Can undergraduate paramedic and nursing students accurately estimate patient age and weight?

The accuracy of total body weight estimation in adults - A systematic review and meta-analysis

BACKGROUND

Weight estimation is required in adult patients when weight-based medication must be administered during emergency care, as measuring weight is often impossible. Inaccurate estimations may lead to inaccurate drug doses, which may cause patient harm. Little is known about the relative accuracy of different methods of weight estimation that could be used during resuscitative care. The aim of this study was to evaluate the performance and suitability of existing weight estimation methods for use in adult emergency care.

METHODS

A systematic literature search was performed for suitable articles that studied the accuracy of weight estimation systems in adults. The study characteristics, the quality of the studies, the weight estimation methods evaluated, the accuracy data, and any information on the ease-of-use of the method were extracted and evaluated.

RESULTS

A total of 95 studies were included, in which 27 different methods of total body weight estimation were described, with 42 studies included in the meta-analysis. The most accurate methods, determined from the pooled estimates of accuracy (the percentage of estimates within 10% of true weight, with 95% confidence intervals) were 3-D camera estimates (88.8% (85.8 to 91.8%)), patient self-estimates (88.7% (87.7 to 89.7%)), the Lorenz method (77.5% (76.4 to 78.6%)) and family estimates (75.0% (71.5 to 78.6%)). However, no method was without significant potential limitations to use during emergency care.

CONCLUSION

Patient self-estimations of weight were generally very accurate and should be the method of choice during emergency care, when possible. However, since alternative estimation methods must be available when confused, or otherwise incapacitated, patients are unable to provide an estimate, alternative strategies of weight estimation should also be available.

Development and validation of a length- and habitus-based method of total body weight estimation in adults

BACKGROUND

Erroneous weight estimation during the management of emergency presentations in adults may contribute to patient harm and poor outcomes. Patients can often not be weighed during emergencies and a weight estimation is required to facilitate weight-based therapies. Many existing methods of weight estimation are either unacceptably inaccurate or very difficult to use during the provision of emergency care.

METHODS

The weight estimation system developed in this study was based on and modified from the PAWPER XL-MAC method, a pediatric weight estimation system that uses recumbent length and mid-arm circumference (MAC) to predict total body weight. This model was validated in the 2015-2018 National Health and Nutrition Examination Survey (NHANES) datasets. The primary outcome measure was to achieve >95% of estimations within 20% of measured weight (P20 > 95%).

RESULTS

The modified PAWPER XL-MAC model achieved a P20 of 96.0% and a P10 of 71.3% in the validation dataset (N = 11,520). This accuracy (P20 > 95%) was maintained in both sexes, all ages, all ethnic groups, all lengths and in all habitus-types, except for the subgroup of severely obese individuals.

CONCLUSIONS

The modified PAWPER XL-MAC model proved to be a very accurate method of weight estimation. It is more accurate than most other published reports of existing methods of weight estimation, except for patients' own estimations. It therefore could have a role in facilitating emergency drug dose calculations, if prospective studies bear out the accuracy found in this study.

Weight estimation among multi-racial/ethnic infants and children aged 0-5·9 years in the USA: simple tools for a critical measure

OBJECTIVE

In resource-constrained facilities or during resuscitation, immediate paediatric weight estimation remains a fundamental challenge. We aimed to develop and validate weight estimation models based on ulna length and forearm width and circumference measured by simple and portable tools; and to compare them against previous methods (advanced paediatric life support (APLS), Theron and Traub-Johnson formulas).

DESIGN

Cross-sectional analysis of anthropometric measurements. Four ulna- and forearm-based weight estimation models were developed in the training set (n 1016). Assessment of bias, precision and accuracy was examined in the validation set (n 457).

SETTING

National Children's Study-Formative Research in Anthropometry (2011-2012).

SUBJECTS

Multi-racial/ethnic infants and children aged <6 years (n 1473).

RESULTS

Developed Models 1-4 had high predictive precision (R 2=0·91-0·97). Mean percentage errors between predicted and measured weight were significantly smaller across the developed models (0·1-0·7 %) v. the APLS, Theron and Traub-Johnson formulas (-1·7, 9·2 and -4·9 %, respectively). Root-mean-squared percentage error was overall smaller among Models 1-4 v. the three existing methods (range=7·5-8·7 v. 9·8-13·3 %). Further, Models 1-4 were within 10 and 20 % of actual weight in 72-87 and 95-99 % of the weight estimations, respectively, which outperformed any of the three existing methods.

CONCLUSIONS

Ulna length, forearm width and forearm circumference by simple and portable tools could serve as valid and reliable surrogate measures of weight among infants and children aged <6 years with improved precision over the existing age- or length-based methods. Further validation of these models in physically impaired or non-ambulatory children is warranted.

A systematic review and meta-analysis of the accuracy of weight estimation systems used in paediatric emergency care in developing countries

Introduction

When weight cannot be measured during the management of medical emergencies in children, a convenient, quick and accurate method of weight estimation is required, as many drug doses and other interventions are based on body weight. Many weight estimation methodologies in current use have been shown to be inaccurate, especially in low- and middle-income countries with a high prevalence of underweight children. This meta-analysis evaluated the accuracy of weight estimation systems in children from studies from low- and middle-income countries.

Methods

Articles from low- and middle-income countries were screened for inclusion to evaluate and compare the accuracy of existing systems and the newer dual length- and habitus-based methods, using standard meta-analysis techniques.

Results

The 2D systems and parental estimates performed best overall. The PAWPER tape, parental estimates, the Wozniak method and the Mercy method were the most accurate systems with percentage of weight estimates within 10% of actual weight (PW10) accuracies of 86.9%, 80.4%, 72.1% and 71.4% respectively. The Broselow tape (PW10 47.1%) achieved a moderate accuracy and age-based estimates a very low accuracy (PW10 11.8–47.5%).

Conclusions

The PAWPER tape, the Wozniak method and the Mercy method achieved an acceptable level of accuracy in studies from low- and middle-income countries and should preferentially be used and further advanced for clinical emergency medicine practice. Parental estimates may be considered if the regular caregiver of the child is present and a recent measured weight is known. The Broselow tape and age-based formulas should be abandoned in low- and middle-income country populations as they are potentially dangerously inaccurate.

The accuracy of emergency weight estimation systems in children-a systematic review and meta-analysis

The safe and effective administration of fluids and medications during the management of medical emergencies in children depends on an appropriately determined dose, based on body weight. Weight can often not be measured in these circumstances and a convenient, quick and accurate method of weight estimation is required. Most methods in current use are not accurate enough, but the newer length-based, habitus-modified (two-dimensional) systems have shown significantly higher accuracy. This meta-analysis evaluated the accuracy of weight estimation systems in children. Articles were screened for inclusion into two study arms: to determine an appropriate accuracy target for weight estimation systems; and to evaluate the accuracy of existing systems using standard meta-analysis techniques. There was no evidence found to support any specific goal of accuracy. Based on the findings of this study, a proposed minimum accuracy of 70% of estimations within 10% of actual weight (PW10 > 70%), and 95% within 20% of actual weight (PW20 > 95%) should be demonstrated by a weight estimation system before being considered to be accurate. In the meta-analysis, the two-dimensional systems performed best. The Mercy method (PW10 70.9%, PW20 95.3%), the PAWPER tape (PW10 78.0%, PW20 96.6%) and parental estimates (PW10 69.8%, PW20 87.1%) were the most accurate systems investigated, with the Broselow tape (PW10 55.6%, PW20 81.2%) achieving a lesser accuracy. Age-based estimates achieved a very low accuracy. Age- and length-based systems had a substantial difference in over- and underestimation of weight in high-income and low- and middle-income populations. A benchmark for minimum accuracy is recommended for weight estimation studies and a PW10 > 70% with PW20 > 95% is suggested. The Mercy method, the PAWPER tape and parental estimates were the most accurate weight estimation systems followed by length-based and age-based systems. The use of age-based formulas should be abandoned because of their poor accuracy.

The PAWPER tape: A new concept tape-based device that increases the accuracy of weight estimation in children through the inclusion of a modifier based on body habitus

AIMS

Weight estimations in children, which are required when actual weight cannot be measured, are often very inaccurate because of variations in body habitus not accounted for in the estimating methodology. This study was conducted to evaluate the accuracy of the PAWPER tape, a new two-step weight-estimation tape device which employs a length-based habitus-modified weight estimation system.

METHODS

This was a prospective study in the Emergency Departments of two hospitals in Johannesburg, South Africa on a population of children aged from 1 month to 12 years. Each child had their weight estimated by both the Broselow tape and the PAWPER tape. These weight estimates were then compared against measured weight to determine the bias and precision of the estimation techniques.

RESULTS

The PAWPER tape performed well, and better than the Broselow tape in every analysis performed. The mean percentage error was -3.8% vs. 0% and the root mean squared percentage error was 9.1% vs. 4.5% for the Broselow tape and PAWPER tape, respectively (p<0.0001). The Broselow tape predicted weight to within 10% of actual weight in 63.6% of children and the PAWPER tape in 89.2% (p<0.0001). The difference between the performances of the Broselow tape and PAWPER tape was most pronounced in children >20 kg, and in children above or below average weight-for-length.

CONCLUSIONS

The PAWPER tape has been shown to be a simple and reliable method of weight estimation in children and infants. The inclusion of an appraisal of body habitus in the methodology considerably improved the accuracy of weight estimation.