The effect of different types of nutrition on the gastrointestinal response of the preterm infant

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[Truncated] Background: Delayed gastric emptying is a common complication in preterm infants and may indicate the onset of feeding intolerance or serious disease such as necrotizing enterocolitis. Feed composition and intragastric curding are thought to impact gastric emptying, and pasteurized donor human milk (PDHM) is used in the absence of mother’s own milk (MOM) although the effect of their differing compositions on gastric emptying is not known. A thorough examination of gastric emptying and curding in response to feeds of differing compositions is essential to the advancement of knowledge and management of preterm nutrition, yet there have been no validated methods available to achieve this.

Aims: In this study we aimed to validate a sonographic method of measuring stomach volume and identifying the echogenic characteristics of breastmilk feeds, and to determine intra-individual repeatability. We then evaluated the effects of feed composition on gastric emptying and curding in preterm infants, specifically with regard to unfortified and fortified mother’s own milk (MOM) and pasteurized donor human milk (PDHM).

Methods: To determine the accuracy of ultrasound in measuring stomach volume, we studied 24 stable preterm infants born <34 weeks gestation that were receiving breastmilk feeds via an intragastric tube. Infants were monitored during a single intragastric tube feed with two stomach ultrasound images and one antral cross-sectional area (ACSA) image recorded when 50, 75 and 100% of the feed was delivered. Image measurements were used to calculate ACSA and stomach volume using three different methods. Raw measurements, ACSA and volume calculations were tested for intra- and inter-rater agreement. Calculated stomach volumes and ACSA were compared to delivered feed volumes, with echogenic characteristics of stomach images graded at each time point.

To determine the repeatability of sonographic stomach volume calculations and ratings of echogenicity and gastric curding 20 preterm infants were studied. Paired feeds of identical composition and volume (n=29) were monitored pre and post feed and every 30 minutes thereafter. Statistical comparisons of paired stomach volume calculations and agreement between echogenicity and curding ratings were made for each time point.

The influence of biochemical and energy concentrations as well as fortification on gastric emptying of MOM was studied in 25 preterm infants. Paired feeds of MOM +/- human milk fortifier (HMF) were monitored pre and post feed and at 30 minute intervals with two differing HMF compared; S-26 (casein and whey, n=8) and FM 85 (whey only, n=17). Influences of infant and feed characteristics were also explored. MOM samples from each feed were analysed to determine concentrations of total protein, casein, whey, lactose, fat, and energy. Fortified feed compositions were calculated using unfortified MOM and HMF biochemical and energy concentrations.

To investigate whether PDHM differed from MOM with respected to gastric emptying paired feeds of unfortified and FM 85 fortified PDHM (n=15) and MOM (n=17) were examined with ultrasound (gastric volume and curding) as previously described. The influence of biochemical and energy concentrations, HMF, infant and feed characteristics were again explored.


Original languageEnglish
QualificationDoctor of Philosophy
Publication statusUnpublished - 2015


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