The most accurate method of determining a paediatric patient's weight is to weigh them, however this is not as practical in the pre-hospital setting as it is in the hospital emergency department (ED). A recent study by Winship et al (2012) found that the most accurate formula for estimating a child's weight is the best guess formula, however, this is not currently used in the pre-hospital setting due to it's complexity. Previous studies into the estimation of a patient's age and weight have shown gross inaccuracies (Williams et al. 2010), and although there are certain paediatric weight estimation formula, in some cases, an estimation of the patient's age is required to do this, hence the introduction of inaccuracy.
One of the issues associated with existing weight estimation formula is they have been predominately developed using western values and hence may not be appropriate for children from developing countries. This has been demonstrated by Cattermole et al (2011), who developed a more accurate specific weight estimation formula for children aged between one and ten years within a Chinese population. Other studies have also been conducted on non-western populations that demonstrate variation in weights depending on the formula used (such as Advanced paediatric life support (APLS), Nelson, Argall's, Luscombe and Owens, Shann, Leffler, the Oakley resuscitation chart, and the Broselow Tape method) (Theron et al. 2005; Varghese et al. 2006; Geduld et al. 2011; Ali et al. 2012). These studies looked at a range of populations including Indian, Trinidadian, Pacific Island, Maori, and Western Cape South Africa children.
One of the major pifalls appears to lie in the accuracy of weight estimation in children between the ages between one and ten years, nor have the formula been updated with a change in the increasing weight of children over time. For the Broselow tape, it can only be used on children less than 145 cm in height, with the accuracy in children over 25 kg questionable, something that may need to be changed as children continue to get taller and heavier. If a weight estimation formula is to be used in the pre-hospital setting, then it needs to be simple, without a need for a complicated calculation, and though it could be argued that the best guess formula is relatively accurate in the ED setting, it may be too complicated pre-hospitally considering its different formula for three different age ranges (Casey and Borland, 2010). Therefore, it would appear there is a need for a validated paediatric weight estimation formula to suit every country, where the formula accounts for local fluctuations within the paediatric population, and not as a ‘catch all’ definition.