Recognizing Cardiac Arrest: More Than Meets the Eye

During CPR training you are taught to start CPR on someone who is unresponsive and not breathing normally. This seems simple enough but how can you be sure an unconscious person really is in cardiac arrest? Here's some guidance to help build your confidence in doing this assessment.

How Can I Be Sure?
Although recognizing the two signs of cardiac arrest (unresponsive and not breathing normally) seems straight forward, many lay responders stall at this assessment. They’re thinking “there’s probably someone here who knows CPR better than me…so they wait” says paramedic Mike Helbock who has seen this many times in his twenty-year career in EMS. Responders lose confidence and fail to start CPR.

You may have doubts at first: Is he really in cardiac arrest? What if there is an underlying medical problem? Will I hurt him? However, experienced responders will tell you to cast aside your doubt because the signs tell all.

“You will be correct every time if you look for signs of life,” says Helbock who is Program Director at EMS Associates, Inc. He encourages lay rescuers to trust what you observe when assessing responsiveness and breathing and emphasizes:
• No response from tap and shout = unresponsive and unconscious
• No obvious chest rise after 5 to 10 seconds = not breathing

Don’t hesitate when you see these signs or a clinically dead patient and will become permanently dead. Every minute you delay lowers a person’s chance of survival. You will recognize the two signs of cardiac arrest if you simply act on what you see.

What is Unconscious and Unresponsive?
As a CPR-trained responder, you should be aware there are different levels of consciousness. An altered level conscious means there has been some type of insult to the brain or the neurologic system. It can have one of any number of causes such as: hypoglycemia (diabetes), drug overdose, alcohol overdose, seizures, trauma to the head, fainting or stroke. Regardless of the cause your job is to look for a response from the patient.

A conscious person will respond in some way to your engaging them, for example, he or she will move, blink, grimace or try to speak, move or react. A semi-conscious person may try to respond by moving a limb, blinking or trying to speak or gesture.

Total unconsciousness, also called "comatose", is a state in which someone is unaware of both self and surroundings. The person who is comatose will not respond to a tap or shout, like someone in cardiac arrest.

If the victim doesn’t respond you should yell for help and have someone call 911 and get an AED. Next, you should check breathing.

Not Breathing
The body will stop breathing at some point after the heart stops because there is no oxygen being delivered to the brain. The respiratory center in the brain can't function without oxygen. Therefore, if you find the person unresponsive and not breathing this means the heart is not working.

When you assess breathing look for movement in the chest. Take at least 5 seconds but no more than 10 seconds (1) to scan the chest. Watch for the chest to rise and fall. If you see no movement, the patient is not breathing.

Another clue is that you might also notice a non-normal appearance such as a skin color that is pale, ashen or bluish.

What is Gasping or Agonal Breaths?
One thing that tricks CPR-trained responders is gasping or “agonal” breaths. Also called “agonal respirations," this abnormal breathing pattern is the body's attempt to breathe after the heart has stopped.

The term “agonal” is derived from the fact that these people sometimes sound as if they are in agony. The gasps may be forceful or weak and they may sound like a snore or groan.

Agonal breaths are sporadic, gasping breaths you may see in the early stages of cardiac arrest. They occur because the respiratory center of the brain continues to send signals to the respiratory muscles even though the heart has stopped. As the oxygen supply is used up this reflex ceases.

An agonal breath is often heard as irregular or infrequent gasping sound. They may sound like a snore or a groan. The victim may appear as if he was trying to breathe. These breaths are not effective and do not provide adequate oxygen to the body.

Agonal breathing occurs in about half of all witnessed cardiac arrests so they are fairly common. It is associated with a higher chance of survival. (2)

It is important to note that they can be mistaken as regular breathing. They key difference is that they are irregular or sporadic when compared to normal breathing. Therefore, you should always start CPR in an unresponsive person who is gasping.

CPR is a life-saving intervention that must be started as soon as possible. As a lay responder you must know what to look for and trust your ability to assess the signs of cardiac arrest in anyone who has collapsed.

Start CPR if you don’t see a response and you don’t see normal breaths. Don’t wait for someone else to confirm your assessment. Look for the two signs—unresponsiveness and not breathing normally—and you won’t be wrong in knowing when to start CPR.

Finally, watch out for agonal breathing. If you see infrequent breathing or gasping, this is a sign of cardiac arrest.

Here's a quick review of the initial steps you should take in CPR:
1. Tap and shout: if he doesn't move or respond
2. Yell for help: have someone call 911 and get the AED
3. Check breathing: look for no breathing or only gasping
4. Expose chest the chest and deliver 30 chest compressions
5. Open the airway using the head tilt, chin lift
6. Give two breaths (continue CPR until AED arrives)


1. Gonzales L, Lynch MW, Bork S (eds). Heartsaver First Aid and CPR AED Student Workbook. 1st ed. Dallas:American Heart Association, 2011.

2. Eisenberg MS. Resuscitate: How Your Community Can Improve Survival from Sudden Cardiac Arrest. Seattle: U. of Washington Press; 2009.