Low blood pressure as a late sign of sepsis in children
In a young child with suspected sepsis, low blood pressure is a very serious late sign, because children keep their blood pressure normal until the circulation is failing.
Remember
In a young child with suspected sepsis, do not wait for low blood pressure, because it is a very serious late sign that the circulation is failing. Act on the earlier signs: fast breathing, a fast heart rate, and a change in appearance or behaviour.
Memory aid
children keep their blood pressure until the very end, so a low reading is the last warning light, not the first.
A low reading is the last warning light, so look to the earlier signs first.
Children are very good at compensating for infection: the body speeds up the heart and tightens the blood vessels, which keeps the circulation going. Because of this, a child with sepsis can look much like a child with an ordinary viral illness until the child collapses.
The result is that blood pressure stays normal for a long time. While compensation works, the pressure looks normal even though the child is seriously ill. Once the pressure does fall (hypotension), the compensating mechanisms have failed and the child is close to collapse.
That makes low blood pressure a very serious late sign, and it needs immediate management and senior help. In adults the blood pressure tends to decline more gradually, so the pattern in children is different.
So act on the earlier signs instead of waiting for hypotension:
- The respiratory rate is usually the first vital sign to rise in an acutely unwell child.
- A fast heart rate (tachycardia) is one way a child compensates for infection.
- A prolonged capillary refill time (slow return of colour to pressed skin) can be an early clue, but cold exposure can also prolong it.
- A child who looks mottled (blotchy, patterned skin from poor blood flow), or who lies quietly and does not interact, is more worrying than one who is active, talking and crying.
A normal blood pressure does not exclude sepsis in a child. A normal temperature is not reassuring either, because a child with serious infection may have a normal or low temperature.
Key facts
- Late sign
- Low blood pressure in a young child with suspected sepsis is a very serious late sign that needs immediate management.
- Why it is late
- Children raise their heart rate and tighten their blood vessels, which keeps the blood pressure normal until late.
- Early sign
- The respiratory rate is usually the first vital sign to rise in an unwell child.
- Normal pressure
- A normal blood pressure does not exclude sepsis in a child.
- Temperature
- A normal or low temperature cannot rule sepsis out.
- Appearance
- Mottled skin and reduced interaction signal severe illness even when the blood pressure is normal, so call for senior help.
Exam traps
- A fast respiratory rate is an early and sensitive warning, but it does not show that the circulation has failed, because it is usually the first vital sign to rise in an acutely unwell child.
- Fever does not mark a late sign of sepsis: it suggests infection but does not show how severe it is, and sepsis can also cause a low temperature.
- A normal blood pressure in a child does not exclude sepsis, because children keep their blood pressure until late.
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