A child can lose what percent of their blood before systolic blood pressure decreases?

• A. 10%
• B. 20%
• C. 30%
• D. 40%

Answer: (C)

In children, the body compensates for blood loss with tachycardia and peripheral vasoconstriction to keep blood pressure normal. Systolic blood pressure doesn’t start to fall until a substantial portion of the circulating blood volume has been lost—roughly 30%. So, about 30% of blood volume can be lost before SBP decreases. Before that point, signs like a fast heart rate and other perfusion cues may appear, but the BP remains preserved. At around 40% loss, decompensation becomes more evident with significant hypotension and poor perfusion.