How and Why Paediatric Weight Estimation Systems Fail - A Body Composition Study

Abstract

Background Weight estimation during medical emergencies in children is essential, but fraught with errors if the wrong techniques are used, which may result in critical drug dosing errors. Individualised weight estimation is required to allow for accurate dosing in underweight and obese children in particular. This study was designed to evaluate the associations between weight estimations from different systems and body composition in order to establish how and why they may perform well or poorly. Methods A convenience sample of 332 children aged from one month to 16 years had weight estimations using four age-based formulas: the Broselow™ Pediatric Emergency Tape (Armstrong Medical Industries, Inc., Lincolnshire, IL), the Mercy Method, and the Pediatric Advanced Weight Prediction in the Emergency Room, Extra-large/Extra-long Tape (PAWPER XL) Tape. They also had an assessment of body composition using dual x-ray absorptiometry (DXA). The weight estimates were compared against total body weight (TBW), calculated ideal body weight (IBW), and DXA-measured fat-free mass (FFM). Analyses of associations between age, length, weight estimation outcomes, and body composition were performed. Results Age-based formulas were very inaccurate because of the erratic relationship between age and body composition. The Broselow tape estimated IBW well in obese children because of the strong relationship between length and fat-free mass. It predicted TBW poorly in underweight and obese children, however, because of the poor relationship between length and fat mass. The Mercy Method's performance was unrelated to body composition, but estimated TBW reasonably well and could not predict IBW or FFM. The PAWPER XL Tape's performance was the most closely associated with body composition and, therefore, achieved an acceptable accuracy for estimations of TBW, IBW, and FFM. Conclusions Of the systems evaluated, the PAWPER XL Tape has the best association with body composition and the most accurate estimations of TBW, IBW, and FFM.

The PAWPER tape as a tool for rapid weight assessment in a Paediatric Emergency Department: Validation study and comparison with parents’ estimation and Broselow tape

“…Similarly, Wells et al found that none of the age-based formulas could predict the actual body weight with reasonable accuracy, especially in obese subjects. 18 , 19 Our data reinforce the ERC guidelines that discourage using age-based formulas in paediatric clinical settings.…”

“…Indeed, either over- or under-weight approximation can lead to suboptimal medication dosage and related morbidity and mortality. 10 , 18 …”

Development and validation of a length- and habitus-based method of total body weight estimation for critically ill adults requiring urgent weight-based medical intervention

“…In addition to accuracy, usability is also important in a weight estimation system – it must not require a substantial amount of training to learn, and must be quick and easy to use, as weight estimation itself can lead to delays in emergency treatment [44]. The PAWPER XL and PAWPER XL-MAC systems were designed for emergency use, and data from paediatric studies suggested that they fulfil the accuracy and usability criteria and are relatively less impacted by human factor errors than other weight estimation systems [27, 47, 48]. This needs to be established in prospective studies of emergency care in adult patients, however.…”

Weighty Matters: A Real-World Comparison of the Handtevy and Broselow Methods of Prehospital Weight Estimation

“…The Broselow method was developed in the 1980s and has been modified and studied fairly extensively in the intervening years, with varying results. 4,[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] The Handtevy system, initially developed in 2010 as a length and age-based system, has been adapted and can now be used as an exclusively age-based tool for weight estimation. 21 There are few studies evaluating the Handtevy system, most of which were published prior to the development of the solely age-based application, however Rappaport, et al recently published a manuscript reporting almost 90% dosing accuracy using the Handtevy Field Guide (accuracy was based on correct use of the field guide/patient age, not patient weight).…”