Hidden sources like saline flushes make a significant contribution to the fluid intake of very low birthweight infants during the first postnatal week.

AIM: We examined actual fluid intake, and routes of administration, in very low birthweight (VLBW) infants during the first week of life in a neonatal intensive care unit.

METHODS: This retrospective cohort study comprised 953 infants born at <32 weeks and 1500 g and treated at Helsinki University Children's Hospital from 2005 to 2013. All parenterally and enterally administered fluids, and their sources, were obtained from our patient information system. Infants were divided into three groups according to their gestational age: 23-26, 27-29 and 30-31 weeks.

RESULTS: Fluid intake exceeded European guidelines during the first 3 days. On days 1-7, total fluid intake was highest in the most premature group (P < .001) and the median total fluid intake in this group peaked at 177 mL/kg/d (IQR 154-209) on day three. Intravascular flushes provided a considerable source of fluids, with the median intake in the most preterm group peaking at 26.4 mL/kg/d, which represented 15.6% of total fluid intake.

CONCLUSION: During the first 3 days of life, our VLBW infants had a higher total fluid intake than the European guidelines. A considerable percentage came from hidden sources, such as saline flushes, which should be taken into account when prescribing fluids.