The New England journal of medicine
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In normal subjects, chronic hyperventilation lowers plasma bicarbonate concentration, primarily by inhibiting the urinary excretion of net acid. The quantitative relation between reduced arterial carbon dioxide tension (PaCO2) and the plasma bicarbonate concentration in the chronic steady state has not been studied in humans, however, and the laboratory criteria for the diagnosis of chronic respiratory alkalosis therefore remain undefined. We wished to provide such reference data for clinical use. Moreover, because chronic hyperventilation paradoxically lowers blood pH still further in dogs with metabolic acidosis, we desired to study the effect of chronic hypocapnia on the plasma bicarbonate concentration (and blood pH) in normal human subjects in whom acidosis had been induced with ammonium chloride. ⋯ These results provide reference data for the diagnosis of chronic respiratory alkalosis in humans. Although chronic hypocapnia decreased plasma bicarbonate levels similarly in normal subjects with acidosis and without acidosis, the percent reduction in PaCO2 was always greater than the corresponding percent reduction in the plasma bicarbonate concentration. Therefore, as was not true of the response in dogs, the subjects' blood pH always increased with hyperventilation, regardless of the initial plasma bicarbonate concentration.
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Although even in the elderly most falls are not associated with fractures, over 90 percent of hip fractures are the result of a fall. Few studies have assessed whether the risk factors for falls are also important risk factors for hip fracture. ⋯ A number of factors that have been identified as risk factors for falls are also associated with hip fracture, including lower-limb dysfunction, neurologic conditions, barbiturate use, and visual impairment. Given the prevalence of these problems among the elderly, who are at highest risk, programs to prevent hip fracture should include measures to prevent falls in addition to measures to slow bone loss.
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Randomized Controlled Trial Multicenter Study Clinical Trial
A randomized clinical study of a calcium-entry blocker (lidoflazine) in the treatment of comatose survivors of cardiac arrest. Brain Resuscitation Clinical Trial II Study Group.
Abnormalities of cellular calcium homeostasis have been implicated in the pathophysiology of postischemic encephalopathy. Calcium-entry-blocking drugs inhibit the influx of calcium into cells and have been shown to mitigate postischemic encephalopathy in animal models. ⋯ The administration of lidoflazine after cardiac arrest was not found to be beneficial. Our data do not support the routine use of this calcium-entry-blocking drug in comatose survivors of cardiac arrest.
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To define the risk factors associated with neonatal acquisition of herpes simplex virus (HSV) infection, we prospectively obtained HSV cultures from the cervix and external genitalia of 15,923 pregnant women in early labor who were without symptoms or signs of genital HSV infection. Follow-up of the women with positive cultures for HSV and their HSV-exposed infants included serologic tests and serial cultures for HSV. ⋯ Of the asymptomatic women who shed HSV in early labor, about a third have recently acquired genital HSV, and their infants are 10 times more likely to have neonatal HSV than those of women with asymptomatic reactivation of HSV. The presence of maternal antibodies specific to HSV-2 but not HSV-1 appears to reduce the neonatal transmission of HSV-2. Further studies are necessary to determine whether screening and prophylactic treatment are warranted for infants of HSV-2-seronegative mothers who shed HSV-1 or HSV-2 in early labor.
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In 1983 the proportion of health care expenditures consumed by administration in the United States was 60 percent higher than in Canada and 97 percent higher than in Britain. To assess the effects of recent health policy initiatives on the administrative efficiency of health care, we examined four components of administrative costs in the United States and Canada for 1987: insurance overhead, hospital administration, nursing home administration, and physicians' billing and overhead expenses. Most data were provided by the two nations' federal health and statistics agencies, supplemented by state and provincial data and published sources. Because data on physicians' billing costs were limited, we estimated a range for these costs by two methods that rely on different sources of data. All figures are reported in 1987 U.S. dollars. ⋯ The administrative structure of the U.S. health care system is increasingly inefficient as compared with that of Canada's national health program. Recent health policies with the avowed goal of improving the efficiency of care have imposed substantial new bureaucratic costs and burdens.