What’s the Best Pediatric Weight Estimator?

November 19, 2019

Written by Clay Smith

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Parental weight estimation was the most accurate way to approximate a child’s true weight. The next best was the Broselow tape.

Why does the matter?
It can be difficult to determine a child’s weight for drug dosing, etc during resuscitation. Often, the child is too unstable to be be weighed. What is the best way to estimate weight?

And weighing in at… (how much do they weigh, mom?)
This was a prospective study in Thailand of various weight estimation methods in children. The best was parental weight estimate. Parents underestimated weight by 0.83kg, were within 10% of actual weight 89% of the time and within 20% of actual weight 97% of the time. The Broselow was next best, overestimating weight by 0.25kg and predicting weight within 10% of actual just 46% of the time; within 20% of actual 78% of the time. Broselow was best in children under 5. The Broselow was also thought to be the most practical weight estimation tool. Other methods, such as the Mercy method, original APLS formula*, or revised APLS formula** performed more poorly. However, in kids over 5, the Mercy method was most accurate behind parental estimate. Of note, this may not apply to other settings, although similar findings have been shown in an Australian population.

*APLS formula: weight = (age + 4) × 2
**revised APLS formula: weight = 3(age) + 7

Source
A Comparison of Pediatric Weight Estimation Methods for Emergency Resuscitation. Pediatr Emerg Care. 2019 Oct;35(10):705-711. doi: 10.1097/PEC.0000000000001137.

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