Clinical and investigative medicine. Médecine clinique et experimentale
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The urine osmolal gap is defined as the difference between measured urine osmolality and the sum of the concentrations of sodium, potassium, chloride, bicarbonate, urea and glucose. Normally, this gap is 80-100 mosmol/kg H2O. ⋯ For example, with "hybrid" metabolic acidosis, a low urine osmolal gap will suggest the absence of excessive organic aciduria (ketoacidosis) and the basis of the normal anion gap type of acidosis will be determined by the urine anion gap or "net charge". Where "hybrid" metabolic acidosis has occurred due to wide anion gap metabolic acidosis with loss of organic acid anion in the urine, the urine osmolal gap will be high and can be used in a semi-quantitative fashion to estimate the sum of urinary ammonium plus ketone body anion concentrations.
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To test the hypothesis that the reduction of ventilatory response to CO2 during nasal breathing of cold air is due to cooling of the hypothalamus, four adult male volunteers breathed either cold air (3 degrees C) or warm air (33 degrees C) through the nose by means of a face mask. Ventilation was increased to a mean of 30 l/min by increasing inspired CO2 concentration, which was adjusted so as to match ventilation in the two conditions. Cold air through the nose reduced the ventilatory response to CO2 so that with cold, higher inspired CO2 concentrations were required to produce the same ventilation as during warm air breathing. ⋯ A hand immersion water calorimeter was used to measure the peripheral vascular response to hypothalamic regulatory changes. There was no measurable change in hand heat loss, rectal, or tympanic membrane temperature. This suggests that the depressant effect of cold air breathing is mediated by skin and mucosal temperature receptors connected to the respiratory centres rather than by direct cooling of the hypothalamus.
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In order to provide information for decision making regarding urolithiasis treatment programs for the population of the Central West Region (population 1.8 million) of Ontario, we conducted an incremental cost-effectiveness analysis of standard surgery, percutaneous ultrasonic lithotripsy, and extracorporeal shock wave lithotripsy for the removal of renal and ureteric stones. Estimates of costs and effects were calculated for a 5-year period, beginning in 1985. Direct medical costs estimated were fees, both professional and technical, operating costs, and hospitalization costs for standard surgery, percutaneous ultrasonic lithotripsy, and extracorporeal shock wave lithotripsy. ⋯ At 400 procedures per year, the cost of each disability day averted by extracorporeal shock wave lithotripsy, compared to percutaneous ultrasonic lithotripsy, is $35.60. At 500 procedures per year, extracorporeal shock wave lithotripsy costs less and generates fewer disability days than percutaneous ultrasonic lithotripsy and is therefore the desired alternative. Sensitivity analyses demonstrate that cost effectiveness results are most affected by the number of procedures performed, the length of stay, and the number of disability days generated.
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Historical Article
Medicine and the two cultures: science and humanism in medicine.
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A major nonrespiratory function of the mammalian lung is that of a polymorphonuclear leukocyte reservoir. Within this reservoir, granulocytes are distributed between marginating and circulating pools. Under normal conditions these cells release little, if any, toxic metabolites. ⋯ Nevertheless, adult respiratory distress syndrome does arise under conditions facilitating chemotactic factor release from macrophages (e.g. hyperoxia), in situations where widespread activation of complement occurs (e.g. sepsis, trauma, microemboli), and in shock conditions where pulmonary blood flow is often lowered. Correlations exist between adult respiratory distress syndrome and activation of complement, acute neutropenia, sequestration of polymorphonuclear leukocytes and enhanced functional and metabolic activity of granulocytes. Although these findings suggest that polymorphonuclear leukocytes are an important factor in the pathogenesis of adult respiratory distress syndrome, its precise role remains to be determined.