A 7-week-old male infant is admitted to the pediatric ICU with bowel obstruction. The most appropriate fluid for resuscitation would be which?

A 7-week-old male infant is admitted to the pediatric ICU with bowel obstruction. The most appropriate fluid for resuscitation would be which?

• A. D5W
• B. D5W with 0.45 sodium chloride and 20 mEq/L potassium chloride
• C. 0.45% sodium chloride
• D. 0.9% sodium chloride

Answer: (D)

When a young infant is hypovolemic from bowel obstruction, the priority is rapidly restoring intravascular volume with a fluid that stays in the extracellular space without shifting water into cells. The best choice for this is an isotonic crystalloid, such as normal saline (0.9% sodium chloride). Its osmolality is closest to plasma, so it expands the intravascular compartment effectively without causing a shift of water into cells or diluting serum sodium. Dextrose-containing solutions like D5W are not ideal for initial resuscitation because, once the glucose is metabolized, they become free water, which can lower serum sodium and potentially lead to hyponatremia and cerebral edema in a shocky child. A hypotonic solution such as 0.45% saline would draw water into cells and can worsen cellular edema or fail to provide adequate intravascular volume expansion. A solution combining dextrose or potassium with half-normal saline also carries the risk of hypotonicity or inappropriate electrolyte shifts in the acute setting. Therefore, starting with normal saline to replenish extracellular volume is the most appropriate approach.

When a young infant is hypovolemic from bowel obstruction, the priority is rapidly restoring intravascular volume with a fluid that stays in the extracellular space without shifting water into cells. The best choice for this is an isotonic crystalloid, such as normal saline (0.9% sodium chloride). Its osmolality is closest to plasma, so it expands the intravascular compartment effectively without causing a shift of water into cells or diluting serum sodium.

Dextrose-containing solutions like D5W are not ideal for initial resuscitation because, once the glucose is metabolized, they become free water, which can lower serum sodium and potentially lead to hyponatremia and cerebral edema in a shocky child. A hypotonic solution such as 0.45% saline would draw water into cells and can worsen cellular edema or fail to provide adequate intravascular volume expansion. A solution combining dextrose or potassium with half-normal saline also carries the risk of hypotonicity or inappropriate electrolyte shifts in the acute setting.

Therefore, starting with normal saline to replenish extracellular volume is the most appropriate approach.