Assessment of the test–retest reliability of laboratory polysomnography

Statement of the problem  When conducting a treatment intervention study, it is assumed that a level of reliability can be obtained from the measurement tool such that the outcome can be reasonably assessed. Purpose of study  Investigate the reliability of laboratory polysomnography, the gold standard for assessment of treatment outcomes for obstructive sleep apnea, at a 1-month interval. Materials and Methods  In a clinical trial of 118 patients recruited to assess the effects of a pharmaceutical treatment intervention, a subset of 20 patients designated as placebo controls completed two polysomnography studies, one at baseline and one at least one month later. Results  The correlation between the overall Apnea/Hypopnea indices from the two polysomnography (PSG) studies was poor (r = 0.44) and the results were biased, with a mean increase of seven events per hour on night 2. Twenty-five percent of the subjects had an increase greater than 20 events/hour on night 2 and only 45% of participants had a night-to-night difference of ≤5 events/hour. The correlation between overall apnea indexes for nights 1 and 2 (r = 0.61) was improved, compared to the overall apnea/hypopnea indexes. The correlation in sleep efficiency across the two nights was relatively week (r = 0.52) but significant. The correlations between nights 1 and 2 for the percentage of time supine (r = 0.70) and the supine apnea–hypopnea index (AHI) (r = 0.69) were similar and highly significant. The correlation for the non-supine AHI was only 0.25 Conclusions  In this study, the reliability of a single-night PSG in measuring treatment outcome was compromised as a result of the large night-to-night variability of subjects’ obstructive sleep apnea (OSA). Studies employing the AHI as an outcome need to be adequately powered with respect to the inherent night-to-night variability in the measurement. When assessing treatment intervention outcomes, there may be benefit from the acquisition and averaging of multiple nights of data in order to mitigate the inherent night-to-night variability of OSA and improve the accuracy of the outcome assessment.     

Natural course of complex sleep apnea—a retrospective study

Patients with complex sleep apnea syndrome (CompSAS) have obstructive sleep apnea but develop troublesome central sleep apnea activity or Cheyne–Stokes breathing when provided continuous positive airway pressure (CPAP) therapy. We examined whether CompSAS activity persists with long-term CPAP treatment. We retrospectively identified all patients with CompSAS who underwent two therapeutic polysomnograms (PSGs) separated by at least 1 month during 2003–2005. We compared PSG findings between the initial and follow-up study and noted clinical responses to therapy. We identified 13 CompSAS patients meeting criteria. Most follow-up PSGs were ordered after an abnormal overnight oximetry on CPAP or because of CPAP intolerance after 195 (49–562) days. The residual apnea–hypopnea index (AHI) on CPAP decreased from 26 (23–40) on the first PSG to 7 (3–21.5) on the follow-up PSG. Only seven patients reached AHI < 10 and 6 had AHI ≥ 10 (“CPAP nonresponders”) at follow-up. “CPAP nonresponders” were sleepier (Epworth Sleepiness Score 13 [12.5–14] vs 9 [6–9.5], p = 0.03) and trended toward lower body mass index (29.7 [28.6–31.6] vs 34.3 [32.5–35.1], p = 0.06). Both groups were equally compliant with CPAP therapy. Although the AHI tends to improve over time in CompSAS patients treated with CPAP, in this retrospective study nearly half-maintained a persistently elevated AHI. A prospective trial is merited to determine the optimal treatment for these patients.     

自动持续气道正压系统诊断睡眠呼吸暂停综合征的临床评价

目的评价简易的自动持续气道正压系统（AutoSet）在临床上诊断睡眠呼吸暂停综合征（SAS）的应用价值。方法120例患者同时进行AutoSet和多导睡眠图（PSG）的监测研究,比较两种方法的呼吸暂停指数（AI）及呼吸暂停＋低通气指数（AHI）。结果两种方法的AI及AHI呈显著相关（r＝0．88,P＜0．001;r＝0．93,P＜0．001）。AutoSet上显示的呼吸紊乱指数（RII）与PSG的觉醒指数（Ai）呈显著相关（r＝0．72,P＜0．001）。如以AHI≥5、10、15、20次／小时为诊断标准,AntoSet诊断SAS的敏感性分别为94％、92％、91％、91％,特异性分别为80％、85％、92％、91％。结论AutoSet系统是一个诊断SAS敏感和有价值的工具,尤其对AHI≥30次／小时的SAS患者,其诊断价值更大,但对于轻、中度患者有一定的误差。     

Is the clinical presentation different between men and women admitting to the sleep laboratory?

Objectives  Sleep and sleep disorders are different in several important ways between men and women. We aimed to investigate gender differences in initial symptoms and associating medical diseases of patients admitting to our sleep clinic. Methods  Ninety-one patients, 20 women (22%) and 71 men (78%), admitting consecutively to the sleep clinic were studied. A detailed sleep and medical history of the patients was recorded. All patients were questioned for Epworth Sleepiness Scale (ESS) and underwent an entire night of diagnostic polysomnography. Apnea–hypopnea index (AHI) was identified as the total number of apnea and hypopnea per hour of sleep. Hypopnea was defined as a decrease of airflow by at least 50% and desaturations were defined as ≥4% decrease in oxygen saturation. Results  The mean values for age, body mass index, blood pressures and ESS score did not significantly differ between men and women, but AHI (events/h) was significantly higher in men (29.1 ± 22.7) than women (17.9 ± 17.7, p < 0.05). Snoring was the most common symptom in both men (95%) and women (90%). Among the main presenting complaints, only morning headache (12 of women 60%, 31 of men 43%, p = 0.04) and dry mouth on awakening (ten of women 50%, 57 of men 80%, p = 0.02) showed a significant difference between the two genders, while among the medical diseases only hypothyroidism (four of women 20% and three of men 4%, p = 0.03) and depression (nine of women 45% and 16 of men 22%, p = 0.02) were seen as statistically higher in women than in men. Conclusions  Primary care physicians should be aware of obstructive sleep apnea (OSA) in women and the importance of referring women for sleep studies when they complain of symptoms associated with OSA, even if other non-specific symptoms such as morning headaches are reported. Also, hypothyroidism and depression are accompanied with sleep disorders especially in women.     

Sleep apnea syndrome: improved detection of respiratory events and cortical arousals using oxymetry pulse wave amplitude during polysomnography

Respiratory events (RE) during sleep induce cortical arousals (A) and marked changes in autonomic markers in sleep apnea syndrome (SAS). The aims of the study were double. First, we assessed whether pulse wave amplitude (PWA) added to polysomnography (PSG) could improve RE and A detection; second, we wanted to know whether the quality of detection of these two parameters could be improved using PWA. Respiratory disturbance index (RDI) and A were randomly scored twice by the same observer in 12 male patients with SAS. The first scoring was done using conventional PSG signals, the second scoring adding PWA to PSG. We also measured interobserver agreement by randomly selecting and reading 100 PSG sequences of 5 min with and without PWA by two observers. Adding PWA to PSG parameters allowed to detect significantly more RDI (53.9 ± 21.6 h⁻¹ versus 48.3 ± 22.3 h⁻¹, p < 0.001) and more A (68.0 ± 14.4 versus 59.4 ± 16.5, p < 0.001). Moreover, after using PWA, there was no significant disagreement between two observers for detecting RE, showing better quality of RE detection. PWA is a simple and cheap parameter that improves the diagnostic value of conventional PSG in sleep apnea syndrome by better detecting respiratory events and A.     

Mandibular advancement splint titration in obstructive sleep apnoea

Introduction  Mandibular advancement splints (MAS) allowing self-adjustment may be better tolerated, but the optimum titration protocol needs systematic study. Aim  The aims of the study are to assess the effectiveness of a titratable MAS device in consecutive patients with body mass index (BMI) < 35 kg/m² and obstructive sleep apnoea [OSA, apnoea–hypopnoea index (AHI) 10–40/h] and compare two methods of adjustment [self-adjustment or adjustment after polysomnographic (PSG) feedback]. Materials and methods  Twenty-eight patients (24 M, mean age 49 years, mean BMI 27.6 kg/m²) with symptomatic (Epworth Sleepiness score > 8/24, snoring, choking or poor sleep quality) OSA (mean AHI 25.7/h, range 10–46/h) had a MAS set at 70% maximal protrusion and were randomised to subjective self-adjustment for 6 weeks (n = 16) or objective adjustment (n = 12; fixed position for 3 weeks, then PSG based feedback at 3 weeks with self-adjustment instructions). Primary outcome variable (AHI) and OSA symptoms were compared by t tests and chi-squared tests at baseline and after 6 weeks. Resolution of apnoea was defined as AHI < 5/h; improvement was defined as AHI decreased by >50% but still >5/h. Results  The groups had similar baseline demographics, OSA severity and occlusal type. MAS therapy improved or resolved OSA in 20 out of 28 (71%) and was reportedly used nightly by 91% of the objective group and 63% of the subjective group (p = 0.04). MAS were used all night by 75% of the objective group and 69% of the subjective group (p > 0.05). MAS adjustment following PSG feedback did not lower AHI further from 3 weeks (baseline 26.5 ± 12.0/h, 3 weeks 15.3 ± 13.5/h p = 0.01, 6 weeks 11.7 ± 10.0/h, p = 0.11). The overall improvement was similar to that achieved with subjective adjustment (baseline AHI 25.4 ± 7.4/h, 6 weeks 14.3 ± 10.7/h, p = 0.0002). Symptomatic benefit was reported by both groups. Conclusion  In selected patients, titratable MAS improved or resolved OSA in the majority of patients and was well tolerated. PSG-based feedback at 3 weeks allowed objective confirmation of efficacy and increased device use but did not result in greater improvement in AHI or symptoms. Neither titration method was significantly superior for us to provide firm endorsement. However, we recommend a follow-up sleep study to confirm MAS efficacy.     

Automated detection of sleep disordered breathing using a nasal pressure monitoring device

To assess the accuracy of a single channel portable monitoring device (RUSleeping™ RTS, Respironics, Murrysville, PA) that measures nasal pressure (a surrogate for airflow) to detect sleep disordered breathing (SDB). Twenty-five adult patients referred to a community sleep laboratory with suspected obstructive sleep apnea (OSA) participated in this investigation. The portable monitoring device was used in the sleep laboratory to acquire data concurrently with a standard multi-channel polysomnogram (PSG) to assess SDB. Respiratory events were scored manually on the PSG using standard criteria for clinical research to quantify an apnea–hypopnea index (AHI) based on events during sleep. The portable monitoring device automatically calculated an unedited respiratory event index (REI) based on recording time. These data were then compared using the Pearson product–moment correlation coefficient, Bland–Altman analysis, receiver operating characteristic (ROC) curves, and likelihood ratios. All 25 subjects completed the study. Mean age of subjects was 42.4 ± 12.9 years and mean body mass index was 31.0 ± 7.4 kg m⁻². There was good agreement between the REI and the AHI (R = 0.77, p < 0.001, mean difference 2.6 events per hour [2 SD: 39.8] using a Bland–Altman plot). The area under the ROC curve for detecting SDB (PSG AHI greater than or equal to five events per hour) with the REI was 0.94 (95% CI 0.84–1.0). For an REI >11.9 events per hour, the sensitivity was 0.89 (95% CI 0.65–0.99) and the specificity was 0.86 (95% CI 0.42–1.0) with a likelihood ratio of 6.2 for a positive test (LR+) and 0.13 for a negative test (LR−). Similar results were observed for detecting moderate–severe SDB (PSG AHI ≥ 15 events h⁻¹) using REI >15.2 events h⁻¹. In a population of subjects with suspected OSA, this portable monitoring device can automatically quantify an REI that compares well to the AHI scored manually on a concurrent PSG. Such a device may prove useful to assess SDB in high risk populations with self-administered testing in ambulatory settings such as the home. This study was performed at the Sleep Center of Greater Pittsburgh Sleep Laboratory.     

Evaluation of a portable recording device (ApneaLink?) for case selection of obstructive sleep apnea

Objective  This study was designed to assess the sensitivity and specificity of a portable sleep apnea recording device (ApneaLink™) using standard polysomnography (PSG) as a reference and to evaluate the possibility of using the ApneaLink™ as a case selection technique for patients with suspected obstructive sleep apnea (OSA). Materials and methods  Fifty patients (mean age 48.7 ± 12.6 years, 32 males) were recruited during a 4-week period. A simultaneous recording of both the standard in-laboratory PSG and an ambulatory level 4 sleep monitor (ApneaLink™) was performed during an overnight study for each patient. PSG sleep and respiratory events were scored manually according to standard criteria. ApneaLink™ data were analyzed either with the automated computerized algorithm provided by the manufacturer following the American Academy of Sleep Medicine standards (default setting DFAL) or The University of British Columbia Hospital sleep laboratory standards (alternative setting, ATAL). The ApneaLink respiratory disturbance indices (RDI), PSG apnea–hypopnea indices (AHI), and PSG oxygen desaturation index (ODI) were compared. Results  The mean PSG-AHI was 30.0 ± 25.8 events per hour. The means of DFAL-RDI and ATAL-RDI were 23.8 ± 21.9 events per hour and 29.5 ± 22.2 events per hour, respectively. Intraclass correlation coefficients were 0.958 between PSG-AHI and DFAL-RDI and 0.966 between PSG-AHI and ATAL-RDI. Receiver operator characteristic curves were constructed using a variety of PSG-AHI cutoff values (5, 10, 15, 20, and 30 events per hour). Optimal combinations of sensitivity and specificity for the various cutoffs were 97.7/66.7, 95.0/90.0, 87.5/88.9, 88.0/88.0, and 88.2/93.9, respectively for the default setting. The ApneaLink™ demonstrated the best agreement with laboratory PSG data at cutoffs of AHI ≥ 10. There were no significant differences among PSG-AHI, DFAL-RDI, and ATAL-RDI when all subjects were considered as one group. ODI at 2%, 3%, and 4% desaturation levels showed significant differences (p < 0.05) compared with PSG-AHI, DFAL-RDI, and ATAL-RDI for the entire group. Conclusion  The ApneaLink™ is an ambulatory sleep monitor that can detect OSA and/or hypopnea with acceptable reliability. The screening and diagnostic capability needs to be verified by further evaluation and manual scoring of the ApneaLink™. It could be a better choice than traditional oximetry in terms of recording respiratory events, although severity may be under- or overestimated.     

Gender differences in Saudi patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) remains under-recognized in women possibly due to differences in clinical presentation, difference in tolerance to symptoms, and rate of usage and referral to sleep services. No reports have addressed OSA in women in the Middle Eastern (Arab) population. Therefore, we conducted this study to assess the differences in demographics, clinical presentation, and polysomnographic (PSG) findings between Saudi women and men diagnosed to have (OSA). The study group comprised 191 consecutive Saudi women and 193 consecutive men who were referred to the Sleep Disorders Centre and were found by in-laboratory PSG to have OSA. Demographic and clinical data were obtained by personal interviews. Women were significantly older than men (53.9 and 43.0 years, respectively; p < 0.001). Similarly, their body mass index was significantly higher than men (p < 0.001). Insomnia was more common among women (39.8%) compared to men (25.9%; p = 0.005). Other sleep symptoms including witnessed apnea, and excessive daytime sleepiness did not show any statistical difference between the two groups. Women were more likely than men to be diagnosed with hypothyroidism, diabetes, hypertension, cardiac disease, and asthma. Apnea–hypopnea index (AHI) was statistically higher in men compared to women; however, most of apnea/hypopnea events in women occurred during rapid eye movement sleep, and the mean duration of hypopnea and apnea was significantly lower in women (p = 0.004). Sleep efficiency was lower in women (71.5% vs. 77.7%) in men (p < 0.001). The desaturation index was higher in men (p = 0.01), but no difference was found in lowest SaO₂ or time with SaO₂ less than 90%. The present study showed important clinical and PSG differences between Saudi women and men with OSA. Clinicians need to be aware of these differences when assessing women for the possibility of OSA as they may be symptomatic at a lower AHI and have significant comorbid conditions that can be adversely affected if their OSA was not timely managed.     

The minimum period of polysomnography required to confirm a diagnosis of severe obstructive sleep apnoea

Background and objective: To combine the diagnosis of OSA with titration of positive airway pressure (PAP), current guidelines recommend that split‐night polysomnography (PSG) be performed if an AHI of ≥40/h is recorded over 2 h. However, the diagnostic validity of partial‐night PSG is uncertain. This study aimed to test the validity of partial‐night PSG and to determine the optimum AHI cut‐off points. Methods: Patients who visited the sleep centre at a tertiary medical centre between January and December 2008, for symptoms related to sleep disorders (sleepiness, snoring, sleep disturbance), and who completed full‐night PSG, were evaluated for this study. Full‐night PSG data were processed to obtain partial‐night PSG data, from which AHI were computed as a reference for diagnosing severe OSA. Full‐night and partial‐night PSG data obtained over different recording times (expressed as x‐h PSG, where x = 1–6) were compared using receiver operating characteristic (ROC) curve analysis. The diagnostic validity of 2‐h PSG with different AHI cut‐off points (25/h to 45/h) was also calculated. Results: Data from 198 PSG recordings was processed. For 2‐h PSG, an AHI cut‐off point of 30/h gave the highest accuracy of 90.9%. Comparing areas under the ROC curves (AUC), 2‐h PSG (AUC = 0.97) was as good as 2.5‐h PSG (AUC = 0.977, P = 0.057) and 3‐h PSG (AUC = 0.978, P = 0.125), but was better than 1.5‐h PSG (AUC = 0.955, P = 0.016). Conclusions: Partial‐night PSG is effective for diagnosing severe OSA. If there is an unabridged PSG recording indicating an AHI of ≥30/h for 2 h, severe OSA can be diagnosed and PAP titration initiated.     

Home-based diagnosis of obstructive sleep apnea by polysomnography type 2: accuracy,reliability, and feasibility

Purpose

Despite being used in large cohort studies, role of polysomnography (PSG) type 2 is still controversy. This study was aimed to determine its accuracy, reliability, and feasibility in diagnosis of obstructive sleep apnea (OSA) compared to gold standard.

Methods

Adult patients with stable medical conditions who complained of snoring or excessive sleepiness and lived around Bangkok were recruited from a sleep clinic. All were asked to fill questionnaires and have PSG done in laboratory (in-Lab PSG) and at home (Home PSG) on separate nights within 2–4 weeks interval.

Results

Eighty-six patients, 48 males and 38 females, were included. Mean of total sleep time, sleep efficiency, and stage R were significantly greater in Home PSG than in-Lab PSG (p?p?=?0.04), but with excellent reliability, intra-class correlation coefficients of 0.96 (95 % CI; 0.93–0.97), and good agreements (κ?=?0.59–0.70) between both tests. The sensitivity, specificity, and accuracy of Home PSG at cut-off point of AHI ≥5, were 0.97, 0.56, and 0.85, respectively, and at AHI ≥15 were 0.95, 0.76, and 0.85, respectively. Sixty-four patients (74.4 %) preferred home-PSG but four patients (4.7 %) needed repeated tests due to significant data loss.

Conclusions

This is the first report in Asia demonstrating that home-based diagnosis of OSA by PSG type 2 was feasible performing with good reliability, high accuracy, and a low failure rate. However, further studies focusing on its cost-effectiveness are required.     

Sleep disordered breathing analysis in a general population using standard pulse oximeter signals

Objectives

Obstructive sleep apnea reported as the apnea–hypopnea index (AHI) is usually measured in sleep laboratories using a high number of electrodes connected to the patient’s body. In this study, we examined the use of a standard pulse oximeter system with an automated analysis based on the photoplethysmograph (PPG) signal for the diagnosis of sleep disordered breathing. Using a standard and simple device with high accuracy might provide a convenient diagnostic or screening solution for patient evaluation at home or in other out of center testing environments.

Methods

The study included 140 consecutive patients that were referred routinely to a sleep laboratory [SleepMed Inc.] for the diagnosis of sleep disordered breathing. Each patient underwent an overnight polysomnography (PSG) study according to AASM guidelines in an AASM-accredited sleep laboratory. The automatic analysis is based on photoplethysmographic and saturation signals only. Those two signals were recorded for the entire night as part of the full overnight PSG sleep study. The AHI calculated from the PPG analysis is compared to the AHI calculated from the manual scoring gold standard full PSG.

Results

The AHI and total respiratory events measured by the pulse oximeter analysis correlated very well with the corresponding results obtained by the gold standard full PSG. The sensitivity and specificity of AHI = or > 5 and 15 levels measured by the analysis are both above 90 %. The sensitivity and positive predictive value for the detection of respiratory event are both above 84 %.

Conclusions

The tested system in this study yielded an acceptable result of sleep disordered breathing compared to the gold standard PSG in patients with moderate to severe sleep apnea. Accordingly and given the convenience and simplicity of the standard pulse oximeter device, the new system can be considered suitable for home and ambulatory diagnosis or screening of sleep disordered breathing patients.     

Is portable monitoring for diagnosing obstructive sleep apnea syndrome suitable in elderly population?

Purpose

Obstructive sleep apnea syndrome (OSAS) is highly prevalent in the elderly. Unattended, at-home portable monitoring (PM) is a diagnostic alternative to polysomnography in adults with high clinical probability of OSAS. However, no studies have evaluated the diagnostic accuracy of PM in elderly population. The aim of our study was to evaluate the effectiveness of PM in elderly patients.

Methods

We selected patients aged over 65 years with suspected OSAS. Two-order randomized evaluations were performed: one night of at-home PM (PMhome) and one night of simultaneous PM and polysomnography (PSG) in the sleep lab (PSG+PM). We obtained three different apnea–hypopnea index (AHI): AHI from PSG (AHI PSG), AHI from at-home PM (AHI PMhome), and AHI from PM+PSG (AHI PM+PSG). Two technicians, blinded to the recording order, scored each sleep study.

Results

We studied a total of 43 patients. No difference between the AHI values for each of the different recordings was found (p?>?0.05). There was good correlation between AHI PSG and AHI PMhome (r?=?0.67) and AHI PSG+PM (r?=?0.84). The area under the receiver operator curve was above 0.83, indicating good sensitivity and a positive predictive value for AHI with cutoffs of 5, 15, and 30 and good specificity and negative predictive value for AHI values above 15. Correlation, accuracy, and agreement were greater when the recordings were made simultaneously.

Conclusions

PM was effective for diagnosing OSAS in the elderly and can be used as an alternative to PSG in elderly patients with a high clinical probability of OSAS.     

老年与非老年阻塞性睡眠呼吸暂停低通气合征象患者心律失常的比较

目的探讨老年阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患者夜间心律失常的特点及其与非老年人的差别。方法经多导睡眠图(PSG)确诊的老年OSAHS患者38例,同时作Holter检查,44例非老年患者作为对照组。结果老年与非老年OSAHS患者夜间心律失常发生率分别为63.2%和27.3%,老年组心律失常发生率明显高于非老年组(P<0.01)。夜间心律失常表现为多种形式,同一患者也可同时发生多种心律失常,窦缓在老年组中较常见;心律失常发生率与暂停-低通气指数(AHI)以及缺氧时间成正相关;同等严重程度比较,老年组心律失常的发生率亦明显高于非老年组。结论老年OSAHS患者夜间可发生多种形式的心律失常,并与AHI和缺氧时间密切相关;OSAHS对老年人心血管系统的影响较非老年人更严重。     

The Berlin questionnaire for sleep apnea in a sleep clinic population: relationship to polysomnographic measurement of respiratory disturbance

The Berlin questionnaire (BQ) has been used to help identify patients at high risk of having sleep apnea in primary care and atrial fibrillation patients. The BQ may be a useful adjunct in sleep medicine and research, but it has never been validated in a sleep clinic population. The aim of the study is to determine the specificity and sensitivity of the BQ compared to the respiratory disturbance index (RDI) values obtained from two nights of polysomnographic recording in a sleep clinic population. This is a retrospective chart review study of 130 sleep clinic patients. Patients’ demographics, BQ scores, RDI measurements, and sleep study parameters were extracted from the patients’ chart. Of the 130 charts reviewed, the BQ identified 76 (58.5%) as being at high-risk of having sleep apnea, but overnight polysomnography found only 34 of the 130 patients (26.2%) had an RDI > 10. The BQ performed with 0.62 sensitivity and 0.43 specificity at the RDI > 10 level. Due to the low sensitivity and specificity as well as the large number of false negatives and positives, the Berlin questionnaire is not an appropriate instrument for identifying patients with sleep apnea in a sleep clinic population.     

Mild to moderate sleep respiratory events: one negative night may not be enough

STUDY OBJECTIVES: Reports on the reproducibility of apnea-hypopnea indexes (AHIs) across sequential polysomnography (PSG) sessions are conflicting, leading to a lack of clear recommendations on the optimal use of this technique: is one night of monitoring sufficient or is a second night required in order to safely reject the diagnosis? DESIGN: Retrospective comparison of two consecutive nights. SETTING: Sleep unit of a tertiary-care facility. PATIENTS: Two hundred forty-three subjects with suspected sleep apneas. INTERVENTIONS: Two sequential PSG sessions in a sleep unit. Measurements and results: Using analysis of covariance for repeated measures, with age and body mass index as covariates and gender as a cofactor, a classic first-night effect was found for sleep variables. In addition, a night effect was demonstrated for sleep respiratory variables. Moreover, the high variability of AHIs showed that many patients had their condition diagnosed on only one of the two nights, and more often on the second night than on the first. The gain in detection by adding a second night when the results of testing on the first were negative was between 15% and 25%, according to the AHI obtained on night 1. CONCLUSIONS: Considering the disability associated with sleep apnea/hypopnea syndrome, as well as its global cost for society, the present study shows that it is worth performing two consecutive PSG sessions or at least a second one when the result of the first one is negative in all patients admitted for apnea detection.     

Prevalence of positional sleep apnea in patients undergoing polysomnography

STUDY OBJECTIVES: The primary aim of this study was to determine the prevalence of positional obstructive sleep apnea using a functional definition. Positional sleep apnea was defined as a total apnea-hypopnea index (AHI) > or = 5 with a > 50% reduction in the AHI between the supine and nonsupine postures, and an AHI that normalizes (AHI < 5) in the nonsupine posture. A secondary aim was to determine if positional sleep apnea can be diagnosed accurately during a split-night study. DESIGN: Retrospective chart review. SETTING: Two sleep centers in Buffalo, NY, one a Veterans Affairs Western New York Healthcare System Sleep Center (VAWNY) and the other a freestanding ambulatory center (Associated Sleep Center [ASC]). PATIENTS: Three hundred twenty-six patients from the VAWNY, including 57 patients who underwent a split-night study and 242 patients from the ASC who underwent polysomnography. INTERVENTIONS: None. MEASUREMENTS: Patient characteristics and sleep study results. RESULTS: Positional sleep apnea was seen in 49 of 99 patients (49.5%) with mild sleep apnea (AHI, 5 to 15/h), 14 of 72 patients (19.4%) with moderate sleep apnea (AHI, 15 to 30/h), and 5 of 77 patients (6.5%) with severe sleep apnea (AHI > 30/h). Sufficient sleep (> 15 min) in both postures was not seen in 104 of 269 patients (38.7%) and 80 of 242 overnight studies (33.1%) at the VAWNY and ASC, respectively, and was not seen in 47 of 57 split-night studies (82.5%). The percentage of studies with insufficient sleep in both postures was significantly greater for split-night studies (p < 0.0001). CONCLUSIONS: Positional sleep apnea is common particularly in patients with mild disease. Positional sleep apnea cannot usually be assessed during a split-night study.     

NREM-AHI greater than REM-AHI versus REM-AHI greater than NREM-AHI in patients with obstructive sleep apnea: clinical and polysomnographic features

Purpose  

Previous studies show a high prevalence of obstructive sleep apnea (OSA) patients with a higher non-rapid eye movement (NREM) apnea–hypopnea index (AHI) (NREM-AHI) than rapid eye movement (REM) AHI (REM-AHI). However, the clinical significance of this phenomenon in patients with OSA is unknown. This study aimed to investigate whether there were significant differences in clinical and polysomnographic features between the NREM-AHI > REM-AHI group and the REM-AHI > NREM-AHI group and to determine whether NREM-AHI > REM-AHI or REM-AHI > NREM-AHI is a specific clinical entity.     

Home Polysomnography in Methadone Maintenance Patients with Subjective Sleep Complaints

Objective: Most patients in methadone maintenance treatment (MMT) complain of poor sleep. Few studies have examined MMT patients' sleep using polysomnography (PSG), and none to our knowledge have employed home PSG. Standard sleep laboratory research protocols often require two consecutive PSG nights because of inter-night variability in sleep attributed to first-night adaptation to a novel sleep environment and recording procedures. The purpose of this study was to assess the stability of sleep measures across two consecutive nights of home PSG in opioid-dependent MMT patients. Methods: Home PSG was performed in 50 MMT patients with subjective sleep complaints. Participants were 54% female and 82% white with mean age = 36.8 years, median methadone dose = 100 mg/day, and median MMT duration = 286 days. Results: Thirty-six participants completed two consecutive nights of at-home PSG and 14 completed one. For the former group, no differences in sleep measures were found across recordings. The one-night group had significantly less total sleep time, Stage 2 sleep, REM sleep, and shorter REM latency than the two-night group. Conclusions: Home PSG is a viable method for recording sleep in opioid-dependent MMT patients, and was stable across consecutive nights of study. Two nights of home PSG for MMT patients, therefore, are not necessarily required and confidence in the reliability of data from one night of recording can be assumed. Excluding MMT research participants with one PSG may exclude patients with the worst sleep—precisely the group that most warrants investigation.     

Comparison between reported and recorded total sleep time and sleep latency in 6- to 11-year-old children: the Tucson Children’s Assessment of Sleep Apnea Study (TuCASA)

Research comparing parental report of sleep times to objectively obtained polysomnographic evidence of sleep times in schoolchildren is lacking. This report compares habitual sleep time and objectively recorded sleep time and sleep latency with parental reports of sleep time immediately after a night of polysomnography in elementary schoolchildren. Unattended home polysomnograms (PSG) were obtained from 480 children. On the night of the PSG, a parent was asked to complete a Sleep Habits Questionnaire, which inquired about the habitual total sleep time (HABTST) and habitual sleep onset latency (HABSOL) of his/her child on both school days and nonschool days. On the morning after the PSG, the parent was asked to estimate the total sleep time (ESTTST) and sleep onset latency (ESTSOL) of his/her child on the night of the recording. Comparisons were made to actual total sleep time (PSGTST) and sleep latency (PSGSOL) on the PSG. The sample was comprised of 50% girls, 42.3% Hispanic, and 53% aged 6–8 years. The mean HABTST, ESTTST, and PSGTST were 578, 547, and 480 min, respectively. HABTST was greater than both ESTST and PSGTST (p < 0.001). Moreover, ESTTST was greater than PSGTST (p < 0.001). The mean HABSOL, ESTSOL, and PSGSOL were 15, 17, and 11 min. ESTSOL was longer than PSGSOL (p < 0.001). There were no gender differences. However, Hispanic parents reported significantly less HABTST in their children than Caucasian parents (566 vs 587 min, p < 0.001). Parents of schoolchildren in this population-based sample substantially overestimated their children’s actual total sleep time and sleep onset latency.