Introduction
Medic 44 and Engine 18 respond to an elementary school on a report of a child having a seizure. When they arrive, they find a seven-year-old male lying in the gymnasium floor surrounded by other children and two adult teachers. One of the teachers says the kids were playing basketball when the boy suddenly collapsed and began convulsing. Someone from the office contacted the boy’s mother, who is now on her way to the school.
The child is motionless with agonal respirations. Medic Stevens cannot detect a pulse and instructs two of the firefighters to begin cardiopulmonary resuscitation (CPR). The boy’s electrocardiogram (ECG) reveals ventricular fibrillation. Using a weight-based measuring tape, Medic Ortiz estimates the child’s height to be between 122 cm and 133.5 cm, which corresponds to a weight range of 24 kg to 29 kg. Medic Stevens delivers a single countershock at 50 Joules (2 J/kg) and the firefighters resume CPR. Medic Ortiz quickly establishes intraosseous access in the boy’s left tibia and administers 2.5 ml of epinephrine 1:10,000 (0.01 mg/kg).
After two minutes of high quality CPR, the boy remains in VF. Medic Stevens delivers a second countershock of 100 Joules (4 J/kg) and the firefighters resume CPR. Ventilation with a bag-valve mask is adequate and the medics agree that endotracheal intubation is not warranted. Medic Ortiz delivers a 125 mg dose of amiodarone (5 mg/kg). At the two-minute mark, the boy receives a third countershock at 100 joules, the firefighters resume CPR, and the resuscitation team prepares for transport.
On the way to the hospital, the boy receives three additional doses of epinephrine, two additional doses of amiodarone, and two additional countershocks. On arrival in the emergency department (ED), the patient’s ECG displays asystole. The hospital staff continues the resuscitation effort for about an hour however, the patient does not respond.
Back at the station, the medics and the firefighters talk about the call and why nothing seemed to work. Medic Ortiz says that he delivered the correct drug dose recommendation from the weight-based measuring tape, but wondered if the doses were too small given the fact that the child was overweight.
Review
Researchers in West Virginia sought to determine the accuracy of the Broselow™ Pediatric Emergency Tape in estimating pediatric weight (Knight et al., 2011). The Broselow™ Tape is calibrated for pediatric patients between 46 cm and 146.5 cm in length, which correspond to a weight range of 3 kg to 34 kg. The tape is divided into nine color zones with precalculated drug doses, fluid volumes, and equipment sizes for each zone. All children whose length places them within a single color zone receive the same dose. For obvious reasons, healthcare providers cannot use the tape when children who are too short or too tall to fit within the measurement boundaries of the tape.
Using the medical records at a level-one trauma center, researchers identified 2359 pediatric patients treated for a trauma-related complaint during a five-year period beginning in 2002. Of these, only 657 (27.9%) of the children had both length measurements covered by the Broselow™ Tape and actual weight measurements recorded by the hospital staff. Researchers plotted the actual length measurements against the Broselow™ Tape to get an expected weight for each child and then compared the predicted weight against the actual weight.
Results
Of the 657 patients included in the study, the Broselow™ Tape accurately predicted the child’s weight less than half of the time (46.9%). When the tape was incorrect, three-quarters of the patients (77.1%) were heavier than what the tape predicted, which would have resulted in medication under dosing, insufficient fluid replacement volumes, lowered defibrillation energy levels, and undersized equipment.
The tape was least accurate in taller children, correctly predicting weight in about 46% of the children over 75 cm in length (29.5 inches). When incorrect, the actual weight differed from the predicted weight in the taller children by only one color interval. On the other hand, the tape correctly predicted weight in two-thirds of the children under 75 cm in length. However, when incorrect, the actual weight differed from the predicted weight by two or three color intervals.
What it means for you
Most healthcare providers calculate pediatric medication doses, fluid resuscitation volumes, and even defibrillation energy settings based on the child’s weight. In these situations, the therapeutic value of these interventions obviously depends upon the accuracy of the caregiver’s estimation of the child’s weight. Visual estimation of pediatric weight by nurses, physicians, and even the child’s parents is generally unreliable (Harris, Patterson, & Morse, 1999; Leffler & Hayes, 1997), although parent and legal guardian estimates are usually more accurate than nurses’ estimates (Partridge et al., 2009). Epinephrine doses calculated by paramedics based on a visual estimation of a child’s weight resulted in a calculated dose that was 10 times higher than the recommended dose for about 10% of the children (Vilke, Marino, Fisher, & Chan, 2001). Calculating weight based on the child’s age usually produces the least reliable estimate (Black, Barnett, Wolfe, & Young, 2002; Luten et al., 1992).
Current American Heart Association (AHA) guidelines recommend that healthcare providers make medication dose decisions based on the child’s weight, if known (Kleinman et al., 2010). When unknown, the AHA recommends that healthcare providers use a weight-based measuring tape with precalculated doses.
The Broselow™ Pediatric Emergency Tape is a tool that healthcare providers can use to quickly estimate a child’s weight, thereby allowing quick calculation of the correct weight-based drug dose during an emergency situation (Frush, n.d.). Data collected from multiple site across the United States found that weight estimates generated by use of the Broselow™ tape had a margin of error of more than 15% in one-fifth of children measured (Lubitz et al., 1988). Researchers at the University of Alabama found that the tape underestimates body weight in all groups of children (DuBois, Baldwin, & King, 2007). Paramedics in Los Angeles found the greatest measurement error in the bigger children (Heyming, Bosson, Kurobe, Kaji, & Gausche-Hill, 2012), which may result in 8 kilogram underestimation of weight for children between 30 and 36 cm in length (Sinha, Lezine, Frechette, & Foster, 2012). Researchers in Zurich found the tape accurately predicted endotracheal tube size in 55% of pediatric patients but underestimated the correct size in 39% of the cases (Hofer, Ganter, Tucci, Klaghofer, & Zollinger, 2002).
The tape accurately predicted resuscitation drug doses (within 10%) in only 60% of children (Nieman, Manacci, Super, Mancuso, Fallon, 2006). In fact, having parent provide their best guess of the child’s weight proved more accurate than weights estimated by the Broselow™ tape (Krieser et al., 2007).
Almost 17% of all children and adolescents in the United States are obese, defined as a body mass index greater than or equal to the age- and sex-specific 95th percentiles of the 2000 Centers for Disease Control and Prevention (CDC) growth charts (Ogden, Carroll, Kit, & Flegal, 2012). Using data from the 2009 Pediatric Nutrition Surveillance System, the CDC (Centers for Disease Control and Prevention, n.d.) reports that one out of every three low-income children in the United States will be overweight by his or her fifth birthday.
An estimation method that accounts for body habitus is generally more accurate than the Broselow™ tape (Yamamoto, Inaba, Young, & Anderson, 2009) or using 50th percentile weight from standard weight curves or from age alone (Garland, Kishaba, Nelson, Losek, & Sobocinski, 1986). Body habitus assigns a number value to children based on whether they are slim - 1, average - 2, or heavy – 3 (Garland, Kishaba, Nelson, Losek, & Sobocinski, 1986). A mathematical formula using that number along with the Broselow™ measurement determines the weight used for selecting drug doses and properly-sized equipment.
This study had a number of limitations. The patient measurements all occurred at a single institution in West Virginia. The authors report the state childhood obesity prevalence during the study period to be between 13.9% and 18.8%, depending on age range. Since the authors do not report obesity prevalence in their sample, we cannot be sure that the weight characteristics of the sample accurately reflect the state or even that national population of children.
The investigation sample included less than 30% of the children who actually arrived at the trauma center. While some of the children had heights that fell outside the possible measurement range of the Broselow™ tape, the authors excluded 961 patients with no explanation of why. This is almost one and one-half as many children as actually participated in the study. Inclusion of those children could possibly have altered the study results.
When the research team conducted this experiment, they used the 2007b version of the Broselow™ tape, which used height and weight measurements based on the 2007 National Health and Nutrition Examination Survey (NHANES). In 2011, the manufacturer released a newer version of the Broselow™ Tape with updated height and weight measurements advocated by the latest NHANES data (Armstrong Medical Industries, Inc., n.d.).
Finally, despite the fact that this study (along with others) demonstrated some inaccuracy of the Broselow™ measurements for certain groups of children, there is no evidence that the small differences in drug doses has any negative effect on the children’s clinical condition. For example, for children over 75 cm in length, the margin of error for measurement was only one color interval. During cardiac arrest, a deviation of one color interval could potentially change the epinephrine dose by only .03 milligrams. Whether that small difference has any clinical effect is a matter of speculation only.
References
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The author has no financial interest, arrangement, or direct affiliation with any corporation that has a direct interest in the subject matter of this presentation, including manufacturer(s) of any products or provider(s) of services mentioned. Send correspondence concerning this article to Kenneth W. Navarro, The University of Texas Southwestern Medical School at Dallas, 6300 Harry Hines Blvd, MC 9134, Dallas, Texas 75390-9134. E-mail: kenneth.navarro@utsouthwestern.edu
