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Query: UMLS:C0037315 (sleep apnea)
 8,000 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nonobstructive (i.e., central) sleep apnea is a major cause of sleep-disordered breathing in patients with stable congestive heart failure (CHF). Although central sleep apnea (CSA) is prevalent in this population, occurring in 40-50% of patients, its pathogenesis is poorly understood. Dynamic loop gain and delay of the chemoreflex response to CO(2) was measured during wakefulness in CHF patients with and without CSA by use of a pseudorandom binary CO(2) stimulus method. Use of a hyperoxic background minimized responses derived from peripheral chemoreceptors. The closed-loop and open-loop gain, estimated from the impulse response, was three times greater in patients with nocturnal CSA (n = 9) than in non-CSA patients (n = 9). Loop dynamics, estimated by the 95% response duration time, did not differ between the two groups of patients. We speculate that an increase in dynamic gain of the central chemoreflex response to CO(2) contributes to the genesis of CSA in patients with CHF.
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PMID:Dynamic ventilatory response to CO(2) in congestive heart failure patients with and without central sleep apnea. 1140 58

Prediction formulae for sleep-disordered breathing can be useful for excluding a diagnosis, establishing an a priori probability of having a positive test, and for prioritizing patient testing. In general, prediction models have high sensitivity but low specificity. In a study analyzing the performance of four previously described prediction models, sensitivities ranged from 76% to 96%, specificities ranged from 13% to 54%, while positive predictive values ranged between 69% and 77%. The models were useful in identifying patients with a respiratory disturbance index of > or = 20 so that these patients could undergo alternative diagnostic testing strategies. The Berlin Questionnaire was tested in primary care settings and was able to identify high-risk patients fairly accurately. A regression neural network performed well with a sensitivity of 99%, a specificity of 80%, a positive predictive value of 88%, and a negative predictive value of 98%. In obese snorers, a regression model utilizing daytime arterial O2 saturation and specific respiratory conductance was effective for excluding obstructive sleep apnea (OSA). In congestive heart failure patients, risk factors for central sleep apnea include male gender, atrial fibrillation, age >60 years, and wake time PaCO2 <38 mm Hg. In children, risk factors for sleep apnea include obesity, African-American race, sinus problems, and persistent wheezing. There are also racial anthropomorphic differences in OSA patients, with whites having a tendency towards brachycephaly facial types (reduced anterior-posterior cranial dimension) and African-Americans having a tendency toward leptoproscopic facial types (longer facial height and decreased facial width). Further refinement of prediction formulae will improve diagnostic accuracy.
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PMID:Prediction formulae for sleep-disordered breathing. 1170 12

Congestive heart failure (CHF) is a serious medical condition frequently associated with sleep-related breathing disorders, which remain underdiagnosed and undertreated. Recent studies have provided important insight into the pathophysiology of sleep apnea syndrome in patients with CHF, with potential therapeutic implications. In addition to abolition of sleep apnea, continuous positive airway pressure (CPAP) treatment can improve cardiac function and relieve symptoms of CHF. Postulated mechanisms include beneficial hemodynamic effects on ventricular remodeling, unloading of fatigued respiratory muscles, and neurohormonal modulation. Although medium-term studies using CPAP to treat sleep-related breathing disorders associated with CHF have been encouraging, more definitive data from ongoing large clinical trials are necessary to clarify its therapeutic role.
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PMID:The role of continuous positive airway pressure in the treatment of congestive heart failure. 1171 53

An 81-year-old man with ischemic dilated cardiomyopathy complained of frequently awakening from sleep due to choking; subsequent polysomnography revealed Cheyne-Stokes respiration (CSR) with sleep apnea. With continuous positive airway pressure (CPAP) through a nasal mask, both the CSR and symptoms disappeared. After 6-12 months, chest X-ray and echocardiographic findings continued to improve without any change in pharmacological treatment. For three years, CPAP had been effective to eliminate CSR during sleep. Long-term CPAP treatment, which is rarely applied for congestive heart failure in Japan, is useful in alleviating the adverse effects of CSR and, thereby, maintaining a good quality of life in these patients.
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PMID:Long-term treatment of ischemic dilated cardiomyopathy with continuous positive airway pressure. 1175 68

Hypocapnia contributes to the genesis of Cheyne-Stokes respiration and central sleep apnoea in patients with congestive heart failure (CHF) and is associated with increased mortality. However, the cause of hypocapnia in patients with chronic stable CHF is unknown. Since pulmonary congestion can induce hyperventilation via stimulation of pulmonary vagal afferents, the present study tested the hypothesis that in patients with CHF (carbon dioxide tension in arterial blood (Pa,CO2)) is inversely related to pulmonary capillary wedge pressure (PCWP), and that alterations in PCWP would cause inverse changes in Pa,CO2. In 11 CHF patients undergoing diagnostic cardiac catheterization, haemodynamic variables and arterial blood gas tensions were measured simultaneously at baseline. In three patients, these measurements were repeated after coronary angiographic dye infusion and nitroglycerine infusion. At baseline, Pa,CO2 correlated inversely with PCWP (r=-0.80, p=0.003). In the three patients in whom multiple measurements were made, acute alterations in PCWP caused inversely proportional changes in Pa,CO2. The present study concludes that in patients with congestive heart failure, pulmonary capillary wedge pressure is an important determinant of carbon dioxide tension in arterial blood. These findings imply that hypocapnia in patients with chronic stable congestive heart failure is a respiratory manifestation of elevated left ventricular filling pressures.
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PMID:Relationship of carbon dioxide tension in arterial blood to pulmonary wedge pressure in heart failure. 1184 25

The purpose of this study was to determine the frequency of central and obstructive sleep apnea in adult patients who have echocardiographic evidence of left ventricular dysfunction and pulmonary hypertension. Subjects with left ventricular dysfunction, pulmonary hypertension (pulmonary artery systolic pressure >30 mm Hg) and no lung disease were evaluated for risk factors associated with pulmonary hypertension. Of eight eligible adults, six completed the study. Subjects were from suburban and inner city family practices. Spirometric assessment, pulse oximetry on room air, rheumatologic evaluation, polysomnography, and additional history were taken. All six subjects had sleep apnea (apnea-plus-hypopnea index, or AHI, > or = 20): obstructive, central, or mixed. All were obese, and almost all the subjects had a restrictive pattern on spirometry, which is consistent with obesity. All had a pulmonary artery systolic blood pressure of 35 mm Hg or greater. None had daytime hypoxemia or collagen vascular disease, and none had ever used appetite suppressants. This study found a strong association between pulmonary hypertension and obstructive or central sleep apnea in obese patients with congestive heart failure (CHF). We propose that a pulmonary artery systolic pressure of 35 mm Hg or greater in ambulatory patients with CHF may signify an increased risk of sleep apnea.
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PMID:Left ventricular dysfunction, pulmonary hypertension, obesity, and sleep apnea. 1186 42

Nasal continuous positive airway pressure therapy has recently been studied as a nonpharmacologic adjunct to congestive heart failure therapy. In patients with congestive heart failure, it was reported that continuous positive airway pressure therapy for the condition Cheyne-Stokes respiration with central sleep apnea led to long-term improvements in cardiac function and alleviation of heart failure symptoms. Cheyne-Stokes respiration with central sleep apnea is a frequent breathing disorder well described in patients with congestive heart failure, and is an associated risk factor for increased cardiovascular morbidity and mortality. These apneas cause an increase in sympathetic nervous system activity, which would maintain afterload at a high level or tend to increase it with time, leading to further compromise of ejection fraction. Continuous positive airway pressure appears to benefit the failing heart by increasing intrathoracic pressure, which is believed to cause an increase in cardiac output by decreasing the pressure gradient across the heart wall and allowing the left-ventricular end diastolic volume to decrease, thereby reducing the afterload. This beneficial "resting" of the heart has been documented to increase left-ventricular ejection fraction, increase cardiac index, improve inspiratory muscle strength, lower blood pressure and heart rate, decrease plasma and overnight urinary levels of norepinephrine, lower levels of atrial natriuretic peptide and endothelin-1, and increase heart rate variability. Other benefits include improvement in New York Heart Association functional class status and improvement in dyspnea.
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PMID:Congestive heart failure and continuous positive airway pressure therapy: support of a new modality for improving the prognosis and survival of patients with advanced congestive heart failure. 1197 41

To understand the pathogenesis of central sleep apnea (CSA) in patients with congestive heart failure (CHF), we measured the end-tidal carbon dioxide pressure (PET(CO2)) during spontaneous breathing, the apnea-hypopnea threshold for CO2, and then calculated the difference between these two measurements in 19 stable patients with CHF with (12 patients) or without (7 patients) CSA during non-rapid eye movement sleep. Pressure support ventilation was used to reduce the PET(CO2) and thereby determine the thresholds. In patients with CSA, 1.5-3% CO2 was supplied temporarily to stabilize breathing before determining the thresholds. Unlike patients without CSA whose eupneic PET(CO2) increased during sleep (37.7 +/- 1.4 mm Hg versus 40.2 +/- 1.5 mm Hg, p < 0.01), patients with CSA showed no rise in PET(CO2) from wakefulness to sleep (37.5 +/- 0.9 mm Hg versus 38.2 +/- 1.0 mm Hg, p = 0.2). Patients with CHF and CSA had their eupneic PET(CO2) closer to the threshold PET(CO2) than patients without CSA (DeltaPET(CO2) [eupneic PET(CO2) - threshold PET(CO2)] was 2.8 +/- 0.3 mm Hg versus 5.1 +/- 0.7 mm Hg for apnea, p < 0.01; 1.7 +/- 0.7 versus 4.1 +/- 0.5 mm Hg for hypopnea, p < 0.05). In summary, patients with CHF and CSA neither increase their eupneic PET(CO2) during sleep nor proportionally decrease their apnea-hypopnea threshold. The resultant narrowed DeltaPET(CO2) predisposes the patient to the development of apnea and subsequent breathing instability.
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PMID:Apnea-hypopnea threshold for CO2 in patients with congestive heart failure. 1255 31

The prevalence, prognosis, clinical presentation, pathophysiology, diagnosis, and treatment of the central sleep apnoea syndrome (CSAS) are reviewed and its relationship with congestive heart failure (CHF) is discussed. Adequately powered trials are needed with survival and health status as end points to establish whether correction of sleep related breathing abnormalities improves the outcome in patients with CHF.
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PMID:Central sleep apnoea syndrome in patients with chronic heart disease: a critical review of the current literature. 1203 32

Obstructive sleep apnoea is a disease of increasing importance because of its neurocognitive and cardiovascular sequelae. Abnormalities in the anatomy of the pharynx, the physiology of the upper airway muscle dilator, and the stability of ventilatory control are important causes of repetitive pharyngeal collapse during sleep. Obstructive sleep apnoea can be diagnosed on the basis of characteristic history (snoring, daytime sleepiness) and physical examination (increased neck circumference), but overnight polysomnography is needed to confirm presence of the disorder. Repetitive pharyngeal collapse causes recurrent arousals from sleep, leading to sleepiness and increased risk of motor vehicle and occupational accidents. The surges in hypoxaemia, hypercapnia, and catecholamine associated with this disorder have now been implicated in development of hypertension, but the association between obstructive sleep apnoea and myocardial infarction, stroke, and congestive heart failure is not proven. Continuous positive airway pressure, the treatment of choice for obstructive sleep apnoea, reduces sleepiness and improves hypertension.
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PMID:Obstructive sleep apnoea. 1250 19


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