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Emergency Medicine Australasia (2015) 27, 239–244
doi: 10.1111/1742-6723.12382
PAEDIATRIC EMERGENCY MEDICINE
Comparison of the finger counting method, the Broselow tape and common weight estimation formulae in Filipino children after Typhoon Haiyan Timothy P YOUNG, Omar WASHINGTON, Andrew FLANERY, Mindi GUPTILL, Ellen T REIBLING, Lance BROWN and Besh BARCEGA Division of Paediatric Emergency Medicine, Department of Emergency Medicine, Loma Linda University Medical Center and Children’s Hospital, Loma Linda, CA, USA
Abstract Objectives: We sought to evaluate commonly used paediatric weight estimation techniques in a sample of children in the Philippines. Methods: We prospectively collected age, height and weight data for a sample of 207 children aged 1–9 years seen during a medical aid trip. Weights were estimated using the finger counting method, the Broselow method and four formulae. Bland–Altman analysis was performed to evaluate agreement with measured weight. Results: Mean difference and range of agreement in kilograms were as follows: 0.6 (95% CI 0.1–1.1) and 14.9 (95% CI 13.1–16.7) for the Broselow method; 1.1 (95% CI 0.5– 1.7) and 17.3 (95% CI 15.2–19.3) for the traditional APLS formula; 3.1 (95% CI 2.4–3.7) and 18.6 (95% CI 16.4–20.8) for the finger counting method; 4.0 (95% CI 3.2–4.8) and 23.1 (95% CI 20.3–25.8) for the updated APLS method; 5.1 (95% CI 4.4–5.8) and 21.1 (95% CI 18.6– 23.6) for the Luscombe formula; and 5.3 (95% CI 4.5–6.1) and 22.5 (95%
CI 20–25.2) for the Best Guess formulae. Conclusions: The Broselow tape and the traditional APLS formula performed best in our sample. The finger counting method also outperformed newer weight estimation formulae. ‘Updated’ age-based formulae created recently in developed countries should not be used in disaster relief efforts in the Philippines. Caution should be used when applying these formulae to other developing countries and in disaster response. Key words: finger counting method, paediatrics, weight estimation.
Introduction Weight estimation is necessary in the care of ill and injured children in the ED. Multiple methods have been described for this purpose, including formulae,1–4 devices that measure surrogates for weight, such as length,5 and estimation by a parent or caregiver.6 In recent years, the number of agebased formulae available for paediatric weight estimation has particularly
Correspondence: Associate Professor Timothy P Young, Department of Emergency Medicine, Loma Linda University Medical Center and Children’s Hospital, 11234 Anderson Street, A-108, Loma Linda, CA 92354, USA. Email: [email protected] Timothy P Young, MD, FACEP, FAAP, Paediatric Emergency Physician, Associate Professor; Omar Washington, MD, Emergency Medicine Resident; Andrew Flanery, MD, Emergency Medicine Resident; Mindi Guptill, MD, FACEP, Emergency Physician, Assistant Professor; Ellen T Reibling, PhD, Director of Emergency Medicine Research, Associate Professor; Lance Brown, MD, MPH, FACEP, FAAP, Division Chief, Professor; Besh Barcega, MD, MBA, FAAP, FACEP, Paediatric Emergency Physician, Assistant Professor. Accepted 10 February 2015
Key findings • The Broselow tape and traditional APLS method estimated paediatric weights best in a sample of Filipino children after Typhoon Haiyan. • The finger counting method also outperformed newer weight estimation formulae. • The three newest methods (updated APLS, Luscombe and Best Guess) performed worst in this sample.
increased. This is mostly due to concerns that older techniques have become inaccurate in the face of increasing rates of childhood obesity in developed countries.2–4 Some formulabased techniques now employ multiple formulae for specific age groups in an effort to increase accuracy.2,4 We previously evaluated an age-based technique for weight estimation that employs counting on one’s fingers.7 This technique performed similarly to the Broselow tape and better than the traditional Advanced Paediatric Life Support (APLS) formula in a population of children presenting to an ED in the United States.7 Unlike other methods, it does not require special equipment. Our emergency medicine and paediatric emergency medicine trainees anecdotally report that it is easier to remember than other age-based formulae. We have a strong international medicine interest at our institution. We have an active international emergency
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
240
TP YOUNG ET AL.
medicine fellowship programme and arrange frequent trips to countries outside of the United States to provide medical aid in rural settings, where sizes and weights of children might differ from developed countries. Similar to the ED, these settings may require weight estimation for administration of medications and selection of equipment for children; however, less is known about the accuracy of available techniques in these circumstances. The simplicity of the finger counting method is appealing in such a setting, where resources are scarce. We sought to examine the agreement with measured weight of the finger counting method, as well as other commonly used paediatric weight estimation techniques, in one such setting in the Philippines.
Methods
ability to stand or lay down, or a chronic illness known to affect size and growth. Exclusion criteria were agreed on by all the investigators and were made available as a reminder during enrolment. We determined our target sample size based on Bland’s suggested sample size of 200 to estimate the limits of agreement between two methods of measurement using a Bland–Altman plot.10 To avoid a skewed age distribution, we enrolled equal numbers of children of each age, 1–9 years. To meet our target sample size with equal numbers of each age, we aimed to enroll 23 children of each age for a total of 207 subjects. We created separate data collection forms for each age with space for 23 children and enrolled children until each age-specific data collection form was full. In this way, we enrolled a convenience sample of children blocked by age.
Study design We prospectively collected crosssectional data on a sample of children living in the city of Ilagan in the Philippines. The study was approved by our institutional review board.
Study setting and population We collected our data in April 2014 on a trip to the city of Ilagan in the Philippine province of Isabela. Ilagan has a population of 135 174.8 The average annual income for the region is 195 000 pesos per family,9 equivalent to 4470 US or 5027 Australian dollars. This is less than the average family income for the entire country, which is 235 000 pesos.9 The trip consisted of temporary clinics set up in the city and in rural communities around the city. We enrolled children aged 1 to 9 years who presented to one of these clinics. We chose children of this age group for several reasons: it is the age range applicable to the finger counting method, it avoids the postpubertal population that has a wide variance in weight, and based on our previous study, it largely avoids the population that is taller than the largest category on the Broselow tape.7 We excluded children with a tracheostomy, cerebrospinal fluid shunt, any indwelling catheter or feeding tube, the in-
Study protocol Once we identified a child as being eligible for the study based on our criteria, we explained the study to the caregiver and obtained verbal consent. We collected data on each child’s age, sex and medical history. We measured weight by having the child stand on a Healthometer model 349KLX digital medical weight scale (Pelstar LLC, McCook, IL, USA) placed on a hard surface. Children were lightly clothed; outer clothing and shoes were removed. This scale is accurate to within 10 g and its use is established in the medical literature.11,12 The scale was bought new and was first used on this trip.
According to the manufacturer, the scale is factory calibrated and does not require calibration prior to use.13 It was zeroed prior to each weight. If the child was old enough to stand, we measured height against a wall. A square metal tool was constructed to check the wall for perpendicularity. Height was marked against the wall at the top of the child’s head using a square object. Distance from the floor to that point was measured using a model 45 Prestige tape measure (Prestige Medical Company, Northridge, CA, USA). If the child was too young to stand, we measured the weight of an adult holding the child and then subtracted the adult’s weight, and distance from head to heel was measured on a flat surface using the same Prestige tape measure.
Weight estimation methods Once we returned from the trip, the child’s weight was estimated using the finger counting method,7 the Broselow method5 and four age-based formulae: the widely used traditional APLS formula,1 the updated APLS formulae, 2 the United Kingdom-derived Luscombe formula,3 and the Australiaderived Best Guess formulae4 (Table 1). The finger counting method was first described by Alson Inaba over 20 years ago.14 Dr Inaba’s technique involves using both hands to estimate the child’s weight, by counting age in years by odd numbers on one hand and weight in kilograms on the other, starting with 10 kg and counting by 5 kg (Fig. 1). The technique is used for children aged 1–9 years. A video description is available online.15 To obtain the Broselow
TABLE 1. Age-based formulae Traditional APLS (2005)1
Weight (kg) = (2 × age in years) + 8 = (age in years + 4) × 2
Updated APLS (2011)2
Emergency Medicine Australasia (2015) 27, 239–244
doi: 10.1111/1742-6723.12382
PAEDIATRIC EMERGENCY MEDICINE
Comparison of the finger counting method, the Broselow tape and common weight estimation formulae in Filipino children after Typhoon Haiyan Timothy P YOUNG, Omar WASHINGTON, Andrew FLANERY, Mindi GUPTILL, Ellen T REIBLING, Lance BROWN and Besh BARCEGA Division of Paediatric Emergency Medicine, Department of Emergency Medicine, Loma Linda University Medical Center and Children’s Hospital, Loma Linda, CA, USA
Abstract Objectives: We sought to evaluate commonly used paediatric weight estimation techniques in a sample of children in the Philippines. Methods: We prospectively collected age, height and weight data for a sample of 207 children aged 1–9 years seen during a medical aid trip. Weights were estimated using the finger counting method, the Broselow method and four formulae. Bland–Altman analysis was performed to evaluate agreement with measured weight. Results: Mean difference and range of agreement in kilograms were as follows: 0.6 (95% CI 0.1–1.1) and 14.9 (95% CI 13.1–16.7) for the Broselow method; 1.1 (95% CI 0.5– 1.7) and 17.3 (95% CI 15.2–19.3) for the traditional APLS formula; 3.1 (95% CI 2.4–3.7) and 18.6 (95% CI 16.4–20.8) for the finger counting method; 4.0 (95% CI 3.2–4.8) and 23.1 (95% CI 20.3–25.8) for the updated APLS method; 5.1 (95% CI 4.4–5.8) and 21.1 (95% CI 18.6– 23.6) for the Luscombe formula; and 5.3 (95% CI 4.5–6.1) and 22.5 (95%
CI 20–25.2) for the Best Guess formulae. Conclusions: The Broselow tape and the traditional APLS formula performed best in our sample. The finger counting method also outperformed newer weight estimation formulae. ‘Updated’ age-based formulae created recently in developed countries should not be used in disaster relief efforts in the Philippines. Caution should be used when applying these formulae to other developing countries and in disaster response. Key words: finger counting method, paediatrics, weight estimation.
Introduction Weight estimation is necessary in the care of ill and injured children in the ED. Multiple methods have been described for this purpose, including formulae,1–4 devices that measure surrogates for weight, such as length,5 and estimation by a parent or caregiver.6 In recent years, the number of agebased formulae available for paediatric weight estimation has particularly
Correspondence: Associate Professor Timothy P Young, Department of Emergency Medicine, Loma Linda University Medical Center and Children’s Hospital, 11234 Anderson Street, A-108, Loma Linda, CA 92354, USA. Email: [email protected] Timothy P Young, MD, FACEP, FAAP, Paediatric Emergency Physician, Associate Professor; Omar Washington, MD, Emergency Medicine Resident; Andrew Flanery, MD, Emergency Medicine Resident; Mindi Guptill, MD, FACEP, Emergency Physician, Assistant Professor; Ellen T Reibling, PhD, Director of Emergency Medicine Research, Associate Professor; Lance Brown, MD, MPH, FACEP, FAAP, Division Chief, Professor; Besh Barcega, MD, MBA, FAAP, FACEP, Paediatric Emergency Physician, Assistant Professor. Accepted 10 February 2015
Key findings • The Broselow tape and traditional APLS method estimated paediatric weights best in a sample of Filipino children after Typhoon Haiyan. • The finger counting method also outperformed newer weight estimation formulae. • The three newest methods (updated APLS, Luscombe and Best Guess) performed worst in this sample.
increased. This is mostly due to concerns that older techniques have become inaccurate in the face of increasing rates of childhood obesity in developed countries.2–4 Some formulabased techniques now employ multiple formulae for specific age groups in an effort to increase accuracy.2,4 We previously evaluated an age-based technique for weight estimation that employs counting on one’s fingers.7 This technique performed similarly to the Broselow tape and better than the traditional Advanced Paediatric Life Support (APLS) formula in a population of children presenting to an ED in the United States.7 Unlike other methods, it does not require special equipment. Our emergency medicine and paediatric emergency medicine trainees anecdotally report that it is easier to remember than other age-based formulae. We have a strong international medicine interest at our institution. We have an active international emergency
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
240
TP YOUNG ET AL.
medicine fellowship programme and arrange frequent trips to countries outside of the United States to provide medical aid in rural settings, where sizes and weights of children might differ from developed countries. Similar to the ED, these settings may require weight estimation for administration of medications and selection of equipment for children; however, less is known about the accuracy of available techniques in these circumstances. The simplicity of the finger counting method is appealing in such a setting, where resources are scarce. We sought to examine the agreement with measured weight of the finger counting method, as well as other commonly used paediatric weight estimation techniques, in one such setting in the Philippines.
Methods
ability to stand or lay down, or a chronic illness known to affect size and growth. Exclusion criteria were agreed on by all the investigators and were made available as a reminder during enrolment. We determined our target sample size based on Bland’s suggested sample size of 200 to estimate the limits of agreement between two methods of measurement using a Bland–Altman plot.10 To avoid a skewed age distribution, we enrolled equal numbers of children of each age, 1–9 years. To meet our target sample size with equal numbers of each age, we aimed to enroll 23 children of each age for a total of 207 subjects. We created separate data collection forms for each age with space for 23 children and enrolled children until each age-specific data collection form was full. In this way, we enrolled a convenience sample of children blocked by age.
Study design We prospectively collected crosssectional data on a sample of children living in the city of Ilagan in the Philippines. The study was approved by our institutional review board.
Study setting and population We collected our data in April 2014 on a trip to the city of Ilagan in the Philippine province of Isabela. Ilagan has a population of 135 174.8 The average annual income for the region is 195 000 pesos per family,9 equivalent to 4470 US or 5027 Australian dollars. This is less than the average family income for the entire country, which is 235 000 pesos.9 The trip consisted of temporary clinics set up in the city and in rural communities around the city. We enrolled children aged 1 to 9 years who presented to one of these clinics. We chose children of this age group for several reasons: it is the age range applicable to the finger counting method, it avoids the postpubertal population that has a wide variance in weight, and based on our previous study, it largely avoids the population that is taller than the largest category on the Broselow tape.7 We excluded children with a tracheostomy, cerebrospinal fluid shunt, any indwelling catheter or feeding tube, the in-
Study protocol Once we identified a child as being eligible for the study based on our criteria, we explained the study to the caregiver and obtained verbal consent. We collected data on each child’s age, sex and medical history. We measured weight by having the child stand on a Healthometer model 349KLX digital medical weight scale (Pelstar LLC, McCook, IL, USA) placed on a hard surface. Children were lightly clothed; outer clothing and shoes were removed. This scale is accurate to within 10 g and its use is established in the medical literature.11,12 The scale was bought new and was first used on this trip.
According to the manufacturer, the scale is factory calibrated and does not require calibration prior to use.13 It was zeroed prior to each weight. If the child was old enough to stand, we measured height against a wall. A square metal tool was constructed to check the wall for perpendicularity. Height was marked against the wall at the top of the child’s head using a square object. Distance from the floor to that point was measured using a model 45 Prestige tape measure (Prestige Medical Company, Northridge, CA, USA). If the child was too young to stand, we measured the weight of an adult holding the child and then subtracted the adult’s weight, and distance from head to heel was measured on a flat surface using the same Prestige tape measure.
Weight estimation methods Once we returned from the trip, the child’s weight was estimated using the finger counting method,7 the Broselow method5 and four age-based formulae: the widely used traditional APLS formula,1 the updated APLS formulae, 2 the United Kingdom-derived Luscombe formula,3 and the Australiaderived Best Guess formulae4 (Table 1). The finger counting method was first described by Alson Inaba over 20 years ago.14 Dr Inaba’s technique involves using both hands to estimate the child’s weight, by counting age in years by odd numbers on one hand and weight in kilograms on the other, starting with 10 kg and counting by 5 kg (Fig. 1). The technique is used for children aged 1–9 years. A video description is available online.15 To obtain the Broselow
TABLE 1. Age-based formulae Traditional APLS (2005)1
Weight (kg) = (2 × age in years) + 8 = (age in years + 4) × 2
Updated APLS (2011)2
