Infant with sunken fontanelles, decreased capillary refill, no tears, and few wet diapers most likely has dehydration; which IV fluid is indicated?

• A. Dehydration - LR
• B. Dehydration - D51/2NS
• C. Dehydration - Normal saline
• D. Dehydration - D5W

Answer: (B)

When a child shows signs of dehydration, the first goal is to restore circulating blood volume with an isotonic crystalloid (like LR or normal saline). After circulation is stabilized, maintenance fluids are needed to replace ongoing losses and provide calories for an infant who may not be taking enough oral fluids. A dextrose-containing maintenance solution such as D5 1/2 NS delivers both electrolytes (sodium and chloride) and glucose, helping to prevent hypoglycemia and keep fluid and electrolyte balance as the child recovers. Pure D5W offers free water without electrolytes, which can dilute serum sodium over time; a hypotonic maintenance like D5/0.45NS can risk hyponatremia in a dehydrated child with ongoing ADH effects. Thus, for maintenance in a dehydrated infant, D5 1/2 NS is the most appropriate choice.