A Review on Automated Sleep Study

In recent years, research on automated sleep analysis has witnessed significant growth, reflecting advancements in understanding sleep patterns and their impact on overall health. This review synthesizes findings from an exhaustive analysis of 87 papers, systematically retrieved from prominent databases such as Google Scholar, PubMed, IEEE Xplore, and ScienceDirect. The selection criteria prioritized studies focusing on methods employed, signal modalities utilized, and machine learning algorithms applied in automated sleep analysis. The overarching goal was to critically evaluate the strengths and weaknesses of the proposed methods, shedding light on the current landscape and future directions in sleep research. An in-depth exploration of the reviewed literature revealed a diverse range of methodologies and machine learning approaches employed in automated sleep studies. Notably, K-Nearest Neighbors (KNN), Ensemble Learning Methods, and Support Vector Machine (SVM) emerged as versatile and potent classifiers, exhibiting high accuracies in various applications. However, challenges such as performance variability and computational demands were observed, necessitating judicious classifier selection based on dataset intricacies. In addition, the integration of traditional feature extraction methods with deep structures and the combination of different deep neural networks were identified as promising strategies to enhance diagnostic accuracy in sleep-related studies. The reviewed literature emphasized the need for adaptive classifiers, cross-modality integration, and collaborative efforts to drive the field toward more accurate, robust, and accessible sleep-related diagnostic solutions. This comprehensive review serves as a solid foundation for researchers and practitioners, providing an organized synthesis of the current state of knowledge in automated sleep analysis. By highlighting the strengths and challenges of various methodologies, this review aims to guide future research toward more effective and nuanced approaches to sleep diagnostics.

Home Sleep Testing versus Traditional Polysomnography: Pros and Cons

Obstructive sleep apnea (OSA) is associated with long-term cardiovascular and respiratory comorbidities and increased burden on the health-care system. Early and accurate diagnosis is essential to reduce physical and financial implications of the disease. Polysomnography uses neurophysiologic channels as well as basic respiratory and sleep parameters to best estimate the presence and/or severity of OSA. Although home sleep testing may have the potential for more variable results, it is a viable alternative to increase access to diagnosis of OSA and facilitate initiation of positive airway pressure.

Sleep Testing as a Pre-requisite for Commercial Motor Driving License is a Need of the Hour

Commercial drivers, including pilots, suffering from untreated sleep-related disorders endanger many lives. This puts them at risk of increased daytime somnolence. Through this brief communication, we urge the authorities to make the sleep study mandatory for these drivers to diagnose underlying sleep disorders like sleep apnea.

Obstructive sleep apnea diagnosis and beyond using portable monitors

Obstructive sleep apnea (OSA) is a chronic sleep and breathing disorder with significant health complications, including cardiovascular disease and neurocognitive impairments. To ensure timely treatment, there is a need for a portable, accurate and rapid method of diagnosing OSA. This review examines the use of various physiological signals used in the detection of respiratory events and evaluates their effectiveness in portable monitors (PM) relative to gold standard polysomnography. The primary objective is to explore the relationship between these physiological parameters and OSA, their application in calculating the apnea hypopnea index (AHI), the standard metric for OSA diagnosis, and the derivation of non-AHI metrics that offer additional diagnostic value. It is found that increasing the number of parameters in PMs does not necessarily improve OSA detection. Several factors can cause performance variations among different PMs, even if they extract similar signals. The review also highlights the potential of PMs to be used beyond OSA diagnosis. These devices possess parameters that can be utilized to obtain endotypic and other non-AHI metrics, enabling improved characterization of the disorder and personalized treatment strategies. Advancements in PM technology, coupled with thorough evaluation and validation of these devices, have the potential to revolutionize OSA diagnosis, personalized treatment, and ultimately improve health outcomes for patients with OSA. By identifying the key factors influencing performance and exploring the application of PMs beyond OSA diagnosis, this review aims to contribute to the ongoing development and utilization of portable, efficient, and effective diagnostic tools for OSA.

Complications and predictors associated with moderate to severe obstructive sleep apnoea in bariatric surgery: Evaluation of routine obstructive sleep apnoea screening

PURPOSE

Obstructive sleep apnoea (OSA) is a breathing disorder resulting in blockage of airflow and hypo-oxygenation. The incidence of OSA in patients with class 2 or 3 obesity (Body Mass index, BMI >35) is 60-70%. Unfortunately, most bariatric patients are unaware they suffer from OSA. Untreated OSA can lead to perioperative cardiopulmonary complications. The aim of this study was to identify predictors associated with moderate to severe OSA and asses the incidence of OSA-related complications in a large cohort of patients who underwent OSA-screening and treatment if indicated before bariatric surgery.

METHODS

All consecutive patients who underwent primary bariatric surgery between September 2013 and September 2019 were included. Univariable and multivariable logistic regression analysis was performed to identify potential predictors for moderate to severe OSA using sleep studies.

RESULTS

A total of 2872 patients who underwent bariatric surgery were included for analysis. Overall, OSA was identified in 62.5% of all patients and moderate to severe OSA (AHI ≥15) in 28.6%. Independent predictors for moderate to severe OSA were male gender (p < 0.001), age (p < 0.001), preoperative BMI (p < 0.001), preoperative waist circumference (p < 0.001), hypertension (p < 0.001), and dyslipidaemia (p = 0.046). The incidence of OSA-related complications was low (0.8%) and not significantly different among the different OSA severity classes.

CONCLUSION

This is the largest study to assess OSA presence and OSA-related complications in patients undergoing bariatric surgery. The incidence of potential OSA-related complications was low (0.8%). We believe focus could be shifted towards more cost-efficient strategies where OSA screening is omitted such as perioperative continuous monitoring.

Changes in sleep-disordered breathing from the acute to the stable phase of pulmonary embolism: The ESAET study

BACKGROUND

/Objective: Sleep-disordered breathing (SDB) may change from the acute to stable phase of some cardiovascular disorders, but little is known whether these dynamic changes also exist in pulmonary embolism (PE). This study aimed to analyze the changes in the apnea-hypopnea index (AHI) from the acute to stable phase of PE as well as the factors associated.

PATIENTS/METHODS

We conducted a prospective, longitudinal and multicenter study of consecutive adults requiring hospitalization for non-hypotensive acute PE, with a protocol including clinical, imaging (transthoracic echocardiography [TTE] and computed tomography), blood tests and a sleep study within 48 h of diagnosis of PE. After 3 months of follow-up, the sleep study was repeated. Right ventricular (RV) dysfunction was defined according to TTE criteria.

RESULTS

One hundred and eleven patients (mean age [SD]: 63 [15] years; body mass index: 28.4 [4.7] kg/m2) were included. The initial AHI was 24.4 (21.8) events/h (AHI≥5: 82.8 %; AHI≥30: 33.3 %). Seventy-seven patients (69.4 %) had RV dysfunction. In the overall cohort, the AHI decreased by 8.7 events/h from the acute to stable phase (24.4/h vs. 15.7/h; p=0.013). Patients with RV dysfunction showed a greater decrease in AHI (mean decrease 12.3/h vs. 0.43/h). In the multivariable analysis a drop of an AHI≥5 events/hour was independently associated with the presence of initial RV dysfunction (hazard ratio 3.9; 95%CI 1.3 to 12.1).

CONCLUSIONS

In hemodynamically stable patients with acute PE, there is a transient but clinically significant decrease in the AHI from the acute to stable phase, particularly when initially presenting with RV dysfunction.

How to interpret a negative high-resolution pulse oximetry in hospitalized patients screened for obstructive sleep apnea: an exploratory analysis

INTRODUCTION

Obstructive sleep apnea (OSA) is a highly prevalent disorder that often is unrecognized. Recently, a novel protocol for screening hospitalized patients for OSA resulted in early initiation of positive airway pressure (PAP) therapy and early post-discharge follow-up. The protocol utilizes a combination of high-resolution pulse oximetry (HRPO) and home sleep apnea tests (HSATs); the former has been well-validated in previous studies against HSAT and polysomnography. While a definitive treatment plan can be generated for patients with a positive HRPO for OSA, it is less clear how best to manage patients with a negative HRPO.

MATERIALS AND METHODS

A retrospective analysis of a registry of patients screened for OSA was conducted. Consecutive patients with HRPO-derived ODI (oxygen desaturation index) < 5/h who underwent same-night HRPO and HSAT were identified. The demographic and clinical characteristics of patients with ODI < 5/h and AHI (apnea hypopnea index) < 5/h were compared with patients with ODI < 5/h and AHI ≥ 5/h.

RESULTS

The analysis revealed 190 patients with ODI < 5/h. Only 23 (12%) of these patients had AHI ≥ 5/h. When compared with patients who had ODI < 5/h and AHI < 5/h, there was no difference in most testing and patient characteristics. However, antiplatelet use and total time in minutes with saturation < 88% greater than 100 min were associated with a higher likelihood of discordant ODI and AHI.

CONCLUSION

HRPO-derived ODI has a low rate of false negativity. Clinicians should be aware of the possibility of a false negative ODI for patients with antiplatelet use and time with saturation < 88% greater than 100 min and antiplatelet therapy.

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.

Acceptability, adaptability and adherence to CPAP therapy among Aboriginal Australians with OSA - "The A5 study"

BACKGROUND

Studies examining how Australian Aboriginal people will accept, adapt and adhere to interventions such as continuous positive airway pressure (CPAP) therapy in the management of obstructive sleep apnoea (OSA) are sparsely reported.

METHODS

In this study, clinical, demographic, polysomnographic (PSG) and CPAP data were utilised to assess and predict acceptance and adherence to CPAP therapy among adult Aboriginal Australians diagnosed to have OSA.

RESULTS

Of the 649 Aboriginal patients with OSA, 49% accepted to trial CPAP therapy. Patients who accepted to trial CPAP showed more severe OSA (65vs.35% with severe OSA), reported higher daytime sleepiness (median 10vs.9), and had a higher BMI (83vs.73% obese). Of those who accepted to trial CPAP, 62% adapted to therapy (used the device for more than 30 days). Patients who adapted had more severe OSA (71vs.54% with severe OSA), and were more likely to live in urban areas (63vs.40%). Of those who adapted, 32% were adherent to therapy. Adherent patients were more likely to live in urban areas (84vs.53%), though there was no difference in OSA severity between adherent and non-adherent patients. In multivariate models remote location and more severe OSA predicted CPAP acceptance, while urban location and more severe OSA predicted adaptation, and urban location and higher oxygen saturation nadir predicted adherence.

CONCLUSIONS

Acceptance to trial CPAP therapy was observed in the presence of symptomatic and severe OSA. However, long term adherence to CPAP therapy was significantly influenced by patients' residential location, with patients residing in remote/rural settings demonstrating significantly lower adherence rates.

Sleep testing during the pandemic

BACKGROUND

The COVID-19 pandemic disrupted the U.S. healthcare system, reducing the capacity available for unrelated conditions, such as sleep disordered breathing, and increasing concerns about the safety of in-lab testing. This study characterizes how the pandemic impacted the assessment of sleep disordered breathing and use of associated services.

METHODS

Sleep testing claims occurring between January 2019 and June 2021 were extracted from the database of a national healthcare organization. Utilization was trended. Logistic regressions were run to assess the association between quarter of initial testing, whether testing was followed by treatment, and whether testing was followed by a clinical visit with a diagnosis related to sleep apnea, after controlling for patient-related factors. A Cox proportional hazards model assessed factors influencing time to treatment. Finally, a logistic regression assessed factors influencing the finality of home-based testing.

RESULTS

In Q2 2021, home-based testing utilization was 134% of its initial level, while in-lab and split night testing were both at 61% of initial levels. Patients receiving initial home-based testing did not significantly differ in their likelihood of treatment, but were significantly less likely to have a clinical visit for sleep apnea (P < 0.01). Patients initially tested in 2021 were treated significantly more quickly than those initially tested in Q1 2019. Home-based testing occurring in Q4 2019 or later was significantly more likely to be definitive than home-based testing occurring Q1 2019.

CONCLUSIONS

Home-based sleep testing increased significantly and durably in 2020, and was associated with faster time to treatment than initial in-lab testing.

Evaluation of auditory system in obstructive sleep apnea patients

OBJECTIVES

Obstructive sleep apnea (OSA) has been associated with auditory dysfunction both to the cochlear and higher auditory pathways. However, available literatures presented conflicting results. We aimed to study the impact of OSA severity and their polysomnography parameters on hearing function.

MATERIALS AND METHODS

A total of 44 patients were included after evaluation for sleep disorders and were divided into four groups in accordance with apnea-hypopnea index (AHI). Pure tone audiometry (PTA), distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) were compared in commensurate with the severity of AHI. Polysomnography oximetry parameters of oxygen desaturation index, mean SPO2, minimum SPO2 and percent SPO2 < 90% were correlated with their respective PTA, DPOAE and ABR results.

RESULTS

There was no significant change in the PTA, DPOAE and ABR results in connection with AHI severity. However, we found significant correlations between mean SPO2 and percent SPO2 < 90% with ABR wave I, III and V absolute latencies. Minimum SPO2 was also significantly correlated with wave III peak latency changes.

CONCLUSIONS

Mean SPO2, percent SPO2 < 90% and minimum SPO2 could be key prognostic indicators of central auditory dysfunction in OSA patients. These parameters should be explored further as indicators of OSA severity rather than utilizing AHI alone. The hypoxic burden derived could be a better predictor of auditory function abnormalities rather than one derived from AHI.

Weaning oxygen in infants with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a form of chronic lung disease commonly seen in preterm infants as the sequelae following respiratory distress syndrome. The management of evolving BPD aims to minimise lung injury and prevent the impact of hypoxia and hyperoxia. Proposed morbidities include respiratory instability, pulmonary hypertension, suboptimal growth, altered cerebral oxygenation and long-term neurodevelopmental impairment. The ongoing management and associated morbidity present a significant burden for carers and healthcare systems. Long-term oxygen therapy may be required for variable duration, though there is a lack of consensus and wide variation in practise when weaning supplemental oxygen. Furthermore, a shift in care towards earlier discharge and community care underlines the importance of a structured discharge and weaning process that eliminates the potential risks associated with hypoxia and hyperoxia. This review article describes recent evidence outlining oxygen saturation reference ranges in young infants, on which structured guidance can be based.

Influence of Obstructive Sleep Apnoea Severity on Coronary Collateral Recruitment During Coronary Occlusion

PURPOSE

Obstructive sleep apnoea (OSA) which results in hypoxia may affect the ability to recruit coronary collaterals. The aim of this study was to determine whether the severity of OSA affects collateral recruitment in patients with total coronary occlusions.

METHODS

Patients with total coronary artery occlusion were reviewed. Records from the sleep investigation laboratory were reviewed to identify those patients who had undergone diagnostic polysomnography. Robust coronary collaterals were those with Rentrop grade 2 or 3 collaterals.

RESULTS

Sixty-four patients with a total coronary occlusion had polysomnography performed, of whom 60 patients had OSA. Thirty-two patients (53.3%) had poor collaterals, whilst 28 (46.7%) had robust collaterals. Twenty-four (40%) patients had mild OSA, 10 (16.7%) had moderate OSA and 26 (43.3%) had severe OSA. Patients with robust collaterals were more likely to be males (96.4% vs 74.3%, p < 0.05) and have a history of hypercholesterolaemia (88.9% vs 51.6%, p < 0.01). Patients with robust collaterals had a lower apnoea-hypopnoea index (13.6 vs 45.5, p < 0.05), a higher MinS_aO₂ (85.4% vs 79.8%, p < 0.05), less time S_aO₂ < 90% (0 min vs 30.4 min, p < 0.05) and lower oxygen desaturation index (6.9 vs 26.8, p < 0.05). Those with moderate OSA had a higher mean Rentrop grade (1.6 ± 0.3) than those with mild OSA (1.5 ± 1.1) and severe OSA (0.6 ± 0.2).

CONCLUSION

The presence of more severe OSA is associated with poorer coronary collateral recruitment in patients with total coronary artery occlusion. The effect of treatment of OSA on subsequent ability to recruit collaterals and other cardioprotective mechanisms requires further research.

Low arousal threshold is associated with unfavorable shift of PAP compliance over time in patients with OSA

PURPOSE

To determine the predictive factors of initial and long-term adherence to positive airway pressure (PAP) therapy and factors leading to an unfavorable shift of PAP compliance.

METHODS

This follow-up study was comprised of newly diagnosed patients with obstructive sleep apnea (OSA) amenable to PAP therapy from January 2017 to April 2019. Information on basic demographics, comorbidities, and sleep-related symptoms were collected. PAP adherence data were collected at the end of the first week and the third month.

RESULTS

Of 166 patients enrolled, data from 142 (86%) were in the final analysis. Overall PAP usage was worse at 3 months declining from the first week. After adjusting for age and gender, multinomial logistic regression analysis showed that a small number of sleep-related symptoms (OR, 0.69; 95% CI, 0.52-0.91) and low arousal threshold (ArTH) (OR, 4.44; 95% CI, 1.52-12.98) were associated with higher odds of noncompliance. Low ArTH (OR, 2.87; 95% CI, 1.09-7.57) and lower body mass index (BMI) (OR, 0.88; 95% CI, 0.78-0.99) increased the risk of compliance-to-noncompliance shift. Sixty-two patients with polysomnography were analyzed separately. After adjustment for age and gender, poor sleep efficiency (OR, 0.80; 95% CI, 0.68-0.94) was associated with higher odds of consistent noncompliance. Low ArTH (OR, 15.36; 95% CI, 1.44-164.24) increased the risk of compliance-to-noncompliance shift in this subgroup.

CONCLUSIONS

Lower BMI and low ArTH were associated with an unfavorable shift of PAP compliance over time in patients with OSA, which was different from the predictors of consistent PAP noncompliance of patients with OSA.

Robin Sequence: Neonatal Mandibular Distraction

Pierre Robin sequence is defined by the clinical triad: mandibular hypoplasia, glossoptosis, and airway obstruction. Mandibular distraction osteogenesis (MDO) is a standard treatment of Robin sequence associated with severe airway obstruction and is the only intervention that directly corrects the underlying anatomic pathologic condition. Compared with tongue-lip adhesion, MDO has demonstrated more success in treating airway obstruction in infants with Pierre Robin sequence, including patients with syndromic diagnoses and concomitant anomalies. This article provides a current, comprehensive review of neonatal mandibular distraction and offers treatment guidelines based on a combined surgical experience of more than 400 patients.

Efficacy, predictors of success and failure of an updated lateral pharyngoplasty approach as an independent procedure in treating obstructive sleep apnea with CPAP failures

PURPOSE

To assess predictors of success and failure of an updated lateral pharyngoplasty as an independent procedure in treating obstructive sleep apnea with CPAP failures.

METHODS

Forty-six patients with known OSAS who were resistant to CPAP or failures were included. BMI, Stop-Bang score, and sleep study data were recorded before and after the updated Cahali pharyngoplasty procedure. Pre-operative DISE was done for all cases; however, postoperative DISE was done only for non-responders.

RESULTS

Successful operation outcomes achieved in 69.6% (32 cases) and 30.4% (14 cases) were failure rates. Postoperative snoring index, Stop Bang score, and AHI were significantly decreased compared to pre-operative data (p value < 0.001). There is statistically a significant increase in minimal and baseline SpO₂ postoperatively (p value < 0.001). Patients with no laryngeal collapse (L0) predict operation success. However, patients with high pre-operative snoring index, collapse at lateral wall hypopharynx, high tongue collapse, laryngeal collapse, tongue palate interaction, and low grades tonsils (1, 2) predict the failure of the surgery (p value = 0.006*,0.024*,0.047*, respectively).

CONCLUSION

Updated Cahali lateral pharyngoplasty could not be used as an independent procedure in all OSA patients. The lack of laryngeal collapse (L0) is a considerable success predictor for the procedure. However, the pre-operative low-grade tonsils (1, 2) and high snoring index predict operation failure.

Agreement analysis of sleep patterns between self-reported questionnaires and actigraphy in adults

PURPOSE

To investigate the agreement in sleep pattern recording by self-reported sleep questionnaires and actigraphy in adults.

METHODS

This is a cross-sectional study. Men and women who met inclusion criteria were recruited for this study. The inclusion criteria were apparently healthy Omani nationals ages 19 to 50 years. Sleep questionnaires were randomly distributed in Muscat either directly or via electronic and paper announcements. Data were collected from the participants using the self-reported questionnaires with four piloted questions for sleep pattern identification and through the actigraphy wristband given to subjects to wear for a week. Cohen's kappa test was performed for agreement analysis.

RESULTS

A total of 964 Omani subjects between ages 18 and 59 years of both genders were recruited and completed the questionnaires successfully. Out of these, only 321 subjects wore the actigraphy wristband for 1 week (response rate = 33%). Agreement analysis reported a mild level of agreement for the monophasic (41%), moderate level for biphasic (59%), and good level for polyphasic (70%) sleep patterns. The overall agreement level of sleep patterns between the two methods was 57%. There is a low specificity of self-reported assessment in reporting sleep pattern.

CONCLUSION

The average agreement level of subjective versus objective assessments of sleep patterns was moderate at 57% and self-reported sleep pattern is not specific. The study recommends the use of actigraphy along with sleep questionnaires for accurate assessment of sleep patterns in cohort studies.

Obstructive sleep apnea during acute coronary syndrome is related to myocardial necrosis and wall stress

BACKGROUND

The relative contribution of pathophysiological mechanisms in acute coronary syndrome (ACS) towards obstructive sleep apnea (OSA) is not well-studied. We examined the correlation between severity of OSA and inflammation, myocardial necrosis, wall stress, and fibrosis.

METHODS

A total of 89 patients admitted with ACS underwent a sleep study during index admission. Plasma levels of high-sensitivity C-reactive protein (hs-CRP), troponin I, N-terminal pro-brain natriuretic peptide (NT-proBNP), and suppression of tumorigenicity 2 (ST2) were prospectively analyzed. Two patients diagnosed with central sleep apnea were excluded.

RESULTS

The recruited patients were divided into no (AHI <5 events/hour, 9.2%), mild (5-<15, 27.6%), moderate (15-<30, 21.8%), and severe (≥30, 41.4%) OSA. Compared to the no, mild and moderate OSA groups, the severe OSA group had a higher body mass index (p = 0.005). They were also more likely to present with ST-segment elevation ACS (versus non-ST-segment elevation ACS) (p = 0.041), have undergone previous coronary artery bypass grafting (p = 0.013), demonstrate complete coronary occlusion during baseline coronary angiography (p = 0.049), and have a larger left atrial diameter measured on echocardiography (p = 0.029). Likewise, the severe OSA group had higher plasma levels of hs-CRP (p = 0.004), troponin I (p = 0.017), and NT-proBNP (p = 0.004), but not ST2 (p = 0.10). After adjustment for the effects of confounding variables, OSA was independently associated with troponin I (ie, myocardial necrosis; p = 0.001) and NT-proBNP (ie, myocardial wall stress; p = 0.008).

CONCLUSION

Severe OSA during the acute phase of ACS was associated with extensive myocardial necrosis and high myocardial wall stress, but not with inflammation and myocardial fibrosis.

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.

Adherence to prescribed overnight sleep study in patients suspected of sleep apnea: problem size and influential factors

PURPOSE

Despite the serious consequences of sleep apnea, some patients do not follow their physicians' advice to undergo a sleep study. The present study aimed to determine the rate of adherence and influencing factors in conducting a polysomnography test in patients suspected of obstructive sleep apnea.

METHODS

This qualitative and quantitative analysis was conducted between July 2017 and November 2019 on patients suspected of sleep apnea. The quantitative analysis aimed at determining the rate of adherence through a retrospective cross-sectional study. The qualitative content analysis was conducted on purposefully selected subgroup of patients suspected of obstructive sleep apnea who were referred for polysomnography. The required data were collected through the semi-structured in-depth interviews and then recorded, transcribed, and analyzed using SPSS.22 and MAXQDA10.

RESULTS

Quantitative part: Of 311 patients (mean age: 47.6 ± 13.1 years) referred for polysomnography, 283 patients (91%) were at a high risk of developing obstructive sleep apnea. Among those referred for polysomnography, 31% (n = 95) adhered to recommendations for a sleep study. Qualitative part: Factors affecting adherence to polysomnography were categorized as "barriers" and "triggers." Barriers included inadequate knowledge, psychological factors, cost, and the service system. Triggers included adequate knowledge and tangible experience of consequences of the illness.

CONCLUSION

The majority of patients at risk of developing obstructive sleep apnea did not follow the recommendation for polysomnography, indicating a need for systematic interventions. Among the identified barriers, knowledge and psychological factors are modifiable ones that can be addressed with the patient. We theorize that raising awareness among patients by providing additional information and eliminating concerns may help to increase the rate of adherence. Insurance coverage or subsidy to reduce the sleep study costs may also be an effective strategy to increase adherence to recommendations for polysomnography.

Low arousal threshold is associated with unfavorable shift of PAP compliance over time in patients with OSA

PURPOSE

To determine the predictive factors of initial and long-term adherence to positive airway pressure (PAP) therapy and factors leading to an unfavorable shift of PAP compliance.

METHODS

This follow-up study was comprised of newly diagnosed patients with obstructive sleep apnea (OSA) amenable to PAP therapy from January 2017 to April 2019. Information on basic demographics, comorbidities, and sleep-related symptoms were collected. PAP adherence data were collected at the end of the first week and the third month.

RESULTS

Of 166 patients enrolled, data from 142 (86%) were in the final analysis. Overall PAP usage was worse at 3 months declining from the first week. After adjusting for age and gender, multinomial logistic regression analysis showed that a small number of sleep-related symptoms (OR, 0.69; 95% CI, 0.52-0.91) and low arousal threshold (ArTH) (OR, 4.44; 95% CI, 1.52-12.98) were associated with higher odds of noncompliance. Low ArTH (OR, 2.87; 95% CI, 1.09-7.57) and lower body mass index (BMI) (OR, 0.88; 95% CI, 0.78-0.99) increased the risk of compliance-to-noncompliance shift. Sixty-two patients with polysomnography were analyzed separately. After adjustment for age and gender, poor sleep efficiency (OR, 0.80; 95% CI, 0.68-0.94) was associated with higher odds of consistent noncompliance. Low ArTH (OR, 15.36; 95% CI, 1.44-164.24) increased the risk of compliance-to-noncompliance shift in this subgroup.

CONCLUSIONS

Lower BMI and low ArTH were associated with an unfavorable shift of PAP compliance over time in patients with OSA, which was different from the predictors of consistent PAP noncompliance of patients with OSA.

Preliminary results on the impact of simultaneous palatal expansion and mandibular advancement on the respiratory status recorded during sleep in OSAS children

INTRODUCTION

The study aimed to evaluate the evolution of the respiratory status during sleep of OSAS children treated with a custom-made device combining maxillary expansion and mandibular advancement.

MATERIAL AND METHODS

Sleep studies were performed before and after the treatment for 103 children presenting an initial OSAS and Class II malocclusion. Sleep questionnaires were also addressed to parents several years after the end of the treatment to evaluate its long-term effects.

RESULTS

After nine months of treatment, the sleep breathing quality significantly improved: the Apnea/Hypopnea Index systematically decreased ≤5. According to the sleep questionnaires results, 84% of the patients did not show any loud or troubled breathing several years after the end of the treatment.

DISCUSSION

Simultaneous maxillary expansion and mandibular advancement induced an increase of the oral space in the three spatial dimensions, helping in the significant improvement of the OSAS symptoms, with long-terms effects on the sleep breathing quality.

Managing obstructive sleep apnea patients with CPAP failure with a novel Lateral Pharyngoplasty as a stand-alone procedure

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is caused by a complete or partial obstruction of the upper airway. A new Cahali lateral pharyngoplasty as a stand-alone procedure for the treatment of OSA patients, whatever the level and pattern of airway obstruction in patients with CPAP failure or non-compliant patients, is it?

PATIENTS AND METHODS

40 patients with known OSAS non-compliant with CPAP or CPAP failures included. BMI, Stop-Bang score, and sleep study parameters were reported before and after the new Cahali pharyngoplasty operation. Preoperative DISE was done for all cases.

RESULTS

There were 28 (70%) cases with successful operation outcomes, and 12 (30%) failed cases. Postoperative Stop Bang score, AHI, snoring index were significantly reduced in comparison to preoperative data (p-value <0.001); however, minimal SpO₂ and baseline SpO₂ were significantly increased in comparison to preoperative data. There was a significant improvement in AHI postoperative. Patients collapse at the level of lateral wall hypopharynx, high tongue collapse, laryngeal collapse, tongue palate interaction, all significantly predict failure outcome of the operation (p-value = 0.022). However, the absence of laryngeal collapse (L0) had a successful prediction outcome. The high snoring index significantly predicts operation failure. However, preoperative high baseline SpO₂ predicts operation success significantly.

CONCLUSION

The new Cahali lateral pharyngoplasty can be used as a stand-alone procedure in the absence of lateral wall collapse at the level of the hypopharynx (LH), high tongue base collapse (TH), laryngeal collapse (L1) or tongue palate interaction.

[Expert consensus on sleep study and non-invasive positive airway pressure therapy during the epidemic of coronavirus disease 2019]

Coronavirus disease (COVID-19) is mainly transmitted through respiratory droplets, close unprotected contact, and intense aerosols-generating procedures. Sleep study and non-invasive positive airway pressure (NIPAP) therapy can increase the risk of exposure and transmission of new coronaviruses to medical staff and patients. China's national epidemic control has entered a critical stage of overall prevention and control together with the restoration of normal medical care delivery. Based on the characteristics of sleep-disordered breathing, this consensus elaborates on the recommendations from the following four aspects that include patient and medical staff education, optimization of diagnostic and treatment protocols, sterilization of medical devices and the environment, and control of hospital-acquired infection. It is emphasized that the indications for sleep study and NIPAP should be strictly defined according to the local epidemic situation. Portable home sleep study and auto-titration positive airway pressure is recommended. The applications of disposable nasal pressure transducer for sleep study and disposable or personal masks and ventilator tubing for NIPAP are strongly suggested. Moreover, it is necessary to standardize the procedure of NIPAP, to separate the functional divisions in sleep lab, to comply with the protection regulations for medical personnel, and to strengthen the cleaning and disinfection management.

The effect of in-lab polysomnography and home sleep polygraphy on sleep position

PURPOSE

Little is known regarding the influence of in-laboratory polysomnography (PSG) equipment on sleep position, especially on the prevalence of supine positioning, which in many cases may lead to a more severe sleep apnea diagnosis. The aim of this study was to assess the percentage of supine sleep during an in-laboratory PSG compared to that seen during a home sleep apnea test (HSAT).

METHODS

This was a retrospective cohort study comparing in-laboratory PSG and HSAT using a peripheral arterial tone (PAT) technology device.

RESULTS

Of 445 PSG and 416 HSAT studies analyzed, there was no significant difference in the proportion of supine sleep time between PSG (44%) and HSAT (45%, p = 0.53). Analysis of the differences in sleep position (supine versus non-supine), analyzed by sex, BMI (≥ 30 kg/m2 versus < 30 kg/m2), and age (≥ 60 years versus < 60 years), was significant only for women, who had more supine sleep during HSAT at 61 ± 24% than during PSG at 45 ± 26% (p < 0.001).

CONCLUSION

Overall there was no difference in the percentage of supine sleep when comparing in-laboratory PSG to HSAT. However, women had more supine sleep with HSAT than with PSG.

Prevalence of obstructive sleep apnea in an Asian bariatric population: an underdiagnosed dilemma

BACKGROUND

Obesity is a growing health problem that has become a global epidemic. Serial population studies have shown the same in Malaysia, where the prevalence of obesity increased rapidly in the last decade. Currently, bariatric surgery is the most effective treatment in patients with morbid obesity. Obstructive sleep apnea (OSA) is the most common type of sleep-related breathing disorder seen in obesity.

OBJECTIVES

We aim to ascertain the prevalence and severity of OSA in Asian patients who underwent bariatric surgery and were seen in our center.

SETTING

The study was conducted in our university hospital.

METHODS

Study approval was obtained from our institutional review board for a retrospective chart review. A total of 226 patients were included in this review. OSA was noted as absent or present and graded from mild to severe. The patient population was stratified by body mass index according to the World Health Organization guidelines for Asian population.

RESULTS

The overall sample prevalence of OSA was 80.5%. Of these, 24.3% had mild OSA, 23.9% had moderate OSA, and 32.3% had severe OSA. Only 17.3% have been diagnosed with OSA before bariatric workup. Among men, the prevalence of OSA was 93.7% and 75.5% among women.

CONCLUSION

Based on these findings, Asian patients undergoing bariatric workup should be considered for routine polysomnography to enable treatment of OSA.

Reliability of Home Nocturnal Oximetry in the Diagnosis of Overlap Syndrome in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and sleep apnea are common conditions and often coexist. The proper diagnosis of sleep apnea may affect the management and outcome of patients with COPD.

OBJECTIVE

To determine the accuracy of home nocturnal oximetry to distinguish between nocturnal oxygen desaturation related to COPD alone or to sleep apnea in patients with moderate-to-severe COPD who have significant nocturnal hypoxemia with cyclical changes in saturation.

METHODS

This study involved a comparison of home nocturnal oximetry and laboratory-based polysomnography (PSG) in patients with moderate-to-severe COPD considered for inclusion in a trial of nocturnal oxygen therapy. All of the patients had significant nocturnal oxygen desaturation (defined as ≥30% of the recording time with a transcutaneous arterial oxygen saturation <90%) with cyclical changes in saturation suggestive of sleep apnea.

RESULTS

PSG was obtained in 90 patients; 45 patients (mean age = 68 years, SD = 8; 71% men; mean forced expiratory volume in 1 s [FEV1] = 50.6% predicted value, SD = 18.6%; data from 41 patients) fulfilled the criteria for sleep apnea (mean apnea-hypopnea index = 32.6 events/h, SD = 19.9) and 45 patients (mean age = 69 years, SD = 8; 87% men; mean FEV1 predicted value 44.6%, SD = 15%) did not (mean apnea-hypopnea index = 5.5 events/h, SD = 3.8). None of the patients' characteristics (including demographic, anthropometric, and physiologic measures) predicted the diagnosis of sleep apnea according to PSG results.

CONCLUSION

The diagnosis of sleep apnea in patients with moderate to severe COPD cannot rely on nocturnal oximetry alone, even when typical cyclical changes in saturation are seen on oximetry tracing. When suspecting an overlap syndrome, a full-night, in-laboratory PSG should be obtained.

How Relevant Is Pre-operative Obstructive Sleep Apnoea in the Asymptomatic Bariatric Surgery Patient?

INTRODUCTION

The American Academy of Sleep Medicine recommends patients attending for bariatric surgery (BS) to be evaluated for obstructive sleep apnoea (OSA) as untreated OSA is associated with a greater risk of post-operative complications. Not all bariatric patients have symptoms of OSA and their phenotype may be at less risk than the typical sleep clinic phenotype. Therefore, all patients may not require pre-operative sleep studies. This study aimed to establish whether screened and unscreened BS patients are at increased risk of post-operative complications.

METHODS

A retrospective review of BS patients at a single centre, June 2008-May 2017. Demographic data, sleep study outcomes, post-operative complications, length of stay (LOS), intensive care unit (ICU) admission, and readmission rates were reviewed.

RESULTS

A total of 510 patients underwent gastric bypass, sleeve gastrectomy, or gastric banding. 385/510 (75.5%) were female. Mean age was 46 ± 11.27 years, mean BMI was 49 kg/m² ± 7.42. OSA was diagnosed in 300/510 (58.8%) and normal sleep in 57/510 (11.2%). OSA was not associated with increased post-operative complications. No significant difference between screened and unscreened patients for the development of post-operative pulmonary or cardiac complications, (p = 0.607, p = 0.827, respectively). Increasing age was a predictor for pulmonary (p = 0.011) and cardiac (p = 0.018) complications.

CONCLUSION

OSA is very prevalent in morbidly obese patients. The lack of association between patients diagnosed with OSA and unscreened patients, and post-operative complications suggests that not all patients require pre-operative sleep studies. Further studies may help identify which patients can safely avoid OSA screening.

A novel postal-based approach to diagnosing obstructive sleep apnoea in a high-risk population

OBJECTIVE

More than 50% of patients with diabetic macular oedema (DMO) have obstructive sleep apnoea (OSA), but the majority remain undiagnosed. We used a four-channel device (ApneaLink [AL], ResMed, UK) to establish a remote postal-based diagnostic service for patients with DMO. Here we describe our experience.

METHODS

Patients with DMO were invited to participate. Interested patients returned a free-post reply slip to the study team, who posted an AL with pictorial and written instructions to them. Following a single night study, the AL was returned by a freepost service.

RESULTS

Responses from 733 patients meeting the inclusion criteria were received, comprising 469 males and 264 females, mean age 64 years (standard deviation 10.4 years). ALs were issued to 718 patients, of whom 606 completed a diagnostic study. A total of 71 patients (12%) required a repeat study due to inadequacy of the first attempt. Completed sleep studies showed that 75% of respondents had sleep disordered breathing: 4% ODI 0-4/h, 24%; 5-9/h, 19%; 10-19/h, 23%; ≥20/h, 34%; and AHI 0-4/h, 25%; 5-14/h, 38%; 15-29/h, 20%; ≥30/h, 17%. Among 1592 postal events through the national post service, 20 ALs were lost.

CONCLUSIONS

We have demonstrated that a remote postal-based diagnostic service for populations with a high risk of OSA can be successfully performed. This novel approach, which avoids clinic attendance, may be useful in clinical practice.

Exercise tolerance in obstructive sleep apnea-hypopnea (OSAH), before and after CPAP treatment: Effects of autonomic dysfunction improvement

BACKGROUND

Obstructive sleep apnea hypopnea (OSAH) is associated with decreased exercise tolerance and autonomic abnormalities and represents a risk for cardiovascular diseases. The aim of the study was to evaluate the effects of CPAP on cardiovascular autonomic abnormalities and exercise performance in patients with OSAH without changes in lifestyle and body weight during treatment.

METHODS

Twelve overweight subjects with OSAH underwent anthropometric measures, autonomic cardiovascular and incremental symptom-limited cardio-respiratory exercise tests before and after two months of treatment with CPAP.

RESULTS

Lower frequency component of power spectrum of heart rate variability (59.5±24.2 msec² vs 43.2±25.9 msec²; p<0.05) and improvements of maximal workload (99.3±13.5 vs 108.3±16.8%pred.; p<0.05) and peak oxygen consumption (95.3±7.6 vs 105.5±7.9%pred.; p<0.05) were observed in these patients after CPAP, being their BMI unchanged.

CONCLUSIONS

CPAP-induced decrease of sympathetic hyperactivity is associated with better tolerance to the effort in OSAH patients that did not change their BMI and lifestyle, suggesting that OSAH limits per se the exercise capacity.

A description of sleep behaviour in healthy late pregnancy, and the accuracy of self-reports

Background

The importance of maternal sleep and its contribution to maternal and fetal health during pregnancy is increasingly being recognised. However, the ability to accurately recall sleep practices during pregnancy has been questioned. The aim of this study is to test the accuracy of recall of normal sleep practices in late pregnancy.

Methods

Thirty healthy women between 35 and 38 weeks of gestation underwent level III respiratory polysomnography (PSG) with infrared digital video recordings in their own homes. Data regarding sleep positions, number of times getting out of bed during the night and respiratory measures were collected. A sleep questionnaire was administered the morning after the recorded sleep. Continuous data were assessed using Spearman’s Rho and Bland-Altman. Cohen’s Kappa was used to assess recall in the categorical variables.

Results

Two-thirds of participants went to sleep on their left side. There was good agreement in sleep onset position between video and questionnaire data (Kappa 0.52), however the there was poor agreement on position on wakening (Kappa 0.24). The number of times getting out of bed during the night was accurately recalled (Kappa 0.65). Twenty five out of 30 participants snored as recorded by PSG. Questionnaire data was inaccurate for this measure. Bland-Altman plots demonstrated acceptable agreement between video and questionnaire data for estimated sleep duration, but not the time taken to fall asleep (sleep latency). One participant had mild obstructive sleep apnoea and another probable high upper airways resistance.

Conclusions

Sleep onset position, sleep duration and the number of times getting out of bed during the night were accurately recalled, but sleep latency and sleep position on waking were not. This study identifies the sleep variables that can be accurately obtained by questionnaire and those that cannot.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-0905-0) contains supplementary material, which is available to authorized users.

Oral appliance in sleep apnea treatment: respiratory and clinical effects and long-term adherence

PURPOSE

There is an increasing tendency to use oral appliance (OA) as an alternative treatment for sleep apnea. Here we report the long-term adherence and clinical effects of OA therapy.

METHODS

All sleep apnea patients treated at the Department of Dentistry between the years 2006 and 2013 (n = 1208) were reviewed. A questionnaire about OA adherence, asthma symptoms (Asthma Control Test™, ACT), and general health was sent to all patients who continued OA therapy after the 1-month follow-up visit (n = 811). OA was adjusted to obtain at least 70 % of the maximal protrusion of the mandible.

RESULTS

The response rate was 37.4 % (99 women, 204 men). The mean ± SD age and BMI were 58.7 ± 10.3 years and 27.3 ± 4.0 kg/m(2), respectively. During the mean follow-up period of 3.3 years, there was no significant variation in BMI. Forty-one patients abandoned OA therapy yielding an adherence rate of 86 %. Ninety-seven percent of patients used OA ≥4 h/day, and the mean daily use was 7.2 ± 1.1 h. The ACT score improved with OA use from 16.0 ± 5.9 to 20.1 ± 3.8 (p = 0.004), indicating better asthma control. The apnea and hypopnea index decreased significantly from 27 ± 19 at baseline to 10 ± 10 with OA therapy (p = 0.001).

CONCLUSIONS

After a 1-month trial period, the long-term adherence to oral appliance was good. OA therapy decreased apneas and hypopneas significantly, and its long-term use was associated with an improvement in respiratory and asthma symptoms.

Can apneagraphy change our approach in management of snoring and sleep apnoea?

To evaluate role of overnight domiciliary apneagraph in diagnosing severity of sleep apnoea. Prospective audit of 37 patients with Epworth sleepiness score over ten and all patients with history of sleep apnoea presenting to ENT outpatient clinic investigated with apneagraph. Data analysed initially with pulse oximetry findings alone followed by analysis with full apneagraph findings.

RESULTS

Data analysed with pulse oximetry alone showed 31 patients to be simple snorers, but on analysis with apneagraph, 11 of these were shown to be suffering from moderate and one with severe sleep apnoea. There was no correlation between Epworth sleepiness score and severity of sleep apnoea.

CONCLUSION

Management plan can be more evidence based by using apneagraph as a mini sleep study in investigating patients with history of obstructive sleep apnoea. Apneagraph could also be used in diagnosing the level of obstruction in snorers; however, this aspect needs further studying.

Pediatric polysomnography: the patient and family perspective

STUDY OBJECTIVES

The gold-standard test used to diagnose childhood obstructive sleep apnea is polysomnography. However, this test requires an overnight stay at a sleep laboratory and the attachment of multiple sensors to the patient. The long-term impact of this testing on the child and family are not known. We hypothesized that polysomnography does not precipitate acute or chronic psychological effects in children.

METHODS

A consecutive cohort of children who had undergone sleep studies 2 to 4 months prior to the interview were administered a standardized questionnaire via telephone.

RESULTS

Of the 118 families that were eligible to participate, 67% could be contacted and agreed to participate; 87% of respondents reported the experience to have been satisfactory (mean Likert score of 8.6 ± 2.0 [SD] on a scale of 1-10). Similar levels of satisfaction were reported by parents of children with developmental delay or those who were younger than 3 years. The night's sleep was considered typical in 68% of cases. Sleep was less likely to be typical in children younger than 3 years (47%, p = 0.043). Eight percent of children experienced pain during the study. By caregiver report, of those children who remembered the sleep study, memories were positive in 84%. No child had evidence of serious long-term psychological issues.

CONCLUSIONS

The vast majority of children and families found the polysomnography experience to be satisfactory, with no psychological sequelae. However, many children, especially those younger than 3 years, demonstrated sleep patterns different from their usual sleep. The clinical relevance of this finding merits further study. Further research evaluating the generalizability of this study is also needed.