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At least 433 records · Page 24Linked to original sources

PubMed2006

The effect of sibutramine-assisted weight loss in men with obstructive sleep apnoea.

OBJECTIVE: Obstructive sleep apnoea (OSA) occurs frequently in obese patients and may be reversible with weight loss. Obstructive sleep apnoea and obesity are both independent risk factors for hypertension and increased sympathetic activity. Sibutramine has been increasingly used in the management of obesity, but is relatively contraindicated in patients with hypertension. No studies have investigated the effect of sibutramine on OSA, blood pressure and heart rate. We aimed to assess the changes in OSA and cardiovascular parameters in obese men with OSA enrolled in a sibutramine-assisted weight loss programme (SIB-WL). DESIGN: Open uncontrolled cohort study of obese male subjects with OSA in an SIB-WL. SUBJECTS: Eighty-seven obese (body mass index =34.2+/-2.8 kg/m(2)) middle-aged (46.3+/-9.3 years) male subjects with symptomatic OSA (Epworth score 13.4+/-3.6; respiratory disturbance index (RDI) 46.0+/-23.1 events/h) completed the study. RESULTS: At 6 months, there was significant weight loss (8.3+/-4.7 kg, P<0.0001), as well as a reduction in waist and neck circumference and sagittal height (all P<0.0001). These changes were accompanied by a reduction in OSA severity (RDI fell by 16.3+/-19.4 events/h and Epworth score by 4.5+/-4.6), both P<0.0001). There was no significant change to systolic (P=0.07) or diastolic blood pressure (P=0.87); however, there was a mild rise in resting heart rate (P<0.0001). CONCLUSION: Moderate (approximately 10%) weight loss with SIB-WL results in improvement in OSA severity without increase in blood pressure in closely monitored OSA subjects.

Adult↗

PubMed1994

Upright and supine cephalometric evaluation of obstructive sleep apnea syndrome and snoring subjects.

Specific craniofacial characteristics are reported to occur with obstructive sleep apnea syndrome (OSAS). The purpose of this study was to determine whether craniofacial morphology differs between subjects with OSAS and heavy snorers, and to investigate how change in posture from upright to lying down affects the upper airway passage. Lateral head radiographs of ten persons diagnosed with OSAS(AHI > 50) and ten snorers matched for age, height and weight without any history of daytime sleepiness, doctor-diagnosed OSAS, and no evidence of significant desaturation on overnight oximetry were obtained in both upright seated and awake supine positions. The posterior superior pharyngeal space in both the OSAS and snorers was reduced when changing from upright to supine posture (p < or = 0.05). Significant differences in cranial base alignment, ramus width relative to the middle-cranial fossa, position of the maxilla relative to the cranial base in the seated position (P < or = 0.01) were noted between subjects with OSAS and subjects with snoring and less severe apnea. In addition, differences in the posterior superior pharyngeal space, tongue length, tongue to intermaxillary area ratio and hyoid position (p < or = 0.05) were demonstrated both in the upright and in the supine positions (p < or = 0.05) in the OSAS compared to the snoring group. These results suggest that anatomic factors may predispose some snorers to develop OSAS. Measurements made from awake supine position lateral head radiographs revealed no additional differences between OSAS and snoring subjects when compared to measurements made on radiographs taken in the upright position.

Cephalometry↗

PubMed2001

Sleep-disordered breathing and glucose metabolism in hypertensive men: a population-based study.

OBJECTIVES: Diabetes mellitus and obstructive sleep apnoea (OSA) are two prevalent medical problems. Both are strongly associated with obesity and hypertension. The aim of this study was to investigate whether the association between OSA and diabetes is entirely dependent on obesity in hypertensive men. DESIGN: A population-based study. SETTING: The municipality of Uppsala, Sweden. Subjects and methods. In 1994, 2668 men aged 40-79 years answered a questionnaire regarding snoring, sleep disturbances and somatic diseases. An age-stratified sample of 116 hypertensive men was selected for a whole-night sleep study. Twenty-five of them had diabetes, defined as reporting regular medical controls for diabetes or having a fasting blood glucose > or =6.1 mmol L(-1). RESULTS: The prevalence of severe OSA, defined as apnoea-hypopnoea index (AHI) > or =20 h(-1) was significantly higher in diabetic patients than in normoglycaemic subjects (36 vs. 14.5%, P < 0.05). The sample was divided into four groups based on the presence or absence of severe OSA and the presence or absence of central obesity, defined as waist-to-hip ratio (WHR) > or =1.0. In a logistic regression model with the non-OSA, WHR <1.0 as the reference group, the adjusted odds ratio (95% confidence interval) for diabetes was 11.8 (2.0-69.8) in the OSA, WHR > or =1.0 group, whilst it was 3.6 (0.9-14.8) in the non-OSA, WHR > or =1.0 group and 5.7 (0.3-112) in the OSA, WHR <1.0 group. In a linear regression model, after adjustment for WHR, there was a significant relationship between variables of sleep-disordered breathing and fasting insulin, glucose and haemoglobin A1c. CONCLUSIONS: We conclude that, in hypertensive men, although obesity is the main risk factor for diabetes, coexistent severe OSA may add to this risk. Sleep breathing disorders, independent of central obesity, may influence plasma insulin and glycaemia.

Adult↗

PubMed2000

Does caffeine confound relationships among adrenergic tone, blood pressure and sleep apnoea?

The purpose of this study was to determine whether caffeine consumption confounds the relationship among adrenergic tone, as measured by urinary norepinephrine (NE), blood pressure (BP) and obstructive sleep apnoea (OSA). Data were analysed using correlation and regression analysis, analysis of covariance and t-tests. Subjects included normotensives and hypertensives with and without OSA: 38 men, 23 women, aged 30-60 y; 100-150% of ideal body weight; without other major illness. Patients were studied using polysomnography, caffeine consumption was assessed, 24-h urinary NE levels were examined and ambulatory BP was recorded. Patients with OSA (N=27) reported significantly greater caffeine consumption than those without OSA (N=34) (295 vs. 103 mg, P=0.010), but caffeine was not significantly correlated with their ambulatory BP. In contrast, NE excretion correlated with caffeine consumption (r=0.24, P=0.041), apnoea severity (r=0.65, P < 0.001) and BP (r=0.34, P < 0.005). Significant OSA-NE and BP-NE relationships remained even after controlling for caffeine consumption. Patients with OSA consumed nearly three times the amount of caffeine as patients without OSA. While caffeine partially explains the increased adrenergic tone in patients with OSA and the relationship between BP and NE, it does not appear to contribute significantly to the relationship between OSA and elevated BP.

Adult↗

PubMed2001

Screening of obstructive sleep apnoea: heart rate spectral analysis of nocturnal pulse oximetric recording.

Using heart rate spectral analysis of nocturnal pulse oximetry, we prospectively evaluated the utility of this methodology in patients clinically suspected of having obstructive sleep apnoea (OSA). A hundred and ninety-seven outpatients referred with symptoms compatible with the diagnosis of OSA were studied. All participants had nocturnal pulse oximetry performed simultaneously with conventional polysomnography. Power density of heart rate obtained by nocturnal pulse oximetry was analysed using fast Fourier transformation of a Hamming-windowed signal. Recording test results were classified as abnormal (suspicion of OSA) in the presence of a peak in the periodogram between period boundaries 30-70 sec. A normal test result was defined as the absence of the 30-70 sec peak in the periodogram. The total area of the periodogram (S(TOT)), the area enclosed in the periodogram between the period boundaries 30-70 sec (S(30-70)), the area enclosed in the period boundaries 30-70 sec with respect to the total area of the periodogram (S) and the peak amplitude 30-70 sec (PA) were measured. The presence of a peak in the periodogram has a sensitivity of 81.3%, a specificity of 91.5% a positive predictive value of 89.1% and a negative predictive value of 85.1% for OSA diagnosis. The OSA patients were found to have higher values of S(TOT), S(30-70), S and PA than the non OSA patients. Receiver operating characteristics (ROC) curve was constructed at different thresholds of S(TOT), S(30-70) S and PA. For a PA threshold of 10(%)2, heart rate spectra analysis sensitivity for OSA was 58% and specificity was 92%. Furthermore, the positive and negative predictive values for diagnosis of OSA were 87 and 72% respectively. Apnoea hypopnea index (AHI) correlated significantly with S(TOT) (r=0.44; P<0.001), S(30-70) (r=0.59: P<0.001), S (r=0.58; P<0.001) and PA (r=0.58; P<0.001). According to our results, heart rate spectral analys s obtained by nocturnal pulse oximetry and identification of peak in the periodogram between period boundaries 30-70 sec could be useful as a diagnostic technique for OSA patients.

Adult↗

PubMed2004

[Renal function in hypertensive patients with obstructive sleep apnea].

BACKGROUND: Patients with hypertension often suffer from obstructive sleep apnea (OSA). In addition to hypertension several other risk factors (hypoxemia, hyperlipidemia, and increased sympathic nerve activity) may contribute to progressive renal dysfunction in OSA patients. The aim of this study was to compare renal function in OSA-patients with and without hypertension. METHODS: 81 consecutive patients (50 males, 31 females) were screened for sleep apnea. Parameters of renal function (serum creatinine, creatinine clearance, microalbuminuria), and of lipid and glucose metabolism were correlated to polysomnographic results. RESULTS: OSA (apnea/hypopnea index [AHI] > or = 5) was found in 57 of 81 patients. Mean AHI was 26.7 +/- 26.1. Hypertension (blood pressure > or = 140/90 mmHg or use of antihypertensive drugs) occurred in 63 of 81 patients. Serum creatinine in OSA patients was significantly higher than in patients without OSA (1.11 +/- 0.15 vs. 0.91 +/- 0.12 mg/dl, p < 0.001). Serum creatinine correlated significantly with AHI. Creatinine clearance was associated with age (r = -0.314; p = 0.014) and presence of OSA (r = 0.265; p = 0.093). No correlation was shown between hypertension and serum creatinine or creatinine clearance. Microalbuminuria was not associated with OSA. CONCLUSION: Our results suggest an independent association between OSA and impaired renal function. Further prospective studies will have to be done to elucidate the pathophysiological mechanisms.

Adult↗

PubMed2025

The importance of dopamine levels and single-nucleotide polymorphism within COMT, DRD1 and DRD2 genes in obstructive sleep apnoea.

BACKGROUND: Obstructive sleep apnoea (OSA) is a prevalent sleep disorder that contributes to serious cardiovascular comorbidities. While the mechanical aspects of OSA are well-studied, its neurobiological underpinnings remain underexplored. In this study, we investigated the role of dopamine and its genetic modulators in OSA pathophysiology. PATIENTS AND METHODS: Serum dopamine levels were assessed in a cohort of 153 participants (96 OSA patients and 57 controls), and single-nucleotide polymorphisms (SNPs) in dopamine-related genes, including COMT, DRD1 and DRD2, were analysed in a cohort of 286 participants (141 OSA patients and 145 controls). RESULTS: Elevated serum dopamine levels were observed in OSA patients (p = 0.01), with dopamine levels correlating independently with OSA and male gender. Genotypic analysis identified the DRD2 rs1800497 T allele as a potential independent predictor of OSA severity (p = 0.011), hypopnea (p = 0.005) and arousals (p = 0.024). CONCLUSIONS: This study advances the understanding of OSA by identifying elevated dopamine levels and genetic variations in DRD2 rs1800497 as potential modulators of its occurrence and severity. These findings pave the way for personalized diagnostic and therapeutic approaches. By integrating neurobiology, genetics, and clinical practice, this research contributes to the evolving framework for precision medicine in sleep disorders.

Humans↗

PubMed2006

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.

Adult↗

PubMed2005

Oxidative stress in obstructive sleep apnoea.

AIMS: Any sustained elevation of oxidative stress in patients with obstructive sleep apnoea (OSA) might help explain their increased risk for cardiovascular diseases. We tested the hypothesis that measures of oxidative stress are increased in otherwise healthy subjects with OSA when compared to closely matched OSA-free control subjects. METHODS AND RESULTS: Plasma indices of oxidative stress and lipid peroxidation [thiobarbituric acid-reactive substances (TBARS), oxidized LDL (oxLDL), isoprostanes] were measured in 41 moderate-severe OSA males without other diseases and in 35 matched controls first before sleep, then after 4 h of untreated OSA, and again in the morning after 4 h of effective treatment with continuous positive airway pressure (CPAP). Plasma levels of oxLDL, TBARS, and isoprostanes in OSA patients (n=34, 26, 17, respectively) were comparable to the controls (n=28, 27, 15 for the three markers, respectively). Neither untreated OSA nor CPAP treatment nor normal sleep affected levels of any of the three measures of oxidative stress. There was no association between the severity of sleep apnoea and any measure of oxidative stress. CONCLUSION: Otherwise healthy OSA patients, without any other co-morbidities, do not manifest evidence for higher oxidative stress and lipid peroxidation. Thus, oxidative stress and lipid peroxidation do not appear to be key mediators of increased cardiovascular disease in OSA patients.

Biomarkers↗

PubMed2003

The neuropsychological effects of obstructive sleep apnea: a meta-analysis of norm-referenced and case-controlled data.

STUDY OBJECTIVES: The research literature on the neuropsychological effects of obstructive sleep apnea (OSA) has yielded seemingly contradictory findings, and narrative reviews of this literature are prone to interpretive errors. We used sophisticated meta-analytic models to minimize such errors, with the goal of clarifying the effect of OSA on neuropsychological functioning. DESIGN: Meta-analytic review of research through 2001. PARTICIPANTS: We reviewed studies of neuropsychological functioning among adults with untreated OSA. Twenty-five studies met review criteria, representing 1092 patients with OSA and 899 healthy controls. MEASUREMENTS AND RESULTS: Two sets of effect sizes were generated. One compared OSA group means against those of healthy controls in case-controlled studies. The other compared all OSA group means against published normative data. Within each data set, 10 neuropsychological outcome domains were coded. In both data sets, untreated OSA was found to have a negligible impact on intellectual and verbal functioning but a substantial impact upon vigilance and executive functioning. Data were mixed with regard to visual and motor functioning; posthoc inspection of the data suggested that tests of fine-motor coordination or drawing were more sensitive to OSA than were tests of fine-motor speed or visual perception. Data were also mixed with regard to memory functioning, probably related to methodologic differences across studies. CONCLUSIONS: Etiologic models should emphasize mechanisms known to affect vigilance, executive functioning, and motor coordination but not intelligence, verbal functioning, or visual perception. Clinicians should be alert to OSA symptoms in patients with declines in vigilance, executive functioning, or coordination.

Arousal↗

PubMed2003

Change in periodic limb movement index during treatment of obstructive sleep apnea with continuous positive airway pressure.

STUDY OBJECTIVES: The following hypotheses were investigated: 1) severe obstructive sleep apnea (OSA) can mask concurrent periodic limb movement (PLM) disorder (PLMD), which becomes evident or worsens after treatment with continuous positive airway pressure (CPAP); 2) in patients with mild OSA, PLMs are not masked but may be triggered by subclinical hypopneas or respiratory effort-related arousals and improve after CPAP. DESIGN: Retrospective analysis was performed on 2 polysomnographic studies per patient--1 baseline, the second with CPAP titration. The apnea-hypopnea index (AHI) and PLM index (PLMI) under the 2 conditions were statistically analyzed. SETTING: University hospital sleep disorders center. PATIENTS: Patients were selected if they had a baseline AHI of 5 or greater and CPAP titration resulted in reduced AHI. Also, each needed to have either a PLMI of 5 or greater on baseline PSG or during CPAP titration. Patients who started or discontinued a medication that could affect PLMs after the baseline PSG were excluded. INTERVENTIONS: As clinically indicated, CPAP for OSA. MEASUREMENTS AND RESULTS: Eighty-six patients qualified and were divided into 3 groups based on OSA severity. Significant correlations (P < 0.05) were found between AHI and PLMI on the baseline PSG (-0.50), between AHI on baseline PSG and PLMI on CPAP titration (0.49), and between PLMI on baseline PSG and on CPAP titration (-0.21). The increase in PLMI during CPAP titration in patients with severe OSA was statistically significant (P < 0.001). The PLMI decreased with CPAP in 20 of 86 patients, mostly in the mild OSA subgroup. Regression of post-CPAP reduction of AHI and change in PLMI yielded a significant logarithmic relationship (R2 = 0.3042). CONCLUSIONS: Severity of OSA may determine the effect of CPAP on PLMs. The PLMs may increase in moderate to severe OSA due mainly to "unmasking" of underlying PLMD. The PLMs may decrease in mild OSA post-CPAP due to resolution of PLMs associated with respiratory effort-related arousals. This suggests that PLMs may have more than 1 etiology and may be categorized as spontaneous (as in PLMD) and induced (when secondary to respiratory effort-related arousals).

Adult↗

PubMed2003

Does sleep deprivation worsen mild obstructive sleep apnea?

STUDY OBJECTIVES: Sleep deprivation is believed to worsen obstructive sleep apnea (OSA). We assessed the effect of acute sleep deprivation on polysomnography in a cohort of subjects with mild OSA and a cohort of subjects without OSA. DESIGN: Crossover study in which subjects initially had polysomnography after a normal night's sleep or after 36 hours of sleep deprivation, followed by a 2- to 4-week interval, after which subjects were restudied under the alternate testing condition. SETTING AND PARTICIPANTS: 13 subjects with mild OSA and 16 subjects without OSA were studied in a university teaching hospital sleep laboratory. INTERVENTIONS: 36 hours of supervised sleep deprivation. MEASUREMENTS: Subjects' age, body mass index, neck circumference and Epworth Sleepiness Scale scores were measured; actigraphy and sleep diaries were used to estimate prior sleep debt before each sleep study. RESULTS: Sleep deprivation was found to significantly increase total sleep time, sleep efficiency, and rapid eye movement and slow-wave sleep time. Subjects with OSA showed a lower minimum oxygen saturation after sleep deprivation. However, subjects did not show a significantly different respiratory disturbance index, arousal index, or length of the longest apnea after sleep deprivation. CONCLUSIONS: Acute sleep deprivation did not worsen most OSA parameters as measured by polysomnography. A lower minimum oxygen saturation in mild OSA subjects after sleep deprivation may be important in patients with significant cardiorespiratory disease. More research is needed to assess whether daytime performance and function (eg, driving, sleepiness) is more greatly impaired in OSA subjects who are sleep deprived, compared to normal subjects who are sleep deprived.

Acute Disease↗

PubMed1999

Clinical predictors of obstructive sleep apnea.

OBJECTIVE: To identify physical findings that can be standardized to predict the presence and the severity of obstructive sleep apnea (OSA). STUDY DESIGN: One hundred seventy-two patients who answered questionnaires with responses that suggested they might have OSA were included in this prospective study. METHODS: All patients underwent a physical examination and polysomnography. The physical examination included the measurement of four parameters used by anesthesiologists to identify patients likely to have difficult intubation to determine if these same parameters predict OSA. We recorded modified Mallampati grade (MMP), tonsil size, and body mass index (BMI) and measured thyroid-mental distance (TMD) and hyoid-mental distance (HMD) in the study population. RESULTS: When the physical findings were correlated singly with the respiratory disturbance index (RDI), we found that MMP (P < .001), tonsil size grading (P = .008), and BMI (P = .003) were reliable predictors of OSA. A greater correlation with OSA emerged when an "OSA score" was formulated by factoring the MMP, tonsil grade, and BMI grade (RDI = 7.816 x MMP + 3.988 x Tonsil Size + 4.675 x BMI - 7.544). A high score was not only predictive of OSA but also correlated well with OSA severity. Neither HMD nor TMD correlated with the severity of RDI. CONCLUSIONS: An OSA score may help identify those patients who should have a full sleep evaluation.

Adolescent↗

PubMed2007

Prevalence of normal tension glaucoma in obstructive sleep apnea syndrome patients.

PURPOSE: To explore the prevalence of normal tension glaucoma (NTG) among patients with obstructive sleep apnea syndrome (OSAS) and to examine OSAS as a risk factor of NTG. PATIENTS AND METHODS: Fifty-one consecutive white patients with OSAS were compared with 40 healthy subjects. All the study subjects underwent blood gas analysis, polysomnography, oxyhemoglobin saturation, and an ophthalmologic examination including visual field, visually evoked potential (VEP), and pattern electroretinography (PERG) and disc analysis with the Heidelberg Retina Tomograph II. RESULTS: Three of 51 OSAS patients (5.9%) had NTG. No patient in the control group had OSAS or NTG. The severity of OSAS correlated with intraocular pressure, the mean deviation of the visual field, the cup/disk ratio and the mean of the retinal nerve fiber layer thickness (P<0.01 to 0.001). Apnea hypopnea index and intraocular pressure were significantly greater in OSAS patients with abnormal VEP and PERG, compared to those with normal PERG and VEP. CONCLUSIONS: The present study suggests that the prevalence of NTG in our OSAS patients is higher than expected in a white population of the same age and that OSAS may be an important risk factor for NTG. Our data underline the importance of taking an accurate sleep history from patients with NTG and referring patients with sleep disturbance for polysomnography.

Blood Gas Analysis↗

PubMed2003

Selection incentives in a performance-based contracting system.

OBJECTIVE: To investigate whether a performance-based contracting (PBC) system provides incentives for nonprofit providers of substance abuse treatment to select less severe clients into treatment. DATA SOURCES: The Maine Addiction Treatment System (MATS) standardized admission and discharge data provided by the Maine Office of Substance Abuse (OSA) for fiscal years 1991-1995, provides demographic, substance abuse, and social functional information on clients of programs receiving public funding. STUDY DESIGN: We focused on OSA clients (i.e., those patients whose treatment cost was covered by the funding from OSA) and Medicaid clients in outpatient programs. Clients were identified as being "most severe" or not. We compared the likelihood for OSA clients to be "most severe" before PBC and after PBC using Medicaid clients as the control. Multivariate regression analysis was employed to predict the marginal effect of PBC on the probability of OSA clients being most severe after controlling for other factors. PRINCIPAL FINDINGS: The percentage of OSA outpatient clients classified as most severe users dropped by 7 percent (p < = 0.001) after the innovation of performance-based contracting compared to the increase of 2 percent for Medicaid clients. The regression results also showed that PBC had a significantly negative marginal effect on the probability of OSA clients being most severe. CONCLUSIONS: Performance-based contracting gave providers of substance abuse treatment financial incentives to treat less severe OSA clients in order to improve their performance outcomes. Fewer OSA clients with the greatest severity were treated in outpatient programs with the implementation of PBC. These results suggest that regulators, or payers, should evaluate programs comprehensively taking this type of selection behavior into consideration.

Adult↗

PubMed1993

Periodic limb movements and sleep apnoea.

This study investigated the relationship of Periodic Leg Movements (PLMs) to the severity of Obstructive Sleep Apnoea (OSA) in 52 patients. In addition the prevalence of PLMs in OSA was compared with two other patient populations: narcolepsy and idiopathic PLM disorder (n = 38). All patients were between 20 and 50 years in age and were compared with a control group of 88 asymptotic paid volunteers aged between 20 and 50. PLMs were scored when tibialis anterior EMG activity lasted 0.5-5.0 s with an amplitude of at least half that of pre-sleep voluntary ankle dorsiflexion and when they were part of 4 or more consecutive events separated by 20-90 s. The prevalence of PLMs in OSA was 27.6%, which was similar to the prevalence in our normal controls of 20.5%. However, in the OSA group the majority of the PLMs occurred in the mild OSA patients (40.7%). This was similar to the prevalence of PLMs in narcoleptics (50%). The prevalence of PLMs in moderate OSA, was 24.5%; similar to that of normal controls. In severe OSA, PLMs were also low (12.5%). There is an inverse relationship between PLMs and the severity of OSA. The greater number of arousals and awakenings associated with respiratory irregularities seen in the severe OSA group produced an equivocal manifestation of PLMs.

Journal Article↗

PubMed1995

Respiratory sinus arrhythmia during obstructive sleep apnoeas in humans.

Respiratory sinus arrhythmia (RSA) reflects parasympathetic modulation of heart rate (HR) during the respiratory cycle. Since the time-course of RSA during obstructive sleep apnoea (OSA) is not known, an analysis was made of ECG in samples of consecutive OSA recorded in 5 patients during NREM sleep while breathing room air (OSA-AIR, mean lowest SaO2 83.0 +/- 6.5%) or supplemental oxygen (OSA +/- O2, mean lowest SaO2 91.7 +/- 2.2%), respectively. For each breath, HR at the transition from expiration to inspiration (HRei), and HR at maximal inspiration (HRie) were calculated, and the inspiratory increase in HR estimated as the ratio: HRie/subsequent HRie. Similarly, the expiratory decrease in HR was estimated as: HRie/subsequent HRei. RSA was identified by an inspiratory increase in HR (HRei/HRie < 1), and an expiratory decrease in HR (HRie/HRei > 1). OSA-AIR and OSA + O2 did not differ for duration or oesophageal pressure nadir. During OSA-AIR, the inspiratory increase in HR became progressively more marked from the first occluded to the first open breath, whereas during OSA + O2 it remained stable throughout the apnoeic cycle. The expiratory decrease in HR remained constant during the apnoeic phase, but was blunted in the first open breaths irrespective of O2 administration. In summary, hypoxia appeared to affect inspiratory, but not expiratory HR. Instead, the expiratory slowing of HR transiently disappeared in the immediate post-apnoeic phase, suggesting a possible effect of arousal or pulmonary inflation. These data suggest that the parasympathetic system may contribute to cardiovascular regulation during OSA.

Journal Article↗

PubMed2003

Plasma cytokine levels in patients with obstructive sleep apnea syndrome: a preliminary study.

The levels of some pro- and anti-inflammatory cytokines [interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, IL-6, IL-10, and transforming growth factor (TGF)-beta], were measured by enzyme-linked immunosorbent assay (ELISA) method in the plasma of patients affected by obstructive sleep apnea syndrome (OSAS) at 22:00 hours before polysomnographic recording and immediately after the first obstructive apnea causing an SaO2 below 85%. Significantly higher levels of TNF-alpha were found in OSAS patients assessed before polysomnography compared with the control group (P < 0.01). A slight but significant increase in the plasma levels of IL-6 was also present (P < 0.05). Conversely, a significant decrease in the plasma levels of IL-10 was evident at baseline in OSAS patients (P < 0.04). No significant difference emerged between the mean values of IL-1alpha and TGF-beta between OSAS patients and controls. The present data support a prevailing activation of the Th1-type cytokine pattern in OSAS patients, which is not associated with the severity and duration of OSAS. This can have important consequences for the outcome of OSAS patients, especially with regard to the increased risk for developing atherosclerosis and cardiovascular and cerebrovascular diseases. Immediately after the first obstructive apnea causing an SaO2 <85%, a significant variation was observed in the plasma levels of TNF-alpha in OSAS patients compared with those measured before the beginning of polysomnographic recording (P < 0.001). The role played by this further increase in TNF-alpha levels after the obstructive apnea in OSAS patients remains to be established in the light of the pathogenic mechanisms of this sleep disorder.

Analysis of Variance↗