Variations in physician interpretation of overnight pulse oximetry monitoring

Defining obstructive sleep apnoea syndrome: a failure of semantic rules

Obstructive sleep apnoea syndrome (OSAS) is one of the most ubiquitous medical conditions in industrialised society. Since the recognition that symptoms of excessive daytime somnolence, problems with concentration, mood and cognitive impairment, as well as cardiometabolic abnormalities can arise as a consequence of obstructed breathing during sleep, it has been subject to variation in its definition. Over the past five decades, attempts have been made to standardise the definitions and scoring criteria used for apnoeas and hypopnoea, which are the hallmarks of obstructive sleep apnoea (OSA). However, applying these definitions in clinical and research practice has resulted in over- and under-estimation of the severity and prevalence of OSAS. Furthermore, the definitions may eventually become redundant in the context of rapid technological advances in breathing measurement and other signal acquisition. Increased efforts towards precision medicine have led to a focus on the pathophysiology of obstructed breathing during sleep. However, the same degree of effort has not been focused on how and why the latter does or does not result in diurnal symptoms, integral to the definition of OSAS. This review focuses on OSAS in adults and discusses some of the difficulties with current definitions and the possible reasons behind them.

The definition of obstructive sleep apnoea syndrome appears to be in constant flux dependent on the definitions attributed to its diagnostic componentshttps://bit.ly/3zXrWKg

WRISTOX2 is a reliable tool to diagnose obstructive sleep apnoea syndrome

INTRODUCTION

Overnight pulse oximetry is an alternative to polysomnography (PSG) in diagnosing obstructive sleep apnoea syndrome, but its sensitivity is reported to be low.

AIMS

To determine the (a) diagnostic accuracy, interobserver reliability and reliable oxygen desaturation index of 4% (ODI₄) score at diagnosing obstructive sleep apnoea syndrome in children and (b) correlation between the apnoea hypopnoea index (AHI) with ODI₄ and oxygen nadir between both PSG and oximetry.

METHODS

This cross-sectional study included children aged 1-18 years old, undergoing a fully attended overnight PSG for suspected obstructive sleep apnoea syndrome. The Nonin 3150 WristOx₂ ™ [Fig. 2] was worn simultaneously during the PSG. Poor oximetry recordings were excluded. Pulse oximetry was scored using the McGill Oximetry Score (MOS) whereby a score of 2-4 was positive for OSAS. Specificity, sensitivity, positive predictive values (PPV), negative predictive values (NPV) and interobserver reliability of the WristOx₂ were calculated.

RESULTS

One hundred and sixty-two children with a mean (SD) age of 9.3 (±3.5) years (range 2 years 6 months old - 17 years old) were included after excluding 18 children (poor oximetry data [n = 16] and incomplete PSG [n = 2]). Interobserver agreement of the WristOx₂ was 0.8763 (95% CI:0.80, 0.95). WristOx₂ had a sensitivity 50%, specificity 96.7%, PPV 96% and NPV 53% at diagnosing OSAS. ODI₄ ≥ 2 events/hour in oximetry had a sensitivity of 97.6% and negative predictive value of 85.7% at diagnosing OSA.

CONCLUSION

Overnight pulse oximetry with the Nonin 3150 WristOx₂ ™ is an accurate and reliable tool in diagnosing significant OSAS in children.

Technologic advances in the assessment and management of obstructive sleep apnoea beyond the apnoea-hypopnoea index: a narrative review

Obstructive sleep apnoea (OSA) is a growing and serious worldwide health problem with significant health and socioeconomic consequences. Current diagnostic testing strategies are limited by cost, access to resources and over reliance on one measure, namely the apnoea-hypopnoea frequency per hour (AHI). Recent evidence supports moving away from the AHI as the principle measure of OSA severity towards a more personalised approach to OSA diagnosis and treatment that includes phenotypic and biological traits. Novel advances in technology include the use of signals such as heart rate variability (HRV), oximetry and peripheral arterial tonometry (PAT) as alternative or additional measures. Ubiquitous use of smartphones and developments in wearable technology have also led to increased availability of applications and devices to facilitate home screening of at-risk populations, although current evidence indicates relatively poor accuracy in comparison with the traditional gold standard polysomnography (PSG). In this review, we evaluate the current strategies for diagnosing OSA in the context of their limitations, potential physiological targets as alternatives to AHI and the role of novel technology in OSA. We also evaluate the current evidence for using newer technologies in OSA diagnosis, the physiological targets such as smartphone applications and wearable technology. Future developments in OSA diagnosis and assessment will likely focus increasingly on systemic effects of sleep disordered breathing (SDB) such as changes in nocturnal oxygen and blood pressure (BP); and may also include other factors such as circulating biomarkers. These developments will likely require a re-evaluation of the diagnostic and grading criteria for clinically significant OSA.

Using continuous overnight pulse oximetry to guide home oxygen therapy in chronic neonatal lung disease

AIM

The aims of this study are: (i) to survey the knowledge of paediatric clinicians using overnight continuous pulse oximetry data to guide management of infants with chronic neonatal lung disease (CNLD); (ii) to assess the ability of paediatric clinicians to interpret overnight continuous pulse oximetry data; and (iii) to describe the overnight oximetry interpretation practices of paediatric respiratory specialists.

METHODS

Paediatric clinicians from three tertiary teaching hospitals completed an anonymous survey regarding overnight continuous pulse oximetry in chronic neonatal lung disease. Using a modified Delphi technique, paediatric respiratory specialists participated in a concordance exercise and discussions to establish consensus interpretations for 25 oximetry studies. Paediatric clinicians were invited to complete the same exercise as a comparison.

RESULTS

Self-rated knowledge from 74 surveyed clinicians was proportional to clinical experience. Twenty paediatric clinicians and nine paediatric respiratory specialists completed the oximetry exercise with scores of 64% (κ = 0.25) and 80% (κ = 0.45), respectively. Individual parameters like a mean peripheral arterial haemoglobin saturation (SpO₂ ) below 93% and percentage time spent below SpO₂ 93% correlated poorly with the consensus interpretations. Paediatric respiratory specialists instead relied on visual analysis of SpO₂ waveforms, utilising the frequency and depth of desaturations to guide management.

CONCLUSION

Interpretation of overnight oximetry data is variable amongst both paediatric clinicians and respiratory specialists. This likely reflects inadequate evidence defining clinically significant intermittent hypoxaemia, whether in terms of desaturation duration, frequency or nadir.

The uses of overnight pulse oximetry

Overnight pulse oximetry (OPO) has proven to be an effective and beneficial technique to determine the cardiorespiratory status of patients in both the inpatient and outpatient settings. It is a cheap, safe, reliable, simple, and accurate method of patient monitoring as compared to the expensive and labor-intensive method of multichannel polysomnography for detecting sleep-disordered breathing. It provides accurate information about patient's oxygenation status and also helps in monitoring the response to continuous positive airway pressure and in the surgical treatment of obstructive sleep apnea (OSA). Nocturnal hypoxemia portends a poor prognosis in patients of chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD), and neuromuscular diseases. OPO can help its early detection and management.

The effect of isolated nocturnal oxygen desaturations on serum hs-CRP and IL-6 in patients with chronic obstructive pulmonary disease

INTRODUCTION

A majority of patients with chronic obstructive pulmonary disease (COPD) die of cardiovascular disease (CVD), yet the mechanisms responsible for this association are not fully understood. It remains unknown if isolated nocturnal oxygen desaturation (iNOD) could be one of the potential pathways by which the 'inflammatory COPD' phenotype leads to CVD.

OBJECTIVES

We aimed to evaluate if COPD patients who meet the Medicare guidelines for nocturnal oxygen therapy (iNOT+) had higher serum hs-CRP and IL-6 than those who did not meet the guidelines for iNOT (iNOT-).

METHODS

Patients with moderate to severe COPD (ie FEV1 < 80% and FEV1/FVC < 70), who were not on oxygen, underwent nocturnal oximetry on room air. Serum IL-6 and hs-CRP were collected the morning after the nocturnal oximetry testing.

RESULTS

A total of 28 patients were included in the study, 8 of whom had more than 5 minutes and 5% of their sleep time spent at oxygen saturation less than 88% and constituted the iNOT+ group. Only serum hs-CRP was significantly higher in iNOT+ than iNOT- (P = 0.050). There was no difference in the rate of COPD exacerbations at one and three months, or five-year survival between the groups (P > 0.3).

CONCLUSION

COPD patients who have more than 5 minutes and 5% of their sleep time spent at oxygen saturation less than 88% have increased hs-CRP, which is associated with increased risk of future CVD.

Correlation Between Oxygen Saturation and Pulse Tracing Patterns on Overnight Oximetry With Normal Desaturation Index Is an Independent Predictor of Obstructive Sleep Apnea

STUDY OBJECTIVES

Overnight pulse oximetry (OPO) is commonly used as a screening test for obstructive sleep apnea. Heart rate variability (HRV) correlates well with apnea-hypopnea index during polysomnography (PSG). We hypothesized that visual correlation of episodic increase in HRV with minimal oxygen desaturations on normal OPO (oxygen desaturation index less than 5 events/h) is predictive of OSA.

METHODS

A retrospective analysis of patients undergoing OPO and PSG in 1 year was performed. We included only OPO performed on room air and interpreted as normal. Visual correlation between simultaneous increase in HRV and minimal oxygen desaturation was independently assessed by three raters, resulting in the consensus agreement. The primary outcome was presence of OSA on the subsequent PSG.

RESULTS

Of 936 patients with OPO and PSG, 109 patients had normal overnight oximetry study on room air. Of these, 65 (60%) were females, median (interquartile range) age was 54 years (44, 67), body mass index was 29 kg/m² (25, 32), and the median oxygen desaturation index was 1.8 events/h (1, 2.7). Consensus agreement identified 54 patients with visual correlation between pulse and minimal oxygen desaturations. Thirty-two patients (29%) were found to have OSA on PSG, of which 24 (75%) could have been accurately predicted by the consensus agreement (odds ratio 4.70, 95% confidence interval 1.87-11.8, P < .001). When adjusted for pertinent clinical and demographic variables, consensus agreement was independently associated with diagnosis of OSA on subsequent PSG (odds ratio 5.6, 95% confidence interval 1.76-20.9, P = .003).

CONCLUSIONS

Visual correlation between episodic increase in HRV and minimal oxygen desaturations on OPO is an independent predictor of OSA, and promising marker for clinical use.

The Overlap Syndrome

The overlap syndrome (OS) was first coined by David C. Flenley in 1985 to describe the coexistence of obstructive sleep apnea (OSA) in patients with chronic obstructive pulmonary disease (COPD). Patients with OS experience more profound nocturnal oxygen desaturation (NOD) than patients with OSA or COPD alone. This underlying hypoxia in OS increases the risk of cardiovascular disease including atrial fibrillation, right heart failure, and pulmonary hypertension, thereby increasing the mortality associated with the disease. Keeping in mind the risk of mortality, it is crucial for clinicians to clinically evaluate the patients with OSA or COPD for the occurrence of OS and provide effective treatment options for the same. This review aims to highlight the pathophysiology and the risks associated with the OS along with early detection and appropriate management protocols to reduce the mortality associated with it.

High Interrater Reliability of Overnight Pulse Oximetry Interpretation Among Inexperienced Physicians Using a Structured Template

STUDY OBJECTIVES

To assess the interrater reliability and accuracy of overnight pulse oximetry (OPO) interpretations by pulmonary fellows using a comprehensive structured template and after a brief educational session.

METHODS

Using the template, four pulmonary and critical care (PCC) fellows interpreted OPO saturation waveforms and parameters extracted from 50 adult consecutive in-laboratory sleep studies. The template included three saturation parameters (mean saturation, oxygen desaturation index [ODI], and cumulative desaturation time) and description of the saturation waveform. A scoring system was proposed combining waveform characteristics and ODI to determine the suspicion for moderate to severe sleep apnea. Waveform description and mean saturation determined the suspicion for cardiopulmonary disease (CPD). Cumulative desaturation time determined need for oxygen prescription. Apnea-hypopnea index was extracted from the sleep study results.

RESULTS

The overall interrater reliability for final recommendations (sleep apnea suspicion, presence of CPD, and oxygen prescription) was high (kappa = .81, 95% confidence interval [CI] .76-.88). Good agreement was noted in CPD evaluation and suspicion of moderate to severe sleep apnea (kappa = .70, 95% CI .46-.86 and kappa = .65, 95% CI .56-.77 respectively). The interrater reliability for oxygen prescription was in an excellent range (kappa = .98, 95% CI .91-1.00). The accuracy of a high sleep apnea suspicion score in detecting apnea-hypopnea index ≥ 15 events/h ranged from 88.0% to 94.0% (sensitivity 91.3% to 95.7%, specificity 81.5% to 92.6%). Desaturations due to CPD were identified by 75% of the raters as desaturations due to conditions other than sleep apnea.

CONCLUSIONS

A structured template for OPO interpretation can produce a high interrater agreement and good accuracy, and make it a reliable clinical tool.

COMMENTARY

A commentary on this article appears in this issue on page 497.

Diagnostic approaches to respiratory sleep disorders

Sleep disordered breathing (SDB) comprises a number of breathing disturbances occurring during sleep including snoring, the obstructive sleep apnoea/hypopnea syndrome (OSAHS), central sleep apnoea (CSA) and hypoventilation syndromes. This review focuses on sleep disordered breathing and diagnostic approaches in adults, in particular clinical assessment and overnight assessment during sleep. Although diagnostic approaches to respiratory sleep disorders are reasonably straightforward, they do require a degree of clinical acumen when it comes to assessing severity and management options. Diagnosing respiratory sleep disorders on clinical features alone has limitations. Monitoring and measuring respiration during sleep has undergone many advances in the last 40 years in respect of quality and validity, largely regarding OSAHS. Despite the improvement in our diagnostic standards and recognition of sleep disordered breathing, many limitations still need to be overcome. Apart from assessing the individual patient, population screening for sleep disorders continues to preoccupy health professionals and policy makers in many countries. Research in the field is pushing current boundaries in terms of simplifying diagnosis and enhancing screening for sleep disordered breathing in large populations. At present, a number of these newer approaches require further validation.

Sleep disorders in chronic obstructive pulmonary disease: etiology, impact, and management

ABSTRACT

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality and may frequently be complicated by sleep disorders. Insomnia and obstructive sleep apnea are commonly encountered in patients with COPD. Nocturnal hypoxemia is also prevalent in COPD may occur despite adequate awake oxygenation and can be especially severe in rapid eye movement sleep. Additionally, several factors--some of them unique to COPD--can contribute to sleep-related hypoventilation. Recognition of hypoventilation can be vital as supplemental oxygen therapy itself can acutely worsen hypoventilation and lead to disastrous consequences. Finally, accruing data establish an association between restless leg syndrome and COPD--an association that may be driven by hypoxemia and/or hypercapnia. Comorbid sleep disorders portend worse sleep quality, diminished quality of life, and multifarious other adverse consequences. The awareness and knowledge regarding sleep comorbidities in COPD has continued to evolve over past many years. There are still several lacunae, however, in our understanding of the etiologies, impact, and therapies of sleep disorders, specifically in patients with COPD. This review summarizes the latest concepts in prevalence, pathogenesis, diagnosis, and management of diverse sleep disorders in COPD.

Examination of pulse oximetry tracings to detect obstructive sleep apnea in patients with advanced chronic obstructive pulmonary disease

Nocturnal hypoxemia and obstructive sleep apnea (OSA) are common comorbidities in patients with chronic obstructive pulmonary disease (COPD). The authors sought to develop a strategy to interpret nocturnal pulse oximetry and assess its capacity for detection of OSA in patients with stage 3 to stage 4 COPD. A review of consecutive patients with COPD who were clinically prescribed oximetry and polysomnography was conducted. OSA was diagnosed if the polysomnographic apnea-hypopnea index was >15 events⁄h. Comprehensive criteria were developed for interpretation of pulse oximetry tracings through iterative validation and interscorer concordance of ≥80%. Criteria consisted of visually identified desaturation 'events' (sustained desaturation ≥4%, 1 h time scale), 'patterns' (≥3 similar desaturation⁄saturation cycles, 15 min time scale) and the automated oxygen desaturation index. The area under the curve (AUC), sensitivity, specificity and accuracy were calculated. Of 59 patients (27 male), 31 had OSA (53%). The mean forced expiratory volume in 1 s was 46% of predicted (range 21% to 74% of predicted) and 52% of patients were on long-term oxygen therapy. Among 59 patients, 35 were correctly identified as having OSA or not having OSA, corresponding to an accuracy of 59%, with a sensitivity and specificity of 59% and 60%, respectively. The AUC was 0.57 (95% CI 0.55 to 0.59). Using software-computed desaturation events (hypoxemia ≥4% for ≥10 s) indexed at ≥15 events⁄h of sleep as diagnostic criteria, sensitivity was 60%, specificity was 63% and the AUC was 0.64 (95%CI 0.62 to 0.66). No single criterion demonstrated important diagnostic utility. Pulse oximetry tracing interpretation had a modest diagnostic value in identifying OSA in patients with moderate to severe COPD.

Preoperative screening and perioperative care of the patient with sleep-disordered breathing

PURPOSE OF REVIEW

Emerging data are raising concerns that patients with known or suspected obstructive sleep apnea (OSA) are at increased risk for a myriad of perioperative complications. Strategies to identify patients preoperatively with OSA, or at risk for OSA, are being advocated. In addition, approaches to identify patients most at risk for OSA-related postoperative complications have been described. While lacking solid evidence, a number of perioperative management strategies have been proposed for the care of these patients.

RECENT FINDINGS

Recent studies utilizing different methodologies have provided additional evidence regarding the impact that OSA can have on postoperative outcomes, including increased risk of difficult intubations, adverse pulmonary outcomes, and delirium. Tools, such as the STOP-Bang questionnaire and limited channel monitoring, have been investigated with regards to their utility to identify not only patients at risk for OSA but also those at risk for more severe OSA. Consensus-based guidelines for the perioperative care of OSA patients have recently been published.

SUMMARY

OSA is quite common in patients presenting for elective surgery and has been linked to increased perioperative complications. Attempts to identify these patients preoperatively appear prudent. Protocols on how best to manage these patients are available, although validation of their effectiveness is needed.

Sleep medicine training across the spectrum

There is now a new pathway and examination for sleep medicine, sponsored by the American Board of Internal Medicine, and a number of accredited sleep medicine fellowship programs through the Accreditation Council for Graduate Medical Education. This review takes an historical approach to discuss the process of education for sleep physiology and disorders not only in the postgraduate period but also at all levels of instruction. In reality, there is a continuum of knowledge that needs to be reinforced up and down the educational system, of which Sleep Medicine subspecialty training is just one part. Although progress has been made at all educational levels up to this point, the future of training and education will depend on a sustained effort at several levels from undergraduate to postgraduate continuing medical education and will be facilitated by professional societies and other specialties who will collectively promote the value of and outcomes for clinical sleep medicine.

Nocturnal home pulse oximetry: variability and clinical implications in home mechanical ventilation

BACKGROUND

Nocturnal home pulse oximetry (NHPO) provides information by measuring a series of variables: time spent with SaO(2) <90% expressed as percentage (T90) or in minutes (Tm90), mean SaO(2) (MnS), and lowest SaO(2) (LwS.) The presence of significant nocturnal desaturation has been proposed as a parameter in decision making with regard to initiating home mechanical ventilation (HMV) or monitoring HMV effectiveness. However, there is limited information on the possible variability of the test, and this could influence the interpretation of results.

OBJECTIVES

To explore the variability between 2 consecutive measurements of NHPO and to determine clinical applications in HMV.

METHODS

The patients presented diseases susceptible to HMV treatment and were enrolled in stable condition without respiratory failure. NHPO was conducted on 2 consecutive nights. The variables analyzed were: T90, Tm90, Mns, and LwS. The coefficient of variation (CV), a concordance coefficient (CC), and the Bland-Altman method were used in order to explore the variability.

RESULTS

We studied 40 cases. Two were excluded, and the remaining 38 were aged 58 ± 16 years (19 males). Eighteen were receiving HMV. CV values exceeded 100% for T90 and Tm90 and were below 5% for MnS and LwS. The CC for T90, Tm90, and LwS showed confidence intervals with lower limits below 0.5, while for MnS the value was 0.88 (0.79-0.93).

CONCLUSIONS

There is a wide variability in NHPO recordings for T90, Tm90, and LwS, so a single determination to detect nocturnal desaturation may not be valid for decision making; the parameter with the least interindividual variability and intraindividual variability was MnS.

Sleep-disordered breathing and COPD: the overlap syndrome

Sleep-disordered breathing (mainly obstructive sleep apnea [OSA]) and COPD are among the most common pulmonary diseases, so a great number of patients have both disorders; this "overlap syndrome" causes more severe nocturnal hypoxemia than either disease alone. This common combination of OSA and COPD has important implications for diagnosis, treatment, and outcome. Specifically, patients with COPD and OSA have a substantially greater risk of morbidity and mortality, compared to those with either COPD or OSA alone. Only now are the interactions between these 2 systemic diseases being determined and appreciated. Many questions remain, however, with regard to disease definition, prognosis, and optimal treatment. Treatment currently consists of continuous positive airway pressure, and oxygen as needed. Noninvasive ventilation may be helpful in overlap syndrome patients, but this has not yet been well studied.

Clinical assessment of the obstructive sleep apnoea/hypopnoea syndrome

This review focuses on the clinical presentation of the obstructive sleep apnoea/hypopnoea syndrome in adults. Features consistent with the diagnosis are described. A brief discussion of the objective measurement of sleep-disordered breathing, largely in the form of overnight monitoring, is undertaken.

Use of a screening tool for detection of sleep-disordered breathing

BACKGROUND

Sleep apnoea, whether obstructive or central, is usually diagnosed by polysomnography. A simpler tool for screening high risk populations may be of value.

METHODS

We compared a portable device using nasal pressure cannulae and a high-sensitivity pressure sensor (the ApneaLink) with our standard polysomnography technique for diagnosing sleep apnoea (using the Embletta device), in 67 patients being investigated for possible sleep apnoea. The patients' average age was 52.6, 79 per cent were male, the mean body mass index was 32.3, and the mean Epworth sleepiness score was 13.0.

RESULTS

Twenty-five patients (45 per cent) were identified as having an apnoea-hypopnoea index of >15, as measured by the Embletta. The mean (standard deviation) apnoea-hypopnoea index was 21.5 +/- 23.0 as measured by the Embletta and 24.3 +/- 26.2 as measured by the ApneaLink. The sensitivity of the ApneaLink for an apnoea-hypopnoea index cut-off point of 15 was 92 per cent and the specificity was 96.7 per cent. The negative predictive value of the ApneaLink for an apnoea-hypopnoea index of < or = 15 was 94 per cent.

CONCLUSIONS

The ApneaLink is a useful tool for screening patients thought to have possible sleep apnoea, and for selecting patients for definitive diagnostic testing.

Validation study of a portable monitoring device for identifying OSA in a symptomatic patient population

BACKGROUND AND OBJECTIVE

Obstructive sleep apnoea syndrome (OSAS) is a common disorder associated with early atherosclerosis, diabetes mellitus, ischaemic heart disease and cerebrovascular disease. The gold standard for confirming OSAS is based on an attended overnight polysomnography (PSG) in a sleep laboratory; however lack of health-care resources creates long waiting times for patient access to this diagnostic test. This study evaluated the ability of a portable sleep-monitoring device to identify patients in Hong Kong with suspected OSAS.

METHODS

Patients with symptoms of OSAS were invited to use the ARES (apnoea risk evaluation system) concurrently with an attended inpatient PSG. Several sets of AHI were generated by the ARES provider based on different oxygen desaturation criteria and surrogate parameters of arousal. The results were compared against PSG to determine the optimal sensitivity and specificity.

RESULTS

There were 141 patients who completed the study successfully. Results of AHI from the ARES study were presented in the order of different scoring criteria--4% oxygen desaturation alone, obstructive events with 3% oxygen desaturation and obstructive events with 1% desaturation plus surrogate arousal criteria. The sensitivity was 0.84 (95% confidence interval (CI): 0.77-0.90), 0.89 (95% CI: 0.89-0.94) and 0.97 (95% CI: 0.94-0.99), respectively. The specificity was 1, 1 and 0.63 (95% CI: 0.55-0.71), respectively. The receiver operating curve had an area of 0.96, 0.97 and 0.98, respectively. The kappa coefficient varied from 0.24 to 0.55 for agreement of severity between PSG and ARES. The likelihood ratio positive and the likelihood ratio negative were 2.61, infinity, infinity and 0.16, 0.11, 0.05, respectively, in the order of oxygen desaturation described earlier.

CONCLUSIONS

The ARES device has reasonable sensitivity and specificity for diagnosing severe OSAS in symptomatic Chinese patients. There is moderate agreement between ARES and PSG in the diagnosis of severe disease, but less agreement in patients with mild/moderate disease.