Metabolic and respiratory effects of continuous and discontinuous lipid infusions. Occurrence in excess of resting energy expenditure.

Intravenous hyperalimentation with dextrose can be associated with adverse respiratory and hepatic effects. The purpose of this study was to determine the respiratory and metabolic consequences of fat calories in excess of resting energy expenditure provided both continuously and discontinuously. No significant changes in respiratory mechanics, oxygen consumption, carbon dioxide production, resting energy expenditure, serum substrates, liver function, or nitrogen balance were noted by the addition of 500 kcal of lipid emulsion to dextrose calories sufficient to meet energy requirements. The respiratory quotient declined significantly with the 12- and 24-hour lipid infusions, but persisted for the entire 24 hours only in the latter instance. The sustained and increased (46% v 36%) oxidation of lipid with a 24-hour infusion suggests that a continuous infusion of lipid is preferable to a discontinuous infusion.