Agonal breathing sounds like irregular, labored gasps, often described as guttural, snorting, or groaning. It is not normal breathing. The gasps are slow, spaced apart, and can sound like someone struggling to force air through their throat. If you hear this from someone who is unresponsive, it almost certainly means they are in cardiac arrest and need CPR immediately.
What Agonal Breathing Sounds Like
People who witness agonal breathing use a wide range of words to describe it: gasping, snorting, gurgling, groaning, or even snoring. The 2025 American Heart Association guidelines note that bystanders commonly describe it as “abnormal breathing,” “snoring respirations,” or simply “gasping.” No single word captures it perfectly because the sound varies from person to person.
The gasps tend to be slow and irregular, with long pauses between them. They may involve the jaw opening wide or the chest heaving. On exhale, you may hear grunting or groaning caused by air being forced past relaxed vocal cords. One palliative care description compares the sound to wind blowing through trees on a stormy day. The key feature is that these breaths look and sound effortful but are completely ineffective at getting oxygen into the lungs. The person is not breathing in any meaningful sense.
Why the Body Makes These Sounds
Agonal breathing is a brainstem reflex triggered by dangerously low oxygen levels. When the brain is starved of oxygen (during cardiac arrest, for example), it cycles through a predictable sequence: first a burst of rapid breathing, then a pause lasting seconds to minutes, and finally these deep, irregular gasps. It is the last respiratory pattern before breathing stops entirely.
This reflex kicks in only when oxygen in the blood drops to extremely low levels. It is not a conscious effort to breathe. The dying brain activates accessory muscles in the chest and throat in an uncoordinated way, which is why the breathing looks labored and sounds abnormal. Think of it as the brainstem’s final automatic attempt to restart oxygen flow, not a sign that the person is aware or able to breathe on their own.
Why It Gets Mistaken for Normal Breathing
This is the most dangerous thing about agonal breathing: it convinces bystanders that the person is still breathing, which delays CPR. Research on emergency calls found that when a bystander witnessed someone collapse and heard agonal gasps, they were significantly less likely to start chest compressions. In cases where the person was clearly not breathing at all, about 83% of bystanders began CPR. When agonal breathing was present, only about 54% did.
Agonal breathing is present in 40% to 60% of out-of-hospital cardiac arrests, and it is the most commonly cited reason bystanders fail to recognize that someone’s heart has stopped. The gasps can look purposeful enough to create doubt. But if someone is unresponsive and their breathing is irregular, noisy, or consists of occasional gasps with long gaps, treat it as cardiac arrest. The AHA guidelines are clear: the risk of performing chest compressions on someone who turns out not to need them is low, while the cost of waiting is potentially fatal.
Agonal Breathing vs. Other Sounds
It helps to know what agonal breathing is not. Normal snoring is rhythmic, repetitive, and happens in someone who is otherwise sleeping comfortably. Agonal gasps are irregular, with unpredictable timing and visible physical strain.
The “death rattle” is a different sound entirely. It occurs in people who are actively dying (often over hours or days in a hospice or hospital setting) and is caused by air passing through secretions pooled in the throat that the person can no longer swallow or cough up. It sounds wet, gurgling, and continuous on inhalation or exhalation. Agonal breathing, by contrast, sounds dry and forceful, with distinct gaps of silence between gasps.
Why Agonal Gasps Are a Sign of Better Odds
Counterintuitively, if someone in cardiac arrest is making agonal gasps, their chances of survival are significantly better than if they are completely silent. One large study found a 39% survival rate among cardiac arrest patients who were gasping, compared to just 9% among those who were not. At one year after the event, people who gasped during CPR had a 20% rate of survival with good brain function, compared to 3.7% for those who did not gasp.
The reason is partly physiological. Animal studies show that gasping decreases pressure inside the skull and increases blood flow to the brain, acting as a kind of built-in resuscitation mechanism. It also suggests the brainstem is still active, which is a favorable sign. When gasping was combined with a heart rhythm that could be shocked with a defibrillator, the odds of surviving with good neurological function were dramatically higher.
None of this means you should wait and watch. The gasps will stop without intervention. They are a window of opportunity, not a sign that the person is recovering on their own.
What to Do When You Hear It
If someone collapses and you hear slow, irregular gasping or snorting, check if they respond to you. Tap their shoulders, shout at them. If they are unresponsive, call emergency services and begin chest compressions. Do not wait to see if the breathing improves. Do not assume snoring-like sounds mean they are fine.
Push hard and fast in the center of the chest, about 100 to 120 compressions per minute. If an automated external defibrillator (AED) is available, use it. The agonal gasps may continue while you perform CPR, and that is actually a good sign. Keep going until emergency medical services arrive.