Which fluid is categorized as an isotonic crystalloid used for the initial bolus?

Which fluid is categorized as an isotonic crystalloid used for the initial bolus?

• A. 0.45% saline
• B. 3% saline
• C. 5% dextrose in water
• D. Normal saline (0.9% NaCl)

Answer: (D)

The main idea is using an isotonic crystalloid to rapidly expand the circulating blood volume without shifting water into or out of cells. Normal saline (0.9% NaCl) matches plasma osmolality, stays mainly in the extracellular space, and reliably increases intravascular volume when given as a bolus for pediatric resuscitation. The other options are not suitable for an initial bolus: a hypotonic solution would pull water into cells and not quickly restore circulating volume; a hypertonic solution would draw water out of cells and risk dangerous shifts; and a dextrose-containing solution provides free water after glucose is metabolized, effectively acting hypotonic and not ideal for rapid intravascular expansion.

The main idea is using an isotonic crystalloid to rapidly expand the circulating blood volume without shifting water into or out of cells. Normal saline (0.9% NaCl) matches plasma osmolality, stays mainly in the extracellular space, and reliably increases intravascular volume when given as a bolus for pediatric resuscitation. The other options are not suitable for an initial bolus: a hypotonic solution would pull water into cells and not quickly restore circulating volume; a hypertonic solution would draw water out of cells and risk dangerous shifts; and a dextrose-containing solution provides free water after glucose is metabolized, effectively acting hypotonic and not ideal for rapid intravascular expansion.