Optimising emergency weight estimation in underweight and obese children: the accuracy of estimations of total body weight and ideal body weight

The Effect of Documenting Patient Weight in Kilograms on Pediatric Medication Dosing Errors in Emergency Medical Services

Objectives: Up to 40% of children who receive a medication from emergency medical services (EMS) are subject to a dosing error. One of the reasons for this is difficulties adjusting dosages for weight. Converting weights from pounds to kilograms complicates this further. This is the rationale for the National EMS Quality Alliance measure Pediatrics-03b, which measures the proportion of children with a weight documented in kilograms. However, there is little evidence that this practice is associated with lower rates of dosing errors. Therefore, our objective was to determine whether EMS documentation of weight in kilograms was associated with a lower rate of pediatric medication dosing errors.Methods: We conducted a retrospective cross-sectional study of children 0-14 y/o in the 2016-17 electronic Maryland Emergency Medical Services Data System that received a weight-based medication. Using validated age-based formulas, we assigned a weight to patients without one documented. Doses were classified as errors and severe errors if they deviated from the state protocol by >20% or >50%, respectively. We compared the dosage errors in the two groups and completed secondary analyses for specific medications and age groups.Results: We identified 3,618 cases of medication administration, 53% of which had a documented weight. Patients with a documented weight had a significantly lower overall dose error rate than those without (22 vs. 26%, p<.05). A sensitivity analysis in which we assigned a weight to those patients with a weight recorded did not significantly change this result. Sub-analyses by individual medication showed that only epinephrine (34 vs. 56%, p<.05) and fentanyl (10 vs. 31%, p <.05) had significantly lower dosing error rates for patients with a documented weight. Infants were the only age group where documenting a weight was associated with a lower dosing error rate (33 vs. 53% p<.05).Conclusion: Our findings suggest that documenting a weight in kilograms is associated with a small but significantly lower rate of pediatric dosing errors by EMS. Documenting a weight in kilograms appears particularly important for specific medications and patient age groups. Additional strategies (including age-based standardized dosing) may be needed to further reduce pediatric dosing errors by EMS.

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

Aim

To validate the PAWPER tape and assess its inter-observer reliability in children accessing a Paediatric Emergency Department (PED). As secondary outcome we compared the accuracy of the PAWPER tape with that of parents' estimation, the Broselow tape and the European Paediatric Life Support (EPLS) formula.

Methods

This was a cross-sectional study of children (0-12 years) enrolled in a tertiary Paediatric Emergency Department in Italy. Children's weight was estimated by parents and by trained healthcare providers using the PAWPER tape, the Broselow tape and the EPLS formula. The root mean squared percentage error (RMSPE) for the estimation of precision was calculated. Overall accuracy was evaluated using the percentage of weight estimation falling within 10% (PW10) and 20% (PW20) of real weight.

Results

The study included 2060 children. Parental estimation was the most accurate and precise method. The PAWPER tape was accurate throughout all habitus sizes except for extreme underweight and overweight categories. Furthermore, it was more accurate and more precise than the Broselow tape and the EPLS formula (p adjusted <0.001).

Conclusions

The PAWPER tape served as an accurate method for weight estimation in children accessing a Paediatric Emergency Department, with excellent inter-rater reliability. It performed significantly better than other length or age-based tools, showing good accuracy and precision except for very extreme weights. Whilst parents' estimation yielded to be the most accurate and precise method, the age-based EPLS formula was not reliable for estimating weight in all subcategories of habitus.

Development and Validation of a Length- and Habitus-Based Method of Ideal and Lean Body Weight Estimation for Adults Requiring Urgent Weight-Based Medical Intervention

BACKGROUND AND OBJECTIVE

Accurate drug dosing in obese patients requires an estimation of ideal body weight (IBW) or lean body weight (LBW) for dosing hydrophilic medications. Erroneous weight estimates during the management of adults requiring weight-based treatment may contribute to poor outcomes. Existing methods of IBW and LBW estimation or measurement are very difficult to use during emergency care. A new point-of-care model would be useful to provide rapid estimates of IBW and LBW for this purpose.

METHODS

A model was derived based on the PAWPER XL-MAC tape, a pediatric weight estimation system which uses recumbent length and mid-arm circumference to estimate IBW and LBW. The new adult model was used to generate IBW and LBW estimations for a derivation sample (n = 33155) and a validation sample (n = 5926) from National Health and Nutrition Examination Survey (NHANES) datasets. The model was developed in two steps, with calibration at each step, before being validated on an unused dataset. The outcome measure was to achieve >95% of IBW and LBW estimations within 20% of recognized reference standards (P20 > 95%) and >70% of estimations within 10% of these standards (P10 > 70%).

RESULTS

The new model achieved a P20 of 100% and a P10 of 99.9% for IBW and a P20 of 98.3% and a P10 of 78.3% for LBW. This accuracy was maintained in both sexes, all ages, all ethnic groups, all lengths, and in all habitus types, except for the severely obese female subgroup.

CONCLUSIONS

The modified PAWPER XL-MAC model proved to be an accurate method of IBW and LBW estimation. It could, therefore, have an important role in facilitating emergency drug dose calculations in obese adult patients.

Estimating Lean Body Weight in Adults With the PAWPER XL-MAC Tape Using Actual Measured Weight as an Input Variable

Introduction

Accurate drug dose calculation in obese patients requires an estimation of lean body weight (LBW) for dosing hydrophilic medications. Inaccurate weight estimates during the management of critically ill obese adults may contribute to inaccurate drug doses and consequential poor outcomes. Existing methods of LBW estimation or measurement may be very difficult or impossible to use during emergency care. A point-of-care model that could provide rapid, accurate estimates of LBW would, therefore, be of significant clinical value.

Methods

A model was derived based using the adult version of the PAWPER XL-MAC tape. This derived model used recumbent length and measured total body weight (TBW) to estimate LBW. The derived model was used to generate LBW estimations in a random sample from National Health and Nutrition Examination Survey (NHANES) datasets (n=33,215). The benchmark outcome measure was to achieve >95% of LBW estimations within 20% of DXA-measured fat-free mass (P20>95%) and >70% of estimations within 10% of DXA-measured fat-free mass (P10>70%).

Results

The new model achieved a P20 of 99.7% and a P10 of 86.4% for LBW in the pooled sample and exceeded the minimum accuracy standards. This accuracy was maintained in both sexes, all ages, all ethnic groups, all lengths and in all habitus types.

Conclusions

The modified PAWPER XL-MAC model, using TBW as an input variable, proved to be an accurate method of LBW estimation. It could potentially have an important role in facilitating emergency drug dose calculations in critically ill or injured obese adult patients.

Preclinical trial of noncontact anthropometric measurement using IR-UWB radar

Anthropometric profiles are important indices for assessing medical conditions, including malnutrition, obesity, and growth disorders. Noncontact methods for estimating those parameters could have considerable value in many practical situations, such as the assessment of young, uncooperative infants or children and the prevention of infectious disease transmission. The purpose of this study was to investigate the feasibility of obtaining noncontact anthropometric measurements using the impulse-radio ultrawideband (IR-UWB) radar sensor technique. A total of 45 healthy adults were enrolled, and a convolutional neural network (CNN) algorithm was implemented to analyze data extracted from IR-UWB radar. The differences (root-mean-square error, RMSE) between values from the radar and bioelectrical impedance analysis (BIA) as a reference in the measurement of height, weight, and body mass index (BMI) were 2.78, 5.31, and 2.25, respectively; predicted data from the radar highly agreed with those from the BIA. The intraclass correlation coefficients (ICCs) were 0.93, 0.94, and 0.83. In conclusion, IR-UWB radar can provide accurate estimates of anthropometric parameters in a noncontact manner; this study is the first to support the radar sensor as an applicable method in clinical situations.

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.

The utility of pediatric age-based weight estimation formulas for emergency drug dose calculations in obese children

OBJECTIVES

In obese children, when drug therapy is required during emergency care, an estimation of ideal body weight is required for certain drug dose calculations. Some experts have previously speculated that age-based weight estimation formulas could be used to predict ideal body weight. The objectives of this study were to evaluate how accurately age-based formulas could predict ideal body weight and total body weight in obese children.

METHODS

Three age-based weight estimation formulas were evaluated in a secondary analysis, using a pooled sample of children from 3 academic emergency departments in South Africa. The estimates produced by the 3 formulas (and the PAWPER XL tape as a control) were compared against measured total body weight and ideal body weight. The percentages of estimates falling within 10% of the standard weight were used as the primary outcome measure (PW10).

RESULTS

This study included 1026 children. For ideal body weight estimations in obese children, the old Advanced Life Support formula, the new Advanced Life Support formula, and the Best Guess formula achieved PW10s (with 95% confidence intervals [CIs]) of 29% (27.2%, 30.8%), 41.4% (38.9%, 43.9%), and 48.3% (45.3%, 51.3%), respectively. For total body weight estimations, the formulas achieved PW10s of 3.6% (3.4%, 3.8%), 5.2% (4.9%, 5.5%), and 19.0% (17.8%, 20.2%). The PAWPER XL tape achieved an accuracy of ideal body weight estimation of 100% (93.9%, 100%) and total body weight estimation of 49.7% (46.7%, 52.7%) in obese children.

CONCLUSIONS

The age-based formulas were substantially less accurate at estimating total body weight and ideal body weight than existing length-based methods such as the PAWPER XL tape, and should not be used for this purpose.

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

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.

A systems-centred approach to reducing medication error: Should pre-hospital providers and emergency departments dose children by age during resuscitation?

The high-risk, high-stress and high-stakes environment of out-of-hospital or emergency department paediatric resuscitation is prone to human error, and medication errors are common. This could be contributing to the difference in survival rate of resuscitation in the out-of-hospital versus inpatient setting. Medication for children during resuscitation requires estimation of the child's weight and calculation of the corresponding drug dose. Whilst both of these steps can lead to error, calculation errors (including 10-fold errors) are much more common and harmful than weight errors. Previous solutions aim to optimise each stage of the medication dosing process. Currently, Australian guidelines suggest using the highly inaccurate original advanced paediatric life support formula, weight = 2 × (age + 4), to dose medications in these settings. This means age is converted to weight, which is then converted to dose. There is no evidence that this is causing harm to patients. Therefore, it could be suggested that age could safely be converted straight to dose according to preset doses. This eliminates the need for any weight estimation or dose calculation, thus reducing the potential for error and harm.

A validation of the PAWPER XL-MAC tape for total body weight estimation in preschool children from low- and middle-income countries

Importance

The PAWPER tape system is one of the three most accurate paediatric weight estimation systems in the world. The latest version of the tape, which does not rely on a subjective assessment of habitus, is the PAWPER XL-MAC method which uses length and mid-arm circumference (MAC) to estimate weight. It was derived and validated in a population in the USA and has not yet been fully validated in a population from a resource-limited setting.

Objective

The objective of this study was to evaluate the performance of the PAWPER XL-MAC tape weight estimation system in a large dataset sample of children from resource-limited settings.

Methods

This was a “virtual” study in which weight estimates were generated using the PAWPER XL-MAC tape and Broselow tape 2007B and 2011A editions in a very large open access dataset. The dataset contained anthropometric information of children aged 6 to 59 months from standardised nutritional surveys in 51 low- and middle-income countries. The performance of PAWPER XL-MAC method was compared with the Broselow tape and a new length- and habitus-based tape, the Ralston method.

Main outcomes and measures

The bias of the weight estimation methods was assessed using the mean percentage error (MPE) and precision using the 95% limits of agreement (LOA) of the MPE. The overall accuracy was denoted by the percentage of weight estimates falling within 10% and 20% of actual weight (abbreviated as p10 and p20 respectively).

Results

The MPE (LOA) for the PAWPER XL-MAC tape, the Broselow 2007B and 2011A and Ralston method were 1.9 (-15.3, 19.2), 5.4 (-15.9, 26.7), 7.7 (-13.3, 30.5) and -0.7 (-20.2, 19.3) respectively. The p10 and p20 for each method were 79.3% and 96.9% for the PAWPER XL-MAC tape, 64.3% and 91.0% for the Broselow tape 2007B, 55.5% and 85.9% for the Broselow tape 2011A and 67.4 and 94.0% for the Ralston method respectively. The PAWPER XL-MAC system was statistically significantly more accurate than the Broselow tape 2011A, the Broselow tape 2007B and the Ralston method. The relative difference in accuracy (p10) was 43% (odds ratio 4.4 (4.4, 4.5), p<0.001), 23% (odds ratio 2.9 (2.8, 2.9), p<0.001) and 18% (odds ratio 1.8 (1.8, 1.8), p<0.001) compared to each method, respectively.

Conclusions and relevance

The PAWPER XL-MAC tape performed well in this study and was statistically significantly more accurate than both the Broselow tape editions and the Ralston method. This difference was substantial and clinically important. The tape did not perform as well at extremes of habitus-type, however, and might benefit from recalibration.

The "PAWPER-on-a-page": Increasing global access to a low-cost weight estimation system

BACKGROUND

The PAWPER tape is one of the most accurate weight estimation systems available today, but international access to the tape is limited because it has no commercial distribution. For this reason, the "PAWPER-on-a-page" concept was devised: downloadable image files that allow users to print and assemble their own tapes. However, the feasibility of this method is dependent on users being able to produce accurate tapes. This study was devised to determine whether untrained participants could print and assemble the "PAWPER-on-a-page" easily and accurately.

METHODS

Doctor and nurse volunteers downloaded the "PAWPER-on-a-page" and "PAWPER XL-on-a-page" image files and printed copies on a home-printer and also at a commercial printer. One copy of each tape was then assembled according to instructions from an online video. The accuracy of printing and assembly, the time taken for assembly and the cost were then evaluated.

RESULTS

There were 32 participants. The median time for assembly was 8 minutes 19 seconds and 7 minutes 31 seconds for the "PAWPER-on-a-page" and "PAWPER XL-on-a-page" respectively, with a median cost of USD 0.09 and USD 1.00 respectively. For the assembled tapes, 71.9% of the "PAWPER-on-a-page" tapes and 65.6% of the "PAWPER XL-on-a-page" achieved the required accuracy of 0.2%. Printing errors, related to scaling, were common, but easily detectable.

CONCLUSION

The "PAWPER-on-a-page" system can be easily, quickly, affordably and accurately printed and assembled by end users. Stringent double checking of the printed and fully assembled tapes is essential to ensure accuracy.