An 8-year-old boy with a severe peanut and tree nut allergy is rushed into your ED after accidentally eating a sugar cookie that had been stored with peanut butter cookies. He is struggling to breathe by the time he gets to you, and is audibly wheezing. His lips are pale, his heart rate is 140 bpm, and his blood pressure is 90/58 mm Hg.
You lay the patient down on the Broselow Pediatric Emergency tape to estimate an epinephrine dosage, “red to head.” Based on height, the boy appears to fall within the orange zone, but as you look at the child, it's clear that he is significantly overweight, perhaps even obese. Given his size, is orange-zone dosing sufficient for this patient?
The Broselow Pediatric Emergency Tape, which offers a rapid means of determining correct medication dosage and correct equipment sizing for pediatric patients, has been a staple of emergency departments for more than 25 years, and numerous studies have attested to its reliability. A 2012 review of the literature by Meguerdician and Clapper, published in Pediatric Nursing, found the Broselow tape is the most reliable predictor in most situations compared with other methods of estimating medication dosing and airway equipment size.
“The Broselow tape is the one standardized tool that everyone uses. When you are in an emergency situation, even a simple calculation becomes complex,” said Muhammad Waseem, MD, an attending in pediatrics and emergency medicine at Lincoln Medical and Mental Health Center in the Bronx, NY. “It is very valuable for emergency physicians to have a tool that is easy to use and gives you comfort and confidence that you are not going to make a huge mistake.”
But because the Broselow tape relies strictly on body length for dosage calculation and most medications given to children are based on weight, could the rising rate of childhood obesity be impairing the accuracy of this ED staple?
The May 2013 edition of Academic Emergency Medicine devoted considerable space to the calculation methods for pediatric emergency dosing, including two studies by Dr. Waseem and his colleagues that suggest that the Broselow tape is inaccurate in predicting weight in nearly half of the children presenting to the ED. The researchers' retrospective reviews of two sets of data from 2008 to 2010 looked at 547 records of children up to 96 months of age and also 391 medical records of Hispanic children in the same age range.
The tape was inaccurate in predicting the weight of Hispanic children 45 percent of the time, the researchers found. It was also inaccurate 42 percent of the time in the larger data set of 547 records. Most of the inaccuracies were underestimations, and the tape was usually off by only one color zone. One of the strongest predictors of underestimation was a higher BMI percentile.
James Broselow, MD, who developed the tape with Dr. Robert Luten in the mid-1980s, noted that these data don't take into account the most recent version of his eponymous tape, which was issued in 2011. “Our latest tape does take into account the rising rate of obesity,” he said. Drs. Broselow and Luten are the co-founders of eBroselow, LLC, the developer of the Artemis electronic and digital drug dosing and tracking system for EMS and EDs.
“The Broselow tape is based on the relationship between weight and length across all ages; each color zone estimates the 50th percentile weight for length, which for practical purposes estimates the ideal body weight (IBW) for emergency dosing. The 2011 version of the Broselow tape incorporates revised length weight zones based on the most recent National Health and Nutrition Examination Survey (NHANES) data set,” according to a package insert that accompanies the new version of the tape.
Patients' measured length falls within accurate zones on the revised tape 65 percent of the time; most of the remainder are one heavier zone above, the insert says. “If a child looks obese and you are using a drug that might go into the fat, you just bump up one color,” Dr. Broselow said. “It should be noted that within these studies, the assumption is that our goal is to get to the real weight, but that assumption may be incorrect. Some drugs don't get to the body fat and go straight to the blood.”
Dr. Broselow noted that the universally-accepted system also has the advantage of correlating medication and equipment into the same zones. “A number of studies show that patient length is the best predictor for endotracheal tubes. Obese children don't need bigger tubes,” he said. “You're already going to measure length to get the tube size; in an emergency situation, are you really going to measure twice? What's more, the fact that we have a tape and color for every size makes it more likely that you'll have the right tube, suction catheter, and bag mask for that size. It's a complete system.”
Dr. Waseem said there is a need to improve and to make some adjustments so physicians can make a better judgment. “There is no standardized method,” he said. “It really varies from physician to physician. Every child is different, and obesity has a spectrum.”
Physicians at Children's Mercy Hospitals and Clinics in Kansas City, MO, suggested in the same edition of Academic Emergency Medicine that they may have an improved system for emergency departments to consider. Jennifer Watts, MD, an assistant professor of pediatrics at the University of Missouri-Kansas City, and colleagues compared the Broselow tape with four other commonly used estimation methods: provider estimate (PE), Advanced Pediatric Life Support (APLS), the Devised Weight Estimation Method (DWEM), and Luscombe & Owens (LO) with two versions of Mercy's own Mercy TAPE.
The Mercy TAPE, originally designed by Susan Abdel-Rahman, PharmD, a professor of pediatrics and pharmacy at the University of Missouri-Kansas City School of Medicine, stands for “TAking the guesswork out of Pediatric weight Estimation.” The device resembles a tape measure, and estimates weight based on length and circumference of the upper arm, translating them into a number displayed directly on the device.
“Dr. Abdel-Rahman went on to do studies with trained raters in a couple different parts of the world, and the numbers were just outstanding, almost too good to be true,” Dr. Watts said. Her study also used raters in a classroom setting, but it's the first to use nurses and EMTs who were not previously trained in the system. Five stations were set up, each staffed by a pediatric emergency nurse or an emergency medical technician. “Five kids were rotated through each station, and each rater estimated five children using each of the seven methods on all five kids,” Dr. Watts said. The raters were timed to rate ease of use as well.
Both Mercy tapes were more accurate at estimating weight to within 20 percent of actual than any of the other five methods — 78.3 percent for the 2DT and 76 percent for the 3DT vs. 73 percent for DWEM, 68 percent for Broselow, 67.3 percent for LO, 45 percent for PE, and 42.3 percent for APLS. Things got really interesting when considering the 30 percent of children in the study who were overweight and obese: all estimation methods dramatically dropped in accuracy, with the exception of the Mercy TAPE. The 2DT method estimated weight within 20 percent of actual in 83 percent of this subpopulation, and the 3DT method reached that goal in 74 percent of the children. DWEM dropped to 59 percent, LO to 50 percent, Broselow to 46 percent, PE to 28 percent, and APLS to 14 percent.
It took the untrained raters slightly longer to complete measurements with the Mercy TAPEs — about 30 seconds — but Dr. Watts noted that the raters tended to get faster as they gained more experience with them.
“Some methods of estimation can be very cumbersome, some you know are wrong, and some take a while and you want it done now,” Dr. Watts said. “Everything has limitations. You stand there as a physician and you wonder, is this one of those patients who falls into one of the gaps? If I'm prescribing resuscitation drugs, it's an ethical dilemma. When I see an obese child, my gut tells me when I see the estimation that it's not right and I'll change it. But there's no science behind that either. That's just making the call in the moment.”
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