Effects of fat emulsion on O2 transport and alveolar-arterial gas tensions

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Abstract
Ten dogs were made progressively hypoxic by rebreathing from an air-filled spirometer. Arterial blood samples were drawn at five levels of alveolar Po2 (100, 70, 55, 40, and 25 mm Hg), as well as samples before and after the hypoxia for O2-capacity determinations. Half the animals then were given 25 ml/kg of fat emulsion intravenously and the others were given the same amount of dextran. The same sampling procedure was repeated and the blood was analyzed for O2 content. In separate experiments, the same procedure was followed for five dogs but only fat emulsion was given and the arterial blood was analyzed for Po2 and Pco2. Oxyhemoglobin dissociation curves were constructed from the values of saturation at progressively falling alveolar o2. These were transformed into a linear equation by the Hill equation and treated statistically. No significant differences were found between any of the comparisons of slope or displacement. It was concluded that lipemia offered no practical hindrance to the uptake of O2 by the red cell. Alveolar-arterial gas tension differences revealed no change after intravenous fat emulsion in the Po2 difference, but there was a threefold increase in the Pco2 difference. Submitted on June 12, 1961