PE15.1 | Fluid Requirements — Summary & Reflection

KEY TAKEAWAYS

Children have proportionally more body water than adults (TBW ~75-80% at birth declining to ~60% by adolescence), with a relatively larger ECF compartment that makes them vulnerable to rapid dehydration. Maintenance fluid requirements are calculated using the Holliday-Segar method: 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg, and 20 mL/kg/day for each subsequent kilogram (hourly equivalent: 4-2-1 rule). Dehydration is classified by IMNCI as no dehydration (< 5%), some dehydration (5-9%, Plan B: ORS 75 mL/kg over 4 hours), or severe dehydration (≥10%, Plan C: IV Ringer's lactate). Reduced-osmolarity ORS (osmolarity 245 mOsm/L) is the standard rehydration solution for children. Total fluid orders combine maintenance + deficit + ongoing losses, with the oral route preferred whenever the child can drink safely.

REFLECT

Recall the 14-month-old child from the opening scenario — 9 kg, irritable, sunken eyes, skin pinch returning slowly, drinking eagerly. Using what you have now learned: calculate her maintenance fluid, classify her dehydration, and write her Plan B ORS prescription. Then reflect: what additional information would change your plan? How would fever affect her maintenance needs? What would you tell the mother about home fluids when you discharge her? Completing this reflection consolidates the calculation-and-classification cycle that you will repeat many times in clinical practice.