(742) AAP Maintenance Fluid Tonicity Guidelines: Electrolyte and pH Outcomes

Introduction: Concerns for hospital-acquired hyponatremia leading to encephalopathy prompted the American Academy of Pediatrics (AAP) guidelines in 2018 advocating isotonic intravenous fluid (IVF) use. In 2018, our hospital implemented electronic medical record (EMR) order sets that encouraged guideline compliance. We compared electrolyte and pH values before and after order set implementation.

Methods: Retrospective analysis of ordered IVFs and lab values were obtained from EMR. Inclusion and exclusion criteria were similar to 2018 guidelines. All values of Na, Cl, HCO3-, CO2, pH, and base excess were abstracted. IVF was categorized as: normal saline (NS), Half-NS, Quarter-NS, and Lactated Ringers. Patient data included age and weight at admission, gender, and length of stay. Bivariate comparisons between epoch and categorical variables were assessed using Chi-square. For age and weight, t-tests assessed differences between epochs. For the skewed data of length of stay, median length of stay difference was assessed using the Kruskal-Wallis test. Alpha of 0.05 was used for all statistical tests.

Results: There were 4368 encounters analyzed in Epoch 1 (E1, 2016-2018) and 4336 in Epoch 2 (E2, 2020-2022). Mean encounters per patient (1.4 vs. 1.3 [p=0.069]) were similar. Isotonic IVF administration increased (NS: 36% E1 vs. 76% E2) across epochs, and hypotonic IVF use decreased (Half-NS: 60% E1 vs. 17% E2; Quarter-NS: 2% E1 vs. 0.5% E2). Na by epoch show decreased mild hyponatremia (n=1032 vs. n=872 [p < 0.001]) and increased normal levels (n=8398 vs. n=11510 [p < 0.001]). Across epochs, overall Cl distribution increased (p < 0.001) and HCO3- decreased (p < 0.001). No significant median distribution changes across the epochs were observed in CO2 (42 vs. 41), pH (7.39 vs. 7.39), and base excess (0.9 vs. 0).

Conclusions: Since the 2018 publication of AAP maintenance IVF guidelines, there has been a significant shift towards isotonic IVF use. In conjunction, there has been decreased incidence in mild hyponatremia with increased incidence in normal sodium levels. Initial concerns that widespread isotonic maintenance IVF use will increase clinically significant dysnatremia or metabolic acidosis is not evident in our data analysis. Multicenter studies are still needed to confirm whether these findings are generalizable.