An aid to drug dosing safety in obese children: development of a new nomogram and comparison with existing methods for estimation of ideal body weight and lean body mass

Abstract

SummaryThe risk of accidental over-dosing of obese children poses challenges to anaesthetists during dose calculations for drugs with serious side-effects, such as analgesics. For many drugs, dosing scalars such as ideal body weight and lean body mass are recommended instead of total body weight during weight-based dose calculations. However, the complex current methods of obtaining these dosing scalars are impractical in the peri-operative setting. Arbitrary dose adjustments and guesswork are, unfortunately, tempting solutions for the time-pressured anaesthetist. The study's aim was to develop and validate an accurate, convenient alternative. A nomogram was created and its performance compared with the standard calculation method by volunteers using measurements from 108 obese children. The nomogram was as accurate (bias 0.12 kg vs À0.41 kg, respectively, p = 0.4), faster (mean (SD) time taken 2.8 (1.0) min (vs 3.3 (0.9) min respectively, p = 0.003) and less likely to result in mistakes (significant errors 3% vs 19%, respectively, p = 0.001). We present a system that simplifies estimation of ideal body weight and lean body mass in obese children, providing foundations for safer drug dose calculation.

Growth hormone prescribing and initial BMI SDS: Increased biochemical adverse effects and costs in obese children without additional gain in height

“…Previously validated formulae [4] were used to calculate IBW and LBW for each child. Body surface area (m 2 ) was calculated using the Boyd equation [19].…”

“…Validated algorithms exist to manipulate a child’s actual weight to either an ideal or lean body weight, but these are not widely used within paediatrics [4]. Pharmacokinetic data in obese patients do not exist for the majority of drugs, although it is well understood that it will have substantial effects on the clearance and volume of distribution of many medicines [5].…”

Medication Dosage in Overweight and Obese Children

“…10,15 Lean body weight should be used for maintenance doses because it is most closely related to lean body mass. 9,10,15 Several studies have evaluated equations to estimate lean body mass in children and adolescents; [16][17][18][19] however, more research is needed to support their use. As with chemotherapeutic agents, body surface area may also be considered as an effective body size descriptor for maintenance doses in children ages 1 month to 14 years using the Mostellar equation.…”

Prescribing in paediatric obesity: methods to improve dosing safety in weight-based dose calculations

“…With this objective in mind, the author has previously published a simple, accurate and rapid method to perform calculation of LBM and IBW in children with obesity (see figure 1). 14 …”