Sleep apnea monitoring and diagnosis based on pulse oximetery and tracheal sound signals

Sleep apnea is a common respiratory disorder during sleep, which is described as a cessation of airflow to the lungs that lasts at least for 10 s and is associated with at least 4% drop in blood’s oxygen saturation level (S_aO₂). The current gold standard method for sleep apnea assessment is full-night polysomnography (PSG). However, its high cost, inconvenience for patients, and immobility have persuaded researchers to seek simple and portable devices to detect sleep apnea. In this article, we report on developing a new method for sleep apnea detection and monitoring, which only requires two data channels: tracheal breathing sounds and the pulse oximetery (S_aO₂ signal). It includes an automated method that uses the energy of breathing sounds signals to segment the signals into sound and silent segments. Then, the sound segments are classified into breath, snore, and noise segments. The S_aO₂ signal is analyzed automatically to find its rises and drops. Finally, a weighted average of different features extracted from breath segments, snore segments and S_aO₂ signal are used to detect apnea and hypopnea events. The performance of the proposed approach was evaluated on the data of 66 patients recorded simultaneously with their full-night PSG study, and the results were compared with those of the PSG. The results show high correlation (0.96, P < 0.0001) between the outcomes of our system and those of the PSG. Also, the proposed method has been found to have sensitivity and specificity values of more than 91% in differentiating simple snorers from obstructive sleep apnea patients.     

Autonomic arousal index: an automated detection based on peripheral arterial tonometry

Arousals from sleep are associated with increased sympathetic activation and are therefore associated with peripheral vasoconstriction. We hypothesized that digital vasoconstrictions as measured by peripheral arterial tonometery (PAT), combined with an increase in pulse rate, would accurately reflect arousals from sleep, and can provide an autonomic arousal index (AAI). Based on a previously studied group of 40 sleep apnea patients simultaneously recorded by both polysomnography (PSG) and PAT systems, an automated algorithm using the PAT signal (and pulse rate derived from it) was developed for detection of arousals from sleep. This was further validated in a separate group of 96 subjects (85 patients referred with suspected obstructive sleep apnea and 11 healthy volunteers mean age 46.2+/-14.4 years, BMI 28.5+/-5.4 kg/m2). All underwent a whole night PSG with simultaneous PAT recording. The PSG recordings were blindly manually analyzed for arousals based on American Academy of Sleep Medicine (AASM) criteria, while PAT was scored automatically. There was a significant correlation between PSG and PAT arousals (R=0.82, p<0.0001) with a good agreement across a wide range of values, with a ROC curve having an area under the curve (AUC) of 0.88. We conclude that automated analysis of the peripheral arterial tonometry signal can detect EEG arousals from sleep, in a relatively quick and reproducible fashion.     

Screening of obstructive sleep apnea with empirical mode decomposition of pulse oximetry

Detection of desaturations on the pulse oximetry signal is of great importance for the diagnosis of sleep apneas. Using the counting of desaturations, an index can be built to help in the diagnosis of severe cases of obstructive sleep apnea–hypopnea syndrome. It is important to have automatic detection methods that allows the screening for this syndrome, reducing the need of the expensive polysomnography based studies. In this paper a novel recognition method based on the empirical mode decomposition of the pulse oximetry signal is proposed. The desaturations produce a very specific wave pattern that is extracted in the modes of the decomposition. Using this information, a detector based on properly selected thresholds and a set of simple rules is built. The oxygen desaturation index constructed from these detections produces a detector for obstructive sleep apnea–hypopnea syndrome with high sensitivity (0.838) and specificity (0.855) and yields better results than standard desaturation detection approaches.     

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     

Is a polysomnographic recording prior to MSLT worth the effort?

Objective

It was recently proposed that polysomnography (PSG) may be replaced by actigraphy in order to obtain long-term sleep time prior to the multiple sleep latency test (MSLT). Polysomnography is used to assess sleep time and to detect and classify underlying sleep pathology. In the following article, the contribution of PSG to the diagnostic outcome of the MSLT is discussed.

Methods

MSLT referrals (n?=?81) with in-home polysomnography from the neurology (n?=?39, 23 women, 37 (±13) years) and pulmonary medicine (n?=?42, 20 women, 41 (±14) years) departments were analyzed. The diagnostic outcomes of the PSG and MSLT were examined.

Results

Median total sleep time prior to MSLT was 362 (range, 156–530) min. Sleep apnea (respiratory disturbance index >?15/h and >?30/h) was diagnosed in 21 and 19 patients, respectively. Periodic limb movements (PLM) were identified in 5 patients; 3 of these had a PLM arousal index >?5/h. Sleep onset REM (SOREM) was detected during PSG in 5 patients; 4 of these also had SOREM in the MSLT.

Conclusion

PSG combined with MSLT was found to improve diagnostic outcome and is highly useful for recognition of sleep-related pathology. Various sleep disorders remain undetected if ACT alone is used prior to MSLT procedures.     

Automatic identification of sleep and wakefulness using single‐channel EEG and respiratory polygraphy signals for the diagnosis of obstructive sleep apnea

Polysomnography (PSG) is necessary for the accurate estimation of total sleep time (TST) and the calculation of the apnea–hypopnea index (AHI). In type III home sleep apnea testing (HSAT), TST is overestimated because of the lack of electrophysiological sleep recordings. The aim of this study was to evaluate the accuracy and reliability of a novel automated sleep/wake scoring algorithm combining a single electroencephalogram (EEG) channel with actimetry and HSAT signals. The study included 160 patients investigated by PSG for suspected obstructive sleep apnea (OSA). Each PSG was recorded and scored manually using American Academy of Sleep Medicine (AASM) rules. The automatic sleep/wake‐scoring algorithm was based on a single‐channel EEG (FP2‐A1) and the variability analysis of HSAT signals (airflow, snoring, actimetry, light and respiratory inductive plethysmography). Optimal detection thresholds were derived for each signal using a training set. Automatic and manual scorings were then compared epoch by epoch considering two states (sleep and wake). Cohen's kappa coefficient between the manual scoring and the proposed automatic algorithm was substantial, 0.74 ± 0.18, in separating wakefulness and sleep. The sensitivity, specificity and the positive and negative predictive values for the detection of wakefulness were 76.51% ± 21.67%, 95.48% ± 5.27%, 81.84% ± 15.42% and 93.85% ± 6.23% respectively. Compared with HSAT signals alone, AHI increased by 22.12% and 27 patients changed categories of OSA severity with the automatic sleep/wake‐scoring algorithm. Automatic sleep/wake detection using a single‐channel EEG combined with HSAT signals was a reliable method for TST estimation and improved AHI calculation compared with HSAT.     

Simultaneous recording of ultrasound and polysomnography during natural sleep in patients with obstructive sleep apnea: a pilot study

Tongue base deformation may play a critical role in the phenomenon of obstructive sleep apnea, but polysomnography provides limited information regarding the effect of tongue motion during natural sleep. We reported on preliminary results of combining a novel ultrasound system and polysomnography for simultaneous recordings during natural sleep in volunteers and patients with obstructive sleep apnea. All participants underwent time‐synchronized polysomnography and submental transcutaneous ultrasound examinations. The wearable ultrasound device detected the air–mucosal interface of the tongue surface and automatically determined the maximum tongue base thickness in real time. All participants reported no sensation of heat, no sign of skin allergy, and an average of mild disturbance after the ultrasound recordings. In the individual patient with obstructive sleep apnea, we demonstrated a significant difference (P < 0.001) between the ultrasonic tongue base thickness measured during eupnea and that measured during snoring, hypopnea and apnea. The ultrasonic tongue base thickness increased and remained before the occurrence of obstructive apnea. On average, increased tongue base thicknesses of 2.5 (4.1%), 6.0 (9.8%) and 7.7 mm (12.5%) are associated with snoring, hypopnea and apnea, respectively. Our present data demonstrate that simultaneous examination of ultrasonic tongue base thickness and polysomnography is feasible for prolonged recording during natural sleep. The proposed method also enables the detection of significant differences in ultrasonic tongue base thickness between eupnea and obstructive respiratory events evaluated using polysomnography. This novel technique can be used to generate hypotheses for subsequent investigations of the underlying mechanisms and individualized combined therapy for obstructive sleep apnea. Clinical trial registration: This study has been registered at the Chinese Clinical Trial Registry website with the registration number of ChiCTR‐DDT‐13003313. The date of registration was 13 July 2013.     

Obstructive sleep apnea induced by a parapharyngeal cystic hygroma in an infant

A 7-week-old infant with severe sleep apnea underwent polysomnography that revealed as many as 455 obstructive apneas per night; the apneic episodes had a mean duration of 34 s. A growing tumor in the neck, a parapharyngeal cystic hygroma, was discovered and surgically removed. The infant's condition improved dramatically, and a follow-up polygraphic recording was normal. During the following 10 months the child's condition remained stable. The case reported illustrates a rare cause of severe sleep obstructive apnea. It also reinforces the need for a complete medical approach to the diagnosis and treatment of obstructive sleep apnea in infants.     

Design,construction and evaluation of an ambulatory device for screening of sleep apnea

Obstructive sleep apnea syndrome (OSAS) is a major public health problem. The golden reference for diagnosing OSAS is the sleep-laboratory based polysomnography (PSG). However, screening of population for OSAS may be practical and cost efficient only through ambulatory home recordings. In this work we aimed to design, construct and evaluate a novel ambulatory device for these recordings. The device was designed to record breathing movements, nasal and oral flow, position, snore, blood oxygen saturation and heart rate. The first part of clinical evaluation was done by recording 19 patients simultaneously with the novel device and with clinical reference instrumentation at a sleep laboratory. In the simultaneous recordings, no statistically significant difference was detected in the apnea-hypopnea index. All patients were correctly diagnosed, as compared to the reference instrumentation, with the novel ambulatory device. The second part of clinical evaluation was conducted through 323 ambulatory home recordings of which 275 (193 males and 82 females) were of diagnostically acceptable quality. A total of 106 and 169 recordings were successfully conducted with the novel device and a commercial ambulatory device, respectively. Both devices showed similar diagnostic capability in detecting sleep apnea. The novel device was found clinically applicable, technically reliable and sensitive for the diagnostics of OSAS. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The effect of in-laboratory polysomnography on sleep and objective daytime sleepiness

MSLT guidelines recommend performing MSLTs following polysomnography (PSG) to document the preceding night's sleep. We tested the hypothesis that patients are objectively sleepier after in-laboratory full diagnostic PSG than after a sleep recording at home. Sixteen patients with the sleep apnea/hypopnea syndrome (SAHS; AHI 35+/-SD 28 per hour slept) were recruited into a randomized crossover study. To monitor sleep with minimal disruption at home, only sleep was recorded on 2 consecutive nights, the first for acclimatization. The laboratory limb followed standard PSG. Both study nights were followed next day by MSLT and MWT. There were no differences in MSLT (12.0 SD 5.1 home, 11.6+/-4.7 min laboratory; p=0.7), MWT (32.7+/-8.7, 31.6+/-9.3 min; p=0.6) or total sleep time (362+/-53, 343+/-51 min; p=0.15) between home and laboratory limbs. However, on the home night, fewer microarousals (31+/-14, 54+/-25/hr slept; p<0.0001) and less % wake (15+/-10, 24+/-11; p=0.006) were found. On the home study night, patients had greater % REM sleep, slow-wave sleep and sleep efficiency (all p<0.009). This study does not support the hypothesis that patients are sleepier after laboratory PSG compared to home study night. However, the improved sleep at home raises the question whether laboratory-based polysomnography is always required prior to MSLT/MWT testing or whether less obtrusive monitoring of sleep duration at home would sometimes suffice.     

Body position and obstructive sleep apnea in children

STUDY OBJECTIVES: In adults, sleep apnea is worse when the patient is in the supine position. However, the relationship between sleep position and obstructive apnea in children is unknown. The objective of this study was to evaluate the relationship between obstructive apnea and body position during sleep in children. DESIGN: Retrospective analysis of the relationship between body position and obstructive apnea in obese and non-obese children. SETTING: Tertiary care pediatric sleep center. PATIENTS: Otherwise healthy children, aged 1-10 years, undergoing polysomnography for suspected obstructive sleep apnea syndrome. Obese and non-obese children were evaluated separately. INTERVENTIONS: Retrospective review of the relationship between sleep position and obstructive apnea during polysomnography. MEASUREMENTS AND RESULTS: Eighty polysomnograms from 56 non-obese and 24 obese children were analyzed. Body position was determined by a sensor during polysomnography, and confirmed by review of videotapes. Children had a lower obstructive apnea hypopnea index when supine vs. prone, and shorter apneas when supine then when on their side. There was no difference in apnea duration between the supine and prone positions. Obese and non-obese children showed similar positional changes. CONCLUSIONS: Children with obstructive sleep apnea, in contrast to adults, breathe best when in the supine position.     

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.     

A novel adaptive wrist actigraphy algorithm for sleep-wake assessment in sleep apnea patients

STUDY OBJECTIVES: Current actigraphic algorithms are relatively less accurate in detecting sleep and wake in sleep apnea patients than in people without sleep apnea. In the current study, we attempted to validate a novel automatic algorithm, which was developed for actigraphic studies in normal subjects and patients with obstructive sleep apnea by comparing it on an epoch-by-epoch basis to standard polysomnography. DESIGN: Prospective cohort study. SETTING: Multicenter, university hospital, sleep laboratories. PARTICIPANTS: A total of 228 subjects from 3 different sleep centers (Skara, Boston, Haifa) participated. INTERVENTION AND MEASUREMENTS: Simultaneous recording of polysomnography and Watch_PAT100, an ambulatory device that contains a built-in actigraph. The automatic sleep/wake algorithm is based on both the quantification of motion (magnitude and duration) and the various periodic movement patterns, such as those occurring in patients with moderate to severe obstructive sleep apnea. RESULTS: The overall sensitivity and specificity to identify sleep was 89% and 69%, respectively. The agreement ranged from 86% in the normal subjects to 86%, 84%, and 80% in the patients with mild, moderate, and severe obstructive sleep apnea, respectively. There was a tight agreement between actigraphy and polysomnography in determining sleep efficiency (78.4 +/- 9.9 vs 78.8 +/- 13.4%), total sleep time (690 +/- 152 vs 690 +/- 154 epochs), and sleep latency (56.8 +/- 31.4 vs 43.3 +/- 45.4 epochs). While for most individuals the difference between the polysomnography and actigraphy was relatively small, for some there was a substantial disagreement. CONCLUSIONS: We conclude that this actigraphy algorithm provides a reasonably accurate estimation of sleep and wakefulness in normal subjects and patients with obstructive sleep apnea on an epoch-by-epoch basis. This simple method for assessment of total sleep time may provide a useful tool for the accurate quantification of obstructive sleep apnea in the home environment.     

Manual der American Academy of Sleep Medicine

In the 2007 manual of the American Academy of Sleep Medicine (AASM), all parameters for a cardiorespiratory polysomnography (PSG) were published for the first time in an evidence-based manner including technical specifications and rules for derivations and scoring. After the regularly planned review and revision, the current version 2.0 was published. The significant modifications and their possible impact on clinical routine in Germany are discussed. The most important changes are related to the measurement and scoring of the parameters of breathing. Only one definition remains for the scoring of hypopneas with a flow decrease of 30?% over at least 10 s associated with either a desaturation of at least 3?% or an arousal. In addition, apneas should be rated if they start or end in an epoch scored as wake whenever the patient showed sleep before or afterwards. The revised version allows the measurement of both apneas and hypopneas using an oronasal thermistor or a nasal pressure transducer in the case the other method is not possible due to technical reasons. Furthermore, the definitions and scoring of hypoventilation and Cheyne–Stokes breathing have changed. Concerning sleep scoring, it should be noted that stage N3 can also be determined using C4-M1 depending on the use of recommended or alternative electroencephalogram (EEG) and electrooculogram (EOG) combinations. Although the now unified rule for the rating hypopneas and the possibility to detect apneas or hypopneas using one method seem to be a great simplification for clinical routine, other recommendations must be proven in practice. With the publication of version 2.0 of the AASM manual, it must be asked whether the procedures of the manual should be mandatory for use in Germany or if at least specific basic principles could also be used with older PSG equipment. From the scientific position, the use of the AASM manual version 2.0 for sleep research is indespensible.     

Altered cortical and subcortical local coherence in obstructive sleep apnea: a functional magnetic resonance imaging study

Obstructive sleep apnea (OSA) syndrome is the most common sleep‐related breathing disorder, characterized by excessive snoring and repetitive apneas and arousals, which leads to fragmented sleep and, most importantly, to intermittent nocturnal hypoxaemia during apneas. Considering previous studies about morphovolumetric alterations in sleep apnea, in this study we aimed to investigate for the first time the functional connectivity profile of OSA patients and age–gender–matched healthy controls, using resting‐state functional magnetic resonance imaging (fMRI). Twenty severe OSA patients (mean age 43.2 ± 8 years; mean apnea–hypopnea index, 36.3 h^?1) and 20 non‐apneic age–gender–body mass index (BMI)‐matched controls underwent fMRI and polysomnographic (PSG) registration, as well as mood and sleepiness evaluation. Cerebro‐cerebellar regional homogeneity (ReHo) values were calculated from fMRI acquisition, in order to identify pathology‐related alterations in the local coherence of low‐frequency signal (<0.1 Hz). Multivariate pattern classification was also performed using ReHo values as features. We found a significant pattern of cortical and subcortical abnormal local connectivity in OSA patients, suggesting an overall rearrangement of hemispheric connectivity balance, with a decrease of local coherence observed in right temporal, parietal and frontal lobe regions. Moreover, an increase in bilateral thalamic and somatosensory/motor cortices coherence have been found, a finding due possibly to an aberrant adaptation to incomplete sleep–wake transitions during nocturnal apneic episodes, induced by repetitive choke sensation and physical efforts attempting to restore breathing. Different hemispheric roles into sleep processes and a possible thalamus key role in OSA neurophysiopathology are intriguing issues that future studies should attempt to clarify.     

Sleep apnea in hypoxic and normal kittens

Frequency and characteristics of apneas were studied in 10-, 20-, and 40-day old kittens during several days of exposure to 21%, 10%, or 7% oxygen atmospheres. Ninety-seven percent of all apneas occurred during sleep or at transitions between sleep and waking states. Hypoxic kittens, compared to controls, had greatly decreased apnea frequency, but other characteristics of apneas did not differ significantly. Apneas in both control and hypoxic kittens were normal, stereotyped events and were not considered to represent pathological processes. Evaluation of events preceding apneas indicated that a majority of apneas followed augmented breaths and/or brief arousals. We suggest that apnea, heart rate changes during apnea, and frequently concurrent transitions in sleep-waking state may be causally related to these pre-apnea events. The results of this study and a parallel study of human infants suggest that below-normal apnea frequency may indicate hypoxemia and may be associated with higher risk for Sudden Infant Death Syndrome.     

Low leptin concentration may identify heart failure patients with central sleep apnea

Low leptin concentration has been shown to be associated with central sleep apnea in heart failure patients. We hypothesized that low leptin concentration predicts central sleep apnea. Consecutive ambulatory New York Heart Association (NYHA ) classes I–IV heart failure patients were studied prospectively, including measurement of serum leptin, echocardiography and polysomnography. Sleep apnea was defined by type (central/mixed/obstructive) and by apnea–hypopnea index ≥5 by polysomnography. Subjects were divided into four groups by polysomnography: (1) central sleep apnea, (2) mixed apnea, (3) no apnea and (4) obstructive sleep apnea. Fifty‐six subjects were included. Eighteen subjects were diagnosed with central sleep apnea, 15 with mixed apnea, 12 with obstructive apnea and 11 with no sleep apnea. Leptin concentration was significantly lower in central sleep apnea compared to obstructive apnea (8 ± 10.7 ng mL^?1 versus 19.7 ± 14.7 ng mL^?1, P  ? 0.01) or no sleep apnea (8 ± 10.7 ng mL^?1 versus 17.1 ± 8.4 ng mL^?1, P  ? 0.01). Logistic regression showed leptin to be associated independently with central sleep apnea [odds ratio (OR ): 0.19; 95% confidence interval (CI ): 0.06–0.62; area under the curve (AUC ): 0.80, P  < 0.01]. For the detection of central sleep apnea, a cut‐off value for leptin concentration 5 ng mL^?1 yielded a sensitivity of 50% and specificity of 89%. In conclusion, a low leptin concentration may have utility for the screening of heart failure patients for central sleep apnea.     

Snoring sounds variability as a signature of obstructive sleep apnea

Snoring sounds vary significantly within and between snorers. In this study, the variation of snoring sounds and its association with obstructive sleep apnea (OSA) are quantified. Snoring sounds of 42 snorers with different degrees of obstructive sleep apnea and 15 non-OSA snorers were analyzed. The sounds were recorded by a microphone placed over the suprasternal notch of trachea, simultaneously with polysomnography (PSG) data over the entire night. We hypothesize that snoring sounds vary significantly within a subject depending on the level of obstruction, and thus the level of airflow. We also hypothesize that this variability is associated with the severity of OSA. For each individual, we extracted snoring sound segments from the respiratory recordings, and divided them into three classes: non-apneic, hypopneic, and post-apneic using their PSG information. Several features were extracted from the snoring sound segments, and compared using a nonparametric statistical test. The results show significant shift in the median of features among the snoring sound classes (p < 0.00001) of an individual. In contrast to hypopneic and post-apneic classes, the characteristics of snoring sounds did not vary significantly over time in non-apneic class. Therefore, we used the total variation norm of each subject to classify the participants as OSA and non-OSA snorers. The results showed 92.9% sensitivity, 100% specificity and 96.4% accuracy.     

Polysomnographic assessment of DIMS: empirical evaluation of its diagnostic value

This investigation examined the diagnostic value of polysomnography (PSG) for evaluating disorders of initiating and maintaining sleep (DIMS). The sample consisted of 100 outpatients who presented to the Duke Sleep Disorders Center with a complaint of chronic insomnia. All patients were given comprehensive medical, psychiatric, behavioral, and ambulatory PSG evaluations. Sleep disorder diagnoses were assigned using the criteria of the Association of Sleep Disorders Centers. Overall, PSG yielded important diagnostic information in 65% of the sample: 34% were given a primary sleep disorder diagnosis that was heavily dependent on PSG data [periodic movements of sleep (PMS) = 25%, apnea = 3%, and subjective insomnia = 6%]; 15% were given a secondary diagnosis of one of these three disorders; and PSG ruled out suspected PMS in 9% and sleep apnea in 7% of the sample. Patients greater than 40 years of age had a significantly higher rate of positive PSG findings than younger patients. Using only the clinical exam, two experienced sleep clinicians were able to predict only 14 of 25 PMS cases and one of three cases of sleep apnea. Based on these data, we suggest using PSG routinely with older insomniacs and with younger patients who fail initial treatment.