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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Central sleep apnea is a disorder characterized by apneic episodes during sleep with no associated ventilatory effort. More commonly than not these apneas are seen in patients who also have obstructive and mixed events. Although patients with this disorder frequently complain of insomnia and depression, frank hypersomnolence is rarely encountered. As these complaints are common ones seen in numerous clinical situations, and since sleep studies are rarely conducted to investigate their etiology, the true incidence of central sleep apnea has not been determined. The etiology of central apnea remains unknown, although the association between these breathing events and a number of other disease processes has increased our understanding of the disorder. Central apneas during sleep commonly occur after hyperventilation with the associated hypocapnic alkalosis. This occurs at high altitude when hyperventilation is induced by hypoxia and at sea level when spontaneous nocturnal hyperventilation occurs. This suggests that PCO2 is the primary stimulus to ventilation during sleep and that loss of this drive, as occurs with hypocapnia, may produce dysrhythmic breathing. Patients with complete absence of ventilatory chemosensitivity such as occurs with Ondine's curse (central alveolar hypoventilation) or the obesity-hypoventilation syndrome may also have central apneas. For reasons that remain unexplained, central sleep apnea is commonly seen in patients with congestive heart failure, nasal obstruction, and certain neurologic disorders. However, in most patients with central sleep apnea no obvious cause or association can be found. The treatment of this disorder is not entirely satisfactory. If it is severe, mechanical ventilation during sleep can be provided by any one of a number of techniques. However, for the patient who simply complains of insomnia and is found to have a moderate number of central apneas, the treatment choices are limited. Acetazolamide has been shown to decrease central apneas during short-term use, but results have been variable with prolonged administration. Other ventilatory stimulants seem to have little efficacy. Interestingly, oxygen administration has been shown to reduce central apneas considerably in a number of studies, although the explanation for its success is unknown. Central sleep apnea therefore remains a relatively rare disorder whose etiology is not fully understood and whose treatment is not completely satisfactory.
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PMID:Central sleep apnea. 393 82

Although often coexisting in the same patient, obesity and essential hypertension exert disparate cardiovascular effects. An excess of adipose tissue augments cardiac output, stroke volume, and left ventricular filling pressure, expands intravascular volume, and lowers total peripheral resistance. In contrast, essential hypertension in a non-obese patient is associated with a contracted intravascular volume, high total peripheral resistance, and normal cardiac output, but increased left ventricular stroke work due to high afterload. Left ventricular adaptation will consist of eccentric hypertrophy in the obese (irrespective of arterial pressure) and concentric hypertrophy in the non-obese hypertension patient. The combination of obesity and hypertension burdens the heart with high preload and high afterload, thereby greatly enhancing the risk of congestive heart failure. Peripheral resistance and intravascular volume may be normal in mildly hypertension obese patients because of the mutually antagonising effects of the increase in arterial pressure and the increase in body weight. The fall in arterial pressure associated with weight loss seems to be caused by a decrease in adrenergic activity which leads to a fall in cardiac output without change in vascular resistance. Obesity hypertension may be the result of an inappropriately raised cardiac output in the presence of a relatively restricted arterial capacity due to the low vascularity of adipose tissue. In morbid obesity increased blood viscosity may contribute to the raised arterial pressure.
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PMID:Cardiovascular effects of obesity and hypertension. 612 45

The relationship between the degree of obesity and the incidence of cardiovascular disease (CVD) was reexamined in the 5209 men and women of the original Framingham cohort. Recent observations of disease occurrence over 26 years indicate that obesity, measured by Metropolitan Relative Weight, was a significant independent predictor of CVD, particularly among women. Multiple logistic regression analyses showed that Metropolitan Relative Weight, or percentage of desirable weight, on initial examination predicted 26-year incidence of coronary disease (both angina and coronary disease other than angina), coronary death and congestive heart failure in men independent of age, cholesterol, systolic blood pressure, cigarettes, left ventricular hypertrophy and glucose intolerance. Relative weight in women was also positively and independently associated with coronary disease, stroke, congestive failure, and coronary and CVD death. These data further show that weight gain after the young adult years conveyed an increased risk of CVD in both sexes that could not be attributed either to the initial weight or the levels of the risk factors that may have resulted from weight gain. Intervention in obesity, in addition to the well established risk factors, appears to be an advisable goal in the primary prevention of CVD.
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PMID:Obesity as an independent risk factor for cardiovascular disease: a 26-year follow-up of participants in the Framingham Heart Study. 621 30

Hypertension and obesity frequently coexist in the same patient. However, the two disorders disparately affect cardiovascular function and structure. The presence of obesity significantly affects hypertensive target organ involvement. On one hand, obesity may tend to mitigate the harmful effects of a chronically elevated total peripheral and renal vascular resistance and lessen end-organ damage such as nephrosclerosis in essential hypertension. However, since both obesity and hypertension increase cardiac workload, although by different mechanisms, their presence in the same patient results in a double burden to the left ventricle. Congestive heart failure, sudden death, and coronary heart disease are common sequelae of obesity hypertension. Weight loss reduces arterial pressure by a decrease in intravascular volume and cardiac output associated with a fall in sympathetic activity. Intervention in obesity hypertension diminishes the dual hemodynamic burden imposed on the heart and becomes therefore a major objective in the prevention and treatment of heart disease.
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PMID:Obesity in hypertension: how innocent a bystander? 623 45

Using compartmental analysis techniques, we modeled the biodistribution of Tc-99m(Sn)methylene diphosphonate in humans on a computer, and by selectively perturbing appropriate rate constants, we simulated changes in contrast between bone and soft tissue in a number of systemic disorders. The model predicts low contrast in patients with moderate to marked edema, obesity, congestive heart failure or decreased cardiac output states and high contrast with as little as 25% increase in bone avidity for the tracer. In acute renal failure without fluid-volume imbalance, image contrast should be normal. The model predicts greater contrast shortly after injection in patients with increased cardiac output, skeletal blood flow, or bone avidity; images made at these times would be indistinguishable. These simulations are in keeping with reports in the literature of bone images and bone-to-soft tissue ratios in many of these conditions, suggesting that modeling studies could play an important role image interpretation.
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PMID:Studies in skeletal tracer kinetics. V: Computer-simulated Tc-99m (Sn)MDP bone-scan changes in some systemic disorders: concise communication. 645 64

Because of recent heightened epidemiologic interest in persons with very low cholesterol levels, we compared men and women at the lowest and middle deciles of plasma cholesterol in a large population study for multiple sociologic, biologic, and medical attributes. Two sex-specific age groups were studied, 30-54 years and 55-79 years. In general, comparisons between deciles for each of these four age-sex groups revealed only minor differences for demographic variables; systolic or diastolic blood pressure; fasting plasma glucose; weight; height; obesity; cigarette smoking; dietary eggs or milk; medications for hypertension, hyperglycemia, hyperuricemia, or hyperlipidemia; family history of myocardial infarction, diabetes, or stroke; and personal history of myocardial infarction, congestive heart failure, hypertension, or stroke. Thus, the lowest and the middle deciles of plasma cholesterol in this population shared similar sociologic, biologic, and medical profiles. One unexpected finding was somewhat more diabetics in the lowest decile , and greater obesity and triglyceride levels in the lowest decile diabetics compared to either lowest decile non-diabetics or middle decile diabetics, perhaps suggesting a metabolically distinct subset.
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PMID:Characteristics of persons with marked hypocholesterolemia. A population-based study. 671 3

A new risk classification for patients undergoing cardiac surgery has been used for the last two years by the anaesthesiologists of the Montreal Heart Institute. The following factors known to be associated with a greater operative morbidity and mortality were selected: (1) poor left ventricular function, (2) congestive heart failure, (3) unstable angina or recent (less than 6 weeks) myocardial infarction, (4) age over 65 years, (5) severe obesity (Body Mass Index greater than 30), (6) reoperation, (7) emergency surgery, (8) other significant or uncontrolled systemic disturbances. Patients with none of the above factors were classified as normal risks; those presenting with one of those selected factors were classified as increased risks, and those with more than one factor were said to carry a high risk. In a prospective study of 500 consecutive open-heart surgery patients classified according to this method, we found that the operated population at normal risk (50 per cent of cases) had a mortality of 0.4 per cent, the patient group with increased risk (32 per cent of cases) had a mortality of 3.1 per cent, and the high risk group (18 per cent of cases) had a 12.2 per cent mortality. Furthermore, 50 deaths following open-heart surgery were assessed retrospectively using the classification; 58 per cent of these patients were classified as high risk, 34 per cent had an increased risk, and only eight per cent were found to be in the normal risk group. Thus, this new risk classification has proven to be a reliable and useful tool for preoperative assessment of patients undergoing open-heart surgery and for teaching purposes.
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PMID:A simple classification of the risk in cardiac surgery. 682 88

The effect of obesity on the total body clearance (Cltot) of theophylline was evaluated in nonsmokers and smokers with and without congestive heart failure (CHF). The obese patients were compared with similar nonobese subjects with regard to age, sex, and disease state. The total patient population numbered 150 adults. Cltot of theophylline, based on total body weight (TBW), averaged 0.60 +/- 0.20 ml/min/kg in obese nonsmokers and did not differ from the nonobese, nonsmoking group. In obese nonsmoking patients with CHF, Cltot based on TBW was 0.40 +/- 0.14 ml/min/kg, which was similar to Cltot values in nonsmoking CHF patients who were not obese. A trend toward a reduction in Cltot, based on TBW, as TBW increased, in nonsmoking patients with and without CHF, was observed. In contrast to the Cltot in nonsmokers, the Cltot of theophylline in obese smokers with and without CHF was similar to the Cltot values in nonobese populations only when based on ideal body weight. However, when compared with nonsmoking, nonobese patients, no differences were observed when Cltot was corrected for TBW. These findings suggest that theophylline maintenance dose can be based on TBW in obese patients who are smokers and nonsmokers (with and without CHF), using the average Cltot obtained for the nonsmoking patients with and without CHF.
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PMID:Theophylline clearance in obese patients in relation to smoking and congestive heart failure. 683 57

Left ventricular hypertrophy (LVH), an increase in the muscle mass of the left ventricle, has been identified as a powerful risk factor for future cardiovascular morbidity and mortality. The risk of acute myocardial infarction, congestive heart failure, sudden death, and other cardiovascular events increases sixfold to eightfold with the occurrence of LVH. The increase in myocardial mass lowers coronary reserve and enhances cardiac oxygen requirements, gives rise to ventricular ectopy, and impairs left ventricular filling and contractility. Hypertension, obesity, advanced age, valvular heart disease, and other pathologic disorders that cause an increase in the hemodynamic burden can lead to LVH. LVH and its sequelae can be reduced by specific antihypertensive therapy, but despite these promising findings, future epidemiologic studies are necessary to document the clinical benefits of a reduction in LVH.
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PMID:Left ventricular hypertrophy: a pressure-independent cardiovascular risk factor. 750 40

The management of essential hypertension can no longer be directed toward an isolated reduction in arterial pressure. Optimal reduction in the risk factors associated with hypertension and cardiovascular disease hopefully will reduce coronary heart disease, angina, fatal and nonfatal myocardial infarction, left ventricular hypertrophy, congestive heart failure, and sudden death. Hypertension is a genetic and acquired syndrome that consists of dyslipidemia, insulin resistance and carbohydrate intolerance, central obesity, renal abnormalities, structural abnormalities of smooth muscle, and ion transport abnormalities (membranopathy). The selection of pharmacologic agents should improve the components of the hypertensive syndrome by utilizing the "subsets of hypertension approach" to treatment.
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PMID:The management of hypertension and associated risk factors for the prevention of long-term cardiac complications. 769 47


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