5 vs. 20.2 events/h, p = 0.002), and this difference disappeared in the home test. There was no difference between groups in the shift of OSA severity by abolishing sleep scoring in the lab. However, by comparing lab and home tests, there were greater variations in supine AHI and time spent in the supine position in the group with a clinically relevant difference, either with or without scoring sleep, showing an impact of the site of the test on body position during sleep. These variations presented as a marked increase or decrease in supine outcomes according to the site of the test, with no particular trend. (4) Conclusions: In-lab polysomnography may artificially increase OSA severity in a subset of patients by inducing marked changes in body position compared to home tests. The location of the sleep test seems to interfere with the evaluation of patients with more severe OSA.

Portable evaluation of obstructive sleep apnea in adults: A systematic review

Obstructive sleep apnea (OSA) is a significant healthcare burden affecting approximately one billion people worldwide. The prevalence of OSA is rising with the ongoing obesity epidemic, a key risk factor for its development. While in-laboratory polysomnography (PSG) is the gold standard for diagnosing OSA, it has significant drawbacks that prevent widespread use. Portable devices with different levels of monitoring are available to allow remote assessment for OSA. To better inform clinical practice and research, this comprehensive systematic review evaluated diagnostic performances, study cost and patients' experience of different levels of portable sleep studies (type 2, 3, and 4), as well as wearable devices and non-contact systems, in adults. Despite varying study designs and devices used, portable diagnostic tests are found to be sufficient for initial screening of patients at risk of OSA. Future studies are needed to evaluate cost effectiveness with the incorporation of portable diagnostic tests into the diagnostic pathway for OSA, as well as their application in patients with chronic respiratory diseases and other comorbidities that may affect test performance.

Automated Scoring of Respiratory Events in Sleep with a Single Effort Belt and Deep Neural Networks

OBJECTIVE

Automatic detection and analysis of respiratory events in sleep using a single respiratory effort belt and deep learning.

METHODS

Using 9,656 polysomnography recordings from the Massachusetts General Hospital (MGH), we trained a neural network (WaveNet) to detect obstructive apnea, central apnea, hypopnea and respiratory-effort related arousals. Performance evaluation included event-based analysis and apnea-hypopnea index (AHI) stratification. The model was further evaluated on a public dataset, the Sleep-Heart-Health-Study-1, containing 8,455 polysomnographic recordings.

RESULTS

For binary apnea event detection in the MGH dataset, the neural network obtained a sensitivity of 68%, a specificity of 98%, a precision of 65%, a F1-score of 67%, and an area under the curve for the receiver operating characteristics curve and precision-recall curve of 0.93 and 0.71, respectively. AHI prediction resulted in a mean difference of 0.417.8 and a r² of 0.90. For the multiclass task, we obtained varying performances: 84% of all labeled central apneas were correctly classified, whereas this metric was 51% for obstructive apneas, 40% for respiratory effort related arousals and 23% for hypopneas.

CONCLUSION

Our fully automated method can detect respiratory events and assess the AHI accurately. Differentiation of event types is more difficult and may reflect in part the complexity of human respiratory output and some degree of arbitrariness in the criteria used during manual annotation.

SIGNIFICANCE

The current gold standard of diagnosing sleep-disordered breathing, using polysomnography and manual analysis, is time-consuming, expensive, and only applicable in dedicated clinical environments. Automated analysis using a single effort belt signal overcomes these limitations.

Diagnostic accuracy and feasibility of portable sleep monitoring in patients with obstructive sleep apnea: Re-exploring the utility in the current COVID-19 pandemic

Portable sleep monitoring (PSM) is a promising alternative diagnostic tool for Obstructive Sleep Apnea (OSA) especially in high burden resource limited settings. We aimed to determine the diagnostic accuracy and feasibility of PSM device-based studies in patients presenting for evaluation of OSA at a tertiary care hospital in North-India. PSM studies (using a Type-III PSM device) were compared for technical reliability and diagnostic accuracy with the standard laboratory-based Type-I polysomnography (PSG). Patients were also interviewed about their experience on undergoing an unsupervised PSM studies. Fifty patients (68% males) were enrolled in the study, of which only 30% patients expressed their concerns about undergoing unsupervised PSM studies which included safety issues, ease of use, diagnostic accuracy, etc. Technical acceptability criteria were easily met by the PSM studies with signal loss in 12% studies (complete data loss and inaccessible data in 6% studies), warranting repetition sleep studies in four patients. The overall sensitivity of PSM device (AHI ≥5) was 93.5% (area under curve; AUC: 0.87). The diagnostic accuracy was 68.5%, 80%, and 91.4% for mild, moderate, and severe cases of OSA, respectively. An overall strong correlation was observed between PSM-AHI (apnoea-hypopnoea index) and PSG (r>0.85, p≤0.001), especially in severe OSA. The observed sensitivity was >90% for AHI>20 (clinically significant OSA), with high specificity of 91% for severe OSA (AUC: 0.94, 0.97 for AHI>20, AHI>30 respectively). The overall Bland-Altman concordance analysis also demonstrated only a small dispersion for PSM studies with a Cronbach's coefficient of 0.95. Therefore, there is good diagnostic accuracy as well as feasibility of home-based portable sleep studies in Indian patients. It can be promoted for widespread use in high burden countries like India for diagnosing and managing appropriately selected stable patients with high clinical probability of OSA, especially during the ongoing crises of COVID-19 pandemic.

Screening for obstructive sleep apnea with novel hybrid acoustic smartphone app technology

Background

Obstructive sleep apnea (OSA) has a high prevalence, with an estimated 425 million adults with apnea hypopnea index (AHI) of ≥15 events/hour, and is significantly underdiagnosed. This presents a significant pain point for both the sufferers, and for healthcare systems, particularly in a post COVID-19 pandemic world. As such, it presents an opportunity for new technologies that can enable screening in both developing and developed countries. In this work, the performance of a non-contact OSA screener App that can run on both Apple and Android smartphones is presented.

Methods

The subtle breathing patterns of a person in bed can be measured via a smartphone using the "Firefly" app technology platform [and underpinning software development kit (SDK)], which utilizes advanced digital signal processing (DSP) technology and artificial intelligence (AI) algorithms to identify detailed sleep stages, respiration rate, snoring, and OSA patterns. The smartphone is simply placed adjacent to the subject, such as on a bedside table, night stand or shelf, during the sleep session. The system was trained on a set of 128 overnights recorded at a sleep laboratory, where volunteers underwent simultaneous full polysomnography (PSG), and "Firefly" smartphone app analysis. A separate independent test set of 120 recordings was collected across a range of Apple iOS and Android smartphones, and withheld for performance evaluation by a different team. An operating point tuned for mid-sensitivity (i.e., balancing sensitivity and specificity) was chosen for the screener.

Results

The performance on the test set is comparable to ambulatory OSA screeners, and other smartphone screening apps, with a sensitivity of 88.3% and specificity of 80.0% [with receiver operating characteristic (ROC) area under the curve (AUC) of 0.92], for a clinical threshold for the AHI of ≥15 events/hour of detected sleep time.

Conclusions

The "Firefly" app based sensing technology offers the potential to significantly lower the barrier of entry to OSA screening, as no hardware (other than the user's personal smartphone) is required. Additionally, multi-night analysis is possible in the home environment, without requiring the wearing of a portable PSG or other home sleep test (HST).

Variability and Misclassification of Sleep Apnea Severity Based on Multi-Night Testing

BACKGROUND

Portable monitoring is a convenient means for diagnosing sleep apnea. However, data on whether one night of monitoring is sufficiently precise for the diagnosis of sleep apnea are limited.

RESEARCH QUESTION

The current study sought to determine the variability and misclassification in disease severity over three consecutive nights in a large sample of patients referred for sleep apnea.

METHODS

A sample of 10,340 adults referred for sleep apnea testing was assessed. A self-applied type III monitor was used for three consecutive nights. The apnea-hypopnea index (AHI) was determined for each night, and a reference AHI was computed by using data from all 3 nights. Pairwise correlations and the proportion misclassified regarding disease severity were computed for each of the three AHI values against the reference AHI.

RESULTS

Strong correlations were observed between the AHI from each of the 3 nights (r = 0.87-0.89). However, substantial within-patient variability in the AHI and significant misclassification in sleep apnea severity were observed based on any 1 night of monitoring. Approximately 93% of the patients with a normal study on the first night and 87% of those with severe sleep apnea on the first night were correctly classified compared with the reference derived from all three nights. However, approximately 20% of the patients with mild and moderate sleep apnea on the first night were misdiagnosed either as not having sleep apnea or as having mild disease, respectively.

CONCLUSIONS

In patients with mild to moderate sleep apnea, one night of portable testing can lead to misclassification of disease severity given the substantial night-to-night variability in the AHI.

Contactless recording of sleep apnea and periodic leg movements by nocturnal 3-D-video and subsequent visual perceptive computing

Contactless measurements during the night by a 3-D-camera are less time-consuming in comparison to polysomnography because they do not require sophisticated wiring. However, it is not clear what might be the diagnostic benefit and accuracy of this technology. We investigated 59 persons simultaneously by polysomnography and 3-D-camera and visual perceptive computing (19 patients with restless legs syndrome (RLS), 21 patients with obstructive sleep apnea (OSA), and 19 healthy volunteers). There was a significant correlation between the apnea hypopnea index (AHI) measured by polysomnography and respiratory events measured with the 3-D-camera in OSA patients (r = 0.823; p < 0.001). The receiver operating characteristic curve yielded a sensitivity of 90% for OSA with a specificity of 71.4%. In RLS patients 72.8% of leg movements confirmed by polysomnography could be detected by 3-D-video and a significant moderate correlation was found between PLM measured by polysomnography and by the 3-D-camera (RLS: r = 0.654; p = 0.004). In total, 95.4% of the sleep epochs were correctly classified by the machine learning approach, but only 32.5% of awake epochs. Further studies should investigate, if this technique might be an alternative to home sleep testing in persons with an increased pre-test probability for OSA.

Sleep disordered breathing in Marfan syndrome: Value of standard screening questionnaires

Background

A high prevalence of sleep disordered breathing (SDB) has been reported in persons with Marfan syndrome (MFS), a single gene disorder of connective tissue resulting in premature death from aortic rupture. The burden of SDB and accompanying hemodynamic stress could warrant broad screening in this population. Our goal was to assess the utility of traditional SDB screening tools in our sample of persons with MFS.

Methods

Participants were recruited during an annual Marfan Foundation meeting and Marfan status confirmed using the Ghent criteria. Screening questionnaires were administered and SDB assessed by home sleep testing. We assessed accuracy of screening tools using receiver‐operating characteristic curve analyses.

Results

The prevalence of moderate‐severe SDB was 32% in our sample of 31 MFS participants. The Stop‐Bang questionnaire had the highest positive predictive value (PPV) of 60% and the highest negative predictive value (NPV) of 100% using the high‐ and moderate‐risk cut‐offs, respectively, and the Berlin questionnaire had a PPV of 50% and an NPV of 92.3% at the high‐risk cut‐off. When those with mild SDB were included, the Stop‐Bang and the Sleep Apnea Clinical Score (SACS) questionnaires demonstrated useful screening accuracies with PPVs of 94.7% and 92.9%, and NPVs of 63.6% and 47.1%, respectively, at the moderate‐risk cut‐offs.

Conclusion

A survey of SDB in a sample of persons with MFS reveals not only a high burden of SDB but also that conventional screening instruments have utility if adapted appropriately. Future studies should validate the utility of these screening tools given concerns that SDB may contribute to progression of aortic pathology in MFS.

Distance to Specialist Medical Care and Diagnosis of Obstructive Sleep Apnea in Rural Saskatchewan

Obstructive sleep apnea (OSA) is the most common sleep-disordered breathing condition. Patients with OSA symptoms are often not diagnosed clinically, which is a concern, given the health and safety risks associated with unmanaged OSA. The availability of fewer practicing medical specialists combined with longer travel distances to access health care services results in barriers to diagnosis and treatment in rural communities. This study aimed to (1) determine whether the proportion of adults reporting OSA symptoms in the absence of a sleep apnea diagnosis in rural populations varied by travel distance to specialist medical care and (2) assess whether any distance-related patterns were attributable to differences in the frequency of diagnosis among adults who likely required this specialist medical care. We used a cross-sectional epidemiologic study design, augmented by analysis of follow-up survey data. Our study base included adults who completed a 2010 baseline questionnaire for the Saskatchewan Rural Health Study. Follow-up occurred until 2015. 6525 adults from 3731 households constituted our sample. Statistical models used log-binomial regression. Rural adults who reported the largest travel distances (≥250 km) to specialist medical care were 1.17 (95% CI: 1.07, 1.29) times more likely to report OSA symptoms in the absence of a sleep apnea diagnosis than those who reported the smallest (<100 km; referent) distances. However, the proportion of sleep apnea diagnoses was low and unaffected by reported travel distance among adults who likely required this specialist medical care. Our findings suggest factors other than travel distance may be contributing to the low sleep apnea diagnostic rate. This remains important as undiagnosed and untreated OSA has serious implications on the health of people and populations, but effective treatments are available. Health care access barriers to the diagnosis and treatment of OSA require evaluation to inform health care planning and delivery.

The relationships between improvements in daytime sleepiness, fatigue and depression and psychomotor vigilance task testing with CPAP use in patients with obstructive sleep apnea

OBJECTIVE

The purpose of this study was to determine if the subjective improvements in daytime sleepiness, fatigue and depression experienced by patients with obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) therapy predict an objective improvement in vigilance, and whether patients with mild-to-moderate OSA differ from patients with severe OSA in this regard.

METHODS

A total of 182 patients underwent psychomotor vigilance task (PVT) testing and measurements of subjective daytime sleepiness, fatigue and depression at baseline and after a minimum of one month of adherent CPAP use at an adequate pressure.

RESULTS

Patients with both mild-to-moderate (n = 92) and severe (n = 90) OSA experienced improvements in subjective daytime sleepiness, fatigue and depression, but objective improvement in vigilance was only seen in patients with severe OSA. In patients with severe OSA, while a correlation was found between improvements in daytime sleepiness and some PVT parameters, changes in subjective daytime sleepiness, fatigue and depression scores were not predictive of objective improvement in vigilance while controlling for all these subjective symptoms and for age, gender, body mass index, apnea-hypopnea index/respiratory event index and total sleep time/total recording time with pulse oximetry below 90%.

CONCLUSIONS

We found no predictive relationship between subjective improvements in daytime sleepiness, fatigue and depression and objective vigilance with CPAP use in patients with OSA. These results suggest that subjective complaints of daytime impairment and objective measures of vigilance in patients with OSA should be assessed separately while evaluating the efficacy of CPAP therapy on daytime functioning.

Convergent validity of actigraphy with polysomnography and parent reports when measuring sleep in children with Down syndrome

BACKGROUND

There is a need for rigorous measures of sleep in children with Down syndrome as sleep is a substantial problem in this population and there are barriers to obtaining the gold standard polysomnography (PSG). PSG is cost-prohibitive when measuring treatment effects in some clinical trials, and children with Down syndrome may not cooperate with undergoing a PSG. Minimal information is available on the validity of alternative methods of assessing sleep in children with Down syndrome, such as actigraphy and parent ratings. Our study examined the concurrent and convergent validity of different measures of sleep, including PSG, actigraphy and parent reports of sleep among children with Down syndrome.

METHOD

A clinic (n = 27) and a community (n = 47) sample of children with Down syndrome were examined. In clinic, children with Down syndrome wore an actigraph watch during a routine PSG. In the community, children with Down syndrome wore an actigraph watch for a week at home at night as part of a larger study on sleep and behaviour. Their parent completed ratings of the child's sleep during that same week.

RESULTS

Actigraph watches demonstrated convergent validity with PSG when measuring a child with Down syndrome's total amount of sleep time, total wake time after sleep onset and sleep period efficiency. In contrast, actigraph watches demonstrated poor correlations with parent reports of sleep, and with PSG when measuring the total time in bed and total wake episodes. Actigraphy, PSG and parent ratings of sleep demonstrated poor concurrent validity with clinical diagnosis of obstructive sleep apnoea.

CONCLUSION

Our current data suggest that actigraph watches demonstrate convergent validity and are sensitive to measuring certain sleep constructs (duration, efficiency) in children with Down syndrome. However, parent reports, such as the Children's Sleep Habits Questionnaire, may be measuring other sleep constructs. These findings highlight the importance of selecting measures of sleep related to target concerns.

Devices for home detection of obstructive sleep apnea: A review

One of the most common sleep-related disorders is obstructive sleep apnea, characterized by a reduction of airflow while breathing during sleep and cause significant health problems. This disorder is mainly diagnosed in sleep labs with polysomnography, involving high costs and stress for the patient. To address this situation multiple systems have been proposed to conduct the examination and analysis in the patient's home, using sensors to detect physiological signals that are examined by algorithms. The objective of this research is to review publications that show the performance of different devices for ambulatory diagnosis of sleep apnea. Commercial systems that were examined by an independent research group and validated research projects were selected. In total 117 articles were analysed, including a total of 50 commercial devices. Each article was evaluated according to diagnostic elements, level of automatisation implemented and the deducted level of evidence and quality rating. Each device was categorized using the SCOPER categorization system, including an additional proposed category, and a final comparison was performed to determine the sensors that provided the best results.

Conventional Polysomnography Is Not Necessary for the Management of Most Patients with Suspected Obstructive Sleep Apnea. Noninferiority, Randomized Controlled Trial

RATIONALE

Home respiratory polygraphy may be a simpler alternative to in-laboratory polysomnography for the management of more symptomatic patients with obstructive sleep apnea, but its effectiveness has not been evaluated across a broad clinical spectrum.

OBJECTIVES

To compare the long-term effectiveness (6 mo) of home respiratory polygraphy and polysomnography management protocols in patients with intermediate-to-high sleep apnea suspicion (most patients requiring a sleep study).

METHODS

A multicentric, noninferiority, randomized controlled trial with two open parallel arms and a cost-effectiveness analysis was performed in 12 tertiary hospitals in Spain. Sequentially screened patients with sleep apnea suspicion were randomized to respiratory polygraphy or polysomnography protocols. Moreover, both arms received standardized therapeutic decision-making, continuous positive airway pressure (CPAP) treatment or a healthy habit assessment, auto-CPAP titration (for CPAP indication), health-related quality-of-life questionnaires, 24-hour blood pressure monitoring, and polysomnography at the end of follow-up. The main outcome was the Epworth Sleepiness Scale measurement. The noninferiority criterion was -2 points on the Epworth scale.

MEASUREMENTS AND MAIN RESULTS

In total, 430 patients were randomized. The respiratory polygraphy protocol was noninferior to the polysomnography protocol based on the Epworth scale. Quality of life, blood pressure, and polysomnography were similar between protocols. Respiratory polygraphy was the most cost-effective protocol, with a lower per-patient cost of 416.7€.

CONCLUSIONS

Home respiratory polygraphy management is similarly effective to polysomnography, with a substantially lower cost. Therefore, polysomnography is not necessary for most patients with suspected sleep apnea. This finding could change established clinical practice, with a clear economic benefit. Clinical trial registered with www.clinicaltrials.gov (NCT 01752556).

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.

Investigating Cost Implications of Incorporating Level III At-Home Testing into a Polysomnography Based Sleep Medicine Program Using Administrative Data

Objective

Obstructive sleep apnea is a common problem, requiring expensive in-lab polysomnography for proper diagnosis. Home monitoring can provide an alternative to in-lab testing for a subset of OSA patients. The objective of this project was to investigate the effect of incorporating home testing into an OSA program at a large, tertiary sleep disorders centre.

Methods

The Sleep Disorders Centre in Saskatoon, Canada, has been incorporating at-home testing into their diagnostic pathways since 2006. Administrative data from 2007 to 2013 were extracted (10030 patients) and the flow of patients through the program was followed from diagnosis to treatment. Costs were estimated using 2014 pricing and were stratified by disease attributes and sensitivity analysis was applied.

Results

The overall costs per patient were $627.40, with $419.20 for at-home testing and $746.20 for in-lab testing. The cost of home management would rise to $515 if all negative tests were required to be confirmed by an in-lab PSG.

Discussion

Our review suggests that at-home testing can be cost-effective alternative to in-lab testing when applied to the correct population, specifically, those with a high pretest probability of obstructive sleep apnea and an absence of significant comorbidities.

Snoring Significance in Patients Undergoing Home Sleep Studies

OBJECTIVE: To analyze the impact of snoring, independent of obstructive sleep apnea syndrome on patients referred for home sleep studies and to report a new technology for the reporting of snoring, using sophisticated sound collection and noise-canceling technology.

STUDY DESIGN AND SETTING: A retrospective statistical review of consecutive anonymous data compiled from questionnaires and digital data of snoring loudness and duration measured at the upper lip during unattended home sleep studies in 4,860 patients referred for snoring and sleep-disturbed breathing.

RESULTS: A strong relationship exists between a history of snoring and complaints of daytime sleepiness (80%), obesity (73%), and chronic fatigue (78%) (all yield P < 0.001). By contrast, only 42% to 48% of patients without these symptoms complain of snoring. In 3 multiple-regression analyses, the percent of time snoring, average loudness, and peak loudness are all significantly predicted by the apnea hypopnea index (all P < 0.003), body mass index (all P < 0.001), and age ( P = 0.014). Daytime sleepiness was strongly predicted by percent time snoring ( P = 0.014), weakly by average loudness ( P = 0.046), and not at all by peak loudness (P = 0.303).

CONCLUSION: By using a pair of microphones placed at the upper lip, one that samples breath sounds and the other ambient sound and artifact noise, the NovaSOM QSG measures snoring while canceling ambient noise. The clinical impact of snoring on the patient as well as the bed partner, independent of obstructive sleep apnea syndrome, is an unrecognized factor in sleep-disturbed breathing.

SIGNIFICANCE: Measurable criteria to define snoring are suggested. Snoring loudness is not measured in most laboratory Polysomnograms.

EBM rating: B-3b

Utility of portable monitoring in the diagnosis of obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common but underdiagnosed sleep disorder, which is associated with systemic consequences such as hypertension, stroke, metabolic syndrome, and ischemic heart disease. Nocturnal laboratory-based polysomnography (PSG) is the gold standard test for diagnosis of OSA. PSG consists of a simultaneous recording of multiple physiologic parameters related to sleep and wakefulness including electroencephalography (EEG), electrooculography (EOG), surface electromyography (EMG), airflow measurement using thermistor and nasal pressure transducer, pulse oximetry and respiratory effort (thoracic and abdominal). Multiple alternative and simpler methods that record respiratory parameters alone for diagnosing OSA have been developed in the past two decades. These devices are called portable monitors (PMs) and enable performing sleep studies at a lower cost with shorter waiting times. It has been observed and reported that comprehensive sleep evaluation coupled with the use of PMs can fulfill the unmet need for diagnostic testing in various out-of-hospital settings in patients with suspected OSA. This article reviews the available medical literature on PMs in order to justify the utility of PMs in the diagnosis of OSA, especially in resource-poor, high-disease burden settings. The published practice parameters for the use of these devices have also been reviewed with respect to their relevance in the Indian setting.

Comparative Study between Sequential Automatic and Manual Home Respiratory Polygraphy Scoring Using a Three-Channel Device: Impact of the Manual Editing of Events to Identify Severe Obstructive Sleep Apnea

Objective. According to current guidelines, autoscoring of respiratory events in respiratory polygraphy requires manual scoring. The aim of this study was to evaluate the agreement between automatic analysis and manual scoring to identify patients with suspected OSA. Methods. This retrospective study analyzed 791 records from respiratory polygraphy (RP) performed at home. The association grade between automatic scoring and manual scoring was evaluated using Kappa coefficient and the agreement using Bland and Altman test and intraclass correlation coefficient (CCI). To determine the accuracy in the identification of AHI ≥ 30 eV/h, the ROC curve analysis was used. Results. The population analyzed consisted of 493 male (62.3%) and 298 female patients, with an average age of 54.7 ± 14.20 years and BMI of 32.7 ± 8.21 kg/m². There was no significant difference between automatic and manual apnea/hypopnea indexes (aAHI, mAHI): aAHI 17.25 (SD: 17.42) versus mAHI 21.20 ± 7.96 (p; NS). The agreement between mAHI and aAHI to AHI ≥ 30 was 94%, with a Kappa coefficient of 0.83 (p < 0.001) and a CCI of 0.83. The AUC-ROC, sensitivity, and specificity were 0.99 (CI 95%: 0.98-0.99, p < 0.001), 86% (CI 95%: 78.7–91.4), and 97% (CI 95%: 96–98.3), respectively. Conclusions. We observed good agreement between automatic scoring and sequential manual scoring to identify subjects with AHI ≥ 30 eV/h.

A Comprehensive Evaluation of a Two-Channel Portable Monitor to "Rule in" Obstructive Sleep Apnea

STUDY OBJECTIVES

We hypothesized that a dual-channel portable monitor (PM) device could accurately identify patients who have a high pretest probability of obstructive sleep apnea (OSA), and we evaluated factors that may contribute to variability between PM and polysomnography (PSG) results.

METHODS

Consecutive clinic patients (N = 104) with possible OSA completed a home PM study, a PM study simultaneous with laboratory PSG, and a second home PM study. Uniform data analysis methods were applied to both PM and PSG data. Primary outcomes of interest were the positive likelihood ratio (LR+) and sensitivity of the PM device to "rule-in" OSA, defined as an apnea-hypopnea index (AHI) ≥ 5 events/h on PSG. Effects of different test environment and study nights, and order of study and analysis methods (manual compared to automated) on PM diagnostic accuracy were assessed.

RESULTS

The PM has adequate LR+ (4.8), sensitivity (80%), and specificity (83%) for detecting OSA in the unattended home setting when benchmarked against laboratory PSG, with better LR+ (> 5) and specificity (100%) and unchanged sensitivity (80%) in the simultaneous laboratory comparison. There were no significant night-night (all p > 0.10) or study order effects (home or laboratory first, p = 0.08) on AHI measures. Manual PM data review improved case finding accuracy, although this was not statistically significant (all p > 0.07). Misclassification was more frequent where OSA was mild.

CONCLUSIONS

Overall performance of the PM device is consistent with current recommended criteria for an "acceptable" device to confidently "rule-in" OSA (AHI ≥ 5 events/h) in a high pretest probability clinic population. Our data support the utility of simple two-channel diagnostic devices to confirm the diagnosis of OSA in the home environment.

COMMENTARY

A commentary on this article appears in this issue on page 411.

Hypertension, snoring, and obstructive sleep apnoea during pregnancy: a cohort study

OBJECTIVE

To assess the frequency of obstructive sleep apnoea among women with and without hypertensive disorders of pregnancy.

DESIGN

Cohort study.

SETTING

Obstetric clinics at an academic medical centre.

POPULATION

Pregnant women with hypertensive disorders (chronic hypertension, gestational hypertension, or pre-eclampsia) and women who were normotensive.

METHODS

Women completed a questionnaire about habitual snoring and underwent overnight ambulatory polysomnography.

MAIN OUTCOME MEASURES

The presence and severity of obstructive sleep apnoea.

RESULTS

Obstructive sleep apnoea was found among 21 of 51 women with hypertensive disorders (41%), but in only three of 16 women who were normotensive (19%, chi-square test, P=0.005). [Author correction added on 16 June 2014, after first online publication: Results mentioned in the abstract were amended.] Non-snoring women with hypertensive disorders typically had mild obstructive sleep apnoea, but >25% of snoring women with hypertensive disorders had moderate to severe obstructive sleep apnoea. Among women with hypertensive disorders, the mean apnoea/hypopnoea index was substantially higher in snorers than in non-snorers (19.9±34.1 versus 3.4±3.1, P=0.013), and the oxyhaemoglobin saturation nadir was significantly lower (86.4±6.6 versus 90.2±3.5, P=0.021). Among women with hypertensive disorders, after stratification by obesity, the pooled relative risk for obstructive sleep apnoea in snoring women with hypertension compared with non-snoring women with hypertension was 2.0 (95% CI 1.4-2.8).

CONCLUSIONS

Pregnant women with hypertension are at high risk for unrecognised obstructive sleep apnoea. Although longitudinal and intervention studies are urgently needed, given the known relationship between obstructive sleep apnoea and hypertension in the general population, it would seem pertinent that hypertensive pregnant women who snore should be tested for obstructive sleep apnoea, a condition believed to cause or promote hypertension.

Management of sleep apnea without high pretest probability or with comorbidities by three nights of portable sleep monitoring

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) diagnosis using simplified methods such as portable sleep monitoring (PM) is only recommended in patients with a high pretest probability. The aim is to determine the diagnostic efficacy, consequent therapeutic decision-making, and costs of OSA diagnosis using polysomnography (PSG) versus three consecutive studies of PM in patients with mild to moderate suspicion of sleep apnea or with comorbidity that can mask OSA symptoms.

DESIGN AND SETTING

Randomized, blinded, crossover study of 3 nights of PM (3N-PM) versus PSG. The diagnostic efficacy was evaluated with receiver operating characteristic (ROC) curves. Therapeutic decisions to assess concordance between the two different approaches were performed by sleep physicians and respiratory physicians (staff and residents) using agreement level and kappa coefficient. The costs of each diagnostic strategy were considered.

PATIENTS AND RESULTS

Fifty-six patients were selected. Epworth Sleepiness Scale was 10.1 (5.3) points. Bland-Altman plot for apnea-hypopnea index (AHI) showed good agreement. ROC curves showed the best area under the curve in patients with PSG AHI ≥ 5 [0.955 (confidence interval = 0.862-0.993)]. For a PSG AHI ≥ 5, a PM AHI of 5 would effectively exclude and confirm OSA diagnosis. For a PSG AHI ≥ 15, a PM AHI ≥ 22 would confirm and PM AHI < 7 would exclude OSA. The best agreement of therapeutic decisions was achieved by the sleep medicine specialists (81.8%). The best cost-diagnostic efficacy was obtained by the 3N-PM.

CONCLUSIONS

Three consecutive nights of portable monitoring at home evaluated by a qualified sleep specialist is useful for the management of patients without high pretest probability of obstructive sleep apnea or with comorbidities.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov, registration number: NCT01820156.

CITATION

Guerrero A, Embid C, Isetta V, Farre R, Duran-Cantolla J, Parra O, Barbé F, Montserrat JM, Masa JF. Management of sleep apnea without high pretest probability or with comorbidities by three nights of portable sleep monitoring.

Screening for obstructive sleep apnoea in obesity and diabetes--potential for future approaches

BACKGROUND

It is recognised that sleep-disordered breathing (SDB), in particular, obstructive sleep apnoea (OSA) is associated with obesity and diabetes. The complications of OSA include dysregulation of metabolic and cardiovascular homeostasis. With the growing population of diabetes and obesity globally, it is becoming apparent that identifying and screening patients who are at risk is becoming increasingly crucial. Many patients may remain unaware of the potential diagnosis and continue to be undiagnosed. The high prevalence of OSA poses a demanding challenge to healthcare providers in order to provide sufficient resources and facilities for patient diagnosis and treatment.

DESIGN

In this article, we review the evidence in favour of screening populations deemed to be at increased risk of OSA, with particular reference to patients with obesity and diabetes. We consider the recent advances in potential screening methods that may allow new prognostic and predictive tools to be developed. A detailed search of Medline and Web of Science electronic databases for relevant articles in English was performed.

RESULTS

Apart from the use of screening tools such as questionnaires and clinical decision models, there is increasing evidence to suggest that there are differences in biological parameters in patients with OSA. Although further studies are required, there may be potential for such biomarkers to contribute to and augment the screening process. However, the significance of such biological tools remains to be elucidated.

CONCLUSIONS

A fundamental role for improved screening in patients with conditions such as obesity and diabetes can enable early interventions that may improve health outcomes relating to the adverse consequences of OSA. The future will see further research being carried out in the development of potential screening methods with emphasis on the selection of patients at risk of sleep disorders, thereby allowing more detailed physiological studies to be carried out where needed.

Significance of including a surrogate arousal for sleep apnea-hypopnea syndrome diagnosis by respiratory polygraphy

RATIONALE

Respiratory polygraphy is an accepted alternative to polysomnography (PSG) for sleep apnea/hypopnea syndrome (SAHS) diagnosis, although it underestimates the apnea-hypopnea index (AHI) because respiratory polygraphy cannot identify arousals.

OBJECTIVES

We performed a multicentric, randomized, blinded crossover study to determine the agreement between home respiratory polygraphy (HRP) and PSG, and between simultaneous respiratory polygraphy (respiratory polygraphy with PSG) (SimultRP) and PSG by means of 2 AHI scoring protocols with or without hyperventilation following flow reduction considered as a surrogate arousal.

METHODS

We included suspected SAHS patients from 8 hospitals. They were assigned to home and hospital protocols at random. We determined the agreement between respiratory polygraphy AHI and PSG AHI scorings using Bland and Altman plots and diagnostic agreement using receiver operating characteristic (ROC) curves. The agreement in therapeutic decisions (continuous positive airway pressure treatment or not) between HRP and PSG scorings was done with likelihood ratios and post-test probability calculations.

RESULTS

Of 366 randomized patients, 342 completed the protocol. AHI from HRP scorings (with and without surrogate arousal) had similar agreement with PSG. AHI from SimultRP with surrogate arousal scoring had better agreement with PSG than AHI from SimultRP without surrogate arousal. HRP with surrogate arousal scoring had slightly worse ROC curves than HRP without surrogate arousal, and the opposite was true for SimultRP scorings. HRP with surrogate arousal showed slightly better agreement with PSG in therapeutic decisions than for HRP without surrogate arousal.

CONCLUSION

Incorporating a surrogate arousal measure into HRP did not substantially increase its agreement with PSG when compared with the usual procedure (HRP without surrogate arousal).

Portable diagnostic devices for identifying obstructive sleep apnea among commercial motor vehicle drivers: considerations and unanswered questions

Obstructive sleep apnea (OSA), a syndrome defined by breathing abnormalities during sleep, can lead to fatigue and excessive daytime sleepiness (EDS) with an increased risk of motor vehicle crashes. Identifying commercial motor vehicle operators with unrecognized OSA is a major public health priority. Portable monitors (PMs) are being actively marketed to trucking firms as potentially lower-cost and more accessible alternatives to the reference standard of in-laboratory polysomnography (PSG) in the diagnosis of OSA among commercial motor vehicle operators. Several factors regarding PMs remain uncertain in this unique patient population: their sensitivity and specificity; the cost-benefit ratio of the PMs versus PSG; potential barriers from human factors; and evolving technologic advancement. Human factors that alter test accuracy are a major concern among commercial drivers motivated to gain/maintain employment. Current available data using PMs as a diagnostic tool among CMV operators indicate relatively high data loss and high loss to follow-up. Loss to follow-up has also been an issue using PSG in commercial motor vehicle operators. Furthermore, PM testing and PM results interpretation protocols may have no sleep specialist oversight, and sometimes minimal physician oversight and involvement. Additional studies comparing unattended and unmonitored PMs directly against full in-laboratory PSG are needed to provide evidence for their efficacy among commercial motor vehicle operators.

Is portable monitoring accurate in the diagnosis of obstructive sleep apnea syndrome in chronic pulmonary obstructive disease?

BACKGROUND

No scientific evidence supports the use of portable devices to diagnose obstructive sleep apnea syndrome (OSAS) in patients with co-morbities. Our aim was to evaluate the accuracy of a portable monitoring device (Stardust - STD) in the detection of patients with chronic obstructive pulmonary disease (COPD).

METHODS

Patients with COPD and clinical suspicion of OSAS were recruited for a prospective randomized study. The STD was used on two different nights: (1) at home (STDHome) and (2) at the sleep laboratory simultaneous with polysomnography (PSG-STDLab).

RESULTS

A total of 72 patients underwent the proposed recordings. Forty-six volunteers were excluded due to recording problems, and data from 26 subjects were analyzed. The mean age was (mean±SD) 62.8±8.5 years, 50% were male, and the mean forced expiratory volume in the first second was 55±11%. Significant intraclass correlation was observed between apnea-hypopnea index (AHI)-PSG vs. AHI-STDLab (r=0.61, p<0.0001) and AHI-STDHome (r=0.47, p<0.007). Kappa analysis also showed a significant agreement for severe group.

CONCLUSION

Despite the agreement found in a small number of patients between AHI, a large number of failures in the recording limits the use of this portable device for the diagnosis of OSAS in patients with COPD.

Obstructive sleep apnea devices for out-of-center (OOC) testing: technology evaluation

Guidance is needed to help clinicians decide which out-of-center (OOC) testing devices are appropriate for diagnosing obstructive sleep apnea (OSA). A new classification system that details the type of signals measured by these devices is presented. This proposed system categorizes OOC devices based on measurements of Sleep, Cardiovascular, Oximetry, Position, Effort, and Respiratory (SCOPER) parameters.Criteria for evaluating the devices are also presented, which were generated from chosen pre-test and post-test probabilities. These criteria state that in patients with a high pretest probability of having OSA, the OOC testing device has a positive likelihood ratio (LR+) of 5 or greater coinciding with an in-lab-polysomnography (PSG)-generated apnea hypopnea index (AHI) ≥ 5, and an adequate sensitivity (at least 0.825).Since oximetry is a mandatory signal for scoring AHI using PSG, devices that do not incorporate oximetry were excluded. English peer-reviewed literature on FDA-approved devices utilizing more than 1 signal was reviewed according to the above criteria for 6 questions. These questions specifically addressed the adequacy of different respiratory and effort sensors and combinations thereof to diagnose OSA. In summary, the literature is currently inadequate to state with confidence that a thermistor alone without any effort sensor is adequate to diagnose OSA; if a thermal sensing device is used as the only measure of respiration, 2 effort belts are required as part of the montage and piezoelectric belts are acceptable in this context; nasal pressure can be an adequate measurement of respiration with no effort measure with the caveat that this may be device specific; nasal pressure may be used in combination with either 2 piezoelectric or respiratory inductance plethysmographic (RIP) belts (but not 1 piezoelectric belt); and there is insufficient evidence to state that both nasal pressure and thermistor are required to adequately diagnose OSA. With respect to alternative devices for diagnosing OSA, the data indicate that peripheral arterial tonometry (PAT) devices are adequate for the proposed use; the device based on cardiac signals shows promise, but more study is required as it has not been tested in the home setting; for the device based on end-tidal CO(2) (ETCO(2)), it appears to be adequate for a hospital population; and for devices utilizing acoustic signals, the data are insufficient to determine whether the use of acoustic signals with other signals as a substitute for airflow is adequate to diagnose OSA.Standardized research is needed on OOC devices that report LR+ at the appropriate AHI (≥ 5) and scored according to the recommended definitions, while using appropriate research reporting and methodology to minimize bias.

[Screening for sleep apnea in cardiovascular patients in clinical routine]

Sleep apnea syndromes (SAS) are highly prevalent in cardiovascular patients. Because diagnostics are cost and labor intensive, these patients often remain undiagnosed. For this reason, simple screening methods for SAS in daily clinical practice are very important. Standardized questionnaires are one way to screen patients, i.e., simple standardized questionnaires have been shown to be highly predictive in OSA, but not in CSA patients. Simple ambulatory screening devices use oxymetry and/or nasal flow to determine the apnea-hypopnea index (AHI). These devices have been shown to be highly effective in screening for OSA and CSA. In addition, algorithms that calculate the electrocardiography (ECG)-derived AHI using heart rate variability and/or QRS morphology from Holter ECG recordings are also promising. Especially the latter method could become a simple tool for cardiologists to screen for SAS in clinical routine.

Therapeutic decision-making for sleep apnea and hypopnea syndrome using home respiratory polygraphy: a large multicentric study

RATIONALE

Home respiratory polygraphy (HRP) is an alternative to polysomnography (PSG) for sleep apnea-hypopnea syndrome (SAHS) diagnosis. However, therapeutic decision-making is a different process than diagnosis.

OBJECTIVES

This study aimed to determine the agreement between HRP and in-hospital PSG for therapeutic decision-making in a large sample.

METHODS

Patients with an intermediate or high SAHS suspicion were included in a multicenter study (eight sleep centers) and assigned to home and hospital protocols in a random order. Therapeutic decisions (continuous positive airway pressure, no continuous positive airway pressure, or impossible decision) were made by an investigator in each center, based on using either HRP or PSG and a single set of auxiliary clinical variables. Patients and diagnostic methods (HRP and PSG) were assessed in random order using an electronic database. After a month the same therapeutic decision-making procedure was repeated with the same method.

MEASUREMENTS AND MAIN RESULTS

Of 366 randomized patients, 348 completed the protocol. The "impossible decision" case was not observed with either PSG or HRP. Therapeutic decisions using HRP had a sensitivity of 73%, a specificity of 77%, and an agreement level (sum of true positives and negatives) of 76%. Patients with higher HRP apnea-hypopnea index (AHI) scores (≥ 30; 41% of the total sample) had a sensitivity of 94%, a specificity of 44%, and the agreement level was 91%.

CONCLUSIONS

The HRP-based therapeutic decision was adequate when AHI was high, but deficient in the large population of patients with mild to moderate AHI. Therefore, both selecting patients with a high suspicion and severity of SAHS and future prospective cost-effectiveness studies are necessary.

An integrated health-economic analysis of diagnostic and therapeutic strategies in the treatment of moderate-to-severe obstructive sleep apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is a common disorder associated with substantially increased cardiovascular risks, reduced quality of life, and increased risk of motor vehicle collisions due to daytime sleepiness. This study evaluates the cost-effectiveness of three commonly used diagnostic strategies (full-night polysomnography, split-night polysomnography, unattended portable home-monitoring) in conjunction with continuous positive airway pressure (CPAP) therapy in patients with moderate-to-severe OSA.

DESIGN

A Markov model was created to compare costs and effectiveness of different diagnostic and therapeutic strategies over a 10-year interval and the expected lifetime of the patient. The primary measure of cost-effectiveness was incremental cost per quality-adjusted life year (QALY) gained.

PATIENTS OR PARTICIPANTS

Baseline computations were performed for a hypothetical average cohort of 50-year-old males with a 50% pretest probability of having moderate-to-severe OSA (apnea-hypopnea index [AHI] ≥ 15 events per hour).

MEASUREMENTS AND RESULTS

For a patient with moderate-to-severe OSA, CPAP therapy has an incremental cost-effectiveness ratio (ICER) of $15,915 per QALY gained for the lifetime horizon. Over the lifetime horizon in a population with 50% prevalence of OSA, full-night polysomnography in conjunction with CPAP therapy is the most economically efficient strategy at any willingness-to-pay greater than $17,131 per-QALY gained because it dominates all other strategies in comparative analysis.

CONCLUSIONS

Full-night polysomnography (PSG) is cost-effective and is the preferred diagnostic strategy for adults suspected to have moderate-to-severe OSA when all diagnostic options are available. Split-night PSG and unattended home monitoring can be considered cost-effective alternatives when full-night PSG is not available.

Early diagnosis of sleep related breathing disorders

Obstructive sleep apnea (OSA) being the most frequent sleep related breathing disorder results in non-restorative sleep, an increased cardiovascular morbidity and mortality as well as an elevated number of accidents. In Germany at least two million people have to be expected. If obstructive sleep apnea is diagnosed early enough then sleep may regain its restorative function, daytime performance may be improved and accident risk as well as cardiovascular risk may be normalised. This review critically evaluates anamnestic parameters, questionnaires, clinical findings and unattended recordings during sleep regarding their diagnostic accurracy in recognising OSA. There are numerous tools with insufficient results or too few data disqualifying them for screening for OSA. Promising preliminary results are published concerning neural network analysis of a high number of clinical parameters and non-linear analysis of oximetry itself or in combination with heart rate. Nasal pressure recordings can be used for risk estimation even without expertise in sleep medicine. More data is needed. Unattended portable monitoring used by qualified physicians is the gold standard procedure when screening methods for OSA are compared. It has a very high sensitivity and specificity well documented by several meta-analyses.

Accuracy of automatic analysis of ambulatory recordings of nocturnal breathing disorders is significantly instrumentation dependent

Obstructive sleep apnoea (OSA) is generally diagnosed with ambulatory recordings. Although reliability of automated analysis has been investigated, suitability of one single analysis software for use with different devices is unclear. Here, validity of automatic analysis of recordings with two ambulatory devices and reliability of automatic analysis in detection of mixed and central apnoeas are investigated through 100 and 167 recordings with Venla and Embletta devices, respectively. Recordings were analysed automatically with Somnologica 3.2 and compared to manual analysis. Significant differences were seen between devices in classification of the severity of OSA when automatic analysis was applied. 65.4% and 11.4% of patients with mild obstructive sleep apnoea received false negative diagnosis with Venla and Embletta, respectively. Further, as automatic analysis was seen to have major difficulty in detection and classification of central and mixed apnoeas, manual analysis is suggested when these forms of disease are suspected.

Validation of a portable monitoring system for the diagnosis of obstructive sleep apnea syndrome

STUDY OBJECTIVE

To evaluate if a portable monitor could accurately measure the apnea-hypopnea index (AHI) in patients with a suspicion of obstructive sleep apnea (OSA).

DESIGN

Prospective and randomized.

SETTING

Sleep laboratory.

PARTICIPANTS

80 participants: 70 patients with clinical OSA suspicion and 10 subjects without suspicion of OSA.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Three-order randomized evaluations were performed: (1) STD (Stardust II) used at the participants' home (STD home), (2) STD used simultaneously with PSG in the sleep lab (STD+PSG lab), and (3) PSG performed without the STD (PSG lab). Four AHI values were generated and analyzed: (a) STD home; (b) STD from STD+PSG lab; (c) PSG from STD+PSG (named PSG+STD lab); and (d) PSG lab. Two technicians, blinded to study details, performed the analyses of all evaluations. There was a strong correlation between AHI from the STD and PSG recordings for all 4 AHI values (all correlations above 0.87). Sensitivity, specificity, and positive and negative predictive values at AHI cut-off values of 5, 15, and 30 events/hour were calculated. AHI values from the PSG lab and PSG+STD lab were compared to STD home and STD+PSG lab and showed the best results when STD and PSG were performed simultaneously. In all analyses, the area under ROC curve was at least 0.90. With multiple comparisons, diagnostic agreement was between 91% and 75%. The Bland Altman analyses showed strong agreement between AHI values from the STD and PSG recordings, especially when comparing the AHI from simultaneous STD and PSG recordings.

CONCLUSION

These data suggest that the STD is accurate in confirming the diagnosis of OSA where there is a suspicion of the disorder. Better agreement occurred during simultaneous recordings.

Diagnosis of obstructive sleep apnea syndrome and its outcomes with home portable monitoring

BACKGROUND

The use of portable respiratory monitoring (PM) has been proposed for the diagnosis of obstructive sleep apnea syndrome (OSAS), but most studies that validate PM accuracy have not followed the best standards for diagnostic test validation. The objective of the present study was to evaluate the accuracy of PM performed at home to diagnose OSAS and its outcomes after first validating PM in the laboratory setting by comparing it to polysomnography (PSG).

METHODS

Patients with suspected OSAS were submitted, in random order, to PM at the sleep laboratory concurrently with PSG (lab-PM) or at home-PM. The diagnostic performance was assessed by sensitivity, specificity, positive and negative predictive values, positive likelihood ratio (+LR), negative likelihood ratio (-LR), intraclass correlation coefficients, kappa statistic, and Bland-Altman plot.

RESULTS

One hundred fifty-seven subjects (73% men, mean age +/- SD, 45 +/- 12 yr) with an apnea-hypopnea index (AHI) of 31 (SD +/- 29) events/h were studied. Excluding inadequate recordings, 149 valid comparisons with lab-PM and 121 with unattended home-PM were obtained. Compared to PSG for detecting AHI > 5, the lab-PM demonstrated sensitivity of 95.3%, specificity of 75%, +LR of 3.8, and -LR of 0.11; the home-PM exhibited sensitivity of 96%, specificity of 64%, +LR of 2.7, and -LR of 0.05. Kappa statistics indicated substantial correlation between PSG and PM results. Bland-Altman plot showed smaller dispersion for lab-PM than for home-PM. Pearson product moment correlation coefficients among the three AHIs and clinical outcomes were similar, denoting comparable diagnostic ability.

CONCLUSIONS

This study used all available comparison methods to demonstrate accuracy of PM in-home recordings similar to that of repeated PSGs. PM increases the possibility of correctly diagnosing and effectively treating OSAS in populations worldwide.

Home Sleep Testing in the Diagnosis and Treatment of Sleep Disordered Breathing

Sleep-disordered breathing is a growing public health concern and an integral part of head and neck surgery. Multichannel home sleep testing is a cost-effective, patient-friendly, scientifically valid technique of evaluating patients who present with symptoms of sleep-disordered breathing, typically snoring or daytime sleepiness. Home sleep tests can be dispensed from the physician's office. They have a 95% successful recording rate. Scoring can be autoscore or manual score. There are several protocols that can be followed based on diagnostic outcomes.

Respiratory polygraphy with actigraphy in the diagnosis of sleep apnea-hypopnea syndrome

OBJECTIVE

To determine the utility and reliability of a respiratory polygraphy (RP) device with actigraphy (Apnoescreen II; Erich Jaeger GMBH & CoKg; Wuerzburg, Germany) in the diagnosis of sleep apnea-hypopnea syndrome (SAHS).

DESIGN

A prospective randomized study with blinded analysis.

PATIENTS

Sixty-two patients with suspected SAHS.

MEASUREMENTS

the following two RP studies were performed: one in the sleep laboratory (sleep laboratory RP [LRP]), simultaneously with polysomnography; and the other at home (home RP [HRP]). To study the interobserver reliability of RP, two manual analyses were carried out by two different researchers.

RESULTS

In LRP, when the respiratory disturbance index was calculated using the total sleep time estimated by actigraphy (RDI) as a denominator, the sensitivity ranged between 94.6% and 100%, and the specificity between 88% and 96.7% for the different cutoff points of the apnea-hypopnea indexes studied. When the respiratory disturbance index was calculated according to the total recording time (RDITRT), the sensitivity was slightly lower (91.6 to 96.9%) and the specificity was similar (92 to 96.7%). In HRP, the sensitivity of the RDI ranged between 83.8% and 95.8%, and the specificity between 92% and 100%, whereas, when the RDITRT was used, the sensitivity was between 83.8% and 87.5%, and the specificity was between 94.7% and 100%. With regard to interobserver reliability, the intraclass correlation coefficient for the RDI of the two analyses of the RP was 0.99 for both LPR and HPR.

CONCLUSION

HPR is an effective and reliable technique for the diagnosis of SAHS, although it is less sensitive than LRP. Wrist actigraphy improves the results of HRP only slightly.

Laboratory versus portable sleep studies: a meta-analysis

OBJECTIVE

The objective of this meta-analysis study was to compare the accuracy of home sleep studies with laboratory polysomnography in the diagnosis of obstructive sleep apnea (OSA).

METHODS

Eligible studies included prospective cohort studies of portable and in-laboratory sleep studies performed on the same groups of patients. A comparison of respiratory disturbance index (RDI), mean low oxygen saturation levels, sleep time, rate of inadequate studies, and average cost per examination was made between portable and in-laboratory sleep studies. A total of 18 papers were identified in two independent Medline searches.

RESULTS

RDI values on portable sleep studies were 10% lower on average compared with laboratory studies (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.87-0.92). There was no significant difference in the mean low oxygen saturation on portable versus laboratory studies (OR, 1.0; 95% CI, 0.94-1.10). Recorded sleep time was significantly higher by 13% for laboratory compared with portable studies (OR, 0.87; 95% CI, 0.86-0.89), and portable studies were significantly more likely to give a poor recording when compared with laboratory examinations (P = .0001). The cost of home studies ranged from 35% to 88% lower than laboratory studies across a number of countries.

CONCLUSION

Home sleep studies provide similar diagnostic information to laboratory polysomnograms in the evaluation of sleep-disordered breathing but may underestimate sleep apnea severity. The lower cost of home sleep studies makes it a viable screening tool for patients with suspected OSA; however, these lower costs are partially offset by the higher rate of inadequate examinations.

Cardiorespiratory-based sleep staging in subjects with obstructive sleep apnea

A cardiorespiratory-based automatic sleep staging system for subjects with sleep-disordered breathing is described. A simplified three-state system is used: Wakefulness (W), rapid eye movement (REM) sleep (R), and non-REM sleep (S). The system scores the sleep stages in standard 30-s epochs. A number of features associated with the epoch RR-intervals, an inductance plethysmography estimate of rib cage respiratory effort, and an electrocardiogram-derived respiration (EDR) signal were investigated. A subject-specific quadratic discriminant classifier was trained, randomly choosing 20% of the subject's epochs (in appropriate proportions of W, S and R) as the training data. The remaining 80% of epochs were presented to the classifier for testing. An estimated classification accuracy of 79% (Cohen's kappa value of 0.56) was achieved. When a similar subject-independent classifier was trained, using epochs from all other subjects as the training data, a drop in classification accuracy to 67% (kappa = 0.32) was observed. The subjects were further broken in groups of low apnoea-hypopnea index (AHI) and high AHI and the experiments repeated. The subject-specific classifier performed better on subjects with low AHI than high AHI; the performance of the subject-independent classifier is not correlated with AHI. For comparison an electroencephalograms (EEGs)-based classifier was trained utilizing several standard EEG features. The subject-specific classifier yielded an accuracy of 87% (kappa = 0.75), and an accuracy of 84% (kappa = 0.68) was obtained for the subject-independent classifier, indicating that EEG features are quite robust across subjects. We conclude that the cardiorespiratory signals provide moderate sleep-staging accuracy, however, features exhibit significant subject dependence which presents potential limits to the use of these signals in a general subject-independent sleep staging system.

Evaluation of type 3 portable monitoring in unattended home setting for suspected sleep apnea: factors that may affect its accuracy

OBJECTIVE

This study evaluates the reliability of type 3 portable monitoring (PM) in a home setting.

STUDY DESIGN AND SETTING

Prospective study in sleep laboratory. Type 3 device (Stardust II) was evaluated in comparison with standard polysomnography (PSG) among patients with obstructive sleep apnea. Quality of recorded data and agreement between PM and PSG results were evaluated.

RESULTS

Low quality of recorded data was observed only in 5 cases. Pattern of disordered breathing was recognized correctly by PM. Apnea/hypopnea index (AHI) correlated well with a mean bias of 3.7 +/- 13.1/h. High sensitivity of PM was observed generally, whereas specificity was lower in mild patients. AHI, record time, and sleep position were found to be the main factors that would affect the accuracy of PM.

CONCLUSION

Type 3 PM is feasible in unattended home-setting for routine examination. Influence of the factors above should be comprehensively considered especially for mild patients.

Screening for obstructive sleep apnea: an evidence-based analysis

Sleep disordered breathing is a spectrum of diseases that includes snoring, upper airway resistance syndrome, and obstructive sleep apnea (OSA). Obstructive sleep apnea is a common sleep disorder and is estimated to have an incidence of 24% in men and 9% in women. However, many authors believe that up to 93% of women and 82% of men with moderate to severe OSA remain undiagnosed. There is a strong link between sleep disordered breathing and hypertension, believed to be due to sleep fragmentation, intermittent hypoxemia, and increased sympathetic tone, which results in a higher mortality and morbidity rate among these patients. It is therefore desirable to attempt to diagnose all patients with OSA, to institute early treatment intervention, and to prevent development of cardiovascular complications. The gold standard for diagnosing OSA remains the attended overnight level I polysomnogram. However, in view of the limited resources, including limited number of recording beds, high cost, long waiting lists, and labor requirements, many authors have explored the use of clinical predictors or questionnaires that may help to identify higher-risk patients. Screening devices in the form of single or multiple channel monitoring systems have also been introduced and may represent an alternative method to diagnose OSA. The ideal screening device should be cheap, readily accessible, easily used with minimal instructions, have no risk or side effects to the patient, and be safe and accurate. We review a variety of clinical predictive formulae and several screening devices available for the diagnosis of OSA.

Pulse transit time in paediatric respiratory sleep studies

Pulse transit time (PTT) has emerged over the recent decades as a simple and non-invasive measure to quantify inspiratory effort changes in adults with sleep disordered breathing (SDB). Hence, this shows promise to be an effective screening tool for the paediatrics. However, little is known about its utility and suitability until recent studies has been provided quantitative knowledge about its relevance in clinical investigations. In this review, the origins, normative values, current uses and technical issues in its application to paediatric monitoring, particularly during sleep are discussed. Preliminary findings from these investigations suggest favourably its potential as an important element to screen SDB in the children population.

Description and validation of the apnea risk evaluation system: a novel method to diagnose sleep apnea-hypopnea in the home

STUDY OBJECTIVES

To evaluate the accuracy and practicality of the Apnea Risk Evaluation System (ARES; Advanced Brain Monitoring; Carlsbad, CA), a limited-channel system for diagnosing sleep apnea/hypopnea in the home.

DESIGN

Prospective randomized study with blinded analysis.

SETTINGS

Two independent, community-based, sleep-disorders centers and the participants' homes.

PARTICIPANTS

Two hundred ninety-nine subjects were recruited, including 210 consecutive willing patients referred by community physicians to the centers because of suspected sleep apnea; 36 "general medical" patients recruited from community physicians' offices; and 53 "presumably healthy" subjects recruited from community centers.

MEASUREMENTS AND RESULTS

Manual scoring of attended in-laboratory full-night or split-night polysomnography by trained technologists supervised by physicians board certified in sleep medicine, and automated scoring of the limited-channel system used attended in the laboratory and unattended at home. The definition of the polysomnography apnea-hypopnea index (AHI) and the ARES respiratory disturbance index was the total number of events divided by the study duration in hours. Two hundred eighty-four valid comparisons of in-laboratory simultaneous polysomnography and ARES and 187 valid comparisons of in-laboratory polysomnography with a separate 2 nights of unattended self-applied ARES Unicorder (Advanced Brain Monitoring) were obtained. A diagnostic AHI cutoff of > 10 was used to establish the accuracy and validity of the ARES. The concurrent in-laboratory comparison yielded a sensitivity of 97.4, a specificity of 85.6, a positive predictive value of 93.6, and a negative predictive value of 93.9; in-home comparison sensitivity, specificity, positive predictive value, and negative predictive value were 91.5, 85.7, 91.5, and 85.7, respectively.

CONCLUSIONS

The ARES demonstrated consistently high sensitivity and specificity for both in-laboratory and in-home recordings. In patients at risk for sleep apnea who do not a priori need an attended study, the ARES could provide a low-cost alternative to traditional polysomnography.