Cardiovascular consequences of obstructive sleep apnea

Major Adverse Cardiac and Cerebrovascular Events in Geriatric Patients with Obstructive Sleep Apnea: An Inpatient Sample Analysis

BACKGROUND

Obstructive sleep apnea (OSA) is associated with an increased risk of major cardiac and cerebrovascular events (MACCE). However, data on the burden and predictors of MACCE in geriatric patients with OSA (G-OSA) remain limited.

METHODS

Using the National Inpatient Sample from 2018, we identified G-OSA admissions (age ≥ 65 years) and divided them into non-MACCE vs. MACCE (all-cause mortality, stroke, acute myocardial infarction, and cardiac arrest). We compared the demographics and comorbidities in both cohorts and extracted the odds ratio (multivariate analysis) of MACCE and associated in-hospital mortality.

RESULTS

Out of 1,141,120 geriatric obstructive sleep apnea G-OSA admissions, 9.9% (113,295) had MACCE. Males, Asians, or the Pacific Islander/Native American race, and patients from the lowest income quartile revealed a higher MACCE rate. Significant clinical predictors of MACCE in elderly OSA patients on multivariable regression analysis in decreasing odds were pulmonary circulation disease (OR 1.47, 95% CI 1.31-1.66), coagulopathy (OR 1.43, 95% CI 1.35-1.50), peripheral vascular disease (OR 1.34, 95% CI 1.28-1.40), prior sudden cardiac arrest (OR 1.34, 95% CI 1.11-1.62), prior myocardial infarction (OR 1.27, 95% CI 1.22-1.33), fluid and electrolyte imbalances (OR 1.25, 95% CI 1.20-1.29), male sex (OR 1.22, 95% CI-1.18-1.26), hyperlipidemia (OR 1.20, 95% CI 1.16-1.24), low household income (OR 1.19, CI 1.13-1.26), renal failure (OR 1.15, 95% CI 1.12-1.19), diabetes (OR 1.14, 95% CI 1.10-1.17), metastatic cancer (OR 1.14, 95% CI 1.03-1.25), and prior stroke or TIA (OR 1.12, 95% CI 1.07-1.17) (All p value < 0.05).

CONCLUSIONS

This study emphasizes the significant association between obstructive sleep apnea (OSA) and major cardiac and cerebrovascular events (MACCE) in the geriatric population. Among the elderly OSA patients, a substantial 9.9% were found to have MACCE, with specific demographics like males, Asian or Pacific Islander/Native American individuals, and those from the lowest income quartile being particularly vulnerable. The study sheds light on several significant clinical predictors, with pulmonary circulation disease, coagulopathy, and peripheral vascular disease topping the list. The highlighted predictors provide valuable insights for clinicians, allowing for better risk stratification and targeted interventions in this vulnerable patient cohort. Further research is essential to validate these findings and inform how tailored therapeutic approaches for geriatric OSA patients can mitigate MACCE risk.

CLINICAL IMPLICATIONS

Elderly individuals with a high risk for MACCE should undergo routine OSA screening using tools like the sensitive STOP-BANG Questionnaire. Implementing CPAP treatment can enhance cardiovascular outcomes in these patients.

Leptin: A Potential Link Between Obstructive Sleep Apnea and Obesity

Chronic intermittent hypoxia (CIH), a pathophysiological manifestation of obstructive sleep apnea (OSA), is strongly correlated with obesity, as patients with the disease experience weight gain while exhibiting elevated plasma levels of leptin. This study was done to determine whether a relationship may exist between CIH and obesity, and body energy balance and leptin signaling during CIH. Sprague-Dawley rats were exposed to 96 days of CIH or normoxic control conditions, and were assessed for measures of body weight, food and water intake, and food conversion efficiency. At the completion of the study leptin sensitivity, locomotor activity, fat pad mass and plasma leptin levels were determined within each group. Additionally, the hypothalamic arcuate nucleus (ARC) was isolated and assessed for changes in the expression of proteins associated with leptin receptor signaling. CIH animals were found to have reduced locomotor activity and food conversion efficiency. Additionally, the CIH group had increased food and water intake over the study period and had a higher body weight compared to normoxic controls at the end of the study. Basal plasma concentrations of leptin were significantly elevated in CIH exposed animals. To test whether a resistance to leptin may have occurred in the CIH animals due to the elevated plasma levels of leptin, an acute exogenous (ip) leptin (0.04 mg/kg carrier-free recombinant rat leptin) injection was administered to the normoxic and CIH exposed animals. Leptin injections into the normoxic controls reduced their food intake, whereas CIH animals did not alter their food intake compared to vehicle injected CIH animals. Within ARC, CIH animals had reduced protein expression of the short form of the obese (leptin) receptor (isoform OBR₁₀₀) and showed a trend toward an elevated protein expression of the long form of obese (leptin) receptor (OBRb). In addition, pro-opiomelanocortin (POMC) protein expression was reduced, but increased expression of the phosphorylated extracellular-signal-regulated kinase 1/2 (pERK1/2) and of the suppressor of cytokine signaling 3 (SOCS3) proteins was observed in the CIH group, with little change in phosphorylated signal transducer and activator of transcription 3 (pSTAT3). Taken together, these data suggest that long-term exposure to CIH, as seen in obstructive sleep apnea, may contribute to a state of leptin resistance promoting an increase in body weight.

Validation of a new unattended sleep apnea monitor using two methods for the identification of hypopneas

STUDY OBJECTIVES

The objective of the present study was to evaluate the accuracy of a home sleep apnea test (HSAT), MATRx plus (Zephyr Sleep Technologies, Calgary, Alberta, Canada), in identifying apneas and hypopneas and estimating indices of obstructive sleep apnea (OSA).

METHODS

Individuals with suspected OSA underwent a one-night study wearing both HSAT and polysomnogram (PSG) sensors. The results provided by the overnight HSAT were compared with those from the simultaneously recorded PSG. The PSG data were scored manually, and the HSAT data were analyzed automatically using both preceding peak (PP) and moving average window (MW) methods for determining the reference oxyhemoglobin saturation (O₂ Sat). Accuracy of the HSAT in detecting individual apneic and hypopneic events was evaluated on an epoch-by-epoch basis. The apnea-hypopnea indices from the two recording systems were compared.

RESULTS

Agreement analysis for the individual apneic and hypopneic events yielded median values for sensitivity and specificity of 0.89 and 0.98 and positive and negative likelihood ratios of 37.35 and 0.11, respectively. Comparison of OSA indices between the two systems yielded correlation coefficients in the range of 0.95-0.96 and intraclass correlation coefficients ranging from 0.92-0.96. Bland-Altman analyses showed 0-2 cases lying outside the ± 2 standard deviation (SD) band and biases ranging from 2.1 to 5.3 events/h. The biases were larger for MW than PP.

CONCLUSIONS

The MATRx plus HSAT identifies apneic and hypopneic events and estimates OSA indices with accuracy suitable for clinical purposes but not in children, patients with underlying lung disease, and habitual mouth-breathers.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: PSG Validation of MATRx plus AHI; Identifier: NCT03627169.

Contribution of Neurochemical Inputs to the Decrease of Motoneuron Excitability During Non-REM and REM Sleep: A Systematic Review

The sleep-related depression of excitability of upper airway motoneurons is a major neurological cause of obstructive sleep apnea whereas a disruption in the inhibition of spinal motoneurons during rapid eye movement (REM) sleep causes the REM sleep behavioral disorder. The large amount of experimental data has been obtained that deal with neurochemical mechanisms that are responsible for sleep-related depression of various motoneuron groups. However, there is a disagreement regarding the outcome of these studies primarily due to the use of different animal models and approaches, as well as due to differences in quantification and interpretation of obtained results. In this study, we sought to apply the same calculation methodology in order to uniformly quantify and compare the relative contribution of excitatory or inhibitory inputs to the decrease of excitability of different motoneuronal pools during REM and/or non-REM sleep. We analyzed only published quantitative data that were obtained by using receptor antagonists or chemogenetic approach to block receptors or silence neuronal populations. The outcomes of this analysis highlight the differences in the neurotransmitter mechanisms of sleep-related motoneuron depression between different motoneuronal pools and demonstrate the consistency of these mechanisms for hypoglossal motoneurons among various animal models.

Cuadro clínico del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS)

El pilar para el diagnóstico del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) es el cuadro clínico obtenido mediante una historia clínica detallada. Los síntomas son referidos por el paciente o su compañero de cama y se pueden dar durante el sueño o la vigilia; estos últimos se presentan como consecuencia del trastorno del sueño. Los síntomas son consecuencia de la obstrucción de la vía aérea superior, de la hipoxia intermitente o de la fragmentación repetida del sueño.Para el diagnóstico de SAHOS, se deben tener en cuenta los factores agravantes, las comorbilidades, los antecedentes familiares, el examen físico, la obtención de medidas antropométricas, los signos vitales y los hallazgos anatómicos estructurales asociados con este síndrome o con alteraciones congénitas que lo predispongan. Tener conocimiento de estos aspectos clínicos es fundamental para alcanzar una buena aproximación a su diagnóstico.

Morphological study of upper airways and long-term follow-up of obstructive sleep apnea syndrome in acromegalic patients

Pathogenesis and long-term outcome of obstructive sleep apnea syndrome (OSAS) in acromegalic patients are still under debate. The aim of the study was to assess the prevalence and long-term follow-up of a series of acromegalic patients with OSAS and to investigate site, degree, and possible causes of upper airway obstruction by morphological study. Cross-sectional and longitudinal study was conducted in 58 acromegalic patients (33 active, 25 controlled) with polysomnography in all subjects, repeated in 25 patients with OSAS, and echocardiography. Morphological study including fiberoptic nasopharyngoscopy with the Müller maneuver (FNMM), magnetic resonance imaging (MRI), with 3-dimensional (3D) elaboration was also performed. The prevalence of OSAS was 58.6 % in the whole series: 63.6 % in the active group and 52 % in the controlled one. Left ventricular hypertrophy was more prevalent in patients with OSAS. OSAS improved in 62.5 % of active patients after achieving hormonal control, whereas it persisted or got worse in 66.6 % of the controlled ones. The uvula and tongue base were the main site of obstruction assessed by FNMM. Uvula diameters obtained by MRI study correlated with the severity of upper airway collapse assessed by FNMM and tongue measure with apnea-hypopnea index (p = 0.044). A greater narrowing and a smaller total volume of upper airways were confirmed by 3D-MRI in patients with more severe OSAS. Uvula and tongue hypertrophy plays a relevant role in the pathogenesis and severity of OSAS. Intensive treatment of acromegaly needs to be promptly adopted in order to reverse it.

Revisiting Antagonist Effects in Hypoglossal Nucleus: Brainstem Circuit for the State-Dependent Control of Hypoglossal Motoneurons: A Hypothesis

We reassessed and provided new insights into the findings that were obtained in our previous experiments that employed the injections of combined adrenergic, serotonergic, GABAergic, and glycinergic antagonists into the hypoglossal nucleus in order to pharmacologically abolish the depression of hypoglossal nerve activity that occurred during carbachol-induced rapid-eye-movement (REM) sleep-like state in anesthetized rats. We concluded that noradrenergic disfacilitation is the major mechanism that is responsible for approximately 90% of the depression of hypoglossal motoneurons, whereas the remaining 10% can be explained by serotonergic mechanisms that have net inhibitory effect on hypoglossal nerve activity during REM sleep-like state. We hypothesized that both noradrenergic and serotonergic state-dependent mechanisms indirectly control hypoglossal motoneuron excitability during REM sleep; their activities are integrated and mediated to hypoglossal motoneurons by reticular formation neurons. In addition, we proposed a brainstem neural circuit that can explain the new findings.

Hematological Parameters as Predictors of Cardiovascular Disease in Obstructive Sleep Apnea Syndrome Patients

We investigated the role of the red cell distribution width (RDW) and other parameters including platelet (PLT) count, mean platelet volume (MPV), and platelet distribution width (PDW) in patients with obstructive sleep apnea syndrome (OSAS) having cardiovascular diseases (CVDs). Patients (n = 142) having sleep disorders and who applied for a night polysomnography were included in this study. For statistical analysis, chi-square test, bivarite correlation, and logistic and stepwise regression tests were used. A positive correlation between RDW MPV, RDW, and body mass index as well as PLT and apnea-hypopnea index were observed. A negative correlation between AHI and PDW (P= .041) and a positive correlation between AHI and PLT (P= .010) were found in the patients ≥40 years old with CVD. The RDW was higher in patients ≥40 years old who had CVD (P= .016), and 19% of them had RDW >14%. The PDW (odds ratio = 6.02 [95% confidence interval = 1.3-28.2],P= .023) appeared to be associated with increased risk of hyperlipidemia in patients with severe OSAS. If these results are confirmed, RDW could be used with other markers, especially PLT and PDW, in prediction of CVD in patients with severe OSAS.

Evolution and physiology of neural oxygen sensing

Major evolutionary trends in animal physiology have been heavily influenced by atmospheric O2 levels. Amongst other important factors, the increase in atmospheric O2 which occurred in the Pre-Cambrian and the development of aerobic respiration beckoned the evolution of animal organ systems that were dedicated to the absorption and transportation of O2, e.g., the respiratory and cardiovascular systems of vertebrates. Global variations of O2 levels in post-Cambrian periods have also been correlated with evolutionary changes in animal physiology, especially cardiorespiratory function. Oxygen transportation systems are, in our view, ultimately controlled by the brain related mechanisms, which senses changes in O2 availability and regulates autonomic and respiratory responses that ensure the survival of the organism in the face of hypoxic challenges. In vertebrates, the major sensorial system for oxygen sensing and responding to hypoxia is the peripheral chemoreflex neuronal pathways, which includes the oxygen chemosensitive glomus cells and several brainstem regions involved in the autonomic regulation of the cardiovascular system and respiratory control. In this review we discuss the concept that regulating O2 homeostasis was one of the primordial roles of the nervous system. We also review the physiology of the peripheral chemoreflex, focusing on the integrative repercussions of chemoreflex activation and the evolutionary importance of this system, which is essential for the survival of complex organisms such as vertebrates. The contribution of hypoxia and peripheral chemoreflex for the development of diseases associated to the cardiovascular and respiratory systems is also discussed in an evolutionary context.

Chronic intermittent hypoxia increases sympathetic control of blood pressure: role of neuronal activity in the hypothalamic paraventricular nucleus

Like humans with sleep apnea, rats exposed to chronic intermittent hypoxia (CIH) experience arterial hypoxemias and develop hypertension characterized by exaggerated sympathetic nerve activity (SNA). To gain insights into the poorly understood mechanisms that initiate sleep apnea/CIH-associated hypertension, experiments were performed in rats exposed to CIH for only 7 days. Compared with sham-treated normoxic control rats, CIH-exposed rats (n = 8 rats/group) had significantly increased hematocrit (P < 0.001) and mean arterial pressure (MAP; P < 0.05). Blockade of ganglionic transmission caused a significantly (P < 0.05) greater reduction of MAP in rats exposed to CIH than control rats (n = 8 rats/group), indicating a greater contribution of SNA in the support of MAP even at this early stage of CIH hypertension. Chemical inhibition of neuronal discharge in the hypothalamic paraventricular nucleus (PVN) (100 pmol muscimol) had no effect on renal SNA but reduced lumbar SNA (P < 0.005) and MAP (P < 0.05) more in CIH-exposed rats (n = 8) than control rats (n = 7), indicating that CIH increased the contribution of PVN neuronal activity in the support of lumbar SNA and MAP. Because CIH activates brain regions controlling body fluid homeostasis, the effects of internal carotid artery injection of hypertonic saline were tested and determined to increase lumbar SNA more (P < 0.05) in CIH-exposed rats than in control rats (n = 9 rats/group). We conclude that neurogenic mechanisms are activated early in the development of CIH hypertension such that elevated MAP relies on increased sympathetic tonus and ongoing PVN neuronal activity. The increased sensitivity of Na(+)/osmosensitive circuitry in CIH-exposed rats suggests that early neuroadaptive responses among body fluid regulatory neurons could contribute to the initiation of CIH hypertension.

Polysomnographic sleep aspects in liver cirrhosis: a case control study

AIM

To study sleep aspects and parameters in cirrhotic patients and assess the role of liver dysfunction severity in polysomnographic results.

METHODS

This was a case-control study. Patients with a diagnosis of liver cirrhosis were consecutively enrolled in the study. Clinical examinations and laboratory liver tests were performed in all patients, and disease severity was assessed using the Child-Pugh score. The control group consisted of age- and gender-matched healthy volunteers. All individuals answered a questionnaire about habits, behaviors, and complaints related to sleep and were submitted to polysomnography. Sleep parameters were compared between the two groups, and separate analyses were performed among classes of Child-Pugh classification in the cirrhotic group.

RESULTS

Forty-two cirrhotic patients and forty-two controls were enrolled. Compared to the control group, the cirrhotic group exhibited lower sleep efficiency (mean ± SD: 73.89% ± 14.99% vs 84.43% ± 8.55%, P < 0.01), increased latency (151.27 ± 93.24 min vs 90.62 ± 54.74 min, P < 0.01) and a lower percentage of rapid eye movement (REM) sleep (14.04% ± 5.64% vs 20.71% ± 6.77%, P < 0.05) as well as a higher frequency of periodic limb movements (10.56 ± 2.85/h vs 2.79 ± 0.61/h, P < 0.01). The comparison of sleep parameters among Child A, B and C cirrhotic patients revealed a significant reduction of REM sleep stage occurrence in individuals with severe liver disease (Child C patients) compared to Child A/B patients (polysomnography percentage of REM sleep stage of patients Child A: 16.1% ± 1.2%; Child B: 14.9% ± 1.2%; Child C: 8.6% ± 1.6%, P < 0.05).

CONCLUSION

Cirrhosis was associated with shorter sleep time, reduced sleep efficiency, increased sleep latency, increased REM latency and reduced REM sleep. Additionally, disease severity influences sleep parameters.

Assessment of sleep apnea syndrome in treated acromegalic patients and correlation of its severity with clinical and laboratory parameters

BACKGROUND

Sleep apnea syndrome (SAS) is a frequent disorder in acromegalic patients and its frequency ranges from 45 to 87.5% of patients. Obstructive SAS is the prevailing form in acromegaly and its pathogenesis is based on craniofacial deformations and thickening of soft tissues and mucosas of upper airways and bronchi. Central and mixed types are less frequent. Respiratory complications, and SAS in particular, may contribute to the increased mortality observed in acromegaly.

AIM

Aim of the present study is to assess the presence of SAS in acromegalic patients, its features and to correlate the severity of SAS with factors such as disease duration, body mass index (BMI), smoking, GH/IGF-I serum levels, associated comorbidities.

SUBJECTS AND METHODS

Polygraphy (SOMNOcheck Effort Weinmann V2.05) was performed in 25 consecutive acromegalic patients (9 men and 16 women). Statistical analysis was performed with Mann-Whitney's test and Spearman coefficient.

RESULTS

Fourteen out of 25 patients (56%) were affected by SAS. The prevailing form was obstructive SAS (12/14 patients). Smoking, female gender, and presence of lung disease appear to lead to a more severe form. We also found that the prevalence of hypertension was significantly higher in the group of patients with SAS, whereas no correlation was proved among SAS and disease duration, GH/IGF-I serum levels, somatostatin analogs treatment, BMI, and associated comorbidities.

CONCLUSIONS

SAS is a frequent complication of acromegaly. Severe forms seem to be correlated with smoking and lung disease. Therefore, all acromegalic patients should be subjected to a polygraphic study for an early diagnosis and treatment and smoking should be discouraged.

Obstructive sleep apnea and incidence of postoperative delirium after elective knee replacement in the nondemented elderly

BACKGROUND

Postoperative delirium, a common complication in the elderly, can occur following any type of surgery and is associated with increased morbidity and mortality; it may also be associated with subsequent cognitive problems. Effective therapy for postoperative delirium remains elusive because the causative factors of delirium are likely multiple and varied.

METHODS

Patients 65 yr or older undergoing elective knee arthroplasty were prospectively evaluated for postoperative Diagnostic and Statistical Manual of Mental Disorders-IV delirium. Exclusion criteria included dementia, mini-mental state exam score less than 24, delirium, clinically significant central nervous system/neurologic disorder, current alcoholism, or any serious psychiatric disorder. Delirium was assessed on postoperative days 2 and 3 using standardized scales. Patients' preexisting medical conditions were obtained from medical charts. The occurrence of obstructive sleep apnea was confirmed by contacting patients to check their polysomnography records. Data were analyzed using Pearson chi-square or Wilcoxon rank sum tests and multiple logistic regressions adjusted for effects of covariates.

RESULTS

Of 106 enrolled patients, 27 (25%) developed postoperative delirium. Of the 15 patients with obstructive sleep apnea, eight (53%) experienced postoperative delirium, compared with 19 (20%) of the patients without obstructive sleep apnea (P = 0.0123, odds ratio: 4.3). Obstructive sleep apnea was the only statistically significant predictor of postoperative delirium in multivariate analyses.

CONCLUSIONS

This is the first prospective study employing validated measures of delirium to identify an association between preexisting obstructive sleep apnea and postoperative delirium.

Metabolic syndrome correlates intracoronary stenosis detected by multislice computed tomography in male subjects with sleep-disordered breathing

BACKGROUND

Sleep-disordered breathing (SDB), especially obstructive sleep apnea (OSA), has frequent complications include hypertension, dyslipidemia and insulin resistance based on abdominal obesity or excess visceral fat (called Syndrome Z). OSA is a potential risk factor for cardiovascular diseases. The clinical characteristics of Japanese OSA subjects with OSA remain unclear. The present study investigated prevalence and predictive factors of intracoronary stenosis detected by multislice computed tomography (MSCT) in Japanese male subjects with SDB/OSA.

FINDINGS

The study (O-VFStudy) subjects were 39 Japanese men with SDB/OSA who underwent all-night cardiorespiratory monitoring with fully attended polysomnography, and moreover both fat computed tomography (CT) scan and 64-row MSCT coronary angiography. The prevalence of coronary stenosis in this selected population with SDB/OSA was 15%. Logistic regression analysis showed a significant relationship between age-adjusted CAD and metabolic syndrome (p < 0.05), but not serum adiponectin levels and nocturnal fall in adiponectin. Subjects with the metabolic syndrome had significantly higher prevalence of CAD (31.3 versus 4.3%, p = 0.033), and lower levels of serum adiponectin (4.5 ± 0.6 versus 6.4 ± 0.6 μg/mL, p = 0.014), compared with groups without the metabolic syndrome.

CONCLUSIONS

The present study describes that the prevalence of greater than 50% intracoronary stenotic lesions detected by MSCT was 15% and the metabolic syndrome was correlated with intracoronary stenosis detected by MSCT in Japanese SDB/OSA subjects.

TRIAL REGISTRATION

UMIN 000002997https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000003633&language=E.

Cardiovascular complications of obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common disorder with an increasing public health burden. It is characterized by repeated upper airway narrowing and closure, leading to apneas, hypopneas and increased respiratory effort-related arousals. Continuous positive airway pressure is an effective modality of treatment for OSA. Apart from being responsible for daytime sleepiness and cognitive impairment, OSA has been implicated in various systemic diseases, particularly of the cardiovascular system. This article reviews some of the extensive literature implicating OSA in the development of cardiovascular diseases and describes the intermediary pathophysiologic mechanisms involved. Repetitive nocturnal oxygen desaturation and reoxygenation and increased intrathoracic pressure changes related to OSA result in the intermediary pathophysiologic mechanisms that affect the neural, humoral, thrombotic, inflammatory and metabolic pathways responsible for the development of cardiovascular disorders. This review also examines evidence that suggests that OSA may be a specific cause of certain cardiovascular disorders.

Anemia of aging and obstructive sleep apnea

INTRODUCTION

World Health Organization defined anemia of aging (AOA) when men and women greater than 65 years, respectively, have unexplained hemoglobin (Hgb) less than 13 and 12 g/dl. Recent evidence suggests that this is likely a chronic inflammatory process involving interleukins (IL) 6, 12, and C-reactive protein. Among elderly with obstructive sleep apnea (OSA), hypoxic stimulation of erythropoiesis may obscure AOA. Treatment of OSA may paradoxically restore AOA. We sought to identify OSA and AOA coexistence and OSA treatment AOA interaction.

METHODS

Records of 101 successive patients older than 65 years and with OSA who were treated with continuous positive airway pressure were analyzed retrospectively. Differences among pre/post-treatment of OSA hemograms were assessed using paired two-tailed Student's t test. Hemogram changes were compared to apnea-hypopnea index (AHI), respiratory effort related arousals (RERA), and duration patients slept with oxyhemoglobin saturation <89% (hypoxic time (HT)) and were assessed for correlative significance using Pearson coefficient correlation.

RESULTS

Eighty-two of one hundred one patients (27 men, 55 women; average age 71 years) had charted all the study data variables cited above. Mean pre-treatment and mean 1-year post-treatment of OSA Hgb/hematocrit (Hct) for men and women, respectively, were 13 g/dl/40.7% to 12.7 g/dl/39.1% and 12.1 g/dl/38.1% to 11.9 g/dl/37.6%. Hct changed significantly among both men and women (p < 0.05). Among 56% and 30% of the 82 patient study cohort, 1-year post-treatment of OSA, Hct declined (mean 4.8%) and increased (mean 3.7%), respectively; both changes were statistically significant (p < 0.01). These changes did not correlate significantly with AHI, RERA, or HT.

DISCUSSION

Among the entire cohort for both men and women, we did not see AOA before OSA treatment and we did see AOA 1 year after OSA treatment. However, post-treatment of OSA Hct distributed bimodally, with significant increases and declines of Hct. While these Hct changes did not correlate significantly with selected sleep-breathing variables, we remain intrigued by a possible AOA-OSA interaction. AOA and OSA share common inflammatory processes. We believe OSA inflammatory processes interact with OSA hypoxia-induced erythropoiesis. The balance of these sets of processes determines the effect of OSA and OSA treatment on AOA.

Obstructive sleep apnea and ischemic heart disease in southwestern US veterans: implications for clinical practice

This study describes associations between obstructive sleep apnea (OSA), intake of food rich in antioxidant nutrients, and ischemic heart disease (IHD) in military veterans. Subjects were male veterans (n=211), 54 to 85 years of age, and enrolled in primary care clinics at the Southern Arizona Veterans Affairs Health Care System (SAVAHCS), Tucson, AZ. Measures included the SAVAHCS Minority Vascular Center Questionnaire, the Sleep Heart Health Study Sleep Habits Questionnaire, the Arizona Food Frequency Questionnaire, height, weight, and blood pressure. Veterans with OSA were significantly more likely to be obese, to have elevated systolic blood pressure and physician-diagnosed IHD, more likely to undergo coronary angiography, and less likely to consume foods rich in cardioprotective antioxidants compared to veterans without OSA. After adjusting for confounding variables, the association between OSA and IHD remains significant [adjusted OR=2.99, confidence interval (CI)=1.07-8.42]. These data reinforce the importance of recognizing OSA within the veterans affairs health care system and suggest that early detection of OSA may improve veterans' health and well-being and reduce associated medical costs.

Restless legs syndrome in pediatric patients with chronic kidney disease

Sleep disorders have been shown to be more prevalent in adults and children with chronic kidney disease (CKD) and on dialysis. To date, the prevalence and impact of restless legs syndrome (RLS) in various stages of CKD has not been evaluated. The object of this study was to determine the prevalence of RLS in children with CKD in different stages, and to evaluate its impact on sleep and daytime functioning. We conducted a clinic-based or telephone survey of 26 patients in varying stages of CKD to assess for RLS, sleep schedule, and daytime sleepiness. Thirty-five percent of children met criteria for RLS, the majority being in CKD stages 1-4. There were no significant differences seen in sleep schedule and daytime sleepiness between those children with or without RLS. We found that there is an increased prevalence of RLS in children with CKD compared to the general population. This suggests that children with all stages of CKD should be routinely screened for RLS symptoms.

Validation study of a portable monitoring device for identifying OSA in a symptomatic patient population

BACKGROUND AND OBJECTIVE

Obstructive sleep apnoea syndrome (OSAS) is a common disorder associated with early atherosclerosis, diabetes mellitus, ischaemic heart disease and cerebrovascular disease. The gold standard for confirming OSAS is based on an attended overnight polysomnography (PSG) in a sleep laboratory; however lack of health-care resources creates long waiting times for patient access to this diagnostic test. This study evaluated the ability of a portable sleep-monitoring device to identify patients in Hong Kong with suspected OSAS.

METHODS

Patients with symptoms of OSAS were invited to use the ARES (apnoea risk evaluation system) concurrently with an attended inpatient PSG. Several sets of AHI were generated by the ARES provider based on different oxygen desaturation criteria and surrogate parameters of arousal. The results were compared against PSG to determine the optimal sensitivity and specificity.

RESULTS

There were 141 patients who completed the study successfully. Results of AHI from the ARES study were presented in the order of different scoring criteria--4% oxygen desaturation alone, obstructive events with 3% oxygen desaturation and obstructive events with 1% desaturation plus surrogate arousal criteria. The sensitivity was 0.84 (95% confidence interval (CI): 0.77-0.90), 0.89 (95% CI: 0.89-0.94) and 0.97 (95% CI: 0.94-0.99), respectively. The specificity was 1, 1 and 0.63 (95% CI: 0.55-0.71), respectively. The receiver operating curve had an area of 0.96, 0.97 and 0.98, respectively. The kappa coefficient varied from 0.24 to 0.55 for agreement of severity between PSG and ARES. The likelihood ratio positive and the likelihood ratio negative were 2.61, infinity, infinity and 0.16, 0.11, 0.05, respectively, in the order of oxygen desaturation described earlier.

CONCLUSIONS

The ARES device has reasonable sensitivity and specificity for diagnosing severe OSAS in symptomatic Chinese patients. There is moderate agreement between ARES and PSG in the diagnosis of severe disease, but less agreement in patients with mild/moderate disease.

Obstructive sleep apnea in older adults

The "typical" presentation of obstructive sleep apnea (OSA) is chronic loud snoring and excessive daytime sleepiness in middle-aged obese men. OSA can result in increased risk for cardiovascular morbidity and mortality. The diagnostic features of OSA in older adults are similar to those in younger adults; however, the older adult may be less likely to seek medical attention or have the sleep disorder recognized because symptoms of snoring, sleepiness, fatigue, nocturia, unintentional napping, and cognitive dysfunction may be ascribed to the aging process itself or to other disorders. This article reviews the basic terminology and pathophysiology of sleep-disordered breathing, discusses why OSA may be even more prevalent in older adults than in the middle-aged group, and reviews similarities and differences between the two groups in the manifestations, consequences, and treatments of OSA.

Cerebrovascular reactivity to hypercapnia is unimpaired in breath-hold divers

Hypercapnic cerebrovascular reactivity is decreased in obstructive sleep apnoea and congestive heart disease perhaps as a result of repeated apnoeas. To test the hypothesis that repeated apnoeas blunt cerebrovascular reactivity to hypercapnia, we studied breath hold divers and determined cerebrovascular reactivity by measuring changes in middle cerebral artery velocity (MCAV, cm s(-1)) per mmHg change in end-tidal partial pressure of CO2(PET,CO2 ) in response to two hyperoxic hypercapnia rebreathing manoeuvres (modified Read protocol) in elite breath-hold divers (BHD, n=7) and non-divers (ND, n=7). In addition, ventilation and central (beat-to-beat stroke volume measurement with Modelflow technique) haemodynamics were determined. Ventilatory responses to hypercapnia were blunted in BHD versus ND largely due to lower breathing frequency. Cerebrovascular reactivity did not differ between groups (3.7 +/- 1.4 versus 3.4 +/- 1.3% mmHg(-1) in BHD and ND, respectively; P=0.90) and the same was found for cerebral vascular resistance and MCAV recovery to baseline after termination of the CO2 challenge. Cardiovascular parameters were not changed significantly during rebreathing in either group, except for a small increase in mean arterial pressure for both groups. Our findings indicate that the regulation of the cerebral circulation in response to hypercapnia is intact in elite breath-hold divers, potentially as a protective mechanism against the chronic intermittent cerebral hypoxia and/or hypercapnia that occurs during breath-hold diving. These data also suggest that factors other than repeated apnoeas contribute to the blunting of cerebrovascular reactivity in conditions like sleep apnoea.

Sleep-disordered breathing in nondialyzed patients with chronic renal failure

The prevalence and significance of sleep-disordered breathing (SDB) in dialysis-independent chronic renal failure (CRF) remains unknown. We studied the presence of SDB in nondialyzed CRF patients. Diagnostic polysomnography was performed in consecutive stable nondialyzed CRF patients. Inclusion criteria were age <or=70 years, absence of systolic dysfunction or history of pulmonary edema, FEV(1) > 70% pr, absence of neurologic disease or hypothyroidism, and calculated creatinine clearance <40 ml/min. Thirty-five patients (19 male, 16 female) were studied. An apnea-hypopnea index (AHI) >or=5/h was present in 54.3% (almost exclusively obstructive events). AHI correlated with urea (r = 0.35, p = 0.037), age (r = 0.379, p = 0.025), and body mass index (BMI) (r = 0.351, p = 0.038), but not with creatinine clearance. AHI or SDB were unrelated to gender. In nondiabetics (n = 25), AHI correlated with urea (r = 0.608, p = 0.001) and creatinine clearance (r = -0.50, p = 0.012). Nondiabetics with severe CRF (calculated GFR < 15 ml/min/1.73 m(2)) had a significantly higher AHI compared with less severe CRF. Restless legs syndrome (RLS) was present in 37.1% and periodic limb movements in 28.6%. Daytime sleepiness was not associated with respiratory events, but was more common in patients with RLS. The prevalence of SDB and RLS is high in dialysis-independent CRF. SDB weakly correlates with indices of kidney function and this association becomes stronger in nondiabetics.

Obesity-related cardiovascular disease: implications of obstructive sleep apnea

Obesity and obstructive sleep apnea (OSA) often coexist. OSA has been linked to cardiovascular disease. Thus, OSA may contribute to the cardiovascular consequences of obesity. In this review, we explore clinical and pathophysiological interactions between obesity, cardiovascular disease and OSA. We discuss the mechanisms whereby OSA may contribute to hypertension, atherosclerosis, insulin resistance and atrial fibrillation associated with obesity, and emphasize the potential implications for understanding why only a subgroup of obese patients develop cardiovascular disease. Identification of the OSA-dependent and OSA-independent pathways in the cardiovascular pathophysiology of obesity may hold clinical and therapeutic promise.

Sleep Parameters in Patients Using Pacemakers with Sleep Rate Function on

INTRODUCTION

The cardiovascular system (CVS) is heavily influenced by the autonomic nervous system. Additionally, there is a functional alteration during the various stages of sleep. In nonrapid eye movement (NREM), a state of cardiovascular relaxation occurs during stages three and four. A large amount of rapid ocular movements is concentrated in rapid eye movement (REM) sleep. During this phase, fluctuations in arterial pressure (AP) and heart rate (HR) can be readily noted. Sleep disordered breathing (SDB) has been associated with cardiac rhythm disorders. Recently, cardiac rhythm disorder treatment with pacemaker (PM) highlighted a reduction in abnormal respiratory events during sleep.

OBJECTIVE

Comparison of sleep parameters of patients using PM with a sleep rate (SR) algorithm based on its rate-modulated capability during physical activity (Integrity PM with SR function on and off).

METHODS

Twenty-two patients (14 women, 8 men), implanted with an Integrity PM (St. Jude Medical Cardiac Rhythm Management Division, Sylmar, CA) with SR function for standard clinical indications, were evaluated utilizing a double-blind protocol. The indication for pacing included sinus node disease (SND), atrium ventricular blockage (AVB), and atrial fibrillation (AF). Following randomization, half of our patients had SR function switched to "on" mode while the other half were on "off" mode. During the first stage of the protocol, all patients underwent two consecutive nights of polysomnographic sleep recordings (PSG). During the first night patients slept in the sleep lab only for adaptation purpose. PSG full recording was carried out in the subsequent night. At a later stage, the programing of SR functions was shifted to "on" or "off" modes. One week later, a third assessment was undertaken.

RESULTS

Twelve patients (54%) showed sleep efficiency improvement (total sleeping time/recording time) with PM SR on. This group had the least effective sleep efficiency with PM off, if compared with the others who highlighted no change in this sleep parameter (72 +/- 12 vs 81 +/- 7%, P = 0.01, respectively). This first group displayed a lower latency for REM sleep than the last one (89 +/- 55 vs 174 +/- 107 minutes, P = 0.01, respectively). In 11 (50%) patients, the number per sleep hour of microarousals was reduced when PM SR was switched on. When we compared such findings to the group whose parameters had not changed, we noted that the first set of patients were sleepier (ESE: 9 +/- 4 vs 5 +/- 5, P = 0.04, respectively), and showed more microarousals with PM SR off (20 +/- 14 vs 7 +/- 5 microarousal/hour, P = 0.007).

CONCLUSION

In PM patients with sleep-related issues, the SR function activation improved sleep both from a qualitative and quantitative perspective.

Temas de actualidad en estimulación cardíaca 2005

Currently, three areas of active development in cardiac pacing are of particular interest to clinical cardiologists. Biventricular pacing is now considered a type-I indication for adjuvant treatment in advanced and refractory heart failure. Consequently, some changes in everyday clinical practice will be seen when patients with end-stage heart failure start to receive resynchronization therapy. Secondly, the Cardiac Pacing Working Group of the Spanish Society of Cardiology has developed a national consensus document on sleep apnea and cardiac rhythm abnormalities. It appears that a novel way of tackling the current growing epidemic could be to use permanent cardiac pacing in an attempt to modify the cardiac rhythm alterations, mainly bradyarrhythmias, related to sleep apnea. Finally, promising developments are taking place in systems designed to reduce the unwanted right ventricular stimulation sometimes observed with antibradycardia pacing modalities. These new systems are expected to minimize significantly the well-known deleterious hemodynamic effects sometimes seen in our patients.

Sleep Apnea and Sports Performance

Obstructive sleep apnea is a significant medical disorder that is increasingly recognized for its wide-ranging effects on physical and mental health. It can have a profound negative impact on sleep quality, daytime alertness, mood, and cardiovascular health, and effects on metabolic and endocrinologic parameters. There is little known about the prevalence and presentation of apnea in athletes and its potential effect on athletic performance. A high index of suspicion for apnea should exist, particularly in those who have anatomic features and symptoms consistent with the disorder. This article reviews pathophysiology, diagnostic modalities, and treatment interventions.

Augmented Endothelin Vasoconstriction in Intermittent Hypoxia-Induced Hypertension

We reported previously that simulating sleep apnea in rats by exposing them 7 hours per day to intermittent hypoxia/hypercapnia (IH) elevates plasma endothelin-1 and causes hypertension, which is reversed by an endothelin-1 antagonist. We hypothesized that in this model of sleep apnea–induced hypertension, vascular sensitivity to endothelin-1 is increased in combination with the elevated plasma endothelin-1 to cause the endothelin-1–dependent hypertension. In small mesenteric arteries with endothelial function disabled by passing air through the lumen, diameter and vessel wall [Ca 2+ ] were recorded simultaneously. IH arteries demonstrated increased constrictor sensitivity to endothelin-1 (percentage max constriction 100±0% IH versus 80±10% Sham; P <0.05). This was accompanied by increased calcium sensitivity of IH arteries. In contrast, constrictor sensitivity and increases in vessel wall [Ca 2+ ] to KCl and phenylephrine were not different between IH and Sham arteries. We have shown previously that endothelin-1 constriction in mesenteric arteries is mediated by endothelin A receptors. In the current study, the selective increase in endothelin-1 constriction in IH resistance arteries was accompanied by increased expression of endothelin A receptor expression (densitometry units 271±23 IH versus 158±25 Sham; P <0.05). Thus, IH hypertension appears to cause alterations in signaling components unique to endothelin-1 at the receptor level and in postreceptor signaling that increases calcium sensitivity during endothelin A activation. Future studies will determine the specific changes in vascular smooth muscle signaling in IH hypertension causing this augmented contractile phenotype.

The human diving response, its function, and its control

The purpose of this review is to outline the physiological responses associated with the diving response, its functional significance, and its cardiorespiratory control. This review is separated into four major sections. Section one outlines the diving response and its physiology. Section two provides support for the hypothesis that the primary role of the diving response is the conservation of oxygen. The third section describes how the diving response is controlled and provides a model that illustrates the cardiorespiratory interaction. Finally, the fourth section illustrates potential adaptations that result after regular exposure to an asphyxic environment. The cardiovascular and endocrine responses associated with the diving response and apnea are bradycardia, vasoconstriction, and an increase in secretion of suprarenal catecholamines. These responses require the integration of both the cardiovascular system and the respiratory system. The primary role of the diving response is likely to conserve oxygen for sensitive brain and heart tissue and to lengthen the time before the onset of serious hypoxic damage. We suggest that future research should be focused towards understanding the role of altered ventilatory responses in human breath-hold athletes as well as in patients suffering from sleep-disordered breathing.

Long-term sleep apnea as a pathogenic factor for cell-mediated autoimmune disease

BACKGROUND

Previous medical literature has shown that cell injury from hypoxia, such as that induced by sleep apnea, leads to hyperuricemia. Furthermore, a recent study has shown that when hyperuricemia reaches sufficient concentration to precipitate as monosodium urate, a T-cell immune response is triggered. The frequent repetition of this cell injury and immune response over a prolonged time, as would occur with long-term sleep apnea, may lead to the development, continuation, or aggravation of autoimmune disease.

HYPOTHESIS

Long-term sleep apnea is hypothesized to be a pathogenic factor in the development of cell-mediated autoimmune disease. Several corollaries are presented along with this general hypothesis. First, some of the diseases associated with sleep apnea may have an autoimmune etiology. Second, some autoimmune diseases not usually recognized to be associated with sleep apnea may indeed have that association. Third, resolving sleep apnea in some patients with autoimmune disease to remove that autoimmune stimulus may aid in deceleration, halt, or even reversal of the progress of the autoimmune disease. Fourth, because monosodium urate also causes gouty arthritis in some individuals, diagnosis of gout may allow for resolution of sleep apnea early enough to prevent autoimmune development. Fifth, allopurinol, which suppresses uric acid generation, may be an effective therapy for the remission or prevention of a number of autoimmune diseases.

CONCLUSION

This hypothesis strengthens the evidence pointing to the danger of unresolved sleep apnea by a mechanism previously unrecognized, namely the risk of developing an autoimmune disease. As a result of this realization, new therapies may be adopted for the treatment and prevention of autoimmune disease, specifically, resolving sleep apnea and the use of allopurinol.

Effects of hypertension and obesity on the sympathetic activation of heart failure patients

Previous studies have shown that congestive heart failure is characterized by sympathetic and reflex dysfunctions. Whether these alterations are potentiated in the presence of obesity and hypertension, two conditions that also display neuroadrenergic abnormalities and markedly increase the risk of heart failure, is unknown. In 14 healthy control subjects (C; age, 55.1+/-3.0 years; mean+/-SEM), 13 lean hypertensive subjects (H), 15 obese normotensive subjects (O), 14 lean normotensive subjects with congestive heart failure (CHF, New York Heart Association class II), 14 lean hypertensive subjects with CHF (CHFH), 14 obese normotensive subjects with CHF (CHFO), and 13 obese hypertensive subjects with CHF (CHFOH), all age-matched with C, we measured mean blood pressure (Finapres), heart rate (ECG), and muscle sympathetic nerve traffic (MSNA, microneurography) at rest and during baroreflex testing. Compared with C, body mass index was similarly increased in O, CHFO, and CHFOH, whereas mean blood pressure was similarly increased in HF, CHFH, and CHFOH, and left ventricular ejection fraction (echocardiography) was similarly reduced in CHF, CHFH, CHFO and CHFOH. Compared with C, MSNA was significantly increased in O, H, and CHF (43.0+/-2.2 versus 54.1+/-2.8, 53.1+/-2.5, and 57.4+/-2.8 bursts/100 heart beats, P<0.01). When O or H was combined with CHF, the MSNA increase was significantly more pronounced and maximal when O and H were concomitantly associated with CHF. Baroreflex sensitivity was reduced in O and H, with a further reduction in CHF and a minimal value in CHFOH. These data show that the sympathetic activation characterizing CHF is markedly potentiated when O and H alone or combined together are associated with a low cardiac output state and that this may depend on an arterial baroreflex impairment.