American Journal of Clinical Nutrition, Vol 40, 116-130, Copyright © 1984 by The American Society for Clinical Nutrition, Inc

ORIGINAL RESEARCH COMMUNICATIONS

Respiratory, cardiovascular, and metabolic effects of enteral hyperalimentation: influence of formula dose and composition

SB Heymsfield, CA Head, CB McManus 3d, S Seitz, GW Staton and GD Grossman

Respiratory, cardiovascular, and metabolic changes were monitored during balance studies in undernourished patients receiving continuous enteral formula feeding. The nutrient solutions, either high carbohydrate (83% of kcal) or high fat (50% of kcal), were administered at doses ranging from 2.7 to 6.0 X 10(-2) kcal X kg fat free body mass- 1 X min-1. For both formulas, the observed physiological changes between fasting and the lower rates of energy infusion (ie, maintenance- slow growth) were either zero or relatively small. As formula dose was advanced into the rapid repletional range, physiological changes were more pronounced; there were linear increases in oxygen consumption, carbon dioxide production, minute ventilation, heat production, heat release, nitrogen balance, and change in heart rate from the base-line (all p less than 0.05 for both formulas). The rate at which carbon dioxide production, minute ventilation, and heat production increased with advancing energy infusion rate was also greater for the high carbohydrate formula relative to the high fat formula (p less than 0.02, less than 0.07, and less than 0.06, respectively). The physiological changes caused by continuous intragastric feeding are therefore a function of formula infusion rate and composition. Knowledge of these changes can be applied to patients treated for semistarvation who suffer respiratory or cardiac insufficiency.