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

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

• A. 15%
• B. 30%
• C. 45%
• D. 60%

Answer: (B)

In children the body can compensate for blood loss quite well at first, keeping systolic blood pressure normal through rapid heart rate and peripheral vasoconstriction, along with mobilization of venous reserves. Because a child’s blood volume is fairly high per kilogram, losing about a third of that volume can be the tipping point where these compensations no longer maintain pressure. Once roughly 30% of blood volume has been lost, the stroke volume and vascular tone can no longer be sustained, and systolic blood pressure begins to fall. Smaller losses may show compensatory signs like tachycardia without a drop in SBP, while much larger losses (approaching 45%–60%) correspond to advanced shock with critically low blood pressure.

In children the body can compensate for blood loss quite well at first, keeping systolic blood pressure normal through rapid heart rate and peripheral vasoconstriction, along with mobilization of venous reserves. Because a child’s blood volume is fairly high per kilogram, losing about a third of that volume can be the tipping point where these compensations no longer maintain pressure. Once roughly 30% of blood volume has been lost, the stroke volume and vascular tone can no longer be sustained, and systolic blood pressure begins to fall. Smaller losses may show compensatory signs like tachycardia without a drop in SBP, while much larger losses (approaching 45%–60%) correspond to advanced shock with critically low blood pressure.