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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new diagnostic method is described which identifies the presence of waveform clusters indicative of OSA, and an illustrative OSA screening system is presented which applies the new cluster analysis method to the oximetry waveform. Rather than using the conventional identification of an excess average number of isolated events to infer the presence of upper airway instability, cluster analysis identifies a prolonged spatial pattern of clustered waveforms derived from the underlying mechanism of OSA. The illustrative screening system includes a microprocessor which divides the basic timed oxygen saturation waveform into slope defined dipoles and then further classifies sequential components of the waveform as slope and interval derived "objects" for microprocessor analysis. The microprocessor then performs an analysis of the objects to further derive more complex objects called coupled oscillations and slope clusters. Each new sequential object is added if it has suitable spatial relationships, and occurs in acceptable order and time interval. The building of complex objects from the repetitive derivation of basic objects along a timed waveform exploits the unique self perpetuating physiological events which underlie the propagation of OSA. The identification and comparison of these objects are then used to determine the presence of sleep apnea. The method can also be applied to a secondary plot of a flow signal parameter such as the maximum exhaled CO(2) or the mean attenuation of the inspiratory loop as a function of time. The utilization of cluster based recognition of events to improve the conventional AHI and DI averaging methods of diagnosis is also discussed. In addition, the differentiation of three basic oxygen saturation cluster types and their potential relevance to the induction of sustained ischemia and cardiovascular morbidity are discussed.
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PMID:Cluster analysis: A new technology for the evaluation of oximetry and airflow waveforms in obstructive sleep apnea. 1941 22

Obstructive sleep apnea (OSA) is associated with increased risks of cardiovascular disease and stroke and with elevated rates of postoperative complications (including cardiac ischemia and respiratory failure) in surgical patients. Additionally, the prevalence of OSA is higher in surgical patients than in the general population. Screening for OSA prior to surgery is recommended to identify patients at risk for postoperative complications. The presence of moderate or severe OSA calls for modified strategies of perioperative anesthesia, pain management, and postoperative monitoring to reduce the chance of OSA-associated complications.
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PMID:Perioperative management of obstructive sleep apnea: ready for prime time? 1988 Aug 43

Hypoxic-ischemic brain damage often results from a combination of cardiogenic and respiratory failure. Whether or not hypoxia in the absence of ischemia is injurious to the brain has been a topic of research. An example of hypoxia without ischemia is found in obstructive sleep apnea (OSA), which causes recurrent nocturnal oxygen desaturations. Furthermore, it is a pervasive problem in the general population, particularly in people with common disorders such as obesity or diabetes. Mounting evidence in the past decade indicates that cerebrovascular disease, specifically stroke, and neurobehavioral consequences, including excessive daytime sleepiness and cognitive deficits, are prevalent in people with OSA, at great costs to the individual well-being, public health, and the economy. Investigation of the two disease associations poses similar and unique challenges. Predictors of these sequelae need to be better defined. The apnea-hypopnea index, the most common measure of OSA, has proven to be variably related to stroke and cognitive impairment. The role of individual markers, whether they are comorbidities or differences in inherent cognitive reserve, also is incompletely understood. This review discusses the burgeoning literature on the neurological and neurobehavioral sequelae of OSA and highlights the future avenues of research in the field.
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PMID:Neurological and neurobehavioral sequelae of obstructive sleep apnea. 2013 Mar 57

Breathing-disordered states, such as in obstructive sleep apnea, which are cyclical in nature, have been postulated to induce neurocognitive morbidity in both pediatric and adult populations. The oscillatory nature of intermittent hypoxia, especially when chronic, may mimic the paradigm of ischemia-reperfusion in that tissues and cells are exposed to episodes of low and high O(2) and this may lead to oxidant stress. Therefore, we decided to explore the potential contribution of oxidant stress in our intermittent hypoxia/hypercapnia animal model and the role that mitochondria might play in this stress. Neonatal mice were exposed to intermittent hypoxia/hypercapnia for 10 days and 2 wk. Combined intermittent hypoxia/hypercapnia led to a marked increase in apoptotic cell death in the cerebral cortex. Oxygen consumption studies in isolated mitochondria from intermittent hypoxia/hypercapnia-exposed brains demonstrated significant reductions in both state 4 and state 3 respiratory activities by approximately 60% and 75%, respectively. Electron paramagnetic resonance spectroscopy registered a significant increase in superoxide production during nonphosphorylating state 4 by 37%, although superoxide leakage during state 3 did not increase upon treatment. Neuronal superoxide-specific dihydroethidium oxidation was also greater in exposed animals. These studies indicate that intermittent hypoxia/hypercapnia leads to oxidative stress due to mitochondrial response within the mouse central nervous system.
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PMID:Neuronal death during combined intermittent hypoxia/hypercapnia is due to mitochondrial dysfunction. 2035 79

Patients with obstructive sleep apnea are at risk of respiratory and cardiovascular complications (e.g. hypoxia, hypertensive crisis, cardiac ischemia and arrhythmias) as a result of airway callapse during the perioperative period. Therefore it is essential that the nasal continuous airway pressure (nCPAP-therapy) be maintained during that time. Such patients and the medical staff should be aware of this problem.
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PMID:[Risk of interrupting nocturnal nasal continuous positive airway pressure (nCPAP) in patients with obstructive sleep apnea]. 2040 7

Sleep disordered breathing, especially obstructive sleep apnea, are common in cardiovascular disease. Negative hemodynamic effects are mediated by nocturnal ischemia and intrathoracal pressure swings. Therefore "therapy resistant" arterial hypertension and congestive heart failure, as well as atrial fibrillation or sleep associated bradycardia are suggestive of sleep disordered breathing. Further on, clinical course of coronary artery disease seems to be influenced by nocturnal breathing disorders. Application of continuous positive airway pressure (CPAP) is effective in most of the patients and attenuates cardiodepressive hemodynamic effects of obstructive sleep apnea.
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PMID:[Cardiac effects of obstructive sleep apnea]. 2057 39

Chronic intermittent hypoxia (CIH) is thought to be responsible for the cardiovascular disease associated with obstructive sleep apnea (OSA). Increased sympathetic activation, altered vascular function, and inflammation are all putative mechanisms. We recently reported (Tamisier R, Gilmartin GS, Launois SH, Pepin JL, Nespoulet H, Thomas RJ, Levy P, Weiss JW. J Appl Physiol 107: 17-24, 2009) a new model of CIH in healthy humans that is associated with both increases in blood pressure and augmented peripheral chemosensitivity. We tested the hypothesis that exposure to CIH would also result in augmented muscle sympathetic nerve activity (MSNA) and altered vascular reactivity contributing to blood pressure elevation. We therefore exposed healthy subjects between the ages of 20 and 34 yr (n = 7) to 9 h of nocturnal intermittent hypoxia for 28 consecutive nights. Cardiovascular and hemodynamic variables were recorded at three time points; MSNA was collected before and after exposure. Diastolic blood pressure (71 +/- 1.3 vs. 74 +/- 1.7 mmHg, P < 0.01), MSNA [9.94 +/- 2.0 to 14.63 +/- 1.5 bursts/min (P < 0.05); 16.89 +/- 3.2 to 26.97 +/- 3.3 bursts/100 heartbeats (hb) (P = 0.01)], and forearm vascular resistance (FVR) (35.3 +/- 5.8 vs. 55.3 +/- 6.5 mmHg x ml(-1) x min x 100 g tissue, P = 0.01) all increased significantly after 4 wk of exposure. Forearm blood flow response following ischemia of 15 min (reactive hyperemia) fell below baseline values after 4 wk, following an initial increase after 2 wk of exposure. From these results we conclude that the increased blood pressure following prolonged exposure to CIH in healthy humans is associated with sympathetic activation and augmented FVR.
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PMID:Chronic intermittent hypoxia in humans during 28 nights results in blood pressure elevation and increased muscle sympathetic nerve activity. 2058 Oct 89

In children with sickle cell disease (SCD), adenotonsillar hypertrophy or recurrent tonsillitis are frequently linked with an increased risk of obstructive sleep apnea, cerebrovascular ischemia, or frequent pain episodes and often require an adenoidectomy and/or tonsillectomy. Interventions designed to prevent these complications, control vaso-occlusive pain episodes, and avoid hospitalizations may reduce the significant personal and economic burden of SCD. This study compares episode recurrence and treatment costs for cerebrovascular ischemia, vaso-occlusive pain, acute chest syndrome (ACS), and obstructive sleep apnea in children who had an adenotonsillectomy (A/T surgery, N = 256; 11.7%) and a matched cohort of those who did not (N = 512; 23.3%) from a cohort of 2,194 children and adolescents with SCD from South Carolina's Medicaid system. A/T surgery was associated with a significantly reduced rate of visits over time for obstructive sleep apnea and cerebrovascular ischemia (e.g., stroke, transient ischemic attacks), but not with any change in the rate of visits for vaso-occlusive pain or ACS/pneumonia visits. The rate of mean acute (emergency and inpatient) service costs was significantly decreasing over time after an increase about the time the A/T surgery was performed. The cost-effectiveness of adenoidectomy and/or tonsillectomy for treating obstructive sleep apnea and preventing cerebrovascular ischemia without increasing vaso-occlusive pain episodes or long-term acute service costs in routine clinical practice settings was demonstrated. The matched control group of SCD patients without A/T surgery contained more patients with severe vaso-occlusive pain episodes, ACS visits, and higher mean total costs over time and appears to represent a different phenotype of children with SCD.
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PMID:Cost-effectiveness of adenotonsillectomy in reducing obstructive sleep apnea, cerebrovascular ischemia, vaso-occlusive pain, and ACS episodes in pediatric sickle cell disease. 2071 23

Common, noncentral nervous system medical conditions linked with cognitive impairment in adults and the elderly include: acute respiratory distress syndrome; cancer; chronic kidney disease; chronic obstructive pulmonary disease; coronary heart disease; hypertension; obesity (bariatric surgical candidates); obstructive sleep apnea; and type 2 diabetes. Cross-condition comparison of the nature and frequency of cognitive impairment is difficult as these conditions often coexist, and there exists no consensus as to the definition of cognitive impairment, nor the optimal number and type of neuropsychological tests required for evaluation. There is as yet no clear evidence for condition-specific profiles of cognitive impairment. Rather, a generalized profile consisting of subclinical levels of impairment in attention, processing speed, executive, and memory functions from bilateral frontal-subcortical ischemia fits across all conditions. This profile: occurs only in subgroups of patients; is inconsistently related to measures of illness severity; is unrelated to patient self-report or level of functional independence; is exacerbated by very high levels of emotional distress; and is reversible in some cases but can also progress to frank neurological disease (dementia) in others, especially the elderly, when multiple conditions coexist, and/or when medical condition severity progresses.
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PMID:Cognitive impairment in common, noncentral nervous system medical conditions of adults and the elderly. 2121 18

Obstructive sleep apnea (OSA) is associated with hypertension (HTN) and cardiovascular disease. Transient episodes of hypoxia, hypercapnia, and blood pressure elevation during OSA may lead to neural damage and subsequently white matter disease (WMD). As WMD is usually the result of chronic small vessel ischemia, a relationship between OSA and cerebrovascular disease may exist. This case series aimed to establish a relationship between OSA and WMD. Sixty-two patients without cerebrovascular disease who had both a polysomnogram and brain magnetic resonance imaging were identified. All patients carried the diagnosis of HTN. WMD was evaluated using the age-related white matter changes scale. Although half of the study population had WMD on magnetic resonance imaging, no association was found between WMD with severity of OSA (P=0.9). Our results are limited by the small sample size and by coexistent HTN in all patients. Further studies are needed to elucidate the relationship between OSA and WMD, especially among nonhypertensive patients. Future research should also address if OSA treatment has any effect on WMD.
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PMID:Sleep apnea and white matter disease in hypertensive patients: a case series. 2188 75


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