TABLE 100.2 ESTIMATED DEFICITS AND IV THERAPY: 10-kg CHILD WITH 10% HYPOVOLEMIA AND SERUM SODIUM 140 mEq/L Water and sodium (Na) deficits Water deficit: 10 kg × 10% = L Na deficit: L × 140 mEq/L = 140 mEq Emergent fluid repletion with NS 20 mL/kg × 10 kg = 200 mL (200 mL water and ≈ 30 mEq sodium) Ongoing repletion and maintenance requirements Remaining water deficit: 1,000 mL − 200 mL = 800 mL Daily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day 800 mL + 1,000 mL = 1,800 mL/24 hrs = 75 mL/hr Remaining Na deficit: 140 mEq − 30 mEq = 110 mEq Maintenance sodium requirement: mEq/100 mL water × 1,000 mL/day = 30 mEq/day 110 mEq + 30 mEq = 140 mEq/24 hrs 140 mEq/1,800 mL ≈ 0.45% sodium chloride (½ NS) Maintenance potassium requirement: mEq/100 mL water × 1,000 mL/day = 30 mEq/day 30 mEq/1,800 mL ≈ 15–20 mEq/L Intravenous fluid based upon deficit calculations: D5% ½ NS with 20 mEq/L KCl at 75 mL/hr Ongoing losses Extrarenal losses should be replaced mL for mL if volumes are significant The sodium content of the fluid lost should be estimated or measured in order to select the appropriate replacement fluid Hyponatremic hypovolemia Children with mild to moderate hyponatremia should be provided isotonic or near-isotonic fluids to both complete the repletion phase and continue the maintenance phase of IV fluid therapy Providing hypotonic fluid in the setting of persistent