High frequency region of the snore spectra carry important information on the disease of sleep apnoea

Snoring is the most common symptom of obstructive sleep apnoea (OSA). Several researchers have reported differences between the power spectra of non-OSA and OSA snorers. The traditional approach over the years has been to record snore sounds at a bandwidth of < 5 kHz. Narrowing of the upper airways during OSA events and the resulting upward shift of snore frequencies also lend support to the idea of examining snore sounds beyond 5 kHz. In this paper, we compute the power spectra of snores in three different bands defined as: low-frequency band (LFB: < 5 kHz); middle-frequency band (MFB: 5-10 kHz) and high-frequency band (HFB: 10-20 kHz). We illustrate that there is a significant difference between non-OSA snorers (Apnoea Hypopnoea Index (AHI) < 10) and OSA snorers (AHI > 10) in the region > 5 kHz. We then develop a feature to diagnose OSA based on the spectral differences in the high frequency region and evaluate its performance on a database of 20 subjects. Our results strongly suggest that the high-frequency region of the snore sounds carry information, hitherto disregarded, on the disease of sleep apnoea.     

High frequency region of the snore spectra carry important information on the disease of sleep apnoea

Snoring is the most common symptom of obstructive sleep apnoea (OSA). Several researchers have reported differences between the power spectra of non-OSA and OSA snorers. The traditional approach over the years has been to record snore sounds at a bandwidth of < 5 kHz. Narrowing of the upper airways during OSA events and the resulting upward shift of snore frequencies also lend support to the idea of examining snore sounds beyond 5 kHz. In this paper, we compute the power spectra of snores in three different bands defined as: low-frequency band (LFB: < 5 kHz); middle-frequency band (MFB: 5–10?kHz) and high-frequency band (HFB: 10–20 kHz). We illustrate that there is a significant difference between non-OSA snorers (Apnoea Hypopnoea Index (AHI) < 10) and OSA snorers (AHI > 10) in the region > 5?kHz. We then develop a feature to diagnose OSA based on the spectral differences in the high frequency region and evaluate its performance on a database of 20 subjects. Our results strongly suggest that the high-frequency region of the snore sounds carry information, hitherto disregarded, on the disease of sleep apnoea.     

Sleep abnormalities in untreated patients with mucopolysaccharidosis type VI

Mucopolysaccharidosis type VI (MPS VI) is a lysosomal storage disease that affects an enzyme responsible for the degradation of glycosaminoglycans (GAGs). Partially degraded GAGs accumulate in several tissues, such as the upper airways (UA), which leads to the development of obstructive sleep apnea (OSA). Our objective was to determine the prevalence of OSA in a group of untreated patients with MPS VI and the association of OSA with clinical and echocardiographic findings. Patients aged 4 years or older with a biochemical diagnosis of MPS VI were included. Data about clinical history, physical examination, Doppler echocardiogram, and overnight polysomnography (PSG) were collected. Our results showed that of the 28 participants, 14 were boys; mean age was 98.5 months, and mean age at MPS VI diagnosis was 48.4 months. Snoring, witnessed apnea, pectus carinatum, and macroglossia were the main clinical findings. PSG results showed that 23:27 patients (85.1%) had OSA which was mild in 4, moderate in 5, and severe in 14 patients. Echocardiograms showed evidence of pulmonary hypertension (PH) in 14 patients. Lower (P = 0.037) and nadir SpO(2) (P = 0.007) were positively associated with PH. Clinical signs suggestive of respiratory abnormalities during sleep were not significantly correlated with the results of PSG. We conclude that the prevalence of OSA in patients with MPS VI was high, and the level of desaturation was positively correlated with PH. Symptoms during sleep were not associated with PSG findings, which suggests that this population should undergo routine PSG as earlier as possible. This study provides baseline data to estimate the potential impact of specific treatments in the sleep abnormalities presented by patients with MPS VI.     

Are stroke cases affected by sleep disordered breathings all the same?

Sleep disordered breathings (SDB) worsens the clinical prognosis of stroke patients. Continuous positive airway pressure (CPAP) is a promising effective treatment. Unfortunately, not all patients are compliant with CPAP, suggesting that it is not appropriate for all patients with obstructive sleep apnoea (OSA) after stroke. People with the highest likelihood of benefiting have to be identified. We present a classification of cases with stroke and SDB to be adopted in order to identify the best responders to CPAP treatment. We propose to classify patients in four subgroups: (1) patients who terminate the apnoea by arousing from sleep; these cases are those affected either by an anatomical or a functional obstruction of upper airways that may precede or are the consequence of stroke; (2) cases that alternate OSA to central sleep apnoea (CSA) cause of an altered loop gain; (3) cases in whom ischemic damages have altered the sleep microstructure (CAP); (4) cases that manifest a CSA as the direct consequence of stroke on the central neuronal drive to breath. So far, no study has investigated the consequences of stroke on sleep microstructure. In order to better elucidate these relationships, when reviewing the PSG tracings of stroke patients, the microstructure of sleep should be systematically analysed.     

Utility of portable monitoring in the diagnosis of obstructive sleep apnea

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

Novel apnomonitor for use at home

The monitoring technique for assessing suspected sleep apnea syndrome is a polysomnogram (PSG) performed in hospital. The typical PSG includes EEG, EOG, EMG, air flow at the nose and mouth, SO2, thoracicoabdominal motion and snoring sound. But the PSG test is expensive, and also is a stress load for the patient because this test requires recording throughout the night. Recently, a home-type apnomonitor that is used at home has been developed for the screening of apnea, but this monitor can not distinguish obstructive sleep apnea (OSA) from central sleep apnea (CSA). We evaluated a new home-type apnomonitor that was able to distinguish OSA from CSA using the change of amplitude in the fingertip plethysmogram and respiratory flow curve attained by oronasal transducer. In this study, the respiratory flow curve became flat under OSA conditions, but the change of amplitude on plethysmogram corresponded to thoracioabdominal motion. On the other hand, the change of amplitude in the plethysmogram did not corresponded with thoracicoabdominal motion under CSA conditions. These findings suggest that it is possible to distinguish between OSA and CSA using an apnomonitor system which records a respiratory flow curve and a plethysmogram, and also to develop a new home-type apnomonitor.     

关于混合性睡眠呼吸暂停综合征的研讨

目的：探讨MSAS是否存在及其诊治问题。方法：从近一年鼾症患者PSG监测结果中，筛选出MSA次数占呼吸暂停总次数50％以上者，结合其临床资料进行分析。结果：285例PSG监测结果中，MSA次数与呼吸暂停总次数之比大于50％者9例（3．2％）。其中，二者之比介于50％～70％者4例，70％～90％者5例，行外科手术治疗者4例。结论：根据PSG监测结果和本文判断标准，MSAS是存在的。对有上气道狭窄、无中枢神经病变的MSAS患者，可按照OSAS的治疗方法行手术治疗。     

Predictive value of Kushida index and acoustic pharyngometry for the evaluation of upper airway in subjects with or without obstructive sleep apnea

Acoustic pharyngometry is a relatively new noninvasive method that quantifies geometrically complexed pharyngeal dimensions. Our study aimed to investigate the predictability and usefulness of acoustic pharyngometry in diagnosis of obstructive sleep apnea (OSA), and we developed a prospective clinical trial in 16 subjects without apnea and 54 subjects with apnea. All seventy subjects received polysomnography (PSG) to assess the sleep architecture, including breathing and the degree of apnea hypopnea index. Acoustic pharyngometry was performed in four body positions (sitting, supine, right and left lateral) while awake with tidal breathing in addition to morphometric measurements (Kushida index) of oral cavity. This study shows that the cross-sectional area and volume of the upper airway is smaller in the supine position than any other positions. As well, the oropharyngeal junction area of the supine position is the most predictive parameter to discriminate between subjects with or without OSA. Acoustic pharyngometry can be a clinically useful tool for localizing the narrowed portion of the upper airway and predicting obstructive sleep apnea.     

Role of Upper Airway Dimensions in Snore Production: Acoustical and Perceptual Findings

While considerable efforts have been expended to develop snore-driven markers for detecting obstructive sleep apnea (OSA), there is little emphasis on the relationship between the human upper airway (UA) dimensions and the attributes of snores. This paper aims to investigate the acoustical and perceptual impacts of changing the cross-sectional areas (CSA) of the pharynx and oral cavity on the production of snores. Synthetic snores were generated based on the source-filter theory, whereas natural snores were recorded from 40 snorers during nocturnal polysomnography. First formant frequency (F1), spectral peak frequency (PF), and psychoacoustic metrics (loudness, sharpness, roughness, fluctuation strength, and annoyance) of CSA perturbations were examined, completed with diagnostic appraisal of F1 and PF for single- and mixed-gender groupings using the receiver operating characteristic curve analysis. Results show that (1) narrowing the pharyngeal airway consistently increases F1, but not for PF; and (2) altering the airway dimensions yield no considerable differences in perception of snore sounds, but indirectly affect the psychoacoustics by changing the dynamics of snore source flow. Diagnostic outcomes for all groupings (p-value < 0.0001) demonstrate that F1 is more capable of distinguishing apneic and benign snorers than PF due to the close association of F1 with the UA anatomical structures. Correlation exists between the UA anatomy and the properties of snores; there is a promising future for developing snore-driven screening tools for OSA.     

Severe upper airway obstruction during sleep

Few disorders may manifest with predominantly sleep-related obstructive breathing. Obstructive sleep apnea (OSA) is a common disorder, varies in severity and is associated with significant cardiovascular and neurocognitive morbidity. It is estimated that between 8 and 18 million people in the United States have at least mild OSA. Although the exact mechanism of OSA is not well-delineated, multiple factors contribute to the development of upper airway obstruction and include anatomic, mechanical, neurologic, and inflammatory changes in the pharynx. OSA may occur concomitantly with asthma. Approximately 74% of asthmatics experience nocturnal symptoms of airflow obstruction secondary to reactive airways disease. Similar cytokine, chemokine, and histologic changes are seen in both disorders. Sleep deprivation, chronic upper airway edema, and inflammation associated with OSA may further exacerbate nocturnal asthma symptoms. Allergic rhinitis may contribute to both OSA and asthma. Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA. Treatment with CPAP therapy has also been shown to improve both daytime and nighttime peak expiratory flow rates in patients with concomitant OSA and asthma. It is important for allergists to be aware of how OSA may complicate diagnosis and treatment of asthma and allergic rhinitis. A thorough sleep history and high clinical suspicion for OSA is indicated, particularly in asthma patients who are refractory to standard medication treatments.     

Validation a portable monitoring device for sleep apnea diagnosis in a population based cohort using synchronized home polysomnography

SUBJECT OBJECTIVE: To assess the accuracy of a portable monitoring device based on peripheral arterial tonometry to diagnose obstructive sleep apnea (OSA). To propose a new standard for limited-channel device validation using synchronized polysomnography (PSG) home recordings and a population-based cohort. DESIGN: Single-night, unattended PSG and Watch_PAT 100 (WP_100). SETTING: Home environment. PARTICIPANTS: Ninety-eight subjects (55 men; age, 60 +/- 7 year; body mass index, 28 +/- 4 kg/m2) consecutively recruited from the Skaraborg Hypertension and Diabetes Project. MEASUREMENTS AND RESULTS: The WP_100 records peripheral arterial tone, heart rate, oxygen saturation and actigraphy for automatic analysis of respiratory disturbance index (RDI), apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and sleep-wake state. The accuracy of WP_100 in RDI, AHI, ODI, and sleep-wake detection was assessed by comparison with data from simultaneous PSG recordings. The mean PSG-AHI in this population was 25.5 +/- 22.9 events per hour. The WP_100 RDI, AHI, and ODI correlated closely (0.88, 0.90, and 0.92; p < .0001, respectively) with the corresponding indexes obtained by PSG. The areas under the curve for the receiver-operator characteristic curves for WP_100 AHI and RDI were 0.93 and 0.90 for the PSG-AHI and RDI thresholds 10 and 20 (p < .0001, respectively). The agreement of the sleep-wake assessment based on 30-second bins between the 2 systems was 82 +/- 7%. CONCLUSIONS: The WP_100 was reasonably accurate for unattended home diagnosis of OSA in a population sample not preselected for OSA symptoms. The current design, including simultaneous home PSG recordings in population-based cohorts, is proposed as a reasonable validation standard for assessment of simplified recording tools for OSA diagnosis.     

Effects of nasal pathologies on obstructive sleep apnea

Increased airway resistance can induce snoring and sleep apnea, and nasal obstruction is a common problem in snoring and obstructive sleep apnea (OSA) patients. Many snoring and OSA patients breathe via the mouth during sleep. Mouth breathing may contribute to increased collapsibility of the upper airways due to decreased contractile efficiency of the upper airway muscles as a result of mouth opening. Increased nasal airway resistance produces turbulent flow in the nasal cavity, induces oral breathing, promotes oscillation of the pharyngeal airway and can cause snoring.     

Improving diagnostic ability of blood oxygen saturation from overnight pulse oximetry in obstructive sleep apnea detection by means of central tendency measure

OBJECTIVES: Nocturnal pulse oximetry is a widely used alternative to polysomnography (PSG) in screening for obstructive sleep apnea (OSA) syndrome. Several oximetric indexes have been derived from nocturnal blood oxygen saturation (SaO2). However, they suffer from several limitations. The present study is focused on the usefulness of nonlinear methods in deriving new measures from oximetry signals to improve the diagnostic accuracy of classical oximetric indexes. Specifically, we assessed the validity of central tendency measure (CTM) as a screening test for OSA in patients clinically suspected of suffering from this disease. MATERIALS AND METHODS: We studied 187 subjects suspected of suffering from OSA referred to the sleep unit. A nocturnal pulse oximetry study was applied simultaneously to a conventional PSG. Three different index groups were compared. The first one was composed by classical indexes provided by our oximeter: oxygen desaturation indexes (ODIs) and cumulative time spent below a saturation of 90% (CT90). The second one was formed by indexes derived from a nonlinear method previously studied by our group: approximate entropy (ApEn). The last one was composed by indexes derived from a CTM analysis. RESULTS: For a radius in the scatter plot equal to 1, CTM values corresponding to OSA positive patients (0.30+/-0.20, mean+/-S.D.) were significantly lower (p<0.001) than those values from OSA negative subjects (0.71+/-0.18, mean+/-S.D.). CTM was significantly correlated with classical indexes and indexes from ApEn analysis. CTM provided the highest correlation with the apnea-hipopnea index AHI (r=-0.74, p<0.0001). Moreover, it reached the best results from the receiver operating characteristics (ROC) curve analysis, with 90.1% sensitivity, 82.9% specificity, 88.5% positive predictive value, 85.1% negative predictive value, 87.2% accuracy and an area under the ROC curve of 0.924. Finally, the AHI derived from the quadratic regression curve for the CTM showed better agreement with the AHI from PSG than classical and ApEn derived indexes. CONCLUSION: The results suggest that CTM could improve the diagnostic ability of SaO2 signals recorded from portable monitoring. CTM could be a useful tool for physicians in the diagnosis of OSA syndrome.     

The effect of acute exposure to morphine on breathing variability and cardiopulmonary coupling in men with obstructive sleep apnea: A randomized controlled trial

Opioid‐related deaths from respiratory depression are increasing but there is only limited information on the effect of morphine on breathing during sleep. This study aimed to detect and quantify opioid‐induced cardiorespiratory pattern changes during sleep in obstructive sleep apnea (OSA) patients using novel automated methods and correlate these with conventional polysomnography (PSG) measures. Under a randomized double‐blind placebo‐controlled crossover design, 60 male OSA patients attended two one‐night visits to the sleep laboratory, at least a week apart. Either a 40‐mg controlled‐release oral morphine dose or placebo was administered. Breathing during sleep was measured by standard in‐laboratory PSG. We analysed the inter‐breath interval (IBI) from the PSG flow channel to quantify breathing irregularity. Cardiopulmonary coupling (CPC) was analysed using the PSG electrocardiogram (ECG) channel. Following the consumption of morphine, the 60 OSA patients had fewer breaths (p = .0006), a longer inter‐breath interval (p < .0001) and more irregular breathing with increased IBI coefficient of variation (CV) (p = .0015) compared to the placebo night. A higher CPC sleep quality index was found with morphine use. The change of key IBI and CPC parameters was significantly correlated with the change of key PSG sleep‐disordered breathing parameters. In conclusion, 40 mg controlled‐release morphine resulted in a longer breathing cycle and increased breathing irregularity but generally more stable sleep in OSA patients. The significant links between the IBI and CPC techniques and a range of PSG sleep‐disordered breathing parameters may suggest a practical value as surrogate overnight cardiorespiratory measurements, because both respiratory flow and ECG can be detected by small portable devices.     

The Utility of Single-Channel Nasal Airflow Pressure Transducer in the Diagnosis Of OSA at Home

Rationale:

Given the high prevalence of obstructive sleep apnea (OSA) and the demand on polysomnography (PSG), there is a need for low cost accurate simple diagnostic modalities that can be easily deployed in primary care to improve access to diagnosis.

Study Objectives:

The aim was to examine the utility of single-channel nasal airflow monitoring using a pressure transducer at home in patients with suspected OSA.

Design:

Cross-sectional study

Setting:

Laboratory and home

Participants:

The study was conducted in two populations. Consecutive patients with suspected OSA were recruited from the sleep disorders clinic at a tertiary referral center and from 6 local metropolitan primary care centers.

Interventions:

All patients answered questionnaires and had laboratory PSG. Nasal airflow was monitored for 3 consecutive nights at home in random order either before or after PSG.

Results:

A total of 193 patients participated (105 sleep clinic patients and 88 from primary care). The mean bias PSG apnea hypopnea index (AHI) minus nasal flow respiratory disturbance index (NF RDI) was –4.9 events per hour with limits of agreement (2 SD) of 27.8. NF RDI monitored over 3 nights had high accuracy for diagnosing both severe OSA (defined as PSG AHI > 30 events per hour) with area under the receiver operating characteristic curve (AUC) 0.92 (95% confidence interval (CI) 0.88-0.96) and any OSA (PSG AHI >5), AUC 0.87 (95% CI 0.80-0.94).

Conclusions:

Single-channel nasal airflow can be implemented as an accurate diagnostic tool for OSA at home in both primary care and sleep clinic populations.

Citation:

Makarie Rofail L; Wong KKH; Unger G; Marks GB; Grunstein RR. The utility of single-channel nasal airflow pressure transducer in the diagnosis of OSA at home. SLEEP 2010;33(8):1097-1105.     

Effect of sleep position and sleep stage on the collapsibility of the upper airways in patients with sleep apnea

Collapsibility of the upper airways has been identified as an important pathogenic factor in obstructive sleep apnea (OSA). Objective measures of collapsibility are pharyngeal critical pressure (Pcrit) and resistance of the upstream segment (Rus). To systematically determine the effects of sleep stage and body position we investigated 16 male subjects suffering from OSA. We compared the measures in light sleep, slow-wave sleep, REM sleep and supine vs. lateral positions. The pressure-flow relationship of the upper airways has been evaluated by simultaneous readings of maximal inspiratory airflow (Vimax) and nasal pressure (p-nCPAP). With two-factor repeated measures ANOVA on those 7 patients which had all 6 situations we found a significant influence of body position on Pcrit (p<0.05) whereas there was no significant influence of sleep stage and no significant interaction between body position and sleep stage. When comparing the body positions Pcrit was higher in the supine than in the lateral positions. During light sleep Pcrit decreased from 0.6 +/- 0.8 cm H2O (supine) to -2.2 +/- 3.6 cm H2O (lateral) (p<0.01), during slow-wave sleep Pcrit decreased from 0.3 +/- 1.4 cm H2O (supine) to -1.7 +/- 2.6 (lateral) (p<0.05) and during REM sleep it decreased from 1.2 +/- 1.5 cm H2O to -2.0 +/- 2.2 cm H2O (p<0.05). Changes in Rus revealed no body position nor sleep-stage dependence. Comparing the different body positions Rus was only significantly higher in the lateral position during REM sleep (p<0.05). The results indicate that collapsibility of the upper airways is not mediated by sleep stages but is strongly influenced by body position. As a consequence lower nCPAP pressure is needed during lateral positions compared to supine positions.     

Validation of a Portable Monitoring System for the Diagnosis of Obstructive Sleep Apnea Syndrome

Study Objective:

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

Design:

Prospective and randomized.

Setting:

Sleep laboratory.

Participants:

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

Interventions:

N/A

Measurements and Results:

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

Conclusion:

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

Citation:

Santos-Silva R; Sartori DE; Truksinas V; Truksinas E; Alonso FFFD; TufikS; Bittencourt LRA. Validation of a portable monitoring system for the diagnosis of obstructive sleep apnea syndrome. SLEEP 2009;32(5):629-639.     

成年阻塞性睡眠呼吸暂停患者多导睡眠图及临床特征分析性差异

目的:分析成年男性阻塞性睡眠呼吸暂停(OSA)患者多导睡眠图及临床特征,明确年龄对OSA严重程度的影响。方法:回顾性研究包括836名成年男性OSA患者,按年龄分为三组:青年组312人(平均年龄37.07岁),中年组359人(平均年龄52.14岁),老年组165人(平均年龄69.43岁)。分析其多导睡眠图和临床特征,并进行相关性分析。结果:中年组和老年组呼吸暂停低通气指数(AHI)、阻塞性呼吸暂停指数(OAI)、AHI-NREM和AHI-REM均无显著统计学意义(P>0.05),但均低于青年组(P<0.01);中年组和老年组的最低血氧饱和度(SaO2)均高于青年组;中枢性呼吸暂停指数(CAI)随年龄增长而升高(P<0.05)。在睡眠结构方面,老年组总睡眠时间、非快速眼动(NREM)睡眠时间和快速眼动期(REM)睡眠时间均缩短,睡眠效率亦低于青年组(P<0.01),但睡眠潜伏期和入睡后觉醒时间(WASO)明显延长(P<0.01)。年龄与以下各项均呈现显著的相关性:AHI(P<0.01),OAI(P<0.01),CAI(P<0.01),最低SaO2(P<0.01)。多重回归分析表明年龄作为独立变量分别与AHI,OAI,CAI具有相关性。结论:在成年OSA患者中,年龄与OSA严重程度具有显著的相关性,表现为OSA随年龄增长而降低。本研究为研究年龄与OSA严重程度的关系提供了新的证据。     

Is there a link between intermittent hypoxia-induced respiratory plasticity and obstructive sleep apnoea?

Although neuroplasticity is an important property of the respiratory motor control system, its existence has been appreciated only in recent years and, as a result, its functional significance is not completely understood. The most frequently studied models of respiratory plasticity is respiratory long-term facilitation (LTF) following acute intermittent hypoxia and enhanced LTF following chronic intermittent hypoxia. Since intermittent hypoxia is a prominent feature of sleep-disordered breathing, LTF and/or enhanced LTF may compensate for factors that predispose to sleep-disordered breathing, particularly during obstructive sleep apnoea (OSA). Long-term facilitation has been studied most frequently in rats, and exhibits interesting properties consistent with a role in stabilizing breathing during sleep. Specifically, LTF: (1) is prominent in upper airway respiratory motor activity, suggesting that it stabilizes upper airways and maintains airway patency; (2) is most prominent during sleep in unanaesthetized rats; and (3) exhibits sexual dimorphism (greatest in young male and middle-aged female rats; smallest in middle-aged male and young female rats). Although these features are consistent with the hypothesis that upper airway LTF minimizes the prevalence of OSA in humans, there is little direct evidence for such an effect. Here we review advances in our understanding of LTF and its underlying mechanisms and present evidence concerning a potential role for LTF in maintaining upper airway patency, stabilizing breathing and preventing OSA in humans. Regardless of the relationship between LTF and OSA, a detailed understanding of cellular and synaptic mechanisms that underlie LTF may guide the development of new drugs to regulate upper airway tone, thereby offsetting the tendency for upper airway collapse characteristic of heavy snoring and OSA.     

Portable monitoring and autotitration versus polysomnography for the diagnosis and treatment of sleep apnea

STUDY OBJECTIVES: To compare a clinical pathway using portable monitoring (PM) for diagnosis and unattended autotitrating positive airway pressure (APAP) for selecting an effective continuous positive airway pressure (CPAP) with another pathway using polysomnography (PSG) for diagnosis and treatment of obstructive sleep apnea (OSA). DESIGN: Randomized parallel group SETTING: Veterans Administration Medical Center PATIENTS: 106 patients with daytime sleepiness and a high likelihood of having OSA MEASUREMENTS AND RESULTS: The AHI in the PM-APAP group was 29.2 +/- 2.3/h and in the PSG group was 36.8 +/- 4.8/h (P= NS). Patients with an AHI > or = 5 were offered CPAP treatment. Those accepting treatment (PM-APAP 45, PSG 43) were begun on CPAP using identical devices at similar mean pressures (11.2 +/- 0.4 versus 10.9 +/- 0.5 cm H2O). At a clinic visit 6 weeks after starting CPAP, 40 patients in the PM-APAP group (78.4% of those with OSA and 88.8% started on CPAP) and 39 in the PSG arm (81.2% of those with OSA and 90.6% of those started on CPAP) were using CPAP treatment (P = NS). The mean nightly adherence (PM-APAP: 5.20 +/- 0.28 versus PSG: 5.25 +/- 0.38 h/night), decrease in Epworth Sleepiness Scale score (-6.50 +/- 0.71 versus -6.97 +/- 0.73), improvement in the global Functional Outcome of Sleep Questionnaire score (3.10 +/- 0.05 versus 3.31 +/- 0.52), and CPAP satisfaction did not differ between the groups. CONCLUSIONS: A clinical pathway utilizing PM and APAP titration resulted in CPAP adherence and clinical outcomes similar to one using PSG.