A 3-year-old presents after a fall with tachycardia of 170/min, capillary refill of 4 seconds, cool knees, and a blood pressure of 96/58 mmHg. He is alert and crying. This picture is best described as compensated shock. Why has his systolic blood pressure remained normal?
- A Children have a proportionally larger blood volume than adults relative to body weight
- B Blood pressure is preserved until approximately 25 percent of circulating volume has been lost ✓
- C Tachycardia alone fully compensates for any degree of hemorrhage in young children
- D His blood pressure reading is falsely elevated because he is agitated and crying
Correct answer: B. Blood pressure is preserved until approximately 25 percent of circulating volume has been lost
Explanation
Children mount intense sympathetic vasoconstriction, so blood pressure is maintained near normal until about 20 to 25 percent of blood volume is lost. Hypotension is therefore a late and preterminal sign in pediatric shock, and relying on it delays recognition. Blood volume per kilogram is similar to adults, around 70 to 80 mL/kg, so option A is wrong. Tachycardia cannot compensate indefinitely, and agitation does not reliably produce this pattern.
Reference: Nelson Textbook of Pediatrics, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.