Canadian Medical Association journal
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The mixed venous carbon dioxide tension (PVCO2) can be measured at the bedside by a rebreathing equilibrium technique that is quick, simple and noninvasive. Only one brief period of rebreathing is required. The technique is accurate even when the lungs are not normal, and gives a graphic record that allows verification of the accuracy of the estimate. ⋯ When the cardiac output is abnormal, measurement of both PaCO2 and PvCO2 is useful in determining how much the cardiac output is reduced. Consideration of the relation between oxygen consumption and carbon dioxide production suggests that the equation PaCO2 = 0.8 PVCO2 - 12 indicates a reduction in cardiac output that may impair the oxygen supply to tissues. Simple corrections can be applied to allow for variations in arterial oxygen saturation and hemoglobin concentration that will affect this relationship.
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Biography Historical Article
Sir Andrew Macphail: physician, philosopher, founding editor of CMAJ.
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Confusional states in the elderly are not uncommon and demand a high level of diagnostic and therapeutic skills in the physician. An immediate requirement is to provide protection and care while the cause is being elucidated. ⋯ Confusion may be due to disorder in various body systems with effects on the brain, or to a primary brain disorder. Careful evaluation of general health and also of cognitive, affective and social factors is necessary to clarify diagnosis and management.
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Three cases are described in which Stevens-Johnson syndrome progressed in the course of a few days to toxic epidermal necrolysis. Trimethoprim-sulfamethoxazole, allopurinol in combination with hydrochlorothiazide, phenytoin and possibly ampicillin were implicated in the causation of the disease.