360 - Hyponatremia Associated with Standard Intravenous Fluid Administration in Neonates

Poster Number: 360
Publication Number: 360.132

Amanda Chang, Northwestern University The Feinberg School of Medicine, Chicago, IL, United States; Daniel J. York, Northwestern University, Chicago, IL, United States; Kristi Huisinga, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, United States; Kaeli Heidenreich, Northwestern University The Feinberg School of Medicine, Chicago, IL, United States; Malika Shah, Northwestern University The Feinberg School of Medicine, Chicago, IL, United States

Background: An association between moderately hypotonic fluids, iatrogenic hyponatremia, and increased morbidity has been described in the pediatric population. The effect of intravenous fluid (IVF) on serum sodium (Na) levels in the neonatal population is not well characterized.

Objective: Our study aims to examine the relationship between IVF and serum Na levels at 24 hours in near term and term neonates.

Design/Methods: Retrospective chart review of infants greater than 34 weeks gestational age (GA) who were admitted to Northwestern Medicine NICU between 04/01/18-4/01/21, had an order for dextrose-containing fluids in the first 24 hours and had a serum Na at 24 hours of life. Demographic and clinical data (birth weight, GA, type of delivery, length of stay, amount/type of IVF received, reason for admission, 24-hour serum Na, urine output) were abstracted. Incidence and relative risk for hyponatremia based on 24-hour fluid balance calculated. Positive IVF balance (PIVFB) defined as IVF exceeding urine output, positive total fluid balance (PTFB) defined as IVF plus enteral feeds exceeding urine output. IRB Approval obtained (STU00214976).

Results: Cohort background characteristics in Table 1. In first 24 hours, 107 (58%) infants received enteral feeds, 5 (3%) received electrolytes in IVF, and mean IVF/kg received of 55.9 mL/kg (SD 16.8). Twenty-four-hour serum Na range 124-143 mEq/L (mean 135.6, SD 3.67). Sixty-nine (38%) infants with 24-hour serum Na less than 135. Relative risk of serum Na less than 135 in PIVFB compared to negative IVFB was 2.25 (95% CI 1.43-3.53, p < 0.001), PTFB showed a relative risk of 2.10 (95% CI [1.17 to 3.76], p = 0.01) compared to negative TFB, Figure 2. Linear regression models showed a 0.069 mEq/L decrease in Na for every 1 mL/kg of PIVFB (95% CI [0.048-0.090 mEq/L]; p< 0.00001) and a 0.059 mEq/L decrease in Na for every 1 mL/kg of PTFB (95% CI [0.037-0.080 mEq/L]; p< 0.00001). Adjustments for respiratory support and GA did not substantially change the model (0.065 mEq/L decrease in Na for every 1 mL/kg of PIVFB (95% CI [0.044-0.087 mEq/L]; p< 0.00001). A regression model did not show a significant effect of IV intake/kg alone in the first 24 hours on serum Na, Figure 3.Conclusion(s): PIVFB in the first 24 hours correlates with hyponatremia in neonates, and initiation of enteral feeding may mitigate this effect. While the full impact of early hyponatremia is unclear, a dynamic fluid adjustment strategy that incorporates urine output and examines electrolytes prior to 24 hours of life may optimize fluid management in neonates.
Amanda Chang's CVAmanda Chang_CV.pdf
Figure 2: Effect of 24-Hour Positive and Negative Total and IV Fluid Balance on NaNTFB: negative total fluid balance, PTFB: positive total fluid balance
NIVFB; negative IVF balance, PIVFB: positive IVF balance