A 40-pound, 5-year-old female struck by a vehicle should receive an isotonic crystalloid bolus of how many milliliters?

• A. 180 mL
• B. 360 mL
• C. 600 mL
• D. 1000 mL

Answer: (B)

The main idea is weight-based fluid resuscitation in children using an isotonic crystalloid bolus. The standard initial dose is 20 mL per kilogram of body weight. Convert the child’s weight: 40 pounds is about 18.1 kilograms. Multiply 18.1 kg by 20 mL/kg = roughly 362 mL, which is typically rounded to 360 mL. So a 360 mL isotonic crystalloid bolus is appropriate to start.

This approach rapidly expands intravascular volume to improve perfusion in shock while avoiding fluid overload. If hypotension persists after the first bolus, additional 20 mL/kg increments can be given up to a total of about 60 mL/kg before considering other interventions, such as blood products.