Defibrillation is a time-sensitive intervention in a cardiac emergency, and its success relies on delivering a precise and appropriate electrical current to the heart. When treating a child, the procedure requires specialized equipment and protocols that significantly differ from those used for adults. The most immediate distinction is the size of the paddles or electrode pads used. Selecting the correct size is paramount because it dictates how effectively the electrical energy travels through the smaller body to correct a life-threatening heart rhythm. Using the wrong size can lead to ineffective therapy or severe patient harm.
Why Paddle Size Impacts Current Density
Paddle size directly affects current density, which is the concentration of electrical energy delivered across a specific surface area. A smaller paddle size concentrates the electrical charge into a tighter area, which is necessary for a smaller patient.
The shock must successfully reach the heart, which is impeded by transthoracic impedance—the natural resistance of the chest wall, lungs, and surrounding tissues to the electrical current. Studies indicate that larger paddles, such as the standard adult size, can reduce this impedance more effectively than smaller pediatric paddles when the chest can accommodate them without overlap.
When adult paddles fit, they can lower transthoracic impedance significantly, allowing a higher peak current to flow through the chest, which directly improves the chances of successful defibrillation. Pediatric paddles are necessary for the smallest patients, but they are only preferred when the patient’s body size mandates a smaller contact surface to prevent pad-to-pad contact.
Determining the Appropriate Pediatric Paddle Size
The selection of pediatric-sized paddles is primarily determined by a patient’s weight, which serves as a proxy for chest size. Guidelines recommend using the smaller, pediatric paddles or attenuated electrode pads for infants weighing less than approximately 10 kilograms, typically corresponding to a child under one year of age.
For patients weighing between 10 and 25 kilograms (up to roughly eight years of age), the transition to larger adult-sized pads or paddles is often recommended. A child in this range can usually accommodate the adult paddle size without the risk of the paddles touching. Specialized pediatric attenuated electrode systems deliver a reduced energy dose appropriate for children up to this 25-kilogram limit.
Pediatric paddles typically measure around 4.5 centimeters in diameter, while adult paddles measure between 8 and 10 centimeters. The overarching principle is to use the largest possible pad that fits on the child’s chest without the conductive surface contacting the other pad. This maximizes the surface area for current delivery while minimizing the risk of electrical short-circuiting.
Safety Hazards of Using Oversized Paddles
Using adult-sized paddles on a small child presents several safety hazards that compromise defibrillation outcomes. The most immediate danger occurs when the conductive surfaces overlap or come into direct contact, creating a low-resistance path that bypasses the heart entirely.
This physical overlap causes electrical arcing, resulting in an ineffective shock that fails to reset the heart’s rhythm. Additionally, the concentrated electrical energy flowing through the skin instead of the chest can cause severe cutaneous thermal injury due to the improper distribution of current.
Even without physical contact, using an oversized paddle on a small chest can cause the current to follow a path that skirts around the heart. This misdirection of energy, due to the large surface area relative to the small target organ, can lead to a shock that is not strong enough at the heart muscle level to be therapeutic. The oversized equipment ultimately leads to a failed defibrillation attempt despite the proper energy settings.
Correct Placement Techniques for Pediatric Defibrillation
The proper positioning of the paddles is crucial to ensure the electrical current passes through the heart muscle effectively. The two primary techniques are the anterior-lateral and the anterior-posterior placement. The anterior-lateral method involves placing one paddle on the upper right chest below the clavicle and the other on the lower left chest, near the armpit.
For the smallest patients, the anterior-posterior position is often preferred. This technique places one paddle on the front of the chest over the heart and the second paddle on the child’s back, positioned between the shoulder blades. This front-to-back orientation maximizes the amount of heart tissue included in the current path.
The anterior-posterior placement also ensures the paddles are sufficiently separated on a small torso, preventing the dangerous overlap that can occur with the anterior-lateral placement. Regardless of the position chosen, firm and consistent pressure must be maintained on the paddles to achieve optimal skin contact. This firm contact minimizes transthoracic impedance and ensures the full delivery of the therapeutic electrical current.