The behavioral morbidity of obstructive sleep apnea

Normal multiple sleep latency test values in adults: A systematic review and meta-analysis

Sleep latency is a measure of time it takes to enter sleep. Very short sleep latencies are indicative of excessive daytime sleepiness and pathological sleep conditions such as narcolepsy. The normal range of mean sleep latency calculated from the multiple sleep latency test in healthy adults is not well-established. We provide a review of normative mean sleep latency values on the multiple sleep latency test by synthesizing data from 110 healthy adult cohorts. We also examine the impact of demographic variables such as age, sex, body mass index, sleep architecture and sleep-disordered breathing as well as methodological variables such as sleep onset definitions and multiple sleep latency test protocols. The average mean sleep latency was 11.7 min (95% CI: 10.8-12.6; 95% PI: 5.2-18.2) for cohorts evaluated using the earlier definition of sleep onset and 11.8 min (95% CI: 10.7-12.8; 95% PI: 7.2-16.3) for those evaluated using the later definition. There were no significant associations between mean sleep latency and demographic or methodological variables. A negative association of -0.29 per one unit increase (95% CI: -0.55 to -0.04) was found between mean sleep latency and apnea-hypopnea index on prior night polysomnography. Establishing updated ranges for mean sleep latency among healthy adults may guide clinical decision-making surrounding sleep pathologies and inform future research into the associations between patient variables, daytime sleepiness, and sleep pathologies.

Identification of metabolic fingerprints in severe obstructive sleep apnea using gas chromatography-Mass spectrometry

Objective: Obstructive sleep apnea (OSA) is considered a major sleep-related breathing problem with an increasing prevalence rate. Retrospective studies have revealed the risk of various comorbidities associated with increased severity of OSA. This study aims to identify novel metabolic biomarkers associated with severe OSA. Methods: In total, 50 cases of OSA patients (49.74 ± 11.87 years) and 30 controls (39.20 ± 3.29 years) were included in the study. According to the polysomnography reports and questionnaire-based assessment, only patients with an apnea-hypopnea index (AHI >30 events/hour) exceeding the threshold representing severe OSA patients were considered for metabolite analysis. Plasma metabolites were analyzed using gas chromatography-mass spectrometry (GC-MS). Results: A total of 92 metabolites were identified in the OSA group compared with the control group after metabolic profiling. Metabolites and their correlated metabolic pathways were significantly altered in OSA patients with respect to controls. The fold-change analysis revealed markers of chronic kidney disease, cardiovascular risk, and oxidative stress-like indoxyl sulfate, 5-hydroxytryptamine, and 5-aminolevulenic acid, respectively, which were significantly upregulated in OSA patients. Conclusion: Identifying these metabolic signatures paves the way to monitor comorbid disease progression due to OSA. Results of this study suggest that blood plasma-based biomarkers may have the potential for disease management.

Risk of work-related injury in workers with obstructive sleep apnea: A systematic review and meta-analysis

The objective of this study is to elucidate the relationship between obstructive sleep apnea (OSA) and the risk of work-related injuries (WRIs), synthesize the latest clinical evidence and conduct a systematic review and meta-analysis adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA 2020). Observational studies published before April 2020 in PubMed, Cochrane library, PsycINFO, Scopus, Google Scholar and Web of Science were included. Random-effects Mantel-Haenszel meta-analysis was performed. A total of 15 studies with 21,507 participants were included. Prespecified subgroup analyses based on study design and the characteristics of the enrollees were conducted. Overall, workers with OSA had 1.64-fold increased odds of being involved in WRIs compared to their counterparts (OR = 1.64, 95% CI = 1.24-2.16, p = 0.0005). In addition to the professional drivers that have been studied in the past, such a trend also existed in the general working population (OR = 1.68, 95% CI = 1.14-2.49, p = 0.01). We also found that workers with excessive daytime sleepiness (Epworth Sleepiness Scale score >10) had a 1.68-fold increased risk of WRIs compared to those with lower ESS scores (OR = 1.68, 95% CI = 1.22-2.30, p = 0.002). This study verified that OSA workers had a higher risk of WRIs, and such correlations do not show obvious differences in subgroups with different sample sizes, OSA diagnosis methods, job types or definitions of WRI. Based on the association between OSA and WRIs identified in our study, further studies investigating the protective effects of early identification and management of OSA on WRIs are warranted.

Minimally Invasive Combined Nd:YAG and Er:YAG Laser-Assisted Uvulopalatoplasty for Treatment of Obstructive Sleep Apnea

Objective: In this article, efficacy of minimally invasive outpatient laser-assisted uvulopalatoplasty (LAUP) procedure (NightLase^® LAUP) to reduce apnea-hypopnea index (AHI) in patients with obstructive sleep apnea (OSA) is evaluated. Background: OSA is a serious condition, but its treatment is often not effective or is poorly accepted by patients. Newer modes of therapy that are more effective and also more accepted by patients need to be developed. The latest treatment approaches involve a minimally invasive LAUP procedure. This procedure involves thermal processing of the relaxed soft palate and surrounding tissues using neodimium-doped yttrium aluminum garnet (Nd:YAG) and erbium-doped yttrium aluminum garnet (Er:YAG) lasers, resulting in favorable collagen shrinkage and development of new collagen fibers. Procedure has previously been reported to safely and effectively reduce snoring, as well as increase the volume of the oropharyngeal airway, and is well accepted by patients. Materials and methods: The efficacy of the minimally invasive LAUP procedure, combining Nd:YAG laser (λ = 1064 nm) and Er:YAG laser (λ = 2940 nm) applied to the soft palate for treatment of OSA on 27 patients with different severities of OSA was evaluated based on AHI measurements before and after only three 20-min sessions in an outpatient setting over a period of 45-60 days. Results: A decrease in AHI for all the patients with different severities of OSA tested in this study was achieved, with 66.3% average improvement (32-100%). Fifty percent or more improvement was achieved in 78% (21) of all patients. Conclusions: Based on our observations, the NightLase^® LAUP treatment of OSA represents an effective and safe therapeutic method. Further research and longer term prospective trials are needed to improve the evidence base for the potential integration of this treatment method into the current guidelines for treatment of OSA.

Experimental chronic sleep fragmentation alters seizure susceptibility and brain levels of interleukins 1β and 6

Brain hyperexcitability in sleep apnea is believed to be provoked by hypoxemia, but sleep fragmentation can also play a significant role. Sleep fragmentation can trigger inflammatory mechanisms. The aim of this research was to investigate the effects of chronic sleep fragmentation on seizure susceptibility and brain cytokine profile. Chronic sleep fragmentation in male rats with implanted EEG electrodes was achieved by the treadmill method. Rats were randomized to: treadmill control (TC); activity control (AC) and sleep fragmentation (SF) group. Convulsive behavior was assessed 14 days later by seizure incidence, latency time and seizure severity during 30 min following lindane administration. The number and duration of EEG ictal periods were determined. Levels of IL-1β and IL-6 were measured in the animals' serum and brain structures (hippocampus, thalamus and cerebral cortex), in separate rat cohort that underwent the same fragmentation protocol except lindane administration. Incidence and severity of seizures were significantly increased, while latency was significantly decreased in SF+L compared with TC+L group. Seizure latency was also significantly decreased in SF+L compared to AC+L group. The number and duration of ictal periods were increased in the SF+L compared to the AC+L group. IL-1β was significantly increased in the thalamus, cortex and hippocampus in the SF compared to the AC and TC groups. IL-6 was statistically higher only in the cortex of SF animals, while in the thalamic or hippocampal tissue, no difference was observed between the groups. It could be concluded that fourteen-day sleep fragmentation increases seizure susceptibility in rats and modulates brain production of IL-1β and IL-6.

Brain hyperexcitability in sleep apnea is believed to be provoked by hypoxemia, but sleep fragmentation can also play a significant role. Sleep fragmentation can trigger inflammatory mechanisms. The aim of this research was to investigate the effects of chronic sleep fragmentation on seizure susceptibility and brain cytokine profile. Chronic sleep fragmentation in male rats with implanted EEG electrodes was achieved by the treadmill method. Rats were randomized to: treadmill control (TC); activity control (AC) and sleep fragmentation (SF) group. Convulsive behavior was assessed 14 days later by seizure incidence, latency time and seizure severity during 30 min following lindane administration. The number and duration of EEG ictal periods were determined. Levels of IL-1β and IL-6 were measured in the animals’ serum and brain structures (hippocampus, thalamus and cerebral cortex), in separate rat cohort that underwent the same fragmentation protocol except lindane administration. Incidence and severity of seizures were significantly increased, while latency was significantly decreased in SF+L compared with TC+L group. Seizure latency was also significantly decreased in SF+L compared to AC+L group. The number and duration of ictal periods were increased in the SF+L compared to the AC+L group. IL-1β was significantly increased in the thalamus, cortex and hippocampus in the SF compared to the AC and TC groups. IL-6 was statistically higher only in the cortex of SF animals, while in the thalamic or hippocampal tissue, no difference was observed between the groups. It could be concluded that fourteen-day sleep fragmentation increases seizure susceptibility in rats and modulates brain production of IL-1β and IL-6.

A review of psychosocial factors and personality in the treatment of obstructive sleep apnoea

Effective treatment of obstructive sleep apnoea (OSA) is primarily determined by adherence to the selected intervention. The most common treatment pathways are mechanical devices such as continuous positive airway pressure (CPAP) or a mandibular advancement device, often combined with weight loss therapy. Weight reduction is usually an adjunct therapy but may be used as a secondary treatment in mild-to-moderate OSA when mechanical treatments cannot be tolerated. To enhance the uptake and adherence to treatment, clinicians may assess patient's personality profiles and psychological readiness. There is a paucity of evidence related to these aspects of patient care and this article outlines the current research in relation to patient presentation, treatment uptake and barriers, and methods to enhance treatment adherence.

This article disseminates personality traits observed in patients with OSA and identifies vulnerable groups who may require additional support to increase treatment adherence. It summarises the current evidence for treatment barriers in patients with OSA. Low self-efficacy in relation to CPAP and weight loss adherence will be explored as well as the potential to predict treatment responders and enhance therapeutic uptake and adherence. Extending personality traits into research and clinical practice could potentially result in more successful CPAP therapy and weight loss treatment outcomes.

Obstructive sleep apnea and its controversial effects on cognition

Obstructive sleep apnea syndrome is a sleep disorder that may affect many brain functions. We are interested in the cognitive consequences of the condition with regard to the quality of life of individuals with this disorder. A debate is still underway as to whether cognitive difficulties caused by obstructive sleep apnea actually induce a "pseudodementia" pattern. This work provides a brief overview of the main controversies currently surrounding this issue. We report findings and opinions on structural and cognitive brain changes in individuals affected by obstructive sleep apnea by highlighting the involvement of executive functions and the possible reversibility of signs following-treatment with continuous positive airway pressure. Much research has been done on this issue but, to the best of our knowledge, a review of the present state of the literature evaluating different points of view has not yet been carried out.

Subjective apnoea symptoms are associated with daytime sleepiness in patients with moderate and severe obstructive sleep apnoea: a retrospective study

OBJECTIVES

Most previous studies have failed to show a relation between daytime sleepiness and apnoea severity in patients with obstructive sleep apnoea (OSA). We determined the relation between daytime sleepiness and subjective and objective apnoea severity in newly diagnosed patients with moderate-to-severe OSA.

DESIGN

Retrospective cross-sectional study.

SETTING

Tertiary referral centre.

PARTICIPANTS

A total of 559 adults with newly diagnosed moderate and severe OSA.

MAIN OUTCOME MEASURES

Daytime sleepiness was evaluated using the Epworth Sleepiness Scale (ESS). Subjective and objective apnoea severities were assessed using the Sleep Breathing Scale (SBS) and polysomnography respectively. Sleep quality and depressive symptoms were evaluated using Medical Outcomes Study-Sleep Scale and Beck Depression Inventory (BDI) respectively.

RESULTS

The mean ESS score was 9.8 (SD 5.0). ESS score was correlated with SBS score (P < 0.001), apnoea-hypopnoea index (AHI) (P = 0.027), minimal oxygen saturation (MinSaO2 ) (P = 0.021), body mass index (BMI) (P = 0.007) and BDI score (P < 0.001). Linear regression analysis showed that higher SBS (P = 0.005) and BDI scores (P < 0.001) were associated with higher ESS score after controlling for gender, BMI and AHI. Apnoea-hypopnoea index, MinSaO2 and BMI were not independently related to ESS score.

CONCLUSIONS

Daytime sleepiness was related to subjective OSA symptoms but not objective apnoea severity measured by polysomnography in patients with moderate-to-severe OSA. These findings suggest the usefulness of the subjective apnoea severity as an indicator of OSA disease severity.

Sleep disruption increases seizure susceptibility: Behavioral and EEG evaluation of an experimental model of sleep apnea

Sleep disruption accompanies sleep apnea as one of its major symptoms. Obstructive sleep apnea is particularly common in patients with refractory epilepsy, but causing factors underlying this are far from being resolved. Therefore, translational studies regarding this issue are important. Our aim was to investigate the effects of sleep disruption on seizure susceptibility of rats using experimental model of lindane-induced refractory seizures. Sleep disruption in male Wistar rats with implanted EEG electrodes was achieved by treadmill method (belt speed set on 0.02 m/s for working and 0.00 m/s for stop mode, respectively). Animals were assigned to experimental conditions lasting 6h: 1) sleep disruption (sleep interrupted, SI; 30s working and 90 s stop mode every 2 min; 180 cycles in total); 2) activity control (AC, 10 min working and 30 min stop mode, 9 cycles in total); 3) treadmill chamber control (TC, only stop mode). Afterwards, the animals were intraperitoneally treated with lindane (L, 4 mg/kg, SI+L, AC+L and TC+L groups) or dimethylsulfoxide (DMSO, SIc, ACc and TCc groups). Convulsive behavior was assessed by seizure incidence, latency time to first seizure, and its severity during 30 min after drug administration. Number and duration of ictal periods were determined in recorded EEGs. Incidence and severity of lindane-induced seizures were significantly increased, latency time significantly decreased in animals undergoing sleep disruption (SI+L group) compared with the animals from TC+L. Seizure latency was also significantly decreased in SI+L compared to AC+L groups. Number of ictal periods were increased and duration of it presented tendency to increase in SI+L comparing to AC+L. No convulsive signs were observed in TCc, ACc and SIc groups, as well as no ictal periods in EEG. These results indicate sleep disruption facilitates induction of epileptic activity in rodent model of lindane-epilepsy enabling translational research of this phenomenon.

Obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive collapse of the pharyngeal airway during sleep. Control of pharyngeal patency is a complex process relating primarily to basic anatomy and the activity of many pharyngeal dilator muscles. The control of these muscles is regulated by a number of processes including respiratory drive, negative pressure reflexes, and state (sleep) effects. In general, patients with OSA have an anatomically small airway the patency of which is maintained during wakefulness by reflex-driven augmented dilator muscle activation. At sleep onset, muscle activity falls, thereby compromising the upper airway. However, recent data suggest that the mechanism of OSA differs substantially among patients, with variable contributions from several physiologic characteristics including, among others: level of upper airway dilator muscle activation required to open the airway, increase in chemical drive required to recruit the pharyngeal muscles, chemical control loop gain, and arousal threshold. Thus, the cause of sleep apnea likely varies substantially between patients. Other physiologic mechanisms likely contributing to OSA pathogenesis include falling lung volume during sleep, shifts in blood volume from peripheral tissues to the neck, and airway edema. Apnea severity may progress over time, likely due to weight gain, muscle/nerve injury, aging effects on airway anatomy/collapsibility, and changes in ventilatory control stability.

Mood Predicts Response to Placebo CPAP

Study Objectives. Continuous positive airway pressure (CPAP) therapy is efficacious for treating obstructive sleep apnea (OSA), but recent studies with placebo CPAP (CPAP administered at subtherapeutic pressure) have revealed nonspecific (or placebo) responses to CPAP treatment. This study examined baseline psychological factors associated with beneficial effects from placebo CPAP treatment. Participants. Twenty-five participants were studied with polysomnography at baseline and after treatment with placebo CPAP. Design. Participants were randomized to either CPAP treatment or placebo CPAP. Baseline mood was assessed with the Profile of Mood States (POMS). Total mood disturbance (POMS-Total) was obtained by summing the six POMS subscale scores, with Vigor weighted negatively. The dependent variable was changed in apnea-hypopnea index (ΔAHI), calculated by subtracting pre- from post-CPAP AHI. Negative values implied improvement. Hierarchical regression analysis was performed, with pre-CPAP AHI added as a covariate to control for baseline OSA severity. Results. Baseline emotional distress predicted the drop in AHI in response to placebo CPAP. Highly distressed patients showed greater placebo response, with a 34% drop (i.e., improvement) in AHI. Conclusion. These findings underscore the importance of placebo-controlled studies of CPAP treatment. Whereas such trials are routinely included in drug trials, this paper argues for their importance even in mechanical-oriented sleep interventions.

Personality profiles in patients with obstructive sleep apnea

OBJECTIVE

The Minnesota Multiphasic Personality Inventory (MMPI) responses between snorers and obstructive sleep apnea (OSA) may be different. Thus, we compared the MMPI responses between snorers and OSA.

DESIGN

A clinical-based cross-sectional survey.

PARTICIPANTS

This is a survey of 94 treatment-naive sleep-disordered breathing (SDB) subjects.

METHOD

Clinical information, body mass index (BMI), 36-item Short Form Health Survey, the Turkish version of the MMPI, Epworth sleepiness scale (ESS), fatigue scale, attention-deficit scale, and polysomnography were collected. All patients with OSA and snorers was accepted as individuals with SDB (AHI > 0 events/h). The threshold of five apnea and hypopnea per hour of sleep was chosen to define both OSA and snorers. Disability profile is consisting of four or more MMPI clinical scale elevations.

RESULTS

OSA patients compared to snorers have significantly higher absolute scores on hypochondriasis (Hs) (65.0 ± 12.0 vs 58.4 ± 7.9, p = 0.01, respectively). OSA patients compared to snorers have significantly higher rate of clinical elevation on both psychopathic deviance (13.0 vs 0 %, p = 0.03, respectively) and Hs (26.1 vs 3.3 %, p = 0.01, respectively). People with disability profile has lower the quality of life, a higher score for inattention, a higher fatigue scores, and higher sleepiness scores. The quality of life and attention deficit and daytime sleepiness scores were associated with total MMPI absolute score in individuals with SDB in bivariate analyses.

CONCLUSION

Present study indicated that patients with OSAS compared to snorers displayed significantly more hyopchondriasis and psychopathic deviance personality characteristics. The daytime functions in individuals with sleep-disordered breathing may be influenced by the severity of psychopathology.

Age-related tonsillar regrowth in children undergoing powered intracapsular tonsillectomy

OBJECTIVES

To review our experience with intracapsular tonsillectomy using powered instrumentation (PIT) in the management of tonsillar hypertrophy.

DESIGN

Retrospective database review of pediatric patients undergoing PIT.

METHODS

The medical records of 636 patients under 11 years of age who underwent PIT performed by the senior author (RFW), predominantly for obstructive sleep disturbance, were reviewed. Data were subsequently analyzed from 559 of these patients for clinical evidence of tonsillar regrowth, post-operative tonsillar hemorrhage, and post-operative dehydration due to pain. Specific information for possible correlation of age at the time of surgery and any increased rate of regrowth was primarily examined.

RESULTS

There were a total of 33 patients who had clinical evidence of regrowth. Children less than 5 years of age had 5 times the incidence of regrowth (p<0.001). Out of the group that exhibited regrowth, 5 patients exhibited evidence of recurrent upper airway obstruction and underwent a complete tonsillectomy. The age of this complete tonsillectomy group ranged from 1.1 to 2.7 years. Out of all patients undergoing PIT, there was 1 incident of delayed post-operative dehydration due to emesis but not due to pain. There were 2 incidents of delayed post-operative tonsillar bleeds. All three complications were self-limited and did not require re-hospitalization.

CONCLUSIONS

PIT is a safe procedure with a small risk of tonsillar regrowth being age related. The incidence of postoperative complications following PIT is relatively low (0.54%).

Intermittent hypoxia-induced cognitive deficits are mediated by NADPH oxidase activity in a murine model of sleep apnea

BACKGROUND

In rodents, exposure to intermittent hypoxia (IH), a hallmark of obstructive sleep apnea (OSA), is associated with neurobehavioral impairments, increased apoptosis in the hippocampus and cortex, as well as increased oxidant stress and inflammation. Excessive NADPH oxidase activity may play a role in IH-induced CNS dysfunction.

METHODS AND FINDINGS

The effect of IH during light period on two forms of spatial learning in the water maze and well as markers of oxidative stress was assessed in mice lacking NADPH oxidase activity (gp91phox(_/Y)) and wild-type littermates. On a standard place training task, gp91phox(_/Y) displayed normal learning, and were protected from the spatial learning deficits observed in wild-type littermates exposed to IH. Moreover, anxiety levels were increased in wild-type mice exposed to IH as compared to room air (RA) controls, while no changes emerged in gp91phox(_/Y) mice. Additionally, wild-type mice, but not gp91phox(_/Y) mice had significantly elevated levels of NADPH oxidase expression and activity, as well as MDA and 8-OHDG in cortical and hippocampal lysates following IH exposures.

CONCLUSIONS

The oxidative stress responses and neurobehavioral impairments induced by IH during sleep are mediated, at least in part, by excessive NADPH oxidase activity, and thus pharmacological agents targeting NADPH oxidase may provide a therapeutic strategy in sleep-disordered breathing.

Physical activity attenuates intermittent hypoxia-induced spatial learning deficits and oxidative stress

RATIONALE

Exposure to intermittent hypoxia (IH), such as occurs in sleep-disordered breathing, is associated with substantial cognitive impairments, oxidative stress and inflammation, and increased neuronal cell losses in brain regions underlying learning and memory in rats. Physical activity (PA) is now recognized as neuroprotective in models of neuronal injury and degeneration.

OBJECTIVES

To examine whether PA will ameliorate IH-induced deficits.

METHODS

Young adult Sprague-Dawley rats were randomly assigned to one of four treatment groups including normal activity (NA) or PA for 3 months and then subjected to either normoxia (RA) or exposure to IH during the light phase during the last 14 days.

MEASUREMENTS AND MAIN RESULTS

Significant impairments in IH-exposed rats emerged on both latency and pathlength to locate the hidden platform in a water maze and decreased spatial bias during the probe trials. These impairments were not observed in PA-IH rats. In addition, the PA-IH group, relative to NA-IH, conferred greater resistance to both lipid peroxidation and 8-hydroxy-2'-deoxyguanosine (DNA damage) in both the cortex and hippocampus. In support of a neuroprotective effect from PA, PA-IH versus NA-IH rats showed greater AKT activation and neuronal insulin growth factor-1 in these regions.

CONCLUSIONS

Behavioral modifications such as increased physical activity are associated with decreased susceptibility to IH-induced spatial task deficits and lead to reduced oxidative stress, possibly through improved preservation of insulin growth factor-1-Akt neuronal signaling. Considering the many advantages of PA, interventional strategies targeting behavioral modifications leading to increased PA should be pursued in patients with sleep-disordered breathing.

Continuous positive airway pressure device-based automated detection of obstructive sleep apnea compared to standard laboratory polysomnography

PURPOSE

Obstructive sleep apnea (OSA) is a common health problem that affects more than 2-4% of the US population. Polysomnography (PSG) is the gold standard for diagnosing OSA. PSG is, however, expensive, time-consuming, and not always readily accessible. Hence, alternative diagnostic methods such as home-based testing have been evaluated. We studied the ability of the REMstar Pro (RSP2, a brand of continuous positive airway pressure (CPAP) device) to identify abnormal breathing events in subjects with OSA and compared this with breathing events simultaneously determined by laboratory-based PSG.

METHODS

We evaluated 10 subjects previously diagnosed with OSA (apnea hypopnea index (AHI) > 15, known therapeutic level of CPAP). Subjects underwent attended PSG using the REMstar Pro M series machine and their prescribed interface/mask type. The first 3 h of the study were conducted using a subtherapeutic CPAP (4 cm H2O). The last 3 h or remaining portion of the PSG was completed using the previously determined therapeutic CPAP. Comparison of respiratory events detected by PSG vs the RSP2 was performed.

RESULTS

Subjects included four men and six women, aged 32 to 57 years and with a body mass index ranging from 29.5-66.4. The baseline AHI ranged from 18.3-93.1, with the AHI at therapeutic CPAP ranging from 0-3. Apnea counts at baseline and at therapeutic CPAP by manually scored PSG and REMstar were not significantly different (mean at subtherapeutic 11.7 vs 12.5, p = 0.76; median at therapeutic CPAP 2.0 vs 4.5, p = 0.15). Hypopnea counts at baseline and at effective CPAP by PSG and REMstar were not significantly different (mean at subtherapeutic 38.1 vs. 40.9, p = 0.72; median at therapeutic CPAP 5.0 vs. 2.5, p = 0.34). The correlation coefficient of REMstar and PSG for apnea and hypopnea was significant in subtherapeutic phase only (apnea r = 0.78, p = 0.007; hypopnea r = 0.76, p = 0.01). Agreement between the two methods declined for hypopnea detection at therapeutic CPAP.

CONCLUSIONS

The monitoring of residual sleep-disordered breathing on treatment, in addition to adherence, is an important objective therapeutic target in OSA. The REMstar Pro detects sleep-disordered breathing events similar to that of a manually scored PSG-for apnea but not for hypopnea-and merits further investigation as a device to determine disease severity and treatment efficacy.

Spectral analysis of electroencephalogram and oximetric signals in obstructive sleep apnea diagnosis

This study assessed the hypothesis that blood oxygen saturation (SaO(2)) and electroencephalogram (EEG) recordings could provide complementary information in the diagnosis of the obstructive sleep apnea (OSA) syndrome. We studied 148 patients suspected of suffering from OSA. Classical spectral parameters based on the relative power in specified frequency bands (A(f-band)) or peak amplitudes (PA) were used to characterize the frequency content of SaO(2) and EEG recordings. Additionally, the median frequency (MF) and the spectral entropy (SE) were applied to obtain further spectral information. We applied a forward stepwise logistic regression (LR) procedure with crossvalidation leave-one-out to obtain the optimum spectral feature set. Two features from the oximetric spectral analysis (PA and MFsat) and three features from the EEG spectral analysis (A(delta), A(alpha) and SEeeg) were automatically selected. 91.0% sensitivity, 83.3% specificity and 88.5% accuracy were obtained. These results suggest that MF and SE could provide additional information to classical frequency characteristics commonly used in OSA diagnosis. Additionally, nocturnal SaO(2) and EEG recordings during the whole night could provide complementary information to help in the detection of OSA syndrome.

The Epworth sleepiness scale in the identification of obstructive sleep apnea

The Epworth sleepiness scale (ESS) is often used clinically to screen for the manifestations of the behavioral morbidity associated to obstructive sleep apnea (OSA). The purpose of this study was to assess the sensitivity of the ESS in the identification of OSA, as defined by an elevated apnea-hypopnea index. A retrospective chart review of 268 consecutive patients diagnosed with OSA at a multidisciplinary sleep medicine clinic was conducted. The ESS obtained a relatively low sensitivity (66%) in the identification of an apnea-hypopnea index of 5 and above at the suggested cutoff of 10 and increased to 76% at 8. The results of the study showed only fair discriminatory ability of the ESS as a screener for OSA. A score of 8 (instead of 10) is suggested as the cutoff among clinic populations being screened for a sleep disorder.

Inhibitory motor control in apneic and insomniac patients: a stop task study

The aim of this study was to assess with a stop task the inhibitory motor control efficiency--a major component of executive control functions--in patients suffering from sleep disorders. Twenty-two patients with untreated obstructive sleep apnea syndrome (OSAS) (mean age 46 +/- 9 years; mean apnea-hypopnea index, AHI = 30 +/- 20) and 13 patients with psychophysiological insomnia (mean age 47 +/- 12 years) were compared with individually matched healthy controls. Sleep disturbances in the patient populations were clinically and polysomnographically diagnosed. The stop task has a frequent visual 'Go' stimulus to set up a response tendency and a less frequent auditory 'Stop' signal to withhold the planned or prepotent response. The stop signal reaction time (SSRT) reflects the time to internally suppress the ongoing response. SSRT was slower for the apneic patients than for their respective controls (248 +/- 107 versus 171 +/- 115 ms, anova, P < 0.05) but not for the insomniac patients compared with their controls (235 +/- 112 versus 194 +/- 109 ms, NS). Moreover, in apneic patients, slower SSRT was associated with lower nocturnal oxygen saturation (r = -0.477, P < 0.05). By contrast, neither apneics nor insomniacs differed from their matched controls for reaction times on Go trials. To conclude, unlike insomniacs, OSAS patients present an impaired inhibitory motor control, an executive function which is required in many common everyday life situations. Inhibitory motor control relies on the integrity of the inferior prefrontal cortex, which could be affected by nocturnal oxyhemoglobin desaturation in apneic patients.

Applying time, frequency and nonlinear features from nocturnal oximetry to OSA diagnosis

This study is aimed to improve the diagnostic ability of blood oxygen saturation (SaO(2)) in obstructive sleep apnea (OSA) detection. We studied 74 patients suspected of suffering from OSA. Ten characteristics were derived from each SaO2 recording: arithmetic mean, variance, skewness and kurtosis from both time and frequency domains, central tendency measure and Lempel-Ziv complexity. The diagnostic ability of each feature was assessed by means of a receiver operating characteristics (ROC) analysis. Additionally, forward stepwise logistic regression (LR) was applied. The kurtosis in the time domain and the nonlinear measure of complexity were automatically selected. This methodology reached 93.2% sensitivity, 80.0% specificity and 87.8% accuracy, improving the results from each feature individually. Our study showed that common statistics in the time and frequency domains and nonlinear features could provide additional and complementary information to help in OSA diagnosis.

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.

Psychomotor development in infants with Prader-Willi syndrome and associations with sleep-related breathing disorders

Prader-Willi syndrome (PWS) is a neurogenetic disorder with hypotonia, psychomotor delay, obesity, short stature, and sleep-related breathing disorders. The aim of this study was to evaluate the association between psychomotor development and sleep-related breathing disorders in PWS infants. Bayley Scales of Infant Development were performed in 22 PWS infants, with a median (interquartile range, IQR) age of 1.8 (1.1-3.4) y, and a body mass index SD score (BMISDS) of -0.5 (-1.3 to 1.6). We evaluated psychomotor development in relation to results of polysomnography. Median (IQR) mental and motor development was 73.1% (64.3-79.6%) and 55.2% (46.5-63.1%) of normal children, respectively. All infants had sleep-related breathing disorders, mostly of central origin. The apnea hypopnea index was not associated with psychomotor development. Only four infants had obstructive sleep apnea syndrome (OSAS). They had a significantly delayed mental development of 65.5% (60.0-70.3%) of normal. They had a median BMISDS of 1.4 (0.1-1.6), which tended to be higher than in those without OSAS. Our data indicate that psychomotor development in PWS infants is not related to central sleep-related breathing disorders, but infants with OSAS have more severely delayed mental development, suggesting that PWS infants should be screened for OSAS.

Sleep fragmentation elevates behavioral, electrographic and neurochemical measures of sleepiness

Sleep fragmentation, a feature of sleep apnea as well as other sleep and medical/psychiatric disorders, is thought to lead to excessive daytime sleepiness. A rodent model of sleep fragmentation was developed (termed sleep interruption, SI), where rats were awakened every 2 min by the movement of an automated treadmill for either 6 or 24 h of exposure. The sleep pattern of rats exposed to 24 h of SI resembled sleep of the apneic patient in the following ways: sleep was fragmented (up to 30 awakening/h), total rapid eye movement (REM) sleep time was greatly reduced, non-rapid eye movement (NREM) sleep episode duration was reduced (from 2 min, 5 s baseline to 58 s during SI), whereas the total amount of NREM sleep time per 24 h approached basal levels. Both 6 and 24 h of SI made rats more sleepy, as indicated by a reduced latency to fall asleep upon SI termination. Electrographic measures in the recovery sleep period following either 6 or 24 h of SI also indicated an elevation of homeostatic sleep drive; specifically, the average NREM episode duration increased (e.g. for 24 h SI, from 2 min, 5 s baseline to 3 min, 19 s following SI), as did the NREM delta power during recovery sleep. Basal forebrain (BF) levels of extracellular adenosine (AD) were also measured with microdialysis sample collection and high performance liquid chromatography detection, as previous work suggests that increasing concentrations of BF AD are related to sleepiness. BF AD levels were significantly elevated during SI, peaking at 220% of baseline during 30 h of SI exposure. These combined findings imply an elevation of the homeostatic sleep drive following either 6 or 24 h of SI, and BF AD levels appear to correlate more with sleepiness than with the cumulative amount of prior wakefulness, since total NREM sleep time declined only slightly. SI may be partially responsible for the symptom of daytime sleepiness observed in a number of clinical disorders, and this may be mediated by mechanisms involving BF AD.

Obstructive sleep apnea syndrome in Prader-Willi Syndrome: an unrecognized and untreated cause of cognitive and behavioral deficits?

Prader-Willi Syndrome (PWS) is a rare genetic disorder characterized by a range of physical, psychological, and physiological abnormalities. It is also distinguished by the high prevalence of obstructive sleep apnea syndrome (OSAS), i.e., repetitive upper airway collapse during sleep resulting in hypoxia and sleep fragmentation. In non-PWS populations, OSAS is associated with a range of neurocognitive and psychosocial deficits. Importantly, these deficits are at least partly reversible following treatment. Given the findings in non-PWS populations, it is possible that OSAS may contribute to neurocognitive and psychosocial deficits in PWS. The present review examines this possibility. While acknowledging a primary contribution from the primary genetic abnormality to central neural dysfunction in PWS, we conclude that OSAS may be an important secondary contributing factor to reduced neurocognitive and psychosocial performance. Treatment of OSAS may have potential benefits in improving neurocognitive performance and behavior in PWS, but this awaits confirmatory investigation.

Nonlinear characteristics of blood oxygen saturation from nocturnal oximetry for obstructive sleep apnoea detection

Nocturnal oximetry is an attractive option for the diagnosis of obstructive sleep apnoea (OSA) syndrome because of its simplicity and low cost compared to polysomnography (PSG). The present study assesses nonlinear analysis of blood oxygen saturation (SaO(2)) from nocturnal oximetry as a diagnostic test to discriminate between OSA positive and OSA negative patients. A sample of 187 referred outpatients, clinically suspected of having OSA, was studied using nocturnal oximetry performed simultaneously with complete PSG. A positive OSA diagnosis was found for 111 cases, while the remaining 76 cases were classified as OSA negative. The following oximetric indices were obtained: cumulative time spent below a saturation of 90% (CT90), oxygen desaturation indices of 4% (ODI4), 3% (ODI3) and 2% (ODI2) and the delta index (Delta index). SaO(2) records were subsequently processed applying two nonlinear methods: central tendency measure (CTM) and Lempel-Ziv (LZ) complexity. Significant differences (p < 0.01) were found between OSA positive and OSA negative patients. Using CTM we obtained a sensitivity of 90.1% and a specificity of 82.9%, while with LZ the sensitivity was 86.5% and the specificity was 77.6%. CTM and LZ accuracies were higher than those provided by ODI4, ODI3, ODI2 and CT90. The results suggest that nonlinear analysis of SaO(2) signals from nocturnal oximetry could yield useful information in OSA diagnosis.

Sleep, memory, and learning in off-pump coronary artery bypass patients

In this study, I examined sleep, memory, and learning in off-pump coronary artery bypass (OPCAB) patients. Sixty-six men and women aged >or=60 years wore actigraphs to record sleep and completed sleep diaries for two 24-hour periods following OPCAB surgery. Prior to discharge from the hospital, participants completed the Pittsburgh Sleep Quality Index (PSQI) and Rey Auditory Verbal Learning Test. No significant correlations were found between habitual sleep, sleep time, efficiency, number, and duration of awakenings, daytime napping, or memory and learning. Nighttime sleep was short with frequent disturbances, and daytime sleep accounted for half the daily sleep time. Participants scored low in learning and delayed recall. These findings suggest the need to assess sleep and cognition in patients recovering from OPCAB surgery.

Executive control of attention in sleep apnea patients: theoretical concepts and methodological considerations

Sleep apnea patients' nocturnal breathing disturbances cause daytime sleepiness and cognitive impairments. Attentional capacity and vigilance deficits have often been observed. Moreover, some studies have suggested executive dysfunction, usually assumed to be related to (pre)frontal lobe dysfunction caused by intermittent hypoxemia. However, sleep disruption itself has a pervasive influence on cognitive function and affects not only underlying 'lower-level' processes such as arousal and alertness, but also 'higher-level' cognitive processes such as executive attention. This methodological caveat has not been fully taken into account in the sleep apnea literature. In order to be able to disentangle these cognitive processes on different levels, sound theoretical neurocognitive frameworks are needed to attain careful analyses and interpretations of neuropsychological data. Therefore, this paper firstly presents an overview of relevant theoretical concepts and models of arousal, attention, and executive function. Then, it is being argued that these theoretical considerations have important methodological implications. These methodological concerns are being addressed by specific experimental and statistical approaches, illustrated by some well-known neuropsychological tests. It can be concluded that the reported executive deficits in sleep apnea patients should be regarded as tentative, and that more case-controlled studies are needed using fine-grained analyses to parcel complex cognitive abilities into their subcomponents.

Depression predicts self-reported sleep quality in patients with obstructive sleep apnea

OBJECTIVE

Depression is a common problem in patients with obstructive sleep apnea. The objective of this study was to examine whether depression is independently associated with lower self-reported sleep quality in patients with obstructive sleep apnea (OSA), after controlling for polysomnographic measures of sleep.

METHODS

The sample comprised 135 patients who had been referred to a university teaching hospital's multidisciplinary sleep medicine center for polysomnographic evaluation of OSA. The median age of the subjects was 45 (mean age, 46 years) 55% were female, 69% were white, 31% were black, and their mean body mass index was 37.9 +/- 11.2 kg/m2. Self-reported sleep quality during the past 2 weeks was assessed by the insomnia severity index. Polygraphic measures of sleep quality included the respiratory disturbance index, sleep onset latency, arousals for no apparent reason, sleep efficiency, and periodic leg movements associated with arousal. Depressive symptoms were assessed by the Beck Depression Inventory.

RESULTS

None of the polygraphic measures of sleep quality was related to self-reported sleep quality or depression. Oxygen desaturation was correlated with self-reported sleep quality (r = 0.21, p =.02). Depression correlated with self-reported sleep quality (r = 0.55, p <.0001). In a multiple regression analysis, depression remained a significant predictor of self-reported sleep quality after controlling for all of the polysomnographic measures of sleep quality (F = 9.65, partial r2 = 0.28 p =.0001).

CONCLUSION

Depression is a better predictor of self-reported sleep quality than are polysomnographic measures of sleep in patients with OSA.

Obstructive sleep apnea and cardiovascular disease

Obstructive sleep apnea (OSA) is a common medical condition that occurs in approximately 5% to 15% of the population. The pathophysiology of OSA is characterized by repetitive occlusions of the posterior pharynx during sleep that obstruct the airway, followed by oxyhemoglobin desaturation, persistent inspiratory efforts against the occluded airway, and termination by arousal from sleep. Obstructive sleep apnea is associated with daytime sleepiness and fatigue, likely due to fragmented sleep from recurrent arousals. Substantial evidence shows that patients with OSA have an increased incidence of hypertension compared with individuals without OSA and that OSA is a risk factor for the development of hypertension. Recent studies show that OSA may be implicated in stroke and transient ischemic attacks. Obstructive sleep apnea appears to be associated with coronary heart disease, heart failure, and cardiac arrhythmias. Pulmonary hypertension may be associated with OSA, especially in patients with preexisting pulmonary disease. Although the exact cause that links OSA with cardiovascular disease is unknown, there is evidence that OSA is associated with a group of proinflammatory and prothrombotic factors that have been identified to be important in the development of atherosclerosis. Obstructive sleep apnea is associated with increased daytime and nocturnal sympathetic activity. Autonomic abnormalities seen in patients with OSA include increased resting heart rate, decreased R-R interval variability, and increased blood pressure variability. Both atherosclerosis and OSA are associated with endothelial dysfunction, increased C-reactive protein, interleukin 6, fibrinogen, and plasminogen activator inhibitor, and reduced fibrinolytic activity. Obstructive sleep apnea has been associated with enhanced platelet activity and aggregation. Leukocyte adhesion and accumulation on endothelial cells are common in both OSA and atherosclerosis. Clinicians should be aware that OSA may be a risk factor for the development of cardiovascular disease.

Mood Improvement after Surgery for Obstructive Sleep Apnea

OBJECTIVE

Patients with obstructive sleep apnea (OSA) may experience unfavorable psychologic symptoms such as depression and anxiety. The aim of this study was to confirm this hypothesis and to investigate whether the psychologic symptoms among OSA patients can be relieved by surgical intervention.

STUDY DESIGN

Prospective, longitudinal intervention study.

METHODS

The 5-Item Mental Health scale (MH-5) was used to evaluate the postoperative changes of mood after extended uvulopalatal flap (EUPF) surgery on 84 Taiwanese patients with OSA. The preoperative and postoperative MH-5 data obtained from these patients were compared with a Taiwanese population norm.

RESULTS

Before surgery, the MH-5 scores of the OSA patients were significantly worse than the Taiwanese population norm of 72.8 (P <.0001). Postoperatively, mean MH-5 scores significantly increased from 61.8 +/- 16.0 to 70.0 +/- 15.8 (P =.0006). The effect size of this score change was 0.51, indicating a moderate degree of mood improvement. However, this score was still inferior to that of the population norm (P =.0045). The mood improvement was not significantly associated with the changes in either sleep apnea events or the level of sleepiness. Neither the changes in respiratory disturbance index (P =.4382), maximum arterial oxygen saturation (P =.4866), nor the change in Epworth Sleepiness Scale scores (P =.4951) were predictive of the MH-5 score improvement (R = 0.07).

CONCLUSIONS

This study demonstrated that patients with OSA had a higher level of anxiety, depression, and probable behavior or personality changes than the population norm. EUPF surgery could significantly improve the mood status among OSA patients; the effect of surgery was mild but clinically relevant. However, the extent of mood improvement experienced by OSA patients receiving operations may not simply be attributable to the changes in sleep apnea events or a reduced level of sleepiness.

Sleep . 3: Clinical presentation and diagnosis of the obstructive sleep apnoea hypopnoea syndrome

Patients with OSAHS may present to a sleep clinic or to other specialists with symptoms that are not immediately attributable to the condition. The diagnostic methods available are reviewed.

Serotonin agonists and antagonists in obstructive sleep apnea: therapeutic potential

Obstructive sleep apnea hypopnea syndrome (OSAHS) is a prevalent disorder associated with substantial cardiovascular and neurobehavioral morbidity. Yet this is a disorder for which there are no widely effective pharmacotherapies. The pathophysiology of obstructive sleep apnea namely, normal respiration in waking with disordered breathing only in sleep, suggests that this disorder should be readily amenable to drug therapy. Over the past 10 years, we have gained tremendous insight into the neurochemical mechanisms involved in state-dependent control of respiration. It is apparent from this work that there are many potential avenues for pharmacotherapies, including several seemingly conflicting directions for serotonergic therapies. Serotonin delivery is reduced to upper airway dilator motor neurons in sleep, and this contributes, at least in part, to sleep-related reductions in dilator muscle activity and upper airway obstruction. The dilator motor neuron post-synaptic serotonin receptors are 5-HT(2A) and 5-HT(2C) subtypes, and in adults the presynaptic 5-HT receptor in motor nuclei is 5-HT(1B), an inhibitory receptor. Serotonin receptors are also found within central respiratory neuronal groups, and these receptor subtypes include 5-HT(1A) (inhibitory) and 5-HT(2) receptors. Peripherally, stimulation of 5-HT(2A), 5-HT(2C) and 5-HT(3) receptor subtypes have an inhibitory effect on respiration via action at the nodose ganglion. Many of these receptor subtypes and their signal transduction pathways may be affected by oxidative stress in obstructive sleep apnea. These alterations will make finding drug therapies for sleep apnea more challenging, but not insurmountable. Future directions are suggested for elucidating safe, well-tolerated serotonergic drugs for this disorder. Tryptophan was one of the first serotonergic drugs tested for OSAHS. This drug was withdrawn from the market as a result of reports linking tryptophan use with eosinophilic myalgia syndrome and life-threatening pulmonary hypertension. Newer drugs with serotonergic activity tested in persons with sleep-disordered breathing include buspirone, fluoxetine and paroxetine. Trials are presently being conducted to evaluate the effects of 5-HT(2A) and 5-HT(3) antagonists on OSAHS. Many of the drugs tested have not shown significant improvement in sleep apnea. However, with continued effort to elucidate the pharmacology of neurochemical control of state-dependent changes in respiratory control, the availability of pharmacological therapy for this disorder is not too far away.

Sleep-Disordered Breathing in Patients With Heart Failure: Pathophysiology, Assessment, and Management

PURPOSE

To provide clinicians in primary care settings information on the effects of sleep-disordered breathing in patients with heart failure (HF). Assessment and screening tools, as well as management considerations, are presented.

DATA SOURCES

Review of the scientific literature of the past 10 years, along with classic studies and Internet sources.

CONCLUSIONS

HF is an increasingly prevalent problem with a high degree of associated sleep-disordered breathing. There are two broad categories of sleep-disordered breathing: obstructive sleep apnea and central sleep apnea/Cheyne-Stokes breathing. Both of these occur on a continuum of mild hypopnea to severe apnea with hypoxia. Sleep apneas are particularly harmful to patients with HF and, if left untreated, may adversely affect their prognosis. Yet sleep apnea is not routinely screened for in this population.

IMPLICATIONS FOR PRACTICE

Given the serious consequences of untreated sleep-disordered breathing, there is sound justification to screen for sleep apnea in all patients with HF. Subsequent treatment of those patients with sleep apnea can significantly improve their quality of life and can decrease their mortality.

Taft and Pickwick: sleep apnea in the White House

As President of the United States from 1909 to 1913, William Howard Taft's minimum body mass index was 42 kg/m(2). This article presents evidence that he suffered from obstructive sleep apnea, manifested by excessive daytime somnolence, snoring, systemic hypertension and, perhaps, cognitive and psychosocial impairment. As president, Taft's hypersomnolence was severe and obvious, but never prompted official discussion of his fitness to govern. Within 12 months of leaving office, Taft permanently lost over 60 pounds. His somnolence resolved. As Chief Justice of the United States from 1921 to 1930, he was not somnolent. President Taft's case illuminates historical puzzles of his performance as President, raises public awareness of sleep apnea, and informs discussions of presidential disability and the 25th Amendment to the Constitution of the United States.

Changes in depressive symptoms after continuous positive airway pressure treatment for obstructive sleep apnea

It is generally believed that obstructive sleep apnea (OSA) causes depression in some patients, yet it is unknown whether this depression is an actual clinical phenomenon or purely a result of overlapping somatic/physical symptoms shared by both disorders. The present study investigated changes in both somatic and affective/cognitive symptoms of depression associated with the introduction of continuous positive airway pressure (CPAP) treatment for OSA. Participants were 39 outpatients (35 males, 4 females) with no current or past mental health problems, diagnosed with OSA in a hospital sleep disorders clinic. The Beck Depression Inventory (BDI) was administered prior to treatment and again 3 months after CPAP. Total BDI scores improved after CPAP, independent of objectively monitored CPAP compliance rates. Both somatic and affective/ cognitive symptoms of depression improved in a similar manner after treatment. Our findings suggest that depressive symptoms experienced by OSA patients are not solely the result of physical OSA symptoms but include a mood component as well. We introduce a hypothetical model to conceptualize the relationship between OSA and depression.

To breathe, perchance to sleep: sleep-disordered breathing and chronic insomnia among trauma survivors

Standard psychiatric classification (DSM-IV-TR) traditionally attributes post-traumatic sleep disturbance to a secondary or symptomatic feature of a primary psychiatric disorder. The DSM-IV-TR paradigm, however, has not been validated with objective sleep assessment technology, incorporated nosological constructs from the field of sleep disorders medicine, or adequately addressed the potential for post-traumatic stress disorder (PTSD) sleep problems to manifest as primary, physical disorders, requiring independent medical assessments and therapies. This paradigm may limit understanding of sleep problems in PTSD by promulgating such terms as "insomnia related to another mental disorder," a.k.a. "psychiatric insomnia." Emerging evidence invites a broader comorbidity perspective, based on recent findings that post-traumatic sleep disturbance frequently manifests with the combination of insomnia and a higher-than-expected prevalence of sleep-disordered breathing (SDB). In this model of complex sleep disturbance, the underlying sleep pathophysiology interacts with PTSD and related psychiatric distress; and this relationship appears very important as demonstrated by improvement in insomnia, nightmares, and post-traumatic stress with successful SDB treatment, independent of psychiatric interventions. Continuous positive airway pressure treatment in PTSD patients with SDB reduced electroencephalographic arousals and sleep fragmentation, which are usually attributed to central nervous system or psychophysiological processes. Related findings and clinical experience suggest that other types of chronic insomnia may also be related to SDB. We hypothesize that an arousal-based mechanism, perhaps initiated by post-traumatic stress and/or chronic insomnia, may promote the development of SDB in a trauma survivor and perhaps other patients with chronic insomnia. We discuss potential neurohormonal pathways and neuroanatomatical sites that may be involved in this proposed interaction between insomnia and SDB.

Sleep disordered breathing

Cause and effect relationships between sleep disordered breathing (SDB) and illness, poorer quality of life, and public health have been largely overlooked and undertreated by healthcare providers. Obstructive sleep apnea (OSA), central sleep apnea, upper airway resistance syndrome, and obesity hypoventilation are the primary syndromes that fall under the rubric of SDB. Each of these syndromes is defined; however, OSA is the most common form of SDB, and is the focus of this article. Epidemiology, pathophysiology, behavioral manifestations, cardiovascular comorbidity, clinical evaluation, and treatment for OSA are the main topics covered. The article concludes with the role of the nurse in SDB.

Sleep during hospitalization and recovery after cardiac surgery

Sleep disturbance is common in patients undergoing cardiac surgery and has been recognized for more than 30 years. Research findings suggest that sleep disturbance is a multifactorial process that has many correlates in these patients and persists from the presurgical period throughout recovery. A growing body of literature suggests the importance of sleep for function and well-being of these patients. The research literature is synthesized and implications for future research and practice are discussed.

Did this father's sleep apnea contribute to the inadvertent death of his infant son?

Sleepiness impairs memory and concentration. We report a case of a patient who inadvertently left his infant son in a car, having forgotten to drop him off at day care. The infant died of heat exposure. There is credible evidence that sleepiness from a combination of sleep deprivation and previously undiagnosed severe obstructive sleep apnea contributed to this tragedy.

Cardiovascular medication use in patients with undiagnosed obstructive sleep apnoea

BACKGROUND

A study was undertaken in patients with undiagnosed sleep apnoea/hypopnoea syndrome (OSAS) to document the use of prescribed medications, especially those used in cardiovascular diseases, in the year before the OSAS diagnosis was confirmed.

METHODS

A total of 549 patients with OSAS (401 men of mean age 47.2 years, mean body mass index (BMI) 35.5 kg/m(2), mean apnoea/hypopnoea index (AHI) 47.2 and148 women of mean age 50.2 years, BMI 39.6 kg/m(2), AHI 32.6) were each matched to one general population control by age, sex, geographical location, and family physician. Medication use was evaluated for patients and controls using a database containing information about all prescriptions completed in the province of Manitoba, Canada.

RESULTS

In the year before OSAS was diagnosed, prescribed medication costs were $155.91 (Canadian dollars) (95% CI $91.34 to $220.49) greater for cases than for controls. Cases were dispensed 3.3 (95% CI 1.5 to 5.2) more prescriptions, were on 1.2 (95% CI 0.8 to 1.6) more medications, and were supplied with 157.4 (95% CI 95.9 to 218.8) more daily doses of medication. The odds ratio of OSAS cases being on a prescribed medication was 1.88 relative to controls (95% CI 1.38 to 2.54, p<0.0001). In the same year 36.6% of cases and 19.7% of controls were using medications for cardiovascular disease (OR 2.82, 95% CI 2.05 to 3.89, p<0.0001), consuming 79.4 (95% CI 48.9 to 109.8) more daily doses of medication, having been dispensed 1.7 (95% CI 1.0 to 2.4) more prescriptions, and at a $75.26 (95% CI $44.03 to $106.50) greater cost. The odds ratio of patients with OSAS being on medications indicated for the treatment of systemic hypertension was 2.71 (95% CI 1.96 to 3.77) relative to controls; however, such medications might also be prescribed for other indications such as angina pectoris and congestive heart failure, and for the secondary prevention of myocardial infarction. The use of medications indicated for the treatment of systemic hypertension was predicted significantly by age (odds ratio (OR) 1.10 per year), BMI (OR 1.05 per unit), and AHI (OR 1.01 per unit).

CONCLUSIONS

In the year before OSAS was diagnosed, patients with OSAS were heavy users of medications, particularly those used to treat cardiovascular diseases.

Sleepiness/alertness among healthy evening and morning type individuals

Objective: The aim of this study was to determine the level of sleepiness/alertness among different chronotypes.Background: The Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ) has allowed the characterization of chronotypes that are associated with a number of biological factors including: body temperature, cortisol rhythm, sleep patterns, and architecture.Methods: Fifty-six consecutive normal volunteers underwent an 8-h polysomnogram followed by a multiple sleep latency test (MSLT). Each subject also completed the MEQ and the Sleep/Wake Activity Inventory.Results: Evening types (ET) reported significantly later bedtimes and risetimes than both morning types (MT) and neither types (NT, P<0.05). On nocturnal polysomnography, the ET documented significantly longer latencies to stage 1 and persistent sleep when compared to both the NT and MT (P<0.01). There were no significant differences in the level of sleepiness on the MSLT across the different chronotypes. However, the pattern of sleepiness differed among them. While ET and NT showed differential sleep latencies across nap opportunities, MT showed no evidence of circadian variation on their level of sleepiness.Conclusions: There were no overall differences in daytime sleepiness/alertness across chronotypes. However, a differential pattern of sleep latencies was noted on the MSLT.

Self-reported levels of sleepiness among subjects with insomnia

Objectives: To determine the prevalence of sleepiness in a cohort of insomnia subjects. We evaluated if differential levels of subjective sleepiness predict systematic differences in the polysomnographic characteristics of these subjects.Background: Insomnia is prevalent among the adult population. While it has been speculated that sleepiness may be an important daytime consequence of insomnia, this has not been demonstrated.Methods: Sixty-two subjects with complaints of insomnia for at least 6 months were polysomnographically evaluated. Subjects were asked to self-report their level of sleepiness based on their experiences for the previous 7 days. Subjects were divided into three groups based on their level of sleepiness. Sleepiness was determined using the excessive daytime sleepiness scale of the Sleep/Wake Activity Inventory (SWAI-EDS).Results: Twenty-two percent of insomnia subjects were found to be sleepy on the EDS scale of the SWAI. The level of sleepiness was also found to predict difficulty initiating sleep both on the nocturnal scale of the SWAI, and on nocturnal polysomnography.Conclusions: This study established a base rate of sleepiness among a cohort of insomnia subjects. It also demonstrated a wide spectrum of sleepiness/alertness among subjects with insomnia. Differential levels of sleepiness were found to predict nocturnal sleep latencies.

CPAP therapy in patients with mild OSA: implementation and treatment outcome

Objectives: To determine continuous positive airway pressure (CPAP) treatment compliance and reversal of excessive daytime sleepiness in patients with mild OSA.Background: CPAP therapy is the most widely accepted and used intervention in patients with a diagnosis of obstructive sleep apnea (OSA). There are, however, no widely accepted protocols to help guide the rational use of CPAP therapy. Patients with mild OSA (respiratory event index (REI) >5 or </=25) represent a subset of the OSA population where CPAP implementation needs to be evaluated.Methods: This is a retrospective study of 740 consecutive patients evaluated for sleep apnea in 1996. Mild OSA was documented in 241 patients, of whom, 41 opted for CPAP therapy. Implementation of CPAP treatment included an education session and an overnight clinical polysomnography (CPSG) for titration purposes. Patients returned for follow-ups after 1 week and 1 year of CPAP use. During each appointment, compliance and response to treatment were evaluated.Results: Of the initial 41 patients nine were lost to follow-up, 16 discontinued CPAP use during the first week, and 16 were still using CPAP after 1 year. For the 16 still using CPAP after one year, hours of use the first week was correlated to hours of use the first year (r=0.81). Patients using CPAP more than 4 h/night experienced a marked improvement in daytime sleepiness after 1 year (P<0.01).Conclusions: Patients with mild OSA showed a high rate of CPAP discontinuation. Those patients who manifested good compliance during the first week of treatment continued using CPAP for the entire first year. These patients experienced improved alertness during the day. A 1 week trial on CPAP therapy is warranted to identify patients who benefit from this form of therapy.