In PALS (Pediatric Advanced Life Support), cardiac arrest in a child is identified by three cardinal signs: unresponsiveness, absent or abnormal breathing (apnea or agonal gasps), and no palpable central pulse. But pediatric cardiac arrest rarely strikes without warning. Most cases in children result from progressive respiratory failure or shock, which means recognizing the earlier signs of deterioration is just as critical as identifying the arrest itself.
The Three Defining Signs of Cardiac Arrest
A child in cardiac arrest shows a specific triad of findings. First, the child is unresponsive, meaning no reaction to voice or physical stimulation. Second, breathing is either absent or limited to occasional gasps. Third, there is no detectable central pulse.
Agonal gasps deserve special attention because they fool rescuers into thinking a child is still breathing. These gasps sound like snoring, snorting, gurgling, or moaning. They are irregular, infrequent, and do not move air effectively. They are common immediately after cardiac arrest but fade quickly. PALS guidelines are clear: if a child is unconscious and only taking occasional gasps, treat it as cardiac arrest and begin CPR.
Where to Check for a Pulse
For infants under one year, the brachial artery on the inside of the upper arm is the recommended pulse check location. For children one year and older, the carotid artery in the neck is used, just as in adults. The pulse check should take no more than 10 seconds.
Pulse palpation is less reliable than many providers assume. Studies show that even trained healthcare professionals are only about 78% accurate at detecting a pulse, and lay rescuers perform worse. The 2025 AHA guidelines emphasize that a pulse check alone should not be the sole basis for deciding whether to start CPR. If a child has no signs of life, no obvious breathing, and you cannot confidently feel a pulse within 10 seconds, begin compressions.
Warning Signs Before the Arrest
Pediatric cardiac arrest almost always follows a period of worsening respiratory distress or circulatory shock. PALS teaches a structured approach to catch these warning signs before a child reaches full arrest. The earliest assessment tool is the Pediatric Assessment Triangle, which relies on three observations you can make from across the room: the child’s general appearance, their work of breathing, and their skin circulation.
Respiratory Warning Signs
A child whose breathing is failing will show visible signs of effort. Nasal flaring, where the nostrils widen with each breath, indicates the child is working hard to pull in air. Retractions, meaning the skin pulls inward between the ribs, above the collarbones, or below the breastbone, signal the accessory muscles are being recruited because the diaphragm alone cannot keep up. In infants, head bobbing with each breath is an ominous sign of severe respiratory distress.
Abnormal airway sounds also matter. Stridor (a high-pitched sound on breathing in), grunting (a sound made on breathing out as the child tries to keep the lungs open), and wheezing all point to airway compromise. A child who assumes a tripod position, sitting upright with hands braced on their knees, is maximizing their ability to breathe and is in serious trouble. Perhaps the most dangerous sign of all is a child who was working hard to breathe and suddenly becomes quiet and still. That silence often means respiratory muscles are exhausted and arrest is imminent.
Circulatory Warning Signs
Poor perfusion, meaning the heart is not pumping blood effectively to the body’s tissues, produces its own set of recognizable signs. Skin becomes pale, mottled, or cool to the touch, especially in the extremities. Capillary refill slows noticeably. Normally, pressing on a child’s fingertip and releasing should produce a return of color within two seconds. A delay beyond that suggests inadequate circulation.
The heart rate itself is a key indicator. Tachycardia, an abnormally fast heart rate, is often the body’s first compensatory response to falling blood pressure or low oxygen. In infants, a normal awake heart rate ranges from 100 to 180 beats per minute, while neonates can run as high as 205. Heart rates significantly above these ranges in a sick child suggest the body is under stress. Bradycardia, a dangerously slow heart rate, is a late and ominous sign. PALS guidelines direct providers to start CPR in any child with a heart rate below 60 beats per minute who also shows signs of poor perfusion, even if a pulse is still present.
As shock progresses and the body’s compensatory mechanisms fail, more alarming signs appear: altered mental status (confusion, lethargy, or failure to recognize parents), weak central pulses, and finally, frank hypotension. In children aged one to ten, low blood pressure is roughly defined as a systolic reading below 70 plus twice the child’s age in years. In children over ten, the threshold drops to below 90, similar to adults. By the time blood pressure drops in a child, the situation is already critical, because children compensate for longer than adults before crashing.
The PALS Systematic Assessment
PALS uses a structured sequence to evaluate a child who may be deteriorating. After the initial across-the-room Pediatric Assessment Triangle, providers move through a primary assessment that checks airway, breathing, circulation, disability, and exposure. Each step has specific things to look for.
For the airway, the question is whether it is open and maintainable. For breathing, providers assess respiratory rate, effort, chest rise, and breath sounds on both sides. Circulation means checking heart rate, pulse quality, skin color and temperature, capillary refill, and blood pressure. Disability covers level of consciousness and pupil response. Exposure involves removing clothing to look for rashes, bleeding, or trauma that could explain the deterioration.
This structured approach exists because individual signs can be subtle or ambiguous. A slightly fast heart rate, mildly prolonged capillary refill, and a child who seems unusually drowsy might each be dismissed in isolation. Together, they paint a picture of a child heading toward arrest. The entire framework is designed to force recognition of that pattern before it is too late.
Why Pediatric Arrest Looks Different From Adult Arrest
In adults, cardiac arrest typically starts with a heart rhythm problem, often triggered by coronary artery disease. The heart suddenly stops pumping effectively. In children, the sequence is usually reversed. A breathing problem or a perfusion problem comes first, and the heart stops as a secondary consequence of prolonged oxygen deprivation or metabolic failure. This is why the majority of pediatric cardiac arrests present with non-shockable rhythms (asystole or pulseless electrical activity) rather than the shockable rhythms more common in adults.
This distinction has practical importance. It means the warning window in children is often longer than in adults, but the outcome once arrest occurs tends to be worse. Survival rates for out-of-hospital pediatric cardiac arrest remain significantly lower than for adults. The entire PALS approach to recognition is built around the idea that intervening during respiratory failure or shock, before the heart actually stops, gives a child the best chance of survival.