Composition of Basic Fluids and Replacement Solutions
Maintenance Fluids & Electrolyte Calculations (Pediatr Rev 2001;22:380)
• Basal state maintenance fluid needs determined by basal metabolic rate; amt of fluid needed to dissipate heat via respiratory tract and skin
• Multiple methods: BSA method, basal calorie method, and Holliday–Segar system. Only last (Holliday–Segar) does not require a table of values
• Holliday–Segar formula equates kcal with mL (1:1) of fluid needed for dissipation
• Electrolyte maintenance needs (not for neonates): Na 2–4 mEq/kg/d, K 1–3 mEq/kg/d, Ca 2–3 mEq/kg/d, Phos 0.5–1.5 mEq/kg/d, Mg 0.1–1 mEq/kg/d
• D5 1/2 NS usually used for maintenance w/ 20 mEq/L KCl added once pt has urinated; for pts <1 yo consider D5 1/4 NS (now controversial; does not apply to neonate) (see NICU section) (Arch Dis Child 2008;93:335)
• Some authors recommend NS for maintenance due to risk of iatrogenic hyponatremia with hypotonic IVF (Curr Opinion Pediatrics 2011;23:186; Pediatrics 2011;128:857); postoperative patients appear to be at highest risk. However, evidence is weak for improved outcomes with NS compared with standard therapy (BMC Pediatrics 2011;11:82; Arch Dis Child 2008;93:335)