Mean Apnea Duration Research Articles

Characteristics of overnight obstructive apnea events in patients with obstructive sleep apnea hypopnea syndrome

Objective: To compare the overnight variation trends in the duration of obstructive apnea events, and to explore the adaptive capacity to the pathophysiological consequences of periodic sleep disordered-breathing and its underlying mechanism in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods: A retrospective analysis were performed of the polysomnographic (PSG) results of 89 snoring patients including 10 non-OSAHS, 15 mild, 29 moderate and 35 severe OSAHS. The total record time was divided into four equal phases, and the variation trends of the mean apnea duration (MAD) and the longest apnea duration (LAD) were compared with the progression of sleep phases in different groups. Correlation analysis was conducted with demographic indicators, pulse oxygen saturation (SpO2) and sleep related indicators. In addition, the number of apneas-time variability curve was plotted for fitting analysis. Results: In patients with severe OSAHS, both MAD [26.1(20.9, 31.4) s] and LAD [56.5(46.5, 82.0) s] were significantly higher than those of non-OSAHS, mild and moderate OSAHS (P<0.001). In addition, the MAD in the third and fourth quartiles were significantly higher than that in the first quartile [(28.4±9.0) s, (27.3±9.8) s, (22.3±9.9) s, respectively, P=0.046], and the LAD in the third quartile was significantly higher than that in the first quartile [56.5(38.5, 71.0) s, 41.0(28.0, 53.0) s, respectively, P=0.018]. In all subjects, the MAD and LAD in the third and fourth quartiles were significantly higher than those in the first quartile [MAD: 20.3(10.3, 29.2) s, 18.5(11.3, 24.2) s, 12.9(0.0, 21.8) s, respectively, P<0.001; LAD: 28.0(10.3, 50.5) s, 28.0(12.0, 44.5) s, 14.5(0.0, 32.3) s, respectively, P<0.001]. There was no statistical difference in the lowest SpO2 (LSpO2), the mean SpO2 (MSpO2), and the percent of sleep time oxygen saturation below 90% (T90%) of all subjects in different sleep phases (P>0.05). The LAD was positively correlated with obstructive apnea index (OAI, OR=1.660, P=0.025), but no correlation was observed with other indicators (P>0.05). The MAD increased 0.22 s per episode at the onset of sleep (1-31 apnea events), then dropped to 0.04 s of increase per episode, with a dynamics change of 5.5-fold slower. Conclusions: The MAD and LAD show a gradual prolongation trend with the progression of sleep phases, and the prolongation trend is the most obvious in patients with severe OSAHS, while the dynamic change trend of SpO2 is not obvious. There may be multiple adaptation mechanisms for recurrent hypoxic episodes, and the adaptation occurr in stages, with a rapid increase in MAD at the onset of sleep, follow by a markedly slower increase. Patients with severe OSAHS express the most complete pattern, suggesting the most severe pathophysiological outcomes.

Association and Risk Factors for Obstructive Sleep Apnea and Cardiovascular Diseases: A Systematic Review

Obstructive sleep apnea (OSA) is a serious, potentially life-threatening condition. Epidemiologic studies show that sleep apnea increases cardiovascular diseases risk factors including hypertension, obesity, and diabetes mellitus. OSA is also responsible for serious illnesses such as congestive heart failure, stroke, arrhythmias, and bronchial asthma. The aim of this systematic review is to evaluate evidence for the association between OSA and cardiovascular disease morbidities and identify risk factors for the conditions. In a review of 34 studies conducted in 28 countries with a sample of 37,599 people, several comorbidities were identified in patients with severe OSA—these were: heart disease, stroke, kidney disease, asthma, COPD, acute heart failure, chronic heart failure, hyperlipidemia, thyroid disease, cerebral infarct or embolism, myocardial infarction, and psychological comorbidities including stress and depression. Important risk factors contributing to OSA included: age > 35 years; BMI ≥ 25 kg/m2; alcoholism; higher Epworth sleepiness scale (ESS); mean apnea duration; oxygen desaturation index (ODI); and nocturnal oxygen desaturation (NOD). Severe OSA (AHI ≥ 30) was significantly associated with excessive daytime sleepiness and oxygen desaturation index. The risk of OSA and associated disease morbidities can be reduced by controlling overweight/obesity, alcoholism, smoking, hypertension, diabetes mellitus, and hyperlipidemia.

Detecting Apnea/Hypopnea Events Time Location from Sound Recordings for Patients with Severe or Moderate Sleep Apnea Syndrome

The most common index for diagnosing Sleep Apnea Syndrome (SAS) is the Apnea-Hypopnea Index (AHI), defined as the average count of apnea/hypopnea events per sleeping hour. Despite its broad use in automated systems for SAS severity estimation, researchers now focus on individual event time detection rather than the insufficient classification of the patient in SAS severity groups. Towards this direction, in this work, we aim at the detection of the exact time location of apnea/hypopnea events. We particularly examine the hypothesis of employing a standard Voice Activity Detection (VAD) algorithm to extract breathing segments during sleep and identify the respiratory events from severely altered breathing amplitude within the event. The algorithm, which is tested only in severe and moderate patients, is applied to recordings from a tracheal and an ambient microphone. It proves good sensitivity for apneas, reaching 81% and 70.4% for the two microphones, respectively, and moderate sensitivity to hypopneas—approx. 50% were identified. The algorithm also presents an adequate estimator of the Mean Apnea Duration index—defined as the average duration of the detected events—for patients with severe or moderate apnea, with mean error 1.7 s and 3.2 s for the two microphones, respectively.

Smoking and sleep apnea duration mediated the sex difference in daytime sleepiness in OSA patients.

Daytime sleepiness is a common symptom of obstructive sleep apnea (OSA) and is more common in men, but the underlying mechanism remains unclear. The aim of this study was to assess whether or not sex differences in daytime sleepiness persisted after controlling for age and OSA severity and to explore the factors contributing to daytime sleepiness in patients with OSA. A total of 104 pairs of patients with OSA, matched by age and apnea-hypopnea index (AHI), were enrolled in this retrospective study. Demographic data were collected; daytime sleepiness was measured by the Epworth Sleepiness Scale (ESS); and polysomnography (PSG) was performed on each participant. These measurements were compared between sexes, and the factors affecting daytime sleepiness were explored with correlation and multivariate linear regression analyses. Men had significantly higher ESS scores (p = 0.021) than women. Regarding demographics, BMI, neck/height ratio, and proportion of habitual smoking and alcohol intake were significantly higher in men. Regarding PSG findings, men had more rapid eye movement sleep, a longer mean apnea-hypopnea duration, and a longer mean apnea duration (MAD). Regression analysis showed that two sex-associated variables, habitual smoking (β = 0.189, p = 0.006) and MAD (β = 0.154, p = 0.024), had the strongest association with ESS scores. Further analysis revealed that MAD was significantly influenced by apnea index (β = 0.306, p < 0.001) and sex (β = - 0.193, p = 0.003). The sex difference in daytime sleepiness persists in patients with OSA, even after matching AHI and age. The difference is mediated by sex-specific smoking habits and sex differences in apnea duration.

Clinical and polysomnographic features of hypertension in obstructive sleep apnea: A single-center cross-sectional study.

Objective:Obstructive sleep apnea (OSA) is associated with elevated blood pressure (BP) and increases the risk of developing cardiovascular diseases. This study aimed to determine the clinical and polysomnographic features of OSA that are significantly associated with hypertension (HT).Methods:This is a prospective study that enrolled patients diagnosed with OSA in Ankara University Faculty of Medicine from January 2015 to June 2016. The patients were categorized into normotensives (n=125) and hypertensives (n=141). BP was taken at the evening before and the morning after polysomnography (PSG). The polysomnographic findings of normotensive and hypertensive patients were compared, and independent risk factors that are associated with HT were analyzed.Results:Hypertensive patients exhibited older age and higher Epworth sleepiness scale (ESS), apnea–hypopnea index (AHI), mean apnea duration, arousal index, and oxygen desaturation index (ODI) than normotensive patients. Nocturnal oxygen desaturation (NOD) was more frequent and the percentage of the duration of NOD to total sleep time (TST) was higher in hypertensive than normotensive patients. Multivariate analyses revealed that age (OR: 1.095, 95% CI 1.053 to 1.139, p<0.001), ESS (OR: 1.186, 95% CI 1.071 to 1.313, p=0.001), mean apnea duration (OR: 1.072, 95% CI 1.032 to 1.113, p=0.002), ODI (OR: 1.062, 95% CI 1.025 to 1.101, p=0.001), and NOD (OR: 2.439, 95% CI 1.170 to 5.086, p=0.017) were independent risk factors for HT in OSA.Conclusion:This study suggests that age, ESS, parameters of oxygenation, and apnea duration were associated with HT in patients with OSA. Hence, patients with OSA with these findings should be evaluated for HT.

Sleep phenotype in children with Down syndrome – altered sleep architecture and sleep-disordered breathing

The aim of the study was to assess sleep architecture and breathing in sleep in children with Down syndrome. The study was conducted by using overnight video-polysomnography (V-PSG) in children with Down syndrome and age-matched children from the general population. Analysis of polysomnographic parameters revealed that compared to the norms of healthy age- and maturitymatched children from the general population, children with Down syndrome had significantly shorter sleep latency (p=0.007), shorter total sleep time (p=0.004), lower sleep efficiency (p=0.010), less NREM1 sleep phase (p=0.0002), less NREM3 sleep phase (p=0.034), less REM sleep (p=0.034) in favour of more NREM2 phase but not significantly (p=0.069), and spent more time awake after sleep onset (p=0.0002). Children with Down syndrome had significantly more obstructive sleep apnoeas and hypopnoeas per hour (higher obstructive sleep apnoeas and hypopnoeas index) (p=0.008), but less central sleep apnoea per hour (lower central apnoeas index) (p=0.041), which led to the nonsignificantly lower total apnoea-hypopnoea index (p=0.762) in children with Down syndrome. The mean and longest apnoea duration did not differ significantly between these two groups. Children with Down syndrome had a significantly lower mean and nadir oxygen saturation (p=0.008 and p=0.001, respectively). In conclusion, the majority of respiratory complications in children with Down syndrome can be prevented by raising awareness of sleep disturbances in children with Down syndrome among their parents and health care providers and by introducing early routine V-PSG in the follow up of these children. Key words: CHILD; DOWN SYNDROME; SLEEP APNEA SYNDROMES

Impact of self-reported symptoms of allergic rhinitis and asthma on sleep disordered breathing and sleep disturbances in the elderly with polysomnography study.

BackgroundSleep disordered breathing (SDB) and sleep disturbances have been reported to be associated with allergic rhinitis and asthma. However, population-based studies of this issue in the elderly are rare.ObjectiveTo investigate the impact of self-reported rhinitis and asthma on sleep apnea and sleep quality using polysomnography in an elderly Korean population.MethodsA total of 348 elderly subjects who underwent one-night polysomnography study among a randomly selected sample were enrolled. Study subjects underwent anthropometric and clinical evaluations. Simultaneously, the prevalence and co-morbid status of asthma and allergic rhinitis, and subjective sleep quality were evaluated using a self-reported questionnaire.ResultsEver-diagnosis of allergic rhinitis was significantly more prevalent in subjects with SDB compared with those without SDB. Subjects with an ever-diagnosis of allergic rhinitis showed a higher O2 desaturation index and mean apnea duration. Indices regarding sleep efficiency were affected in subjects with a recent treatment of allergic rhinitis or asthma. Waking after sleep onset was longer and sleep efficiency was lower in subjects who had received allergic rhinitis treatment within the past 12 months. Subjects who had received asthma treatment within the past 12 months showed significantly lower sleep efficiency than others.ConclusionOur study indicates that a history of allergic rhinitis is associated with increased risk of SDB in the elderly. Sleep disturbance and impaired sleep efficiency were found in the subjects who had received recent treatment of allergic rhinitis or asthma. Physicians should be aware of the high risk of sleep disorders in older patients with respiratory allergic diseases.

Estimation of cardiovascular disease from polysomnographic parameters in sleep-disordered breathing.

We aimed to illustrate the causal relationships between cardiovascular diseases (CVDs) and various polysomnographic variables, and to develop a CVD estimation model from these variables in a population referred for assessment of possible sleep-disordered breathing (SDB). Clinical and polysomnographic data of 1162 consecutive patients with suspected SDB whose comorbidity status was known, were reviewed, retrospectively. Variable selection was performed in two steps using univariate analysis and tenfold cross validation information gain analysis. The resulting set of variables with an average merit value (m) of>0.005 was considered to be causal factors contributing to the CVDs, and used in Bayesian network models for providing estimations. Of the 1162 patients, 234 had CVDs (20.1%). In total, 28 parameters were evaluated for variable selection. Of those, 19 were found to be associated with CVDs. Age was the most effective attribute in estimating CVD (m=0.051), followed by total sleep time with oxygen saturation<90% (m=0.021). Some other important variables were apnea-hypopnea index during non-rapid eye movement (m=0.018), lowest oxygen saturation (m=0.018), body mass index (m=0.016), total apnea duration (m=0.014), mean apnea duration (m=0.014), longest apnea duration (m=0.013), and severity of SDB (m=0.012). The modeling process resulted in a final model, with 76.9% sensitivity, 96.2% specificity, and 92.6% negative predictive value, consisting of all selected variables. The study provides evidence that the estimation of CVDs from polysomnographic parameters is possible with high predictive performance using Bayesian network analysis.

Analysis of clinical characteristics and risk factors of obstructive sleep apnea hypopnea syndrome with hypertension

To study the risk factors contributing to the development of hypertension in patients with obstructive sleep apnoea hypopnea syndrome (OSAHS), and the clinical characteristics of OSAHS with hypertension. A total of 2397 OSAHS patients aged above 30 years old and diagnosed by the sleep-disordered breathing center of Guangxi between July 2012 and August 2015 were recruited. OSAHS patients with new-onset hypertension (OSAHS with hypertension group) and those without hypertension (simple OSAHS group) were identified and their clinical data, including general status, family history of hypertension or snoring, Epworth Sleepiness Scale (ESS) score for daytime sleepiness, physical examination findings, and polysomnography monitoring data were collected. OSAHS patients with new-onset hypertension (n=101) and OSAHS patients without hypertension (n=202) matched by age and body mass index (BMI) (age difference, 2 years; BMI difference, 1.5 kg/m(2)) were recruited in the OSAHS with hypertension group and the simple OSAHS group. A case-control study was used to compare the clinical characteristics of these two groups, and univariate and multivariate Logistic regression were used to analyze all the factors contributing to hypertension development besides age and BMI. The average age and BMI of the OSAHS with hypertension group and the simple OSAHS group were respectively (46.2±9.3), (46.2±9.2) years old and (28.2±2.8), (28.2±2.8) kg/m(2). Patients in the two groups were well-matched with respect to age and BMI (P>0.05). The systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the OSAHS with hypertension group were significantly higher than those in the simple OSAHS group at the first admission to the clinic and before and after the PSG examination. ESS values in the OSAHS with hypertension group and the simple OSAHS group were respectively 10.0±6.4 and 9.2±6.3 (P>0.05). There was no significant intergroup difference in neck circumference, waist circumference, duration of snoring, family history of snoring, and family history of hypertension (P>0.05) either. The apnea-hypopnea index (AHI) and apnea index (AI) in the OSAHS with hypertension group were higher than those in the simple OSAHS group (P<0.05); the longest apnea duration (LAD), mean apnea duration (MAD), and the total time spent with oxygen saturation below 90% (T90%) in the OSAHS with hypertension group were significantly longer than those in the simple OSAHS group (P<0.05). The minimal pulse oxygen saturation (MinSpO2) in the OSAHS with hypertension group was significantly lower than that in the simple OSAHS group (P<0.05). Six factors were identified to be associated with OSAHS with hypertension through univariate analysis: AHI (OR=0.985, P=0.001), AI (OR=0.983, P<0.001), LAD (OR=0.955, P=0.013), MAD (OR=0.874, P=0.015), MinSpO2 (OR=0.874, P=0.015), T90% (OR=0.997, P=0.036). Only MinSpO2 (P<0.001, OR=0.894) was closely related to OSAHS hypertension development in the multivariate Logistic regression model. OSAHS patients with hypertension may show lower MinSpO2, higher AHI and AI, and longer LAD, MAD, and T90% than OSAHS patients without hypertension. MinSpO2 is probably closely related to OSAHS hypertension development.

Clinical and polysomnographic predictors of severe obstructive sleep apnea in the South Indian population.

Background:With the emergence of lifestyle diseases in epidemic proportions, obstructive sleep apnea (OSA) is being increasingly recognized in less developed countries as well.Aim:We sought to study the demographic, clinical, and polysomnographic (PSG) predictors of OSA severity in a cohort of South Indian patients.Materials and Methods:Consecutive patients with PSG proven OSA [apnea hypopnea index (AHI) ≥5/h] were prospectively recruited. The study period was from January 2012 to December 2012. Demographic data, history of vascular risk factors, substance abuse, sleep quality, snoring, and witnessed apneas were collected using a structured pro forma. In addition, PSG variables such as AHI, sleep latency and efficiency, duration of slow wave and rapid eye movement (REM) sleep, and other parameters were collected. Correlations between AHI severity and clinical and PSG parameters were done.Results:There were 152 (119 males and 33 females) subjects with a mean age of 53.8 years and body mass index (BMI) of 29.31. Mean AHI was 36.2/h (range: 5.1-110) and 66 subjects had severe OSA. Around 12% had the presenting complaint as insomnia, mainly of sleep maintenance. Of the subjects, 35% had witnessed apneas and 67% had excessive daytime sleepiness (EDS); 40% of patients had ≥2 risk factors. PSG parameters showed short sleep onset latency with a high arousal index. Mean apnea duration was 24.92 s. We found that age >55 years, BMI >25 kg/m2, witnessed apneas, EDS, hypertension, dyslipidemia, reduced slow wave sleep duration, mean apnea duration >20 s, and desaturation index >10/h correlated well with OSA severity while the arousal index, sleep latency and efficiency, and exposure to smoking and alcohol showed no association.Conclusions:Older subjects with witnessed apneas are likely to have more severe OSA. Even though overall sleep architecture was similar between the groups, severe OSA had shorter slow wave sleep, longer apneas, and higher nocturnal hypoxemia.

Relationship between sleep apnea and thyroid function

Sleep apnea is sometimes associated with hypothyroidism, but the significance of thyroid function screening in sleep apnea patients has been controversial. In the present study, we investigated the relationship between thyroid function and sleep apnea in subjects who were suspected to have sleep apnea. We enrolled 156 consecutive subjects suspected of having sleep apnea. Subjects included 117 men and 39 women aged 21 to 84years. They underwent nocturnal multichannel polysomnography during a one-night hospitalization. The examined indices of sleep apnea were apnea-hypopnea index (AHI), lowest oxygen saturation, oxygen desaturation index, longest apnea duration, mean apnea duration, and the percent of apnea time to sleep time. Serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were concomitantly measured by electrochemiluminescence immunoassays. Three subjects (1.9%) were diagnosed with primary hypothyroidism (high TSH and low FT4), and one subject (0.6%) with subclinical hypothyroidism (high TSH and normal FT4). No significant difference in the level of TSH, FT3, or FT4 was seen among subjects with different severity of sleep apnea. The mean apnea duration significantly correlated with TSH in both simple and multiple regression analyses. Subjects with lower FT3 (≤3.75pg/ml) showed longer mean apnea time compared to those with higher FT3 (>3.75pg/ml) (24.9 ± 0.8 vs. 20.2 ± 1.2s; P = 0.009). The other indices of sleep apnea did not show significant correlation with thyroid function. These results suggest that the mean apnea duration and TSH/FT3 may be helpful in understanding reciprocity between the two disease states, and for evaluating the validity of thyroid function tests in patients with sleep apnea.

Polysomnographic Determinants of Nocturnal Hypercapnia in Patients with Sleep Apnea

Identify polysomnographic and demographic factors associated with elevation of nocturnal end-tidal CO2 in patients with obstructive sleep apnea. Forty-four adult patients with obstructive sleep apnea were selected such that the maximal nocturnal end-tidal CO2 was below 45 mm Hg in 15 studies, between 45 and 50 mm Hg in 14, and above 50 mm Hg in 15. Measurements included mean event (i.e., apneas or hypopneas) and mean inter-event duration, ratio of mean post- to mean pre-event amplitude, and percentage of total sleep time spent at an end-tidal CO2 < 45, 45-50, and > 50 mm Hg. An integrated nocturnal CO2 was calculated as the sum of the products of average end-tidal CO2 at each time interval by percent of total sleep time spent at the corresponding time interval. The integrated nocturnal CO2 was inversely correlated with mean post-apnea duration, with lesser contributions from mean apnea duration and age (R (2) = 0.56), but did not correlate with the apnea-hypopnea index, or the body mass index. Mean post-event to mean pre-event amplitude correlated with mean post-apnea duration (r = 0.88, p < 0.001). Mean apnea duration did not correlate with mean post-apnea duration. Nocturnal capnometry reflects pathophysiologic features of sleep apnea, such as the balance of apnea and post-apnea duration, which are not captured by the apnea-hypopnea index. This study expands the indications of capnometry beyond apnea detection and quantification of hypoventilation syndromes.

Effects of Nasal Continuous Positive Airway Pressure on the Glomerular Filtration Rate in Patients with Obstructive Sleep Apnea Syndrome

Previous studies have shown a possible role for obstructive sleep apnea syndrome (OSAS) in the development and/or progression of chronic kidney disease (CKD). However, the impact of treatment for OSAS on CKD has not been clarified. The aim of this study was to investigate the influence of OSAS and the short-term effects of nasal continuous positive airway pressure (CPAP) on the estimated glomerular filtration rate (eGFR). We evaluated 38 men with OSAS diagnosed on polysomnography. The associations between the eGFR and patient characteristics, including polysomnographic parameters, were evaluated. A multivariate linear regression analysis was performed to determine the independent variables associated with eGFR. We reassessed the polysomnographic data and eGFR values after three months of CPAP treatment. The mean serum creatinine level was 0.83±0.10 mg/dL and the mean eGFR was 77.3±12.0 mL/min/1.73 m2. A univariate analysis revealed that an older age (p<0.001), a longer mean apnea duration (p=0.006) and BMI (p=0.022) were significantly associated with lower eGFRs. A multivariate linear regression analysis showed that the independent factors associated with lower eGFRs were older age (p<0.001) and a longer mean apnea duration (p=0.048). Three months after CPAP treatment, there were significant decreases in the serum creatinine levels (p=0.013) and increases in eGFR (p=0.014). OSAS, especially that associated with an older age and a longer mean apnea duration, may contribute to lowering eGFR values, which can be reversed by CPAP treatment.

Normative values of polysomnographic parameters in childhood and adolescence: Cardiorespiratory parameters

To provide normative values for pediatric sleep cardiorespiratory parameters following AASM rules, assessing effects of gender, age, and Tanner stage. One-night polysomnograhy was performed at subjects' habitual bedtimes in 16 laboratories on 209 healthy German children, 1-18 years old. Normative values of cardiorespiratory parameters in pediatric sleep are presented. No obstructive and mixed apneas occurred. Hypopneas were seldom. Respiratory frequency and apnea-hypopnea-index decreased with age (p<0.001). In all groups central apneas ≥ 20 s were present but uncommon. Oxygen desaturations or respiratory arousals following central apnea were rare. Heart rate showed an inverse correlation to age (p<0.001). Heart rate was lower in sleep, lowest in stage N. The mean heart rate of females was higher than males (p<0.05). Neither Tanner stage nor corresponding age (p<0.05) influenced: mean apnea duration, central apnea index ≥ 20 s, hypopnea index, index of periodic breathing, or oxygen saturation nadir. All other parameters except maximal apnea duration and central apnea index after movements with oxygen desaturation show dependency on both Tanner stage and corresponding age (p<0.05). Using AASM rules, the development of cardiorespiratory parameters in healthy children, ages 1-18 is shown. Age-related norms may improve sleep pathology identification.

Amelioration of obstructive sleep apnea in REM sleep behavior disorder: implications for the neuromuscular control of OSA.

The relationship between REM sleep behavior disorder (RBD) and obstructive sleep apnea (OSA) remains unclear. We aimed to (1) explore the association of REM-related EMG activity (REMREEA) with OSA in RBD patients; (2) compare the severity of OSA between RBD patients with OSA (RBD-OSA) and their age-, sex-, AHI-, and BMI- matched OSA controls. a. Correlation study in consecutive RBD subjects and b. case-control study Sleep laboratory 71 RBD patients in the correlation study and 55 subjects (28 RBD-OSA cases and 27 OSA controls) in the case-control study. N/A METHODS: Polysomnographic assessment to document the sleep architecture, sleep apnea related parameters, and REMREEA. (1) In the correlation study, increased REMREEA was associated with lower severity of OSA in RBD patients, including total AHI (r = -0.263), NREM AHI (r = -0.242), obstructive AHI (r = -0.265), and mean apnea duration (r = -0.353) (P < 0.05). (2) In the case-control study, RBD-OSA patients had lesser severity of sleep apnea parameters than OSA controls in terms of higher nadir SpO(2) (85.7% ± 4.9% vs 80.8% ± 5.9%, P < 0.01), shorter maximum hypopnea duration (53.8 ± 16.7 vs 69.4 ± 22.4 seconds, P < 0.05), and maximum (45.8 ± 20.5 vs 60.8 ± 19.6 sec, P < 0.01) and mean apnea duration (22.3 ± 8.1 vs 26.3 ± 5.8 sec, P < 0.05). Significant interaction effects indicated that the usual REM sleep exacerbation of sleep apneas was seen only in OSA controls but not in RBD subjects. This study demonstrated that excessive EMG activity in RBD might protect patients against severe OSA and suggests this may be a naturalistic model for understanding neuromuscular control of OSA.

Lung volumes and mean apnea duration in obstructive sleep apnea

Former studies suggested that lung volumes might play a role in pathomechanisms of obstructive sleep apnea (OSA). Mean apnea duration (MAD) is a rarely investigated parameter in OSA but is possibly a surrogate of arousal threshold. The aim of this study was to evaluate the influence of lung volumes to MAD in OSA. In 69 patients with obstructive sleep apnea (51 male und 18 female, BMI 34.2+/-6.0 kg/m(2), age 53.6+/-9.7 years, AHI 43.1+/-21.1/h) we performed a polysomnography and pulmonary function testing in daytime. There was a significant correlation between MAD and residual volume (RV) (r=0.51; p<0.001), which was the highest correlation we found. In linear regression analysis RV remained the only independent variable with significant influence on MAD (p<0.001). We could show that RV seems to play a role in the mechanisms of apnea termination in terms of MAD. MAD reflects the time until a specific negative intrathoracic pressure is reached to induce an arousal. In this process dependency on RV could explain our results. Despite some limitations these results provide some new aspects in understanding pathophysiology of OSA.

Reproducibility of portable polysomnography values in children with habitual snoring

The purpose of this study was to examine the reproducibility of portable polysomnography for the evaluation of nocturnal sleep breathing in children with habitual snoring. Seven children and nine adults with habitual snoring were monitored at home during nocturnal sleep for three nights by parents or a bed-partner who had been informed about the use of portable polysomnography. Differences in adult polysomnographic values over the three nights were assessed by two-way ANOVA and Friedman test. The difference in polysomonographic values in children between two nights was assessed with an F-test and a Wilcoxon signed-ranks test. We found no differences in polysomnographic values among the three nights in adults. However, there were differences in Factor A (i.e. Mean SpO 2, Lowest SpO 2, Mean Apnea Duration and Mean Pulse Rate) among the adult subjects. In children, there was no difference in polysomnographic values between the two nights; however, there were differences in the variance of Mean SpO 2 and Mean Apnea Duration between the two nights. In conclusion, to permit children to sleep as naturally as possible, sleep-screening tests can be performed reproducibly at home using portable polysomnography over a few days.

Apnoea–Hypopnoea Index during Rapid Eye Movement and Non-Rapid Eye Movement Sleep in Obstructive Sleep Apnoea

This study investigated the differences in apnoea-hypopnoea index (AHI) during rapid eye movement (REM) sleep (AHI-REM) and AHI during non-REM (NREM) sleep (AHI-NREM) in patients with obstructive sleep apnoea (OSA). Nocturnal polysomnography was performed in 102 Japanese OSA patients and their AHI along with a variety of other factors were retrospectively evaluated. Regardless of the severity of AHI, mean apnoea duration was longer and patients' lowest recorded oxygen saturation measured by pulse oximetry was lower during REM sleep than during NREM sleep. Approximately half of the patients (n = 50) had a higher AHI-NREM than AHI-REM. In subjects with AHI >or= 60 events/h, AHI-NREM was significantly higher than AHI-REM. On multivariate logistic regression, severe AHI >or= 30 events/h was the only predictor of a higher AHI-NREM than AHI-REM. This may indicate that important, but unknown, factors related to the mechanism responsible for the severity of OSA are operative during NREM sleep.

Lateral Sleeping Position Reduces Severity of Central Sleep Apnea / Cheyne-Stokes Respiration

The influence of sleeping position on obstructive sleep apnea severity is well established. However, in central sleep apnea with Cheyne Stokes respiration (CSA-CSR) in which respiratory-control instability plays a major pathophysiologic role, the effect of position is less clear. To examine the influence of position on CSA-CSR severity as well as central and mixed apnea frequency. Polysomnograms with digitized video surveillance of 20 consecutive patients with heart failure and CSA-CSR were analyzed for total apnea-hypopnea index, mean event duration, and mean oxygen desaturation according to sleep stage and position. Position effects on mixed and central apnea index, mean apnea duration, and mean desaturation were also examined in non-rapid eye movement sleep. Data are presented as mean +/- SEM unless otherwise indicated. Group age was 59.9 +/- 2.3 years, and total apnea-hypopnea index was 26.4 +/- 3.0 events per hour. Compared with supine position, lateral position reduced the apnea-hypopnea index in all sleep stages (Stage 1, 54.7 +/- 4.2 events per hour vs 27.2 +/- 4.1 events per hour [p < .001]; Stage 2, 43.3 +/- 6.1 events per hour vs 14.4 +/- 3.6 events per hour [p < .001]; slow-wave sleep, 15.9 +/- 6.4 events per hour vs 5.4 +/- 2.9 events per hour [p < .01]; rapid eye movement sleep, 38.0 +/- 7.3 events per hour vs 11.0 +/- 3.0 events per hour [p < .001]). Lateral position attenuated apnea and hypopnea associated desaturation (supine 4.7% +/- 0.3%, lateral 3.0% +/- 0.4%; p < .001) with no difference in event duration (supine 25.7 +/- 2.8 seconds, lateral 26.9 +/- 3.4 seconds; p = .921). Mixed apneas were longer than central (29.1 +/- 2.1 seconds and 19.3 +/- 1.1 seconds; p < .001) and produced greater desaturation (6.1% +/- 0.5% and 4.5% +/- 0.5%, p = .003). Lateral position decreased desaturation independent of apnea type (supine 5.4% +/- 0.5%, lateral 3.9% < or = 0.4%; p = .003). Lateral position attenuates severity of CSA-CSR. This effect is independent of postural effects on the upper airway and is likely to be due to changes in pulmonary oxygen stores. Further studies are required to investigate mechanisms involved.

Serotonin and Noradrenaline Modulate Respiratory Pattern Disturbances Evoked by Glutamate Injection Into the Pedunculopontine Tegmentum of Anesthetized Rats

We hypothesized that 2 important neurotransmitters related to behavioral state control, serotonin and noradrenaline, could also be modulators of pedunculopontine tegmental nucleus (PPT)-induced respiratory dysrhythmia. We examined the impact of serotonin and noradrenaline at respiratory control sites in the PPT functionally identified by immediate apnea of 2.5- to 10-second duration, followed by increased variability of breath time (CVT(T)) (P < .04) after locally injecting glutamate in anesthetized rats. Basic sleep and respiratory neurobiology laboratory. Sixteen adult, male Sprague-Dawley rats. Glutamate-induced respiratory responses, including increases of total apnea duration and CVT(T), were not different between groups of rats in which we further tested monoaminergic modulatory effects (for CVT(T) P = .98, and for total apnea duration, P = .80). Serotonin or noradrenaline injected at the same sites as glutamate had equal impact on CVT(T) (P = .34) and on mean total apnea duration (P = .80), but pretreatment of PPT sites with serotonin blocked (remained equal to preinjection; P = .11), whereas pretreatment with noradrenaline potentiated (P = .04) the increment of respiratory-timing variability induced by glutamate. The serotonergic-blocking effect on glutamate-induced respiratory dysrhythmia was specific to the PPT: the respiratory responses induced by glutamate injection outside the PPT were not modulated by serotonin (for CVT(T), P = .46, and for mean apnea duration, P = .99). The opposed impact of serotonin and noradrenaline on PPT-induced respiratory dysrhythmia, in contrast to their convergent regulatory role in behavioral state control, suggests a functionally distinct role for the PPT in respiratory-pattern control independent of rapid eye movement sleep control.