Retrospective evaluation of the treatment of term newborns with hypernatraemic dehydration over the last decade

Objectives Hypernatraemic dehydration in newborns is a significant cause of mortality and morbidity without general consensus on administering fluid therapy. The objective of the study is to evaluate the efficacy and safety of fluid therapy at different concentrations for term dehydrated hypernatraemic newborns requiring intravenous fluid therapy.

Methods Observational, retrospective cohort study was conducted in primary and secondary neonatal intensive care units of a centre between 2014 and 2023. The study included 138 eligible newborns who had a serum sodium level above 146 mmol/L. Isotonic (0.9% NaCl) and hypotonic (0.45% and 0.2% NaCl) fluids were given as a rehydration therapy. The primary outcomes were

the development of hyponatraemia and/or increased hypernatraemia. The secondary outcomes were hourly sodium changes between these groups.
Results Fluid containing 0.9% NaCl was administered to 44 infants, 0.45% NaCl to 54 and 0.2% NaCl to 40 infants. The mean serum sodium levels before and after treatment were 151.7±3.3 and 149.0±5.6, 150.7±3.2 and 145.6±2.4 and 149.5±3.0 and 142.5±4.2 (mmol/L; p<0.001), respectively. The hourly sodium decrease rates were 0.08, 0.24 and 0.42 mmol/L/hour, respectively (p<0.001). The rate of clinically significant sodium decrease (>0.5 mmol/L/ hour) was 6.8%, 13.0% and 42.5%, respectively (p<0.001). There was no difference between the groups in terms of mortality or morbidity.

Conclusions The study shows that hypotonic fluids were associated with a more rapid decline in serum sodium and higher proportion of infants exceeding the recommended correction rate of 0.5 mmol/L/hour than isotonic fluids, although no difference in morbidity or mortality was observed between groups.