FLUID AND ELECTROLYTE MANAGEMENT IN VLBW NEONATE DURING THE FIRST WEEK OF LIFE - A COMPARISON BETWEEN AGA AND SGA

Extracellular volume (ECV) and redistribution of body fluid after birt h are affected by several factors and intrauterine growth seems to pla y a major role. This study was designed to compare weight loss, serum electrolytes and fluid intake during the first week of life in two gro ups of very low birth weight (VLBW) infants with different intrauterin e growth. Twentynine appropriate for gestational age (AGA) infants (me an Birth weight 1130 gms; mean Gestational age 28,4 weeks) and twentyt wo small for gestational age (SGA) infants (mean Birth weight 830 gms; mean Gestational age 30,5 weeks), all of them in parenteral nutrition , were studied during the first week of life; daily fluid intake was p lanned according to a protocol that takes into account weight loss, se rum sodium levels and urine output. SGA infants, though receiving simi lar amounts of fluids, electrolytes and calories, showed a significant ly lower weight loss than AGA infants (5,2+/-3,2 vs 13.4+/-4,2% - p<0, 001). Moreover, while in the AGA infants the weight loss was inversely related both to the birth weight and to gestational age, this correla tion was not found for the SGA infants. This supports the hypothesis t hat the neonatal weight loss of the SGA infant is caused by catabolic processes more than by dehydration itself. The risk for emoconcentrati on seems to be inversely related to the gestational age both in AGA an d in SGA infants. With similar sodium intake, the AGA hypernatremic su bjects had a significantly lower gestational age than normonatremic (2 6+/-1,0 vs 28,8+/-1,9 weeks) and the same is true for the SGA infants (28+/-0,8 vs 31,0+/-2,0 weeks). The study confirms the importance of s odium balance and the poor reliability of the only weight loss to eval uate the hydration in the VLBW infant.