Effect of nasal continuous positive airway pressure on edema in patients with obstructive sleep apnea

BACKGROUND AND PURPOSE: Previous research has identified an association between idiopathic edema and obstructive sleep apnea (OSA) in women, but a causal relationship between OSA and edema has not been established. This study was undertaken to determine whether nasal continuous positive airway pressure (CPAP) lessens edema in patients with idiopathic edema and OSA. PATIENTS AND METHODS: This was a case-series study that enrolled eight ambulatory, obese, adults with bilateral, pitting pre-tibial edema and OSA from an inner city family practice and a suburban family practice from July 1995 until March 2003. Enrollees underwent subjective and physical examination assessment of changes in edema after initiation of nasal CPAP. RESULTS: All but one of the subjects had severe OSA. The edema was typically 1+ to 2+, and the duration of the edema ranged from 6 months to more than 20 years. Seven of the eight subjects experienced a reduction in the amount of edema following nasal CPAP (P=0.04). CONCLUSIONS: In subjects with OSA and idiopathic edema, nasal CPAP reduces the amount of edema. If valid, these results indicate that OSA can cause edema.     

Obesity, and not obstructive sleep apnea, is responsible for metabolic abnormalities in a cohort with sleep-disordered breathing

OBJECTIVE: To assess the profile of metabolic abnormalities in subjects with obstructive sleep apnea (OSA). PATIENTS AND METHODS: In a case-control study conducted in two years, from April 2003 to March 2005, data obtained from polysomnography study, lipid profile, fasting blood sugar, serum insulin, insulin resistance, leptin and adiponectin levels, were compared between the various groups. Included in the study were OSA subjects from a sleep laboratory and matched controls from the community. Those with recent myocardial infarction, upper airway surgery, class III/IV heart failure, pregnancy, acromegaly, chronic renal failure, or who were on treatment for hyperthyroidism, on systemic steroid treatment, or on hormonal replacement therapy, were excluded from the study. RESULTS: Forty apneic obese subjects (AHI=32.19, range 13-52.75) were compared with 40 non-apneic obese controls (AHI=1.3, range 0-2.45) and 40 normal weight control subjects (AHI=0.7, range 0-1). No significant difference was noted in levels of fasting blood sugar, insulin resistance (obese apneics 61.9, obese controls 47.8, non-obese controls 19.1), leptin (obese apneics 10.65 microg/L, obese controls 8.52 microg/L, non-obese controls 2.83 microg/L) or adiponectin (obese apneics 4959.3 ng/ml, obese controls 5706 ng/ml, non-obese controls 7412 ng/ml) in the OSA group compared to obese controls. CONCLUSIONS: OSA has no independent association with lipid abnormalities, insulin resistance, serum leptin and adiponectin levels. In multivariate analysis, obesity was the major determinant of metabolic abnormalities in this cohort.     

Erectile dysfunction, obstructive sleep apnea syndrome and nasal CPAP treatment

BACKGROUND AND PURPOSE: To evaluate the effect of one month of continuous positive airway pressure (CPAP) in a subgroup of obstructive sleep apnea (OSA) patients with erectile dysfunction (ED) and compare this subgroup with age- and body mass index (BMI)-matched OSA patients without ED. PATIENTS AND METHODS: Prospective general, sleep, psychiatric and sexologic evaluations were conducted. Epworth Sleepiness Scale (ESS), Beck Depression Inventory (BDI), Sleep Disorders Questionnaire (SDQ), Quality of Life SF-36, and polysomnography were used. Seventeen OSA patients with ED were compared prior to CPAP treatment and during CPAP treatment with age- and BMI-matched OSA patients without ED. Parametric and non-parametric statistics, chi-square, Fisher exact test and multiple regression analyses were performed. RESULTS: Ninety-eight men (BMI=28.8 kg/m2, apnea-hypopnea index (AHI)=49.6 events/h, ESS=14.8, BDI=8.4, and lowest SaO2=75.3%) were divided into subgroups of lowest SaO2>80% (A) and lowest SaO2< or =80% (B). (A) Forty-six men had a mean lowest SaO2 of 85.7%+/-2.9, AHI=29.5+/-17.6, age=46.3+/-9.3 years, ESS=13.6+/-4.2, BMI=25.8+/-4.8. Seven of the patients had ED. (B) Fifty-two men had a mean lowest SaO2=60.10+/-10.0%, AHI=67.4+/-24.5, BDI=9.0+/-6.9, age=47.4+/-9.4 years, ESS=16.2+/-4.4, BMI=31.4+/-5.1. Twenty-one of the patients had ED (chi2: P=0.006). Significant variables for ED were lowest SaO2 and age (r=0.17). CPAP-treated subgroup: ED subjects had significantly lower SaO2, ESS, BDI and SF-36 subscale scores than OSA controls. Nasal CPAP eliminated the differences between groups, and ED was resolved in 13 out of 17 cases. CONCLUSIONS: ED in OSAS is related to nocturnal hypoxemia, and about 75% of OSAS patients with ED treated with nasal CPAP showed remission at one-month follow-up, resulting in significant improvement in quality of life.     

A stepped approach for prediction of obstructive sleep apnea in overtly asymptomatic obese subjects: a hospital based study

BACKGROUND AND PURPOSE: Prevalence of obstructive sleep apnea (OSA) is high in obese subjects, many of whom may not be overtly symptomatic. Polysomnography (PSG) is a costly and time-consuming investigation. Since it is not feasible to subject all obese individuals to PSG, it is useful to define predictors of OSA among these subjects. PATIENTS AND METHODS: One hundred and eighteen obese subjects [body mass index (BMI)> or =25 kg/m(2)] presenting to the hospital with non-sleep related complaints were included, of which 53 subjects with PSG evidence of OSA [apnea-hypopnea index (AHI)> or =15/h] were defined as cases and 65 subjects without any evidence of OSA (AHI<15/h) were defined as controls. Anthropometry, biochemical investigations, blood gas analysis, pulmonary function tests, and PSG were performed for all subjects. RESULTS: Waist hip ratio (WHR) (as percentage of a standard) [odds ratio (95% CI): 1.07 (1.00-1.14); P = 0.049] male gender [odds ratio (95% CI): 3.97 (0.99-15.81); P = 0.046] and neck circumference (NC) [odds ratio (95% CI): 1.23 (1.03-1.47); P = 0.023] were found to be independent predictors of OSA. Overnight oxygen desaturation data were evaluated in patients selected as having OSA on the basis of these clinical markers, and the best cut-off for level of desaturation (10%) was defined. The stepped approach had a specificity, sensitivity, positive and negative predictive value of 89.2, 88.5, 86.8 and 90.6%, respectively, for the diagnosis of OSA. CONCLUSIONS: Male gender, WHR and NC are independent predictors of OSA in overtly asymptomatic obese subjects. A stepped approach to diagnose OSA should be used, as it is accurate and cost-effective.     

Gender differences on polysomnographic findings in Greek subjects with obstructive sleep apnea syndrome

BACKGROUND AND PURPOSE: Studies from North American clinics have reported that females with obstructive sleep apnea syndrome (OSAS) are about the same age as males but are heavier, have less severe apnea and make up a much smaller proportion of cases. We examined polysomnographic differences between Greek men and women with OSAS in order to study the influence of gender on clinical presentation and laboratory findings. PATIENTS AND METHODS: This retrospective study included a cohort of 1,010 Greek patients (844 males, 166 females) diagnosed with OSAS by overnight polysomnography (PSG), who were referred to the Sleep Disorders Center of Evangelismos Hospital, Athens Medical School, University of Athens. All patients were studied over a period of three consecutive years, during which time clinical and polysomnography (PSG) findings were compared. RESULTS: Body mass index (BMI) was similar in men and women with OSAS (BMI=31.6+/-5.5kg/m(2) in men versus BMI=32.5+/-8.1 (SD) kg/m(2) in women). Female patients were significantly older than male patients (56.9+/-10.6 versus 50.6+/-11.7 year, P=0.001). The mean apnea-hypopnea index (AHI) during total sleep time was higher in men than in women (42.4+/-28.2 versus 33.2+/-27.7 events/h, P<0.001). The AHI in non-rapid eye movement (NREM) sleep was higher in men than in women (42.9+/-28.9 versus 32.6+/-28.7 events/h, P<0.001), but in rapid eye movement (REM) sleep AHI was similar in men and women (36.0+/-23.3 versus 34.9+/-25.4 events/h). Forty percent of men had AHI-REM sleep >AHI-NREM compared to 62% of women, and the difference between REM and NREM-AHI was significantly less in men than in women (14.21+/-11.18 versus 19.76+/-13.43 events/h, P<0.001)). Several aspects of sleep were worse in women versus men: sleep efficiency index was lower (79.4+/-16.1% versus 85.1+/-12.5%, P<0.001); sleep onset latency (27.7+/-27.7 versus 17.9+/-18.1min, P<0.001), and REM onset latency (161.5+/-76.2 versus 145.7+/-71.4min, P<0.018) were longer; wake time after sleep onset (WASO) was also greater in women (42.6+/-46.5 versus 30.7+/-34.9min, P<0.003). CONCLUSIONS: In Greek subjects with OSAS, there was no difference in BMI, and female patients were significantly older than male patients. OSAS was diagnosed in men five times more often than in women. AHI was greater in men than in women, but women are more likely than men to have a higher AHI in REM than NREM. Sleep quality is worse in female than in male patients.     

Evening and morning blood gases in patients with obstructive sleep apnea

BACKGROUND AND PURPOSE: The purpose of this study was to see if blood oxygen levels deteriorate overnight during obstructive sleep apnea (OSA). Before and after sleep, arterial blood gases (ABGs) in OSA subjects and controls were drawn during a diagnostic night, as well as during a continuous positive airway pressure (CPAP) night for the OSA subjects. PATIENTS AND METHODS: Subjects, both male and female, were referred to our sleep laboratory for symptoms of daytime somnolence. Subjects consisted of a control group (N=13) with a mean apnea hypopnea index (AHI) of 3.3 events/h and a study group (N=22) with a mean baseline AHI of 57 events/h. RESULTS: With the subject supine, resting room air ABGs were drawn at 'lights out' on the evening before (PM) nocturnal polysomnography and in the morning (AM) at discontinuation ('lights on') of the sleep study. In controls, PM PaO(2) (79.4+/-9.7 mmHg) was not significantly different from AM PaO(2) (80.2+/-8.9 mmHg, P=0.5). In apneic subjects, the PM PaO(2) was 78.7+/-7.2 mmHg compared to an AM PaO(2) of 72.6+/-8.3 mmHg (P<0.05). The AM PaO(2) after a night of CPAP treatment in the OSA subjects was 77.5+/-10.2 mmHg compared to the PM PaO(2) of 76.0+/-6.0 mmHg (NS). The PM and AM PaCO(2)s were not different in controls or in study subjects under baseline conditions. However, during titration with nasal CPAP, the PaCO(2) was significantly higher in the morning after CPAP treatment [43.1+/-4.8 vs. 46.1+/-4.8 mmHg, respectively (P<0.05)]. CONCLUSIONS: OSA subjects showed a fall in overnight resting oxygenation. This could be accounted for by overnight deterioration of gas exchange and is ameliorated by CPAP.     

Hypercoagulability in patients with obstructive sleep apnea

BACKGROUND: Obstructive sleep apnea (OSA) has been linked to cardiovascular complications such as stroke and myocardial infarction. Previous studies demonstrate that OSA patients show elevated fibrinogen levels and increased platelet aggregation that are reversed with 1 night of nasal continuous positive airway pressure treatment (NCPAP). Questioning overall coagulability in OSA, we examined whole blood coagulability in 11 chronically NCPAP treated OSA subjects, 22 previously untreated OSA subjects, and in 16 of these after 1 night of NCPAP treatment. PATIENTS AND METHODS: During full polysomnography, subjects from each group had blood drawn prior to bedtime (21:00 h) and upon waking in the morning (07:00 h). RESULTS: Untreated OSA patients had faster P.M. clotting times than chronically treated OSA patients (3.33+/-0.31 versus 6.12+/- 0.66 min, P<0.05 by ANOVA). A.M. values showed similar results (4.31+/- 0.34 min versus 7.08+/-0.52 min, P<0.05 by ANOVA) for the respective groups. One overnight treatment with nasal CPAP did not produce a significant change in A.M. whole blood coagulability (4.35 +/-0.43 to 5.31+/-0.53 min; n=16; P=0.1) in 16 treated subjects. CONCLUSIONS: These data indicate a relationship between obstructive sleep apnea and blood hypercoagulability status that appears to be reversed by chronic NCPAP treatment. These data suggest that NCPAP might protect against the development of cardiovascular complications in OSA patients.     

Comparison of obstructive sleep apnea patients with and without leg edema

BackgroundTo determine the proportion of patients with obstructive sleep apnea (OSA) who have leg edema, and to identify differences between edematous and non-edematous OSA patients.MethodsRetrospective, cross-sectional study of 378 patients with OSA (apnea/hypopnea index [AHI] ⩾15) who had neither heart failure nor chronic lung disease.ResultsThirty-five percent (133/378) of the subjects with OSA had bilateral leg edema. Eighty-one percent (108/133) of the edematous subjects had mild pitting that was 1+. Compared to the non-edematous OSA subjects, the edematous subjects were older (age = 51 ± 13 versus 45 ± 13 years, p = 0.001), more obese (body mass index = 39 ± 9 versus 33 ± 8 kg/m², p = 0.001), had more severe OSA (AHI = 46 ± 71 versus 27 ± 29, p = 0.004), spent a greater proportion of sleep time with an oxygen saturation <90% (20 ± 26 versus 11 ± 18%, p = 0.001), and were more likely to have diabetes mellitus (11% versus 3%, p = 0.001) and hypertension (32% versus 10%, p = 0.001). Age, obesity, hypertension and diabetes mellitus correlated significantly with edema status. After adjusting for these confounding variables, the AHI means remained different between the edema and non-edema groups (41 ± 5 versus 28 ± 3, p = 0.04).ConclusionsApproximately one-third of OSA patients have edema. Edematous OSA patients are older, more obese, more likely to have diabetes mellitus and hypertension, and have more severe OSA than OSA patients who lack edema.     

Obesity, and not obstructive sleep apnea, is responsible for increased serum hs-CRP levels in patients with sleep-disordered breathing in Delhi

OBJECTIVE: The present study was conducted to evaluate serum levels of high-sensitivity C-reactive protein (hs-CRP) in newly diagnosed patients with obstructive sleep apnea (OSA). SUBJECTS AND METHODS: Between April 2005 and March 2006, a total of 231 consecutive adult habitual snorers underwent polysomnography (PSG) in the sleep laboratory. Ninety-seven subjects were found suitable for hs-CRP measurement after application of the following exclusion criteria: patients with diabetes mellitus, hypertension, coronary artery disease, acromegaly, hypothyroidism, chronic renal failure, congestive cardiac failure, or smoking history, patients who were pregnant, on steroid treatment, on hormone replacement therapy, or with chronic use of drugs such as non-steroidal anti-inflammatory drugs, oral anticoagulants and lipid-lowering drugs and patients having undergone upper airway surgery. Patients were classified as apneic [apnea-hypopnea index (AHI)>5], obese non-apneic [body mass index (BMI)>25, AHI<5] and non-obese non-apneic (BMI<25, AHI<5). C-reactive protein levels were measured in stored sera by high-sensitivity enzyme immunoassay (Biocheck, Inc. Foster City, CA, USA). After checking normality with the Kolmogorov-Smirnov test and using a square-root transformation, Pearson's and partial correlation coefficients were calculated for identified risk factors and confounders. A multiple linear regression model was used to identify variables that were independently associated with hs-CRP. RESULTS: The mean serum levels of hs-CRP were found to be 0.25+/-0.23, 0.58+/-0.55, and 0.51+/-0.37 mg/dl in non-obese non-apneics (n=23), obese non-apneics (n=45) and apneics (obese and non-obese, n=29), respectively. Pearson's correlation coefficient of hs-CRP with BMI was found to be 0.25 (p=0.01), and with AHI 0.16 (p=0.12). Partial correlation analysis showed that hs-CRP levels correlated significantly with BMI after adjustment for AHI and age (r=0.22, p=0.03), while correlation with disease severity as assessed by AHI after adjustment for BMI and age was not significant (r=0.10, p=0.33). After stepwise multiple linear regression, only BMI was found to be significantly associated with serum hs-CRP levels (beta=0.02, p=0.01). CONCLUSIONS: In this first comprehensive cross-sectional study on Indian subjects, we found that obesity, and not obstructive sleep apnea, is associated with elevated serum levels of hs-CRP. No independent correlation was found between severity of OSA and hs-CRP in the present study.     

Residual subjective daytime sleepiness under CPAP treatment in initially somnolent apnea patients: a pilot study using data mining methods

BACKGROUND AND PURPOSE: Despite correct treatment with positive airway pressure (PAP), obstructive sleep apnea (OSA) patients sometimes remain subjectively somnolent. The reliability of the Epworth Sleepiness Scale (ESS) has been established for healthy subjects and patients under stable conditions; the ESS may eventually vary among treated OSA patients, biasing the results of a cross-sectional analysis of persisting sleepiness. The objective of this study was to depict the evolution of subjective vigilance under treatment using an index of ESS variability (DeltaESS). METHODS: In 80 OSA patients (apnea-hypopnea index [AHI]=54+/-26/h), initially somnolent (ESS=15+/-3) and treated with auto-titrating PAP (APAP) (oxyhaemoglobin desaturation index 3% [ODIapap]=3.4+/-2.2/h; daily APAP use=5.3+/-1.5 h) during 434+/-73 days, ESS scores were regularly collected four times every 109+/-36 days. DESS was calculated and data mining methods (Segmentation and Decision Tree) were used to determine homogeneous groups according to the evolution of ESS scores. RESULTS: When assessed cross-sectionally, 14-25% of the subjects were recognized as somnolent, depending on the moment when ESS was administered. Using data mining methods, three groups were clearly identifiable: two without residual somnolence - group 1, n=38 (47%), with high DeltaESS=-2.9+/-0.8, baseline ESS=16.3+/-3.3, AHI=58.5+/-26.1/h, mean ESSapap=5.1+/-2.4 and group 2, n=31 (39%), with low DeltaESS=-1.1+/-0.5, baseline ESS=13.2+/-1.4, AHI=53+/-27.3/h, mean ESSapap=8.8+/-1.9; and one with persisting sleepiness; group 3, n=11 (14%), with low DeltaESS=-0.3+/-0.8, baseline ESS=16.3+/-3, AHI=38.7+/-10.8/h, mean ESSapap=14.1+/-1.9. Compliance to PAP was high and comparable in the three groups. Age and body mass index (BMI) did not differ. CONCLUSION: Data mining methods helped to identify 14% of subjects with persisting sleepiness. Validation needs to be done on a larger population in order to determine predictive rules.     

Antioxidant capacity in obstructive sleep apnea patients

OBJECTIVES: Obstructive sleep apnea syndrome (OSA) results in oxygen desaturation and arousal from sleep. Free oxygen radicals are highly reactive molecules, which can be produced by the OSA phenomenon known as hypoxia/reoxygenation. Hypoxic conditions, such as OSA, may also result in transient depletion of cellular reductants, which constitute a main line of antioxidant defense. Both apneas and hypopneas usually end in arousal, where reoxygenation causes the production of reactive oxygen species (free radicals). Living organisms have developed complex antioxidant systems to counteract reactive oxygen species and to reduce their damage. We evaluated the antioxidant capacity in serum from OSA patients and healthy people in order to confirm the hypothesis that there is a relationship between oxidative stress and OSA. MATERIALS AND METHODS: A physician interviewed 25 participants, determining age, smoking habits and symptoms such as excessive daytime sleepiness and snoring. Physical examination and polysomnography were performed during patients' hospitalization. Antioxidant capacity was measured in blood samples by Trolox Equivalent Antioxidant Capacity assay. RESULTS: Seventeen out of 25 subjects had an apnea/hypopnea index (AHI) greater than 10 (OSA group). The measurement of antioxidant capacity did not differ between the OSA patients and our healthy sample (of 25 subjects, seven with an AHI less than 10). Furthermore, patients with severe OSA (AHI >20, N=14) had linearly negative correlation between antioxidant capacity in their blood samples and AHI (R=-0.551, P=0.041). CONCLUSIONS: Reduced antioxidant capacity in serum is an index of excessive oxidative stress. Patients with severe OSA have reduced values of antioxidant capacity.     

Effect of atrial overdrive pacing on obstructive sleep apnea in patients with systolic heart failure

BACKGROUND AND PURPOSE: Obstructive sleep apnea (OSA) is associated with cardiovascular disease. Preliminary studies suggested breathing improvement in patients with apnea and heart disease when atrial overdrive pacing was applied during sleep. However, more recent studies do not show significant beneficial effect for atrial overdrive pacing in OSA. To further investigate this relationship, we conducted a randomized clinical trial evaluating the effect of atrial overdrive pacing on sleep-related breathing events in subjects with OSA and systolic heart failure. PATIENTS AND METHODS: We screened 33 subjects with symptoms consistent with OSA. On a screening overnight polysomnography (PSG), 15 subjects with mean age of 74 years (standard deviation (SD) 6.6) and ejection fraction of 38% (SD 14.4%) had OSA defined as having an apnea/hypopnea index (AHI) of > or =15 per hour of sleep. These subjects underwent additional PSGs including a night with atrial overdrive pacing (O), a night with pacemaker rate set at 40-50 beats per minutes (N), and a positive airway pressure titration night. The O and N nights were consecutive and the order was randomized. For O, the pacemaker rate was set at 15 beats higher than the average nightly heart rate (determined from the screening night). RESULTS: At baseline, mean AHI was 34.8 (15.5) and mean SaO(2) nadir was 85% (3.2%). Average heart rate was significantly higher on O nights compared to N nights (p<0.005). The apnea index (AI) was statistically lower on O nights compared to N nights (18+/-16.6 vs. 24+/-18.9, p<0.05). However, AHI and minimum and average O(2) saturations did not differ significantly between O and N nights. Interestingly, AHI improved statistically significantly on O nights in younger subjects. CONCLUSIONS: While statistically reliable, the small pacing-related reduction in sleep-disordered breathing (SDB) events is of unknown clinical significance. By contrast, continuous positive airway pressure (CPAP) dramatically improved AHI, AI, respiratory arousal index, and O(2) saturation. Thus our data suggest that overdrive pacing exerts a mild effect on respiratory events in some heart failure patients with OSA; however, atrial overdrive pacing was not therapeutically effective for improving airway patency and sleep-related respiratory function.     

Nocturnal cardiac arrhythmia in patients with obstructive sleep apnea

BACKGROUND AND PURPOSE: Nocturnal cardiac arrhythmias occur in patients with obstructive sleep apnea (OSA), reportedly as a consequence of the autonomic effects of recurrent apnea with subsequent oxygen desaturation. We have investigated whether different patterns of OSA are associated with specific arrhythmia during sleep. PATIENTS AND METHODS: Electrocardiographic (ECG) data recorded during polysomnography (PSG) were analysed in 257 consecutive OSA patients to determine the prevalence of cardiac rhythm disturbances, and to relate these to breathing pattern (normal, apnea/hypopnea, recovering ventilation, snoring) and oxygen saturation. RESULTS: Arrhythmias were found in 18.5% of patients. Patients with nocturnal bradyarrhythmia (BA) had higher values of ventilatory disturbance (apnea-hypopnea index [AHI] 58.8+/-36.8 vs 37.2+/-30.3, p=0.02), mean desaturation amplitude (8.9+/-4 vs 5.9+/-3.4%, p=0.03), and a lower SaO(2) nadir (69% vs 77%, p=0.003) than those without arrhythmia. The prevalence of BA in patients with AHI>or=30/h was significantly higher than that observed in those with AHI<30/h (7.8% vs 1.5%, respectively; chi(2)=5.61, p=0.01). In contrast, patients with tachyarrhythmia (TA) had no significant differences in AHI, mean desaturation amplitude or SaO(2) nadir than those without arrhythmia. No associations were found between arrhythmia and the presence of comorbidity or concomitant medical therapy, except for an association between tachyarrhythmia and chronic obstructive pulmonary disease (COPD) (odds ratio 2.53; 95% confidence intervals 1.1-5.8, p=0.03). CONCLUSIONS: We conclude that while BA during sleep is associated with OSA severity, concomitant COPD or beta(2)-treatment may play a role in the development of TA during sleep.     

Assessment of a wrist-worn device in the detection of obstructive sleep apnea

OBJECTIVE: To assess the accuracy of a wrist-worn device (Watch_PAT100) to diagnose obstructive sleep apnea (OSA). METHODS: Thirty adult subjects with and without suspected OSA simultaneously had a standard in-laboratory polysomnogram (PSG) and wore the Watch_PAT100 during a full-night recording. PSG sleep and respiratory events were scored according to standard criteria. Watch_PAT data were analyzed with an automated computerized algorithm which calculated the frequency of respiratory events per hour of actigraphy measured sleep using a combination of peripheral arterial tonometry (PAT) signal attenuation, desaturation on pulse oximetry, and changes in heart rate. This yielded a PAT apnea hypopnea index (AHI). RESULTS: Mean age was 47.0+/-14.8 years, mean body mass index 31.0+/-7.6 kg/m(2), mean PSG AHI 23+/-23.9 events per hour, and mean PAT AHI 23+/-15.9 events per hour. There was a significant correlation between PAT AHI and AHI by PSG (r=0.87, P<0.001). To assess sensitivity and specificity of Watch_PAT, we constructed receiver operator characteristic curves using a variety of AHI threshold values (10, 15, 20, and 30 events per hour). Optimal combinations of sensitivity and specificity for the various thresholds were 82.6/71.4, 93.3/73.3, 90.9/84.2, and 83.3/91.7, respectively. CONCLUSIONS: The Watch_PAT is a device that can detect OSA with reasonable accuracy. Thus, the Watch_PAT may be a useful method to diagnose OSA.     

Retinal nerve fiber layer analysis in idiopathic intracranial hypertension

BACKGROUND: The chronic nature of idiopathic intracranial hypertension (IIH) represents a risk factor for progressive optic nerve damage and structural abnormalities of the retina. AIM: We measured the retinal nerve fiber layer (RNFL) thickness in patients followed with the diagnosis of IIH who had no or mild visual impairment to search for possible structural alterations in the retina for diagnostic and prognostic purposes. SETTINGS AND DESIGN: Case-control prospective study. MATERIALS AND METHODS: The study group consisted of 12 women followed and treated with the diagnosis of IIH in our clinic. The selection criteria were the, normal optic nerve, normal visual fields or mild visual field defects (Grade 1-3) by Humphrey perimeter. Randomly assigned, age-matched 12 healthy women were taken as the control group. Retinal nerve fiber layer thickness was evaluated with scanning laser polarimetry and both eyes were studied for each case in both groups. STATISTICAL ANALYSIS USED: Mann-Whitney U test. RESULTS: The mean ages of the patient and the control groups were 34.58+/-4.2 and 34.42+/-5.7 years respectively (P=0.87). The mean duration of disease was 5.5+/-3 years. Some parameters related to RNFL thickness were found to differ significantly between patients with IIH and control subjects. Namely superior ratio (P=0.007), inferior ratio (P=0.039), superior-nasal ratio (P=0.025), maximum modulation (P=0.01) and symmetry (P=0.006) were lower in the patient group than controls. CONCLUSION: Scanning laser polarimetry might be a good adjunct for determining possible structural affects of IIH on the retina in patients with no or mild visual impairment.     

Obstructive sleep apnea is independently associated with worse diastolic function in coronary artery disease

BackgroundDiastolic dysfunction is common in patients with coronary artery disease (CAD). We hypothesize that patients with CAD and preserved left ventricular ejection fraction (LVEF) and obstructive sleep apnea (OSA) will have worse diastolic function than similar patients without OSA.Material and methodsWe analyzed sleep-study recordings and echocardiographic measurements obtained at baseline in a randomized controlled trial (RICCADSA) of revascularized patients with CAD who had LVEF of at least 50%. OSA was defined as an apnea-hypopnea-index (AHI) ≥15 events/h, and, no OSA, as an AHI <5. Worse diastolic function was defined as assumed elevated left ventricular filling pressure based on peak flow velocity in early diastole/Tissue Doppler of early diastolic ventricular filling (E/é) of >13 (or >9 in patients with an enlarged left atrial diameter [≥39 mm for women and ≥40 mm for men]).ResultsData from 431 patients were evaluated (mean age: 63.7 ± 8.8 y; men: 82.5%; OSA: n = 331). Worse diastolic function was more common among the patients with OSA than those without (54.4% vs 41.0%, p = 0.019). In multivariate analysis, OSA was associated with worse diastolic function (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.13; 3.18) adjusted for female sex (OR 2.28, 95% CI 1.28; 4.07), hypertension (OR 1.84, 95% CI 1.20; 2.82), and diabetes mellitus (OR 2.45, 95% CI 1.42; 4.23). Age ≥60 years, obesity, and current smoking were nonsignificant.ConclusionsIn this cohort with CAD and preserved LVEF, OSA was associated with worse diastolic function independent of the traditionally recognized risk indicators.     

Hippocampal damage in the human brain after cardiac arrest

BACKGROUND AND PURPOSE: Very few reports are available on changes in the human hippocampus after cardiac arrest. The objective of this study was to investigate if specific hippocampal volume losses can be demonstrated in the human brain following reperfusion after cardiac arrest. METHODS: We assessed the volumes of the hippocampal formation (HF) and temporal lobe excluding HF (TL) as the contrast using magnetic resonance (MR)-imaging-based volumetry in 11 vegetative patients after cardiac arrest and in 22 healthy controls of similar age, sex and body size distribution. The measured volumes were normalized for differences in the head size among subjects by dividing by the total intracranial volume (TICV). The MR images of the 11 patients were obtained between days 8 and 21 after cardiac arrest. RESULTS: The observed volumes of HFs and TLs of both patient and control groups were as follows: right HF volume (HFV): 2.67 +/- 0.19 (mean +/- SD, cm(3)) in patients versus 3.89 +/- 0.44 in controls; left HFV: 2.72 +/- 0.17 versus 3.74 +/- 0.35; right TL volume (TLV): 73.37 +/- 6.54 versus 80.08 +/- 7.62, and left TLV: 72. 45 +/- 6.77 versus 78.59 +/- 6.68. The normalized indices (HFV/TICV and TLV/TICV) were as follows: right HF: 0.0021 +/- 0.0002 (mean +/- SD) in patients versus 0.0031 +/- 0.0001 in controls, p < 0.0001, left HF: 0.0022 +/- 0.0002 versus 0.0030 +/- 0.0001, p < 0.0001, right TL: 0.058 +/- 0.002 versus 0.064 +/- 0.004, p = 0.0007, and left TL: 0.058 +/- 0.002 versus 0.062 +/- 0.004, p = 0.0014. The HFV-TLV ratios (HFV/TICV divided by TLV/TICV) of both groups were: right HFV-TLV ratio: 0.037 +/- 0.004 in patients versus 0.049 +/- 0. 004 in controls, p < 0.0001, left HFV-TLV ratio: 0.038 +/- 0.004 versus 0.048 +/- 0.004, p < 0.0001. CONCLUSIONS: The patient group had HFs that were 26.8-30.6% smaller than those of the control group, but in the patient group, the TLs slightly decreased in size by only 7.8-8.2% of the volume of those in the control group within 21 days after cardiac arrest. The volume reductions in the bilateral HFs of patients after cardiac arrest were significantly larger than those in the bilateral TLs. We speculate that this specific rapid hippocampal shrinkage reflects its greater vulnerability to global brain ischemia.     

Effects of CPAP on left ventricular structure and myocardial performance index in male patients with obstructive sleep apnoea

BACKGROUND: Obstructive sleep apnoea (OSA) has the potential to cause heart failure. We aimed to determine the effects of nasal continuous positive airway pressure (CPAP) therapy on left ventricular structure and myocardial performance index (MPI) in severe OSA patients. METHODS: Sixty-seven subjects without any cardiac or pulmonary disease had overnight polysomnography and echocardiography. In 33 males with severe OSA, thickness of interventricular septum (IVS) and posterior wall (LVPW) were measured by M-mode. Left ventricular MPI was calculated as (isovolumic contraction time+isovolumic relaxation time)/aortic ejection time by Doppler. RESULTS: Eight males were non-compliant with CPAP. Mean age was 47.9+/-8.2 years, and 20 of 25 patients (80.0%) were hypertensive. Patients had high body mass index (BMI: 31.0+/-3.9 kg/m(2)), but there was no change in BMI from baseline after 6 months. Thickness of IVS (11.0+/-1.1mm) and LVPW (11.0+/-1.0mm) at baseline were significantly decreased after 6 months of CPAP therapy (10.5+/-0.9 mm, P<0.001 and 10.4+/-0.7 mm, P<0.0001, respectively). Left ventricular MPI (60.1+/-13.8%) significantly decreased (53.0+/-10.7%, P<0.0001) after CPAP usage. CONCLUSIONS: In male patients with severe OSA, CPAP therapy significantly decreases left ventricular wall thickness and improves global function even with 6 months of usage.     

Use of the Epworth Sleepiness Scale in Chinese patients with obstructive sleep apnea and normal hospital employees

OBJECTIVE: To determine the use of the Epworth Sleepiness Scale (ESS) in Chinese patients with obstructive sleep apnea syndrome (OSA) and normal hospital employees. METHODS: Our sample consisted of 61 healthy controls and 100 patients with OSA. The test-retest reliability, internal consistency, and concurrent validity of the Chinese version of the ESS were analyzed. We also compared the ESS scores between controls and patients, studied the association between the ESS score and the apnea-hypopnea index (AHI) and minimum oxygen saturation (mO(2)), and examined to what extent the ESS score was predictive of mean sleep latency of the Multiple Sleep Latency Test (MSLT). RESULTS: The Chinese version of the ESS was found to have satisfactory reliability and validity. The mean+/-S.D. of ESS scores in normals was 7.5+/-3.0; in patients, it was 13.2+/-4.7. The ESS score had a negative association with mean sleep latency of the MSLT (rho=-0.42, P=0.0001) but no correlation with the AHI and mO(2). ESS scores of 14 and above significantly predicted a low mean sleep latency of the MSLT. CONCLUSION: The ESS should be included as one of the methods for assessing sleepiness in clinic samples of patients with OSA. Our data showed that the ESS was useful to separate patients with and without pathological degree of objective daytime sleepiness as determined by the MSLT.     

Influence of nocturnal hypoxemia on the function of the visual tract in the course of the obstructive sleep apnea syndrome

BACKGROUND AND PURPOSE: In patients with obstructive sleep apnea (OSA) syndrome the episodes of upper airway obstruction lead to hypoxemia during sleep. The aim of the study was to establish the influence of sleep hypoxemia on the function of the visual tract in OSA patients. MATERIAL AND METHODS: The latency and amplitude of wave P100 of visual evoked potentials have been studied in 35 patients with OSA syndrome (mean apnea index 48+/-19). The diagnosis of OSA was established on the basis of continuous recordings of the respiratory function during sleep with additional full polysomnography in 17 patients. RESULTS: Mean absolute latency of P100 was longer in OSA patients than in healthy controls (117.0+/-8.8 ms vs. 104.3+/-4.6 ms, p<0.001). The differences in the amplitude of P100 were not significant (5.9+/-2.6 mV in OSA patients and 7.62+/-3.04 mV in healthy persons). In 60% of patients the latency of P100 exceeded 118 ms; in this group of patients the mean SaO2 during sleep apneas was lower than in patients with normal P100 latency (46+/-15% vs. 69+/-10%, p<0.05). Full polysomnographic studies revealed that in patients with prolonged latencies as compared with patients with normal P100 latencies there were lower: minimal SaO2 during NREM sleep (63+/-12% vs. 78+/-8%, p<0.05), as well as mean and minimal SaO2 during REM sleep (53+/-15% vs. 80+/-5% and 46+/-15% vs. 69+/-10%, p<0.05), without differences in apnea index or apnea duration. CONCLUSIONS: In patients with OSA syndrome the electrophysiological abnormalities suggesting damage of the optical tract may develop probably as a consequence of profound sleep hypoxemia.