Manometrics for preterm and term infants: a new tool for old questions

The purpose of this study was to use low-compliance, continuous-perfusion manometry to assess motor activity responses of preterm and term infants to three different methods of feeding commonly used in neonatal intensive care units.

All 48 infants who participated in this study were assigned to one of three feeding trials using a 20-calorie/oz formula. Trial 1 varied the mode of feeding, trial 2 varied the volume of feeding, and trial 3 varied the concentration of feeding.

In trial 1, small intestinal motor activity changed similarly and significantly in response to intragastric (P < .005) and transpyloric feeding (P < .02). In trial 2, feeding containing a small volume (4 mL/kg) and a larger volume (10 mL/kg) elicited significant changes in motor activity compared to that seen during fasting (P < .005). In trial 3, motor activity differed in response to varying caloric density. Motor activity failed to change in response to feedings that contained one-third-concentration formula, but it did change in response to the feedings that contained two-thirds- and full-concentration formula (P < .02). Furthermore, the onset of the motor response to feeding was inversely related to the concentration of formula (P < .01), and the duration of the fed response also was related to the concentration of formula (P < .01).

Gastric and transpyloric feedings are equally potent in eliciting an intestinal motor response to feeding. Furthermore, a volume as small as 4 mL/kg is sufficient to elicit such a response. However, preterm intestinal motility responses are affected significantly by changes in the caloric density of formula, suggesting that diluted formula may not provide an optimal stimulant for the preterm intestinal functional responses to feeding.