Weight estimation in paediatrics: a comparison of the APLS formula and the formula 'Weight=3(age)+7'. Issue 7 (20th July 2010)

• Record Type: Journal Article
• Authors: Luscombe, Mark D; Owens, Ben D; Burke, Derek
• Is Part Of: Emergency medicine journal. Volume 28:Issue 7(2011)
• Page Start: 590
• Page End: 593
• Publication Date: 2010-07-20
• Subjects: Child -- weight -- estimation -- formula -- resuscitation -- anaesthesia -- intensive care -- paediatrics -- paediatrics -- paediatric emergency med -- paediatrics -- paediatric resuscitation; Emergency medicine -- Periodicals; 616.02505
• DOI: 10.1136/emj.2009.087288
• Languages: English
• ISSNs: 1472-0205

Abstract

Abstract : Objectives: To gather data on the ages and weights of children aged between 1 and 16 years in order to assess the validity of the current weight estimation formula 'Weight(kg)=2(age+4)' and the newly derived formula 'Weight=3(age)+7'. Design: Retrospective study using data collected from paediatric attendances at an emergency department (ED). Setting: A large paediatric ED in a major UK city. Patients: 93 827 children aged 1–16 years attending the ED between June 2003 and September 2008. Main outcome measures: Percentage weight difference between the child's actual weight and the expected weight, the latter determined by 'Weight(kg)=2(age+4)' and by 'Weight(kg)=3(age)+7', in order to compare these two formulae. Results: The weights of seriously ill children were recorded in only 20.5% of cases, necessitating a weight estimate in the remainder. The formula 'Weight=2(age+4)' underestimated children's weights by a mean of 33.4% (95% CI 33.2% to 33.6%) over the age range 1–16 years whereas the formula 'Weight=3(age)+7' provided a mean underestimate of 6.9% (95% CI 6.8% to 7.1%). The formula 'Weight=3(age)+7' remains applicable from 1 to 13 years inclusive. Conclusions: Weight estimation is 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=3(age)+7' can be used over a larger age range (from 1 year to puberty) and allows a safe and more accurate estimate of the weight of children today.