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Relationship between nutrition, weight change, and fluid compartments in preterm infants during the first week of
R Heimler1, B T Doumas, B M Jendrzejczak
1Department of Pediatrics, Medical College of Wisconsin, Milwaukee.
Insights
Early weight loss in premature infants is linked to inadequate energy intake and extracellular fluid loss. Stable infants with sufficient energy intake experience minimal weight loss due to intracellular fluid expansion and potential growth.
Area of Science:
- Neonatal Physiology
- Pediatric Nutrition
- Body Fluid Balance
Background:
- Premature infants exhibit significant variability in early postnatal weight loss.
- Understanding fluid compartment shifts is crucial for managing neonatal health.
- Early weight loss can impact infant stability and long-term growth outcomes.
Purpose of the Study:
- To investigate fluid redistribution in preterm infants during the first week of life.
- To identify factors influencing the wide range of early postnatal weight loss.
- To differentiate fluid compartment changes between infants with high and low weight loss.
Main Methods:
- Studied 14 preterm infants at 1 and 7 days of age.
- Measured total body water (deuterium oxide), extracellular volume (bromide dilution), and intracellular volume.
- Grouped infants based on postnatal weight loss (>10% vs. <5% of birth weight).
Main Results:
- Significant decrease in extracellular volume and increase in intracellular volume observed within the first week.
- Infants with >10% weight loss showed reduced extracellular volume and no intracellular change.
- Infants with <5% weight loss had reduced extracellular volume and increased intracellular volume, with adequate energy intake.
- Lower energy intake and higher instability correlated with significant postnatal weight loss.
Conclusions:
- Significant postnatal weight loss in preterm infants is associated with extracellular compartment contraction.
- Inadequate energy intake and physiological instability contribute to substantial weight loss.
- Adequate energy intake supports intracellular compartment expansion, minimizing weight loss and potentially promoting growth.
Abstract:
This study was conducted to investigate the redistribution of fluid compartments and to examine the factors contributing to the variability of early weight loss in premature infants. Fourteen preterm infants (mean +/- SD: birth weight, 1473 +/- 342 gm; gestational age, 30.7 +/- 2.4 weeks) were studied at 1 and 7 days of age. Total body water was measured by deuterium oxide dilution, extracellular volume by bromide dilution, and intracellular volume by the difference between total body water and extracellular volume. There were significant changes in body fluid distribution per concurrent weight from birth to age 1 week. Extracellular volume decreased by 11%, and intracellular volume increased by 8.5% with no change in total body water. Infants were then grouped according to postnatal weight loss (group 1 (n = 7) > 10% and group 2 (n = 7) < 5% of birth weight). In group 1 there was a significant loss of both weight (mean +/- SD: 15.6% +/- 3.7%) and extracellular volume (15.9% +/- 9% of birth weight), with no change in intracellular volume. In group 2 there was no significant weight loss (1.4% +/- 1.8%), but a significant loss of extracellular volume (13.0% +/- 5.4% of birth weight) and a significant increase in intracellular volume. Other differences between the groups were a lower energy intake in group 1 than in group 2 (mean +/- SD: 177 +/- 46 vs 269 +/- 45 kilojoules/kg per day; p < 0.005) and a higher physiologic stability index in group 1 (p < 0.05). We conclude that significant postnatal weight loss as a result of the contraction of the extracellular compartment occurs only in less stable infants whose energy intake is inadequate. With adequate energy intake, weight loss is minimal because of the expansion of the intracellular compartment, which may be related to the onset of growth.