ORIGINAL ARTICLE

Weight estimation in resuscitation: is the current formula still valid?

Mark Luscombe¹, Ben Owens²

¹ The Royal Hallamshire Hospital, Sheffield, South Yorkshire, UK
² Emergency Department, Queen’s Medical Centre, Nottingham, UK

Correspondence to:
Mark Luscombe
The Royal Hallamshire Hospital, Sheffield, South Yorkshire S10 2JF, UK; markluscombe{at}doctors.org.uk

Objectives: To gather data on the ages and weights of paediatric patients between 1 and 10 years of age, and to compare these data with the current weight estimation formula weight(kg) = 2(age+4). If a significant difference was found, the data would be used to derive a more accurate formula.

Design: Retrospective study using data collected from paediatric attendances at an emergency department (ED).

Setting: A large ED in a major UK city, treating both children and adults.

Patients: 17 244 children aged 1–10 years, attending the ED between June and December 2005.

Main outcome measures: Weight difference between the measured weight and the expected weight, the latter given by weight = 2(age+4).

Results: The weights of seriously ill children were recorded in only 41.5% of cases, necessitating a weight estimate in the remainder. The formula weight = 2(age+4) underestimated children’s weights by a mean of 18.8% (95% confidence interval (95% CI) 18.42% to 19.18%). Using linear regression and analysis of each individual age group, ten new formulas were tested. Of these formulas, weight(kg) = 3(age)+7 proved the most accurate with a mean underestimate of just 2.48% (95% CI 2.17% to 2.79%).

Conclusions: Weight estimation remains of paramount importance in paediatric resuscitation. This study shows that the current estimation formula provides a significant underestimate of children’s weights. When used to calculate drug and fluid dosages, this may lead to the under-resuscitation of a critically ill child. The formula weight(kg) = 3(age)+7 provided a safe and more accurate estimate of the weight of today’s child.

Abbreviations: APLS, advanced paediatric life support; 95% CI, 95% confidence interval; ED, emergency department; EPLS, European paediatric life support; MAC, mid-arm circumference; PICU, paediatric intensive care unit

Keywords: child; weight; estimation; formula; resuscitation

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