CO2-induced intracranial hypertension and high-amplitude B-waves in a patient with Chiari 1 malformation and sleep apnea syndrome that resolved following CPAP therapy.

Headaches and cognitive impairment in the elderly population have been described as symptoms related to obstructive sleep apnea (OSA). Although papilledema has been observed in some of these patients, suggesting intracranial hypertension (ICH), there are only a few studies in which intracranial pressure (ICP) has been continuously measured in patients with OSA without neurological disease. We present a patient diagnosed with Chiari Type 1 malformation and OSA, who present normal ICP recording during the day and nocturnal ICH associated with high amplitude B-waves and hypercapnia during obstructive apneas, which disappeared following continuous positive airway pressure (CPAP) therapy. The normalization of the cerebral and respiratory parameters with CPAP therapy is important for performing the correct treatment in these patients.

Obstructive sleep apnea and silent cerebral infarction in hypertensive individuals.

Obstructive sleep apnea syndrome is very prevalent in hypertensive subjects. Moreover, obstructive sleep apnea syndrome activates multiple processes that might be associated with silent cerebral infarct independently of established risk factors. Our aim is to estimate the frequency of obstructive sleep apnea syndrome in hypertensive patients with and without silent cerebral infarct, and to determine whether obstructive sleep apnea syndrome is an independent risk factor of silent cerebral infarct and/or lacunar silent cerebral infarct in patients with hypertension. In this matched cross-sectional study performed in hypertensive subjects, each patient with silent cerebral infarct detected by magnetic resonance imaging was matched with two patients without silent cerebral infarct. Polysomnographic studies were performed, and the apnea-hypopnea index was calculated. Severe obstructive sleep apnea syndrome was considered in those with apnea-hypopnea index >30. One-hundred and eighty-three patients, 61 with silent cerebral infarct and 122 without silent cerebral infarct, were evaluated. The mean age was 64.1 ± 4.5 years, and 72.1% were men. The frequency of severe obstructive sleep apnea syndrome was 44.3% in patients with silent cerebral infarct and 38.5% in the control group. An adjusted conditional logistic regression model did not show a significant increased risk of silent cerebral infarct in patients with severe obstructive sleep apnea syndrome (odds ratio 1.362; 95% confidence interval: 0.659-2.813; P = 0.404). Forty-three patients (70.5%) of the silent cerebral infarct were lacunar. The presence of severe obstructive sleep apnea syndrome was significantly higher in lacunar silent cerebral infarct when compared with patients without lacunar infarcts (55.8% versus 35.7%, P = 0.019), being independently associated on an adjusted logistic regression model (odds ratio 2.177; 95% confidence interval: 1.058-4.479; P = 0.035). In conclusion, severe obstructive sleep apnea syndrome is highly prevalent among hypertensive subjects, and is independently associated with lacunar silent cerebral infarct.

Poor self-reported sleep quality and health-related quality of life in patients with chronic fatigue syndrome/myalgic encephalomyelitis.

Non-restorative sleep is a hallmark symptom of chronic fatigue syndrome/myalgic encephalomyelitis. However, little is known about self-reported sleep disturbances in these subjects. This study aimed to assess the self-reported sleep quality and its impact on quality of life in a Spanish community-based chronic fatigue syndrome/myalgic encephalomyelitis cohort. A prospective cross-sectional cohort study was conducted in 1,455 Spanish chronic fatigue syndrome/myalgic encephalomyelitis patients. Sleep quality, fatigue, pain, functional capacity impairment, psychopathological status, anxiety/depression and health-related quality of life were assessed using validated subjective measures. The frequencies of muscular, cognitive, neurological, autonomic and immunological symptom clusters were above 80%. High scores were recorded for pain, fatigue, psychopathological status, anxiety/depression, and low scores for functional capacity and quality of life, all of which correlated significantly (all p < 0.01) with quality of sleep as measured by the Pittsburgh Sleep Quality Index. Multivariate regression analysis showed that after adjusting for age and gender, the pain intensity (odds ratio, 1.11; p <0.05), psychopathological status (odds ratio, 1.85; p < 0.001), fibromyalgia (odds ratio, 1.39; p < 0.05), severe autonomic dysfunction (odds ratio, 1.72; p < 0.05), poor functional capacity (odds ratio, 0.98; p < 0.05) and quality of life (odds ratio, 0.96; both p < 0.001) were significantly associated with poor sleep quality. These findings suggest that this large chronic fatigue syndrome/myalgic encephalomyelitis sample presents poor sleep quality, as assessed by the Pittsburgh Sleep Quality Index, and that this poor sleep quality is associated with many aspects of quality of life.

Surgical Outcomes in Chiari 1 and Chiari 1.5 Malformation Treated by Posterior Fossa Reconstruction: A Comprehensive Analysis of 110 Pediatric Cases and Literature Review.

Background/Objectives: The management of Chiari malformations (CMs) remains a clinical challenge and a topic of great controversy. Results may vary between children and adults. The purpose of the current single-center study is to critically assess the one-year surgical outcomes of a cohort of 110 children with CM-1 or CM-1.5 who were treated using "posterior fossa reconstruction" (PFR), a surgical technique described in 1994 that has since been used in both adults and children. We also review the literature and discuss the possible causes of the drawbacks and pitfalls in children in whom PFR was ineffective in controlling the disease. Methods: The present cohort was selected from a prospective registry of adults and children with CMs collected since 2006. Patients included in this study were selected from a group of children with CMs who were operated on in our Pediatric Neurosurgical Unit between 1 January 2007 and 31 November 2023. Surgical outcome was defined based on clinical and neuroradiological results as very good, good, or bad. Results: The mean age of our child cohort was 9.9 ± 4.7 years, with 54 girls (49%) and 56 boys (51%). Sixty-six children had CM-1 (60%) while forty-four had CM-1.5 (40%). Following surgery, there was no neurological worsening or death among the children. Most children (70%) had an uneventful recovery and were discharged home on average one week after surgery. However, in 33 children (30%), we recorded at least one postoperative adverse event. Aseptic meningitis syndrome was the most frequent adverse event (n = 25, 22.7%). The final surgical outcome was evaluated one year after PFR by using both clinical and neuroradiological results. The one-year surgical outcome was excellent in 101 children (91.9%), good in 5 (4.5%), and bad in 4 (3.6%). Conclusions: PFR significantly enlarges the volume of the posterior fossa and recreates a CSF environment that generates buoyancy of the cerebellum, with a high percentage of excellent and good clinical results evaluated one year post-surgery.

A Critical Update of the Classification of Chiari and Chiari-like Malformations.

Chiari malformations are a group of craniovertebral junction anomalies characterized by the herniation of cerebellar tonsils below the foramen magnum, often accompanied by brainstem descent. The existing classification systems for Chiari malformations have expanded from the original four categories to nine, leading to debates about the need for a more descriptive and etiopathogenic terminology. This review aims to examine the various classification approaches employed and proposes a simplified scheme to differentiate between different types of tonsillar herniations. Furthermore, it explores the most appropriate terminology for acquired herniation of cerebellar tonsils and other secondary Chiari-like malformations. Recent advances in magnetic resonance imaging (MRI) have revealed a higher prevalence and incidence of Chiari malformation Type 1 (CM1) and identified similar cerebellar herniations in individuals unrelated to the classic phenotypes described by Chiari. As we reassess the existing classifications, it becomes crucial to establish a terminology that accurately reflects the diverse presentations and underlying causes of these conditions. This paper contributes to the ongoing discussion by offering insights into the evolving understanding of Chiari malformations and proposing a simplified classification and terminology system to enhance diagnosis and management.

Sleep-related painful erections associated with obstructive sleep apnea syndrome.

Sleep-related painful erection is a rare syndrome recognized by reports of painful nocturnal erection, an association between REM sleep and pain, and the absence of pain during wakeful sexual activity. Approximately 30 cases have been reported in the literature. We add two more cases, each of which seemed to be associated with severe sleep apnea. Treatment of the apnea with Continuous Positive Airway Pressure device lessened the symptom in both men. Implications of this association are discussed.

Sleep increases leaks and asynchronies during home noninvasive ventilation: a polysomnographic study.

STUDY OBJECTIVES: In patients treated with noninvasive ventilation, sleep-related breathing changes can modify patient-ventilator interactions, which could reduce its effectiveness. The aim of this prospective observational study was to determine the impact of sleep/wake state on leaks, upper airway obstructive events, and asynchronies in patients treated by long-term noninvasive ventilation. METHODS: Stable patients adapted to noninvasive ventilation were considered for nocturnal polysomnography. Unintentional leaks, upper airway obstructive events, and asynchronies were compared between sleep and awake periods. RESULTS: Twenty-eight patients were enrolled. Underlying diagnoses were neuromuscular disease (n = 11), chest wall disease (n = 8), and obesity-hypoventilation (n = 9). Leaks were more frequent in sleep than in awake periods, with a median of 10% (interquartile range [IQR], 0%-75%) vs 1% (IQR, 0%-9%) of time (P < .001), respectively. During sleep, asynchronies with and without associated leak affected 27% of breaths (IQR, 16%-39%) compared with non-leak-related asynchronies that were recorded in 8% (IQR, 3%-25%) of breaths (P < .001). Asynchronies affecting more than 10% of total breaths were more frequent in sleep (25 patients, 89%) than in awake time (8 patients, 29%; P = .25). Eleven patients (39%) presented with 5 or more upper airway obstructive events without reduction in ventilatory drive per hour of sleep. CONCLUSIONS: In patients adapted to home noninvasive ventilation, leaks, asynchronies, and upper airway obstructive events are frequent during the night and are concentrated in sleep periods. Asynchronies are often associated with leaks. These findings may have clinical implications considering that in patients with low sleep efficiency respiratory events could be underestimated if sleep is not evaluated. CITATION: Martí S, Ferré A, Sampol G, et al. Sleep increases leaks and asynchronies during home noninvasive ventilation: a polysomnographic study. J Clin Sleep Med. 2022;18(1):225-233.

Nasal cannula use during polysomnography in children aged under three with suspected sleep apnea.

OBJECTIVE: Early diagnosis of obstructive sleep apnea (OSA) in children is important. The use of a nasal cannula as an airflow sensor during polysomnography has not been evaluated in younger children. The study aims to evaluate the use of nasal cannula in detecting respiratory events in children under three with suspected OSA during daytime nap studies. METHODS: A total of 185 patients were prospectively included. Respiratory events were scored using nasal cannula alone, thermistor alone, and both methods simultaneously as the airflow sensor. Agreement and diagnostic accuracy were assessed. RESULTS: One hundred and seventy-two children were finally analyzed and 110 (64.0%) presented OSA. Total sleep time with an uninterpretable signal was longer with the nasal cannula than with the thermistor (17.8% vs 1.9%; p < 0.001), and was associated with poor sensor tolerance and adenotonsillar hypertrophy. In the estimation of the apnea-hypopnea index, the nasal cannula showed lower agreement than the thermistor with the joint use of the two sensors (intraclass correlation coefficient: 0.79 vs 0.996 with thermistor). Compared with the thermistor, the nasal cannula presented lower sensitivity for detecting OSA (82.7% vs 95.5%) and a lower negative predictive value (76.5% vs 92.4%). Overall, fewer children were diagnosed with severe OSA with the nasal cannula (19.8% vs 30.8% with the thermistor, and 32.6% with both). CONCLUSIONS: In children under the age of three, the ability of the nasal cannula to detect obstructive events was relatively low. Therefore, other non-invasive measurements for identifying respiratory events during sleep may be of additional value.

Nighttime hypoxia affects global cognition, memory, and executive function in community-dwelling individuals with hypertension.

STUDY OBJECTIVES: The objective of this study was to determine which respiratory and architectural sleep parameters are related to cognitive function and cognitive status (mild cognitive impairment [MCI] versus normal cognitive aging [NCA]) in community-dwelling individuals with hypertension. Additionally, it aimed to determine whether the results changed in the presence or absence of vascular brain lesions (silent brain infarcts and extensive white matter hyperintensities [WMHs]). METHODS: In a cohort of individuals with hypertension and without previous stroke or dementia, we conducted in-hospital polysomnography including electroencephalography, electro-oculography, electromyography, and magnetic resonance imaging to assess silent brain infarcts and WMHs. Cognitive testing was carried out with a screening test (Dementia Rating Scale version 2 [DRS-2]) and a complete cognitive visit. RESULTS: This study included 158 participants with a median age of 65.0 years; 32.3% were females, and the median apnea-hypopnea index was 22.3 events/h. MCI was diagnosed in 24 study participants, and the rest had NCA. Regarding respiratory parameters, total DRS-2 scores (ß; 95% CI) 0.121; 0.026, 0.215 were positively associated with mean O2 saturation, whereas total (-0.022; -0.036, -0.009), executive function (-0.016; -0.026, -0.006) and memory (-0.017; -0.029, -0.004) DRS-2 scores were all negatively associated with the percent of time with oxygen saturation < 90% after correcting for education, vascular risk factors, and magnetic resonance imaging lesions. Regarding sleep architecture, Attention DRS-2 scores (0.0153; 0.001, 0.306) were independently associated with total sleep time. Similar results were obtained in the absence of silent brain infarcts or WMHs in the stratified analysis. None of the sleep parameters were associated with cognitive status. CONCLUSIONS: Low oxygen saturation contributes to cognitive performance, and this effect appears even in the absence of vascular brain lesions in individuals with hypertension.

A Conditional Inference Tree Model for Predicting Sleep-Related Breathing Disorders in Patients With Chiari Malformation Type 1: Description and External Validation.

STUDY OBJECTIVES: The aim of this study is to generate and validate supervised machine learning algorithms to detect patients with Chiari malformation (CM) 1 or 1.5 at high risk of the development of sleep-related breathing disorders (SRBD) using clinical and neuroradiological parameters. METHODS: We prospectively included two independent datasets. A training dataset (n = 90) was used to obtain the best model, whereas a second dataset was used to validate it (n = 74). In both cohorts, the same clinical, neuroradiological, and sleep studies were carried out. We used two supervised machine learning approaches, multiple logistic regression (MLR) and the unbiased recursive partitioning technique conditional inference tree (URP-CTREE), to detect patients at high risk of SRBD. We then compared the accuracy, sensitivity, and specificity of the two prediction models. RESULTS: Age (odds ratio [OR] 1.1 95% confidence interval [CI] 1.05-1.17), sex (OR 0.19 95% CI 0.05-0.67), CM type (OR 4.36 95% CI 1.14-18.5), and clivus length (OR 1.14 95% CI 1.01-1.31) were the significant predictor variables for a respiratory disturbance index (RDI) cutoff that was ≥ 10 events/h using MLR. The URP-CTREE model predicted that patients with CM-1 who were age 52 years or older and males with CM-1 who were older than 29 years had a high risk of SRBD. The accuracy of predicting patients with an RDI ≥ 10 events/h was similar in the two cohorts but in the URP-CTREE model, specificity was significantly greater when compared to MLR in both study groups. CONCLUSIONS: Both MLR and URP-CTREE predictive models are useful for the diagnosis of SRBD in patients with CM. However, URP-CTREE is easier to apply and interpret in clinical practice.

Sleep Quality and Levodopa Intestinal Gel Infusion in Parkinson's Disease: A Pilot Study.

BACKGROUND: Sleep problems in patients with advanced Parkinson's disease (PD) have a deleterious impact on quality of life. OBJECTIVE: To assess the effect of levodopa-carbidopa intestinal gel (LCIG) infusion on sleep quality in advanced PD patients. METHODS: Seven patients participated in a prospective pilot study. Before and after 6 months of LCIG infusion, an overnight polysomnography was performed and the Epworth Sleepiness Scale, fatigue scale, Pittsburgh Sleep Quality Index, Beck Depression Inventory, and the Hamilton Anxiety Rating Scale were administered. RESULTS: PSG showed low sleep efficiency. REM sleep without atony was found in 5 patients. After 6 months of LCIG infusion, the percentage of REM sleep decreased as well as the number of arousals especially due to reduction of spontaneous arousals and periodic leg movements during REM sleep, but differences were not statistically significant. Also, scores of all study questionnaires showed a tendency to improve. CONCLUSION: The results show a trend toward an improvement of sleep quality after 6 months of LCIG infusion, although differences as compared to pretreatment values were not statistically significant. The sleep architecture was not modified by LCIG. Further studies with larger study samples are needed to confirm these preliminary findings.

Sleep-Related Breathing Disorders in Chiari Malformation Type 1: A Prospective Study of 90 Patients.

Study objective: The aim of the present study is to describe the prevalence of sleep disorders in a large group of patients with Chiari malformation type 1 (CM-1) and determine the presence of risk factors associated with these abnormalities. Methods: Prospective study with consecutive patient selection. We included 90 adult patients with CM-1, defined by the presence of a cerebellar tonsillar descent (TD) ≥3 mm. Clinical, neuroradiological studies, and nocturnal polysomnography (PSG) was carried out. In addition, patients were also subclassified into 2 CM subtypes: CM-1, with the obex above the foramen magnum (FM) and CM-1.5, in which along with a TD ≥3 mm, the obex was located below the FM. Results: We observed a high prevalence (50%) of sleep-related breathing disorders (SRBDs) with predominant hypopnea. Only six patients showed a central apnea index of ≥5. Hypoventilation was observed in only three patients. SRBD severity was associated with male sex, older age, excess weight, and the presence of hydrocephalus. No differences in clinical or PSG parameters were found when comparing CM subtypes (CM-1 and CM-1.5). Sleep architecture study showed decreased sleep efficiency with an increase in arousal and waking after sleep onset. The presence of SRBDs was found to be associated with poorer sleep architecture parameters. Conclusions: This study confirms a high prevalence of SRBDs in patients with CM-1 and CM-1.5, with a predominant obstructive component. Nocturnal PSG recordings should be systematically conducted in these patients, especially those who are male, older, or overweight or those who present hydrocephalus.

Cephalometric oropharynx and oral cavity analysis in Chiari malformation Type I: a retrospective case-control study.

OBJECTIVE Traditionally, Chiari malformation Type I has been related to downward herniation of the cerebellar tonsils as a consequence of an underdeveloped posterior cranial fossa. Although the common symptoms of Chiari malformation Type I are occipital headaches, cervical pain, dizziness, paresthesia, and sensory loss, patients often report symptoms related to pharyngeal dysfunction such as choking, regurgitation, dysphagia, aspiration, chronic cough, and sleep disorders. In addition, tracheal intubation is often difficult in these patients. The purpose of this study was to analyze the morphological features of the oropharynx and oral cavity in patients with Chiari malformation Type I to help identify underlying anatomical anomalies leading to these debilitating symptoms. METHODS Seventy-six adult patients with symptomatic Chiari malformation Type I with cerebellar tonsillar descent greater than 5 mm below the foramen magnum and a small posterior cranial fossa and 49 sex-matched controls were selected to perform a retrospective case-control MRI-based morphometric study in a tertiary hospital. Eleven linear and areal parameters of the oropharyngeal cavity on midsagittal T1-weighted MRI were measured and the average values between patients and control cohorts were compared. Correlations between variables showing or approaching statistical significance in these structures and posterior cranial fossa measurements related with the occipital bone were sought. RESULTS Significant differences were detected for several oropharynx and oral cavity measures in the patient cohort, primarily involving the length and thickness of the soft palate (p = 9.5E-05 and p = 3.0E-03, respectively). A statistically significant (p < 0.01) moderate correlation between some of these variables and posterior cranial fossa parameters was observed. CONCLUSIONS The existence of structural oropharyngeal and oral cavity anomalies in patients with Chiari malformation Type I was confirmed, which may contribute to the frequent occurrence of respiratory and deglutitory complications and sleep disorders in this syndrome.

Long-term safety and effectiveness of levodopa-carbidopa intestinal gel infusion.

INTRODUCTION: Levodopa-carbidopa intestinal gel (LCIG) infusion has demonstrated to improve motor fluctuations. The aim of this study is to assess the long-term safety and effectiveness of LCIG infusion in advanced Parkinson's disease (PD) patients with motor fluctuations and its effect in nonmotor symptoms. METHODS: Adverse events (AE) and their management, clinical motor, and nonmotor aspects were assessed up to 10 years. Thirty-seven patients were treated with LGIC; in three subsets of patients, specific batteries of tests were used to assess cognitive and behavior assessment for 6 months, quality of sleep for 6 months, and quality of life and caregiver burden for 1 year. RESULTS: There was a high number of AE, but manageable, most of mild and moderate severity. All patients experienced significant improvement in motor fluctuations with a reduction in mean daily off time of 4.87 hr after 3 months (n = 37) to 6.25 hr after 9 years (n = 2). Diskynesias remained stables in 28 patients (75.7%) and improved in 5 patients (13.5%). There was no neuropsychological deterioration, but an improvement in attentional functions, voluntary motor control, and semantic fluency. Quality of sleep did not worsen, and there was an improvement in the subjective parameters, although overnight polysomnography did not change. There was a significant sustained improvement of 37% in PD-Q39 after 3 months and to 1 year, and a significant reduction in caregiver burden of 10% after 3 months. CONCLUSION: LCIG infusion is a safe and efficacious treatment for the control of motor fluctuations, and for improvement or nonworsening of nonmotor aspects, long-term sustained, and feasible for use in routine care.

[Usefulness of the basic exploration of the upper airways and neighbor structures in patients with adult obstructive sleep apnea-hypopnea syndrome]. / Utilidad de la exploración básica de la vía aérea superior y estructuras vecinas en los pacientes adultos con síndrome de apnea-hipopnea obstructiva del sueño.

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a prevalent disease in the general population, associated with an increase in the cardiovascular morbimortality. A basic and/or standardized otolaryngologic exploration could help us to detect the structural abnormalities that alter the upper airway collapsibility and offer a high pre-test risk factor, improve the CPAP adherence or even the possibility of offering alternative treatments. This article offers a revision of the exploration in OSAHS patients. We describe a guideline to identify the main structural abnormalities related to OSAHS. We also include a short algorithm for the diagnosis of OSAHS, when is suspected by primary care physicians.

Effect of continuous positive airway pressure and upper airway surgery on exhaled breath condensate and serum biomarkers in patients with sleep apnea.

INTRODUCTION: Studies on inflammation biomarkers in serum and in exhaled breath condensate (EBC) in obstructive sleep apnea (OSA) have shown conflicting results. The objective of this study is to assess EBC and serum biomarkers in OSA patients at baseline and after continuous positive airway pressure (CPAP) or upper airway surgery (UAS). PATIENTS AND METHODS: Nine OSA patients referred for UAS were matched for anthropometric characteristics and apnea-hypopnea index with 20 patients receiving CPAP. pH, nitrite (NO2(-)), nitrate and interleukin 6 in EBC and NO2(-), nitrate, leukotriene B4 and interleukin 6 in serum were determined. EBC and serum samples were collected at baseline and 3 months after CPAP or UAS. RESULTS: Patients' mean body mass index was 30 (range 24.9-40) kg/m(2). EBC biomarker levels at baseline were within normal range and did not differ significantly after CPAP or UAS. No significant changes were observed in the serum concentration of the biomarkers determined after CPAP but the serum concentration of NO2(-) increased significantly at 3 months after UAS (P=.0078). CONCLUSION: In mildly obese OSA patients, EBC biomarkers of inflammation or oxidative stress were normal at baseline and remained unchanged 3 months after UAS or CPAP. Although UAS was not effective in terms of reducing OSA severity, it was associated with an increase in serum NO2(-).

Neurophysiological two-channel polysomnographic device in the diagnosis of sleep apnea.

STUDY OBJECTIVE: Our objective was to evaluate a portable device (Somté, Compumedics, Australia), which incorporates 2 neurophysiological channels (electroencephalography and electrooculography) with cardiorespiratory monitoring for the diagnosis of obstructive sleep apnea (OSA). METHOD: Full polysomnography (PSG) and Somté recordings were simultaneously performed in 68 patients with suspected OSA. Data were analyzed blindly by 2 scorers. RESULTS: A good agreement between methods in sleep efficiency was observed (68.8% [18.4] with PSG vs 68% [19.1] with Somté [p: n.s.] for scorer 1, and 67.5% [19.1] vs 68.4% [18.5; p: n.s.] for scorer 2). The apnea-hypopnea index (AHI) obtained with Somté was lower than with PSG: 19 (17.8) vs 21.7 (19) (p < 0.001) for scorer 1, and 16.6 (16.7) vs 20 (18.8) (p < 0.001) for scorer 2. The sensitivity of Somté for a PSG-AHI > 5 was 91% for scorer 1 and 90% for scorer 2, while specificity was 77% and 90%, respectively. The areas under the receiver operating curve for different PSG-AHI cutoff points (≥ 5, ≥ 15, and ≥ 30) were 0.81, 0.90, and 0.86, respectively, for scorer 1, and 0.90, 0.88, and 0.83 for scorer 2. CONCLUSIONS: These data suggest that Somté is an effective device to identify sleep and respiratory variables in patients with suspected OSA.