Topics Discussed: acid-base disorders; acid-base equilibrium; acid-base nomogram; acidosis; alkalosis; blood chemical analysis; blood gas; dehydration; electrolyte replacement; fluid replacement, crystalloid colloid; fluid resuscitation; fluids and electrolytes; glucose; hypercalcemia; hyperkalemia; hypermagnesemia; hypernatremia; hypernatremic dehydration; hyperphosphatemia; hypocalcemia; hypokalemia; hypomagnesemia; hyponatremia; hyponatremia euvolemic; hyponatremia hyposmotic hypervolemic; hyponatremia hypovolemic; hypophosphatemia; intravenous fluid; maintenance or restoration of fluid or electrolyte balance; mixed acid-base disorder; oral rehydration solution; osmolar gap; osmolar gap abnormal; potassium; rehydration solutions; rehydration therapy; sodium; water requirement.
Excerpt:"Example: (22 kg child, serum Na 165 mEq/L, 10% dehydration = 2.2 L total fluid deficit)Calculate the free water deficit.
TBW x [(Serum Na – 145)/145]
TBW (L) = [Baseline weight in kg x Age-appropriate constant]
(0.8 for premature infants; 0.6 for infants, children, and adult males; 0.5 for adult females).
- Divide the deficit by 2 or 3 to correct hypernatremia slowly over 2–3 d to avoid rapid correction and possibility of inducing cerebral edema from rapid water shift from extracellular to intracellular space.
Calculate MIVF fluid rate for 24 hour period.
Calculate maintenance Na needs for 24 hr period (2-3 mEq/kg/d)
Combine values in steps 1-3 to determine daily IVF fluid type, volume and rate:
Concentration of Na (mEq/L) in D5W = [Maintenance Na]/[⅓ or ½ of free water deficit volume + Daily maintenance fluid volume]
- Round to standard IV fluid solution if possible (see table above, "Composition of Commonly Used IV Fluids")
Calculate the fluid deficit (ie, account for isotonic Na losses):
% Dehydration x wt(kg)
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