What Should You Do When Using an AED on an Infant?

When an infant goes into cardiac arrest, you should use an AED the same way you would for any other patient: turn it on, attach the pads, and follow the voice prompts. The device analyzes the heart rhythm and decides whether a shock is needed. Your job is to attach the pads correctly, keep performing CPR between prompts, and let the machine make the shock-or-no-shock decision. The key difference with infants is pad selection and placement, and the fact that most infant cardiac arrests involve rhythms that don’t require a shock at all, which means the AED’s role is often monitoring rather than defibrillating.

Start with CPR, Then Attach the AED as Soon as It Arrives

If you find an infant who is unresponsive and not breathing normally, begin CPR immediately. For an infant, that means compressions with two fingers (or two thumbs if another rescuer is present) on the lower half of the breastbone, pressing down about one and a half inches, at a rate of 100 to 120 compressions per minute. Give two rescue breaths after every 30 compressions if you are alone, or every 15 compressions if a second rescuer is helping. Have someone call emergency services and retrieve an AED while you do compressions. If you are alone, perform about two minutes of CPR before leaving to get the AED and call for help.

Once the AED is at the scene, turn it on. Most devices begin giving audio instructions immediately. Do not stop CPR until the device tells you to. The AED will prompt you to attach the pads, then instruct everyone to stand clear while it analyzes the rhythm. If it determines a shock is needed, it will either deliver it automatically or tell you to press the shock button. After any shock, resume CPR right away. The AED will prompt you again for another analysis after a set interval, typically two minutes.

Choosing and Placing the Pads

This is where infant-specific guidance diverges from what you may have learned for adults. If the AED comes with pediatric pads (sometimes called pediatric attenuator pads), use those. These pads reduce the energy the device delivers, bringing it closer to the recommended dose for a small body. Current guidelines recommend using an AED with pediatric dose-attenuating pads for infants whenever a manual defibrillator with a trained operator is not immediately available. If pediatric pads are unavailable, use the standard adult pads rather than withholding defibrillation entirely.¹

Placement also differs. On an adult, both pads go on the front of the chest: one below the right collarbone and one on the lower left side. On an infant, the chest is so small that two pads placed this way can overlap or touch each other, which can cause the current to arc between pads instead of passing through the heart. The standard recommendation for infants is anterior-posterior placement: one pad on the center of the chest (over the breastbone) and the other on the center of the back, between the shoulder blades. This “sandwich” position ensures the pads don’t contact each other and that the electrical current travels through the heart. Make sure the infant’s skin is dry and that no pads are overlapping.

Why Pediatric Pads Are Preferred but Adult Pads Still Work

Pediatric attenuator pads typically reduce the delivered energy to around 50 joules, compared to the 150 to 200+ joules an adult-configured AED might deliver. That lower dose is much closer to the 2 joules per kilogram that guidelines suggest for infant defibrillation. In an early report of pediatric pad use across 27 patients ranging from newborns to young adults, all eight patients who had ventricular fibrillation received shocks that successfully terminated the arrhythmia, with an average of just under two shocks needed per patient. In the 16 patients whose rhythms were not shockable, the AED correctly withheld a shock every time.²

The concern with adult pads on a very small patient is not just theoretical. A case report documented a 3.6-kilogram neonate who received two inappropriate shocks of more than 200 joules each through adult pads during a pulseless resuscitation. The infant was actually in sinus bradycardia, a rhythm that should not have triggered a shock, but the adult pad configuration contributed to the device misreading the rhythm.³ That said, the same case report and broader guidance still endorse using adult pads when pediatric ones are not available, because the risk of withholding defibrillation during true ventricular fibrillation far outweighs the risk of an excessive shock. A baby in cardiac arrest who receives no defibrillation has essentially no chance of surviving a shockable rhythm.

How Reliably Can an AED Read an Infant’s Heart Rhythm?

One of the reasonable fears people have about using an AED on a tiny patient is whether the device can actually tell a dangerous rhythm from a normal one in such a small heart. The evidence here is reassuring. A study analyzing 696 rhythm strips from 191 children aged one day to 12 years found that the AED algorithm had 100% specificity for nonshockable rhythms, meaning it never incorrectly advised a shock when one was not needed. Its sensitivity for detecting ventricular fibrillation was 96%, meaning it correctly identified almost all shockable rhythms.⁴ These numbers held across all age groups in the study, including the youngest children.

That high specificity is particularly important for infants, because most infant cardiac arrests do not involve a shockable rhythm in the first place. When you attach the AED and it says “no shock advised,” that is almost certainly the correct reading. It does not mean the AED failed or that you did something wrong. It means the baby’s heart is in a rhythm that electricity cannot fix, and the right response is to continue CPR.

Most Infant Cardiac Arrests Are Not Shockable

Adults who collapse suddenly in cardiac arrest are often in ventricular fibrillation, the chaotic electrical storm that an AED is specifically designed to stop. Infants are different. The overwhelming majority of infant cardiac arrests arise from respiratory failure or shock rather than a primary electrical problem with the heart. The resulting rhythms are usually asystole (no electrical activity at all) or pulseless electrical activity, neither of which responds to defibrillation. Only about 8 to 18 percent of pediatric cardiac arrests present with a shockable rhythm as the first documented rhythm.⁵

This does not mean attaching an AED to an infant is pointless. You cannot tell what rhythm the heart is in without the AED’s analysis. And in the minority of cases where the infant is in ventricular fibrillation, rapid defibrillation is the only effective treatment. The first documented successful AED use in an infant involved a 50-joule shock that restored a normal rhythm.⁶ That case helped shift professional opinion toward supporting AED use in infants, a population that had previously been excluded from AED recommendations. Even when the AED does not advise a shock, having it attached and monitoring means it will catch any transition to a shockable rhythm during resuscitation, which can happen as CPR restores some circulation.

What the Survival Evidence Shows

Survival data for AED use specifically in infants is thin, because infant cardiac arrests are rare events and AED application to infants is rarer still. The broader pediatric literature, though, supports the value of early defibrillation when a shockable rhythm is present. A systematic review of lay rescuer AED use in children found that AED application was associated with roughly tripled odds of surviving to hospital discharge in children aged 1 to 12, and similar improvements in the 13-to-18 age group. When AED use was combined with bystander CPR, survival with good neurological outcomes also improved.⁷

A more recent retrospective study looking at 25 years of pediatric out-of-hospital cardiac arrest data found that public access defibrillation was associated with substantially higher odds of return of spontaneous circulation and survival to hospital discharge in unadjusted analysis. After adjusting for confounding factors, including changes in emergency care over the decades studied, those associations lost statistical significance, which likely reflects how few pediatric cases involve shockable rhythms and how many other factors influence survival.⁸ The takeaway is not that AEDs do not help children. It is that the benefit is concentrated in the small subset who have a shockable rhythm, and in that subset, the benefit is dramatic.

Common Mistakes and Misconceptions

The biggest mistake bystanders make with infant cardiac arrest is not using the AED at all. Fear of hurting a small baby, uncertainty about whether it is “allowed,” or the assumption that the AED is only for adults leads people to skip the device entirely. Every set of current guidelines agrees: use the AED. The device is designed to withhold a shock if one is not appropriate, so attaching it carries very little risk even in the worst case.

A second common error is stopping CPR for too long while fiddling with the AED. Compressions are the single most important intervention in cardiac arrest. When you pause to attach pads, keep the pause as short as possible. Have one person continue compressions while another opens the AED and prepares the pads if two rescuers are available. Only stop compressions when the device instructs you to stand clear for analysis or shock delivery, and restart the moment it tells you to.

Some people also worry about using an AED on a wet infant, for example one pulled from a bathtub. Quickly towel dry the chest before applying the pads. You do not need the skin to be perfectly dry, but standing water between the pads can cause the current to travel along the skin surface rather than through the heart, and it can also reduce how well the pads stick. A few seconds of toweling is all that is needed.

Another misconception is that an AED shock will restart a heart that has stopped completely. AEDs do not restart hearts; they stop dangerously chaotic rhythms like ventricular fibrillation so the heart’s natural pacemaker can resume a normal beat. If the heart has no electrical activity at all, a shock will not help, and the AED will correctly advise against delivering one. CPR, medications, and addressing the underlying cause are what matter in that scenario.

Legal Protections for Bystanders

Hesitation about legal liability is a real barrier to bystander action, especially when the patient is someone else’s child. In the United States, Good Samaritan laws provide protection to laypeople who provide first aid, including AED use, to someone in an emergency. Health care workers acting outside their professional setting are generally protected as well, except in cases of gross negligence.⁹ The specifics vary by state, but the principle is consistent: if you are acting in good faith to save a life, the law is on your side. Many states have additional AED-specific statutes that shield both the person who uses the device and the entity that owns it.

In practical terms, a bystander who attaches an AED to an infant during cardiac arrest and follows the device’s prompts is doing exactly what medical guidelines recommend. There is no legal or medical scenario in which withholding defibrillation from an infant in cardiac arrest would be considered a better choice than attempting it.

When an Infant Is at Known Risk

Most infant cardiac arrests happen without warning, but some families know their child is at elevated risk. Infants with congenital heart disease, inherited arrhythmia syndromes like long QT syndrome, or a history of near-miss events may be more likely to experience a shockable rhythm. For these families, having an AED accessible at home and knowing how to use it is a conversation worth having with the child’s cardiologist. The first reported successful infant AED defibrillation was in precisely this kind of high-risk setting, where the infant’s known cardiac condition meant an AED was already on hand.⁶

For the general public, the more realistic scenario is encountering an infant in distress in a setting where an AED happens to be available, like a shopping center, airport, or recreation facility. Increasingly, public access AED programs stock pediatric pads alongside adult ones, though this is still not universal. If you are responsible for a space where infants are regularly present, like a daycare or a pediatrician’s waiting room, checking that your AED includes pediatric pads is a straightforward step that can make a meaningful difference in the rare event they are needed.

Quick-Reference Steps

In an actual emergency, you will not have time to read an article. Here is the sequence distilled:

• Call for help: Have someone dial emergency services and retrieve the nearest AED while you begin CPR.
• Start CPR: Two-finger or two-thumb compressions on the lower breastbone, about 1.5 inches deep, 100 to 120 per minute. Give breaths after every 30 compressions (solo) or 15 (two rescuers).
• Turn on the AED: Follow the voice prompts. Select pediatric mode or attach pediatric pads if available.
• Place pads front and back: One pad on the center of the chest, one between the shoulder blades. Ensure pads do not touch each other.
• Stand clear for analysis: Stop compressions only when instructed. Do not touch the infant during analysis or shock delivery.
• Resume CPR immediately: Whether or not a shock is delivered, restart compressions the instant the AED tells you to.
• Repeat the cycle: The AED will re-analyze every two minutes. Continue until emergency medical services arrive or the infant shows obvious signs of life.

If the only AED available has adult pads and no pediatric option, place the adult pads in the same anterior-posterior position and proceed. A shock at higher-than-ideal energy is better than no shock at all when the rhythm is ventricular fibrillation.¹ And remember that in most infant arrests, the AED will analyze and advise no shock, which is itself valuable information. Keep doing CPR and let the professionals take over when they arrive.