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The Science of CPR: Understanding How It Can Save Lives During a Cardiac Arrest Emergency

Updated: May 31, 2023


The Science of CPR
The Science of CPR


Cardiac arrest is a life-threatening condition that can occur at any time and to anyone. According to the American Heart Association (AHA), over 350,000 cardiac arrests occur outside of hospitals every year in the United States, with only about 10% of those affected survive. Performing cardiopulmonary resuscitation (CPR) immediately during a cardiac arrest emergency is one of the critical factors that can increase the chances of survival. In this article, we will explore the science of CPR and how it can save lives during a cardiac arrest emergency, as well as provide a link to another article on "CPR Trained Bystanders: What to Do During a Cardiac Arrest Emergency."


During a cardiac arrest, the heart is unable to pump blood effectively, which can lead to a lack of oxygen supply to vital organs, such as the brain and heart. When the brain is deprived of oxygen for more than four to six minutes, it can result in irreversible brain damage, and death may occur shortly after. Therefore, prompt and efficient CPR is crucial to maintain blood flow to vital organs, including the brain, and provide oxygen and nutrients to prevent permanent brain damage.


CPR is a combination of chest compressions and rescue breaths, which work together to keep blood flowing to vital organs. Chest compressions are the most critical component of CPR because they create a force that pushes blood through the heart and circulatory system. When performed correctly, chest compressions can help to maintain blood flow to the vital organs, including the brain, until advanced medical care can be provided.


Rescue breaths are another important aspect of CPR, as they help to deliver oxygen to the lungs and maintain oxygen saturation in the blood. When performing rescue breaths, it is essential to create an airtight seal over the person's mouth and nose and provide a breath of air that causes their chest to rise. This process helps to fill the lungs with air and provide oxygen to the blood.


In addition to maintaining blood flow and delivering oxygen to vital organs, CPR can also prevent permanent brain damage by delaying brain cell death. CPR helps to preserve brain function by preventing the buildup of carbon dioxide in the blood, which can lead to brain cell death. By performing CPR immediately, you can help to prevent permanent brain damage and increase the chances of survival for the person experiencing cardiac arrest.


The science behind CPR is crucial to understand to appreciate its potential for saving lives during a cardiac arrest emergency. By performing chest compressions and rescue breaths, you can maintain blood flow to vital organs, provide oxygen to the lungs, and prevent permanent brain damage. If you witness someone experiencing a cardiac arrest emergency, remember that every second counts and prompt and efficient CPR can significantly increase the person's chances of survival.


The AHA has recommended guidelines for CPR that are widely recognized and taught in CPR training courses. According to the AHA, the steps to perform CPR are:

  1. Check for responsiveness: Tap the person's shoulder and shout, "Are you okay?" to see if they respond.

  2. Call for help: Call 911 or your local emergency number immediately and activate your emergency response plan if available.

  3. Check breathing: If the person is not responding and not breathing or not breathing normally, have someone call 911, and begin CPR immediately.

  4. Perform chest compressions: Place the heel of one hand on the center of the chest between the nipples and place the other hand on top of the first hand. Press down firmly and quickly, allowing the chest to rise between compressions.

  5. Give rescue breaths: Tilt the person's head back and lift their chin. Pinch their nose closed, and give two rescue breaths into their mouth. Watch for the chest to rise and fall.

  6. Continue CPR: Perform 30 chest compressions and two rescue breaths, repeating until the person starts breathing normally, or EMS arrives.

Performing CPR can be physically demanding, and it is essential to perform it correctly. The AHA recommends taking a CPR course to learn the proper technique and receive hands-on training. CPR training courses are widely available and can be taken in person or online.


In addition to learning how to perform CPR, it is also crucial to know what to do during a cardiac arrest emergency, particularly for bystanders who are CPR trained. These individuals can significantly improve their chances of survival during a cardiac arrest emergency by performing CPR immediately.


Our article "CPR Trained Bystanders: What to Do During a Cardiac Arrest Emergency" provides a comprehensive guide on what to do during a cardiac arrest emergency, including how to recognize the signs of cardiac arrest, call for help, perform CPR, and use an automated external defibrillator (AED).



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