How Should the Preterm Infant Grow?

How is bioelectrical impedance used in neonatal intensive care? A scoping review

Poor growth and nutrition management in the neonatal period can have a negative impact upon both the short- and long-term outcomes for the infant. Improvements in bioelectrical impedance technology and accompanying licencing agreements now make this enhanced device available for use in infants as small as 23 weeks gestational age. An exploration of this technology and its use is now timely. The aim of the scoping review was to answer the following question: in preterm and sick term infants in the neonatal intensive care unit, how is bioelectrical impedance being utilized, in what situations, and when? The scoping review was conducted using Arksey and O'Malley's (Int J Soc Res Methodol 8(1):19-32, 2005) framework. Forty-nine papers were initially identified and 16 were included in the scoping review. Three studies were experimental designs, and 13 were observational studies. The review found that BIA was used in neonatal intensive care in three main ways, for, (1) fluid status evaluation, (2) as a measure of adequate nutrition and growth, (3) to validate the technology as an outcome measure in neonates.

CONCLUSION

There is a paucity of recent robust research papers which investigate the use of bioelectrical impedance in preterm neonates. Available evidence spans a range of 30 years, with technological advancement reducing the application of older studies to the modern neonatal setting. Although this technology may be helpful for decision-making around fluid management and nutrition, in preterm infants, robust evidence is needed to demonstrate the clinical benefit of bioelectrical impedance beyond that of usual care.

WHAT IS KNOWN

• Clinical decisions regarding neonatal nutrition and fluid management are currently based upon the interpretation of vital signs, fluid balance, weight trend, biochemical markers, and physical examination. • Bioelectrical Impedance Analysis (BIA) is a non-invasive method of assessing body composition which is now available to be used in infants as small as 23 weeks gestation.

WHAT IS NEW

• Bioelectrical Impedance has been used in three main ways in the NICU, for fluid status evaluation, for measuring nutrition and growth and to validate BIA as an outcome. • There is a lack of recent robust research data to support the use of the device within clinical decision making in neonatal intensive care.

State of the evidence from clinical trials on human milk fortification for preterm infants

Infants born preterm or low birth weight are at risk for morbidity, mortality and later neuroimpairment. Appropriate early post-natal growth is associated with better outcomes in-hospital and post-discharge. Therefore, nutritional strategies that support growth may improve the long-term health of this population. Mother's milk with donor milk as a supplement are preferred sources of nutrition for these infants but may not always support growth, especially amongst infants born of very low birth weight (<1500 g) and or those with a major morbidity. Systematic reviews of randomised controlled trials to date demonstrate that multi-nutrient fortification of human milk improves in-hospital growth of preterm infants although data on long-term neurodevelopment are lacking. Further, individualised approaches to fortification based on milk analysis or the infant's metabolic response may improve growth over standard fortification. The evidence is insufficient to inform the timing of introducing fortifier, routine fortification of feeds post-discharge or routine use of fortifiers made from human instead of bovine milk. Importantly, there is insufficient data to determine if these fortification practices improve relevant clinical or neurodevelopmental outcomes. In sum, there is an urgent need for well-designed clinical trials to assess potential benefits and risks of fortification practices and at what cost.