Objectives: The objectives of this study were to evaluate the feasibility of using multifrequency bioelectrical impedance spectroscopy (BIS) in newborns and first-semester infants and to assess the influence of diverse methodologic and biological factors on BIS measurements.
Methods: We studied 69 infants of both sexes, from the first day after birth through age 6 mo. They were healthy term infants who had no congenital malformations and were born in a low-income, peri-urban neighborhood of Guatemala City. The design was based on serial, repeated BIS measurements.
Results: Overall mean values of extra- and intracellular resistance (mean+/-standard deviation) were 470.0+/-73.3 Omega and 604.6+/-179.2 Omega, respectively. We found statistical differences in both resistances in relation to advancing age and degree of movement while taking the measurements. With respect to repeat measurements by two separate observers, interobserver differences were a non-significant 7.6 Omega for both resistances. Restraining the infants and previous consumption of milk or formula had a significant effect on extracellular resistance measurements. The mean standard errors of measurement was 4.5 Omega for extracellular resistance and 73.9 Omega for intracellular resistance.
Conclusion: The BIS technique is feasible in newborn and young children when physiologic and methodologic aspects are respected or controlled.