Hypernatraemia in very low birth weight infants admitted at Chris Hani Baragwanath academic hospital: incidence, fluid management and outcome

Abstract

Background: Fluid-management in very-low-birth-weight infants (VLBWI) with hypernatraemia is critical in reducing morbidity and mortality in these infants. Aim: To determine incidence, fluid-management and mortality-rate in VLBWI with hypernatraemia. Methods: A retrospective descriptive study. Hospital records of VLBWI diagnosed with hypernatraemia during the first 72 hours of life were reviewed. Data collected included maternal and infant characteristics, type and volume of fluid administered on admission and at diagnosis, environment in which infants were nursed, time to resolution of hypernatraemia and mortality-rate at 28 days of life. Results: Of the 443 VLBWI born during June-December 2012, 370 files were retrieved, of which 125 infants had hypernatraemia, an incidence of 33.8%. All were started on a sodium-containing fluid on admission, at a volume of 60-110 ml/kg/day. Fluid-increases in response to hypernatraemia were 45-90 ml/kg. Calculation of fluid-increases was based on a formula for water-deficit in 75% of VLBWI. Severity of hypernatraemia was not associated with birthweight (p=0.26), gestational age (p=0.31) or amount of sodium infants were receiving at diagnosis (p=0.58). Common fluid used for correction was 5% dextrose. The correction-rate was fast at >1mmol/hr in 8.4% of patients. The average-time to resolution was 44 hours. The average-time to resolution was longer for infants nursed in an incubator compared to a radiant warmer (49.7 vs. 37.7 hours, p=0.037) and in those nursed under phototherapy (45.6 vs. 40.8 hours, p =0.031). The mortality-rate at 28 days was 22.5%. Conclusion: The incidence of hypernatraemia in VLBWI at Chris Hani Baragwanath Academic Hospital is high. Fluid-management to correct hypernatraemia was appropriate for most infants.