Written by Clay Smith
The Pediatric Advanced Life Support (PALS)/Advanced Trauma Life Support (ATLS) formula to define hypotension in children (i.e. 5th percentile SBP) seems to be a good compromise between German and U.S. population norms for children. The formula is: Low SBP = <70 + 2(age in years).
Why does this matter?
Recognize: You have to spot an abnormal pediatric BP when you see one.
Repeat: Any abnormal BP in a child must be repeated and confirmed as not spurious.
Recheck: Intervene and recheck to see if it is improving.
Record: Document you saw and addressed the abnormal BP and what the response was.
Defining hypotension is not as easy as it looks. If the SBP target is set too low, we may undertriage; too high and we will have excess false positives. What is the right standard?
There was a lack of agreement among differing population-based norms for pediatric BP on how to define hypotension, that is <5th percentile. A German database, KiGGS was on average 7mm higher than US population BP norms. KiGGs 5th percentile could be calculated in children age 3-9 years with the formula: 82 + age = SBP, though this did not hold for ages 10-17 years. PALS and ATLS use the formula to define hypotension of: <70 + 2(age in years) = SBP. This PALS/ATLS definition fell between the German and US population norms for the 5th percentile and seemed to split the difference. Keep in mind, this PALS/ATLS formula should only be used in children ages 1-10 years. The authors express concern that the 90mm definition of hypotension for children ≥10years may lead to undertriage of adolescents, according to the 5th percentile German and U.S. norms. I think this is correct; see figure (SBP plateaus for girls at around age 13).
An unambiguous definition of pediatric hypotension is still lacking: Gaps between two percentile-based definitions and Pediatric Advanced Life Support/Advanced Trauma Life Support guidelines. J Trauma Acute Care Surg. 2019 Mar;86(3):448-453. doi: 10.1097/TA.0000000000002139.
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