Pediatric Profile: Immobilization Using a Kendrick Extrication Device

Author: Michael Tunik, MD

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Q: Is there a safe way to perform defibrillation in young children using an automated external defibrillator?

A: Yes. The FDA-approved Heartstream FR2 automated external defibrillator (AED) can be used with modified pads or leads in children younger than 8 years. The unit is manufactured by Phillips Medical Systems.

How does it work?

You must use pediatric pads and cables, which are available from the manufacturer. Identified by a pink teddy bear, the pediatric pads decrease the energy delivered by increasing the resistance in the cables, reducing output from 150 joules to 50 joules.

How should the pediatric pads be positioned?

Use the anterior/posterior pad placement as illustrated on the package. This allows for easy pad placement on even a small child's torso. In larger children, you can position the pediatric pads on the chest in the standard right and left lateral positions.

Will the pads work with other AEDs?

No. They require a cable connector that fits only the Phillips Heartstream FR2.

How common is it for younger children in arrest to have rhythms that respond to defibrillation?

There are few large prospective studies to draw on for answers, but estimates from available studies suggest that 6% to 19% of children in cardiac arrest have ventricular dysrhythmias. Since most emergency protocols recommend that rescuers first perform BLS maneuvers on these children, there may simply be fewer identified ventricular dysrhythmias, as ventricular fibrillation is likely to devolve into asystole before the rhythm is analyzed.

Will an AED with pediatric pads correctly identify pediatric ventricular dysrhythmias, delivering shocks only to children who need them?

The rhythm detection algorithms vary in different AED models. When the algorithm used in the Heartstream FR2 was tested against 696 pediatric rhythms, it correctly identified a rhythm that would respond to defibrillation in 96% of the cases, and correctly identified a rhythm that should not be defibrillated 100% of the time.

Is the 50-joule energy dose safe and effective for all young children?

There are no large prospective studies on the use of pediatric AEDs in actual arrests involving children, which makes it difficult to answer this question based on empirical data. However, it is easy to calculate the energy delivered to the average infant and child and compare it with current protocols.

Most emergency protocols currently recommend that children in pulseless ventricular tachycardia (VT) or ventricular fibrillation (VF) receive 2 J/kg of energy followed by 4 J/kg. The average weight of a newly born infant is approximately 3.5 kg; a 1-year-old, 11 kg; and 8-year-olds weigh approximately 24 kg. By calculation, the energy dose delivered by the Heartstream FR2 with pediatric pads would range from a maximum of 16J/kg (in the neonate) to a minimum of 2 J/kg in the 8-year-old. The typical 1-year old receives about 4.5 J/kg. Children from 1 to 8 years old receive 4.5 to 2 J/kg depending on size, which is similar to typical pediatric energy doses used with manual defibrillation. The 16 J/kg energy dose is higher than what is commonly used.

Would 16 J/kg harm an infant?

There are few studies available to quantify the energy dose that will cause injury or death in humans. Canine studies have demonstrated that a lethal dose of energy for dogs exceeds 30 J/kg. The Heartstream FR2 equipped with pediatric pads was tested in pigs weighing from 3.5 kg to 25 kg and successfully defibrillated all animals.

How will AED use affect pediatric outcome in children experiencing respiratory arrest with severe bradycardia? Is there a risk that rescuers will focus their efforts on applying the AED rather than on basic life support skills (airway opening, ventilation, compressions)?

This is a very important question, and the answer is unknown. The children who would benefit the most from defibrillation are those in pulseless arrest from VF or VT. Children experiencing respiratory arrest will benefit from immediate airway opening and ventilation, which in many cases can prevent them from progressing to cardiac arrest. These children will have bradycardia and a weak pulse. If rescuers could accurately distinguish a weak pulse from pulselessness in children, appropriate interventions could be administered with lifesaving benefits.

However, bystanders and prehospital professionals alike have difficulty accurately identifying the presence of a pulse in infants and young children. The weak pulse in a child experiencing respiratory arrest may be overlooked, resulting in a mistaken diagnosis of pulseless cardiac arrest. This may distract rescuers' attention from assisted ventilations as they apply a pediatric AED. There are few studies examining the lay response to pediatric arrests. Some of these studies suggest that children received bystander CPR only one-third to one-sixth of the time.

One large prospective study found that the incidence of pediatric respiratory arrest versus cardiac arrest was approximately 1 to 5 (108 cases of respiratory arrest to 591 cases of cardiac arrest), but the survival rate of children in respiratory arrest is much greater than that of children in cardiac arrest (73% versus 8%). Also, children who survive respiratory arrest are much more likely to be neurologically intact (n = 62) than those who survive cardiac arrest (n = 25). (See Gausche M, Lewis RJ, Stratton SJ, et al. "Effect of out-of-hospital pediatric endotracheal intubation on survival and neurological outcome: a controlled clinical trial." JAMA. 2000;283(6):783