AED pads go in two specific spots on an adult’s bare chest: one just below the right collarbone and one on the lower left side of the chest, below the armpit. This positioning sends the electrical shock across the heart, giving the AED the best chance of restoring a normal rhythm. Every AED includes a diagram on the pads or packaging showing exactly where they go, but knowing the landmarks ahead of time can save critical seconds.
Standard Adult Pad Placement
The standard method is called anterior-lateral placement. The first pad goes on the upper right chest, just below the collarbone and to the right of the breastbone. The second pad goes on the lower left side of the chest, along the side of the ribcage below the armpit. On a male patient, this second pad aligns with the bottom edge of the chest muscle. On a female patient, it goes under the left breast.
This positioning places one pad above and one pad below the heart, so the electrical current travels directly through it. The pads need firm, flat contact with the skin to work properly. Press them down smoothly and make sure there are no wrinkles or air pockets underneath.
Placement for Children and Infants
Pediatric pads are designed for children up to 8 years old or weighing less than 55 pounds (25 kg). These pads deliver a lower energy dose appropriate for a smaller body. For children older than 8, use standard adult pads.
For a child large enough that the pads won’t overlap, you can use the same upper-right and lower-left positions as an adult. For infants and very small children, switch to anterior-posterior placement: put one pad on the center of the chest and the other on the center of the back, directly behind the first. This keeps the pads from touching each other, which would short-circuit the shock and make it ineffective. If you only have adult pads and the patient is a child, use them anyway. An AED with adult pads is far better than no AED at all.
Preparing the Chest Before Placing Pads
The pads need direct contact with dry, bare skin. Remove or cut away clothing from the chest before placing them. Several common situations can interfere with good contact.
- Excessive chest hair. If thick hair prevents the pads from sticking flat, shave the area with the prep razor included in most AED accessory kits. A perfectly smooth shave isn’t necessary, just enough to get solid adhesion.
- Wet skin. Quickly wipe the chest dry with a towel or clothing before applying the pads. If the person is lying in water, move them to a dry surface if you can do it in under 10 seconds. In light rain, you can still use the AED as long as you can keep the chest reasonably dry. The key safety rule is that no water should pool between the two pads.
- Medication patches. If a transdermal patch (such as a nicotine or pain patch) sits where a pad needs to go, peel it off and wipe the area before placing the AED pad. Leaving a patch in place can block the electrical current or cause a small skin burn.
Working Around Implanted Devices
Some people have a pacemaker or implanted defibrillator, which typically appears as a hard, rectangular lump under the skin of the upper chest. If one of these devices sits right where you’d normally place a pad, shift the pad so it’s at least 1 inch (2.5 cm) away from the device. You don’t need to identify what the implant is or worry about damaging it. Just avoid placing a pad directly over the bump, and the AED will function normally.
What If the Pads Are in the Wrong Spot?
Speed matters more than perfection. If you’ve placed the pads and the AED is analyzing the heart rhythm, don’t peel them off to reposition. A slightly imperfect placement will still deliver a shock across the heart. The most important thing is that the two pads are not touching or overlapping each other, that they’re stuck firmly to bare skin, and that the electrical path between them crosses the heart.
If you realize mid-application that you’ve mixed up which pad goes where (putting the “upper” pad on the lower left, for example), don’t worry. Modern AEDs work regardless of which specific pad is in which position. The device reads the heart rhythm and delivers the shock the same way either direction.
Anterior-Posterior Placement on Adults
While the standard front-and-side method is recommended for adults because it’s faster to apply and doesn’t require rolling the person over, anterior-posterior placement (one pad on the front of the chest, one on the back between the shoulder blades) is an acceptable alternative. This can be useful if the front of the chest has burns, wounds, or multiple implanted devices that make standard positioning difficult. For most rescuers in an emergency, though, the standard anterior-lateral method is quicker and keeps chest compressions going with minimal interruption.