Rate and volume of intermittent enteral feeding

The purpose of this investigation was to determine the effects of the volume of enteral feedings and the rate at which they were administered on subject tolerance and gastric pressure changes. Fourteen normal volunteers received enteral feedings on 9 or 10 separate days. These feedings (Ensure) were administered in combinations of 3 volumes (250, 350, and 500 ml) and of 2 rates (30 and 85 ml/min). The effect on gastric motility was monitored by an open-tipped catheter. Nine of the subjects also received 750 ml administered at 30 ml/min. Six of the 14 subjects experienced nausea and/or discomfort during the first feeding trial (250 ml at 30 ml/min); however, subsequent feedings were tolerated without this discomfort. The rate at which feedings were administered had little effect on the time following feeding until the return of regular motility or on the mean motility index when 250 ml were administered; however, when larger volumes were administered at the faster rate, longer time was taken for the return of regular motility. Feedings administered at the faster rate were associated with a greater number of subjective complaints of abdominal discomfort, nausea, fullness, and cramping. The volume of a feeding has a significant effect on both the time required for regular motility to return following feeding and on the mean motility index, with the larger feeding volumes suppressing activity progressively longer. The volume of feeding (up to 750) ml) had little effect upon symptomatic tolerance of subjects when these feedings were administered at 30 ml/min. There was no significant interaction effect of rate and volume on the time required for motility to return following feedings. The results of this study indicate that normal subjects can tolerate bolus feedings of (250-750 ml) administered at 30 ml/min without distress. Additional studies are needed to compare bolus and continuous feedings in relation to patient tolerance, gastric emptying, and nutritional outcome.