Randomized trial of two levels of fluid input in the perinatal period - effect on fluid balance, electrolyte and metabolic disturbances in ventilated VLBW infants.

The aim of this study was to determine whether fluid restriction does indeed significantly increase acute adverse effects. One-hundred-and-sixty-eight ventilated infants, median gestational age 27 wk (range 23–33) and birthweight 953 g (range 486–1500), entered into a randomized controlled trial of two fluid regimes. Infants on regime A were to be prescribed 60 ml/kg of fluids on day 1 which was gradually increased over the first week to 150 ml/kg, infants on fluid regime B were to be prescribed approximately 20% less fluid over the first week. Daily fluid input and output were recorded. Serum electrolytes, bilirubin, creatinine and urine osmolalities were measured daily. Arginine vasopressin levels were assessed on days 1, 3 and 5. Episodes of jaundice, hypoglycae-mia and hypotension requiring treatment were noted. Infants on regime B actually received overall 11% and, in the first 4 days, 19% less fluid than those on regime A (p < 0.001). There were no statistically significant differences in the occurrence of episodes of jaundice, hypotension, hypoglycaemia, hypernatraemia or hyponatraemia between infants on the two regimes. Although the infants on regime B had significantly higher urine osmolalities and lower urine output for most of the perinatal period, their median creatinine and arginine vasopressin levels did not differ significantly from those on regime A. We conclude that fluid restriction to less than 90% of usual maintenance fluids is not associated with an excess of acute adverse effects.