May 5, 2025

Good morning, 

This month, we will focus on cardiac arrest care. Our number one goal in the treatment of cardiac arrest is for the patient to have a neurologically intact recovery. Our brain is everything we are, and we must preserve the brain to have the patients walk out of the hospital. There are two ways that we can achieve this goal: by minimizing pauses in chest compressions and by ensuring high-quality post-arrest care. Today, we will review why minimizing compressions is so critical and discuss ways we can minimize pauses.  

Why are pauses in compressions harmful? 

The purpose of chest compressions is to circulate blood to deliver oxygen to vital organs. The most important organs we are trying to preserve are the heart and brain. It takes time to build arterial pressure with this pressure dropping rapidly with even a few seconds of pause. For this reason, any pause in compressions (even if only for a few seconds) can be harmful to the brain and heart. It is also important to remember that the damage is cumulative. Therefore, even short pauses can add up to significant injury if there are enough of them. 

The impact of compression pauses on the heart 

We know that outcomes are often better for patients in a shockable rhythm because it is something that we can rapidly correct. However, without chest compressions, the heart is less likely to respond to a shock. In addition, if the pause in compressions is long enough, the rhythm might degenerate to a non-shockable rhythm. The picture below shows a potential scenario where a patient was in a shockable rhythm at the time of the initial call to 911. The patient did not receive bystander CPR, and by the time EMS arrived, the patient was no longer in a shockable rhythm. 

The impact of compression pauses on the brain 

Brain damage from lack of oxygen is irreversible. After four minutes without oxygen, the brain begins to be injured. After 5 minutes, brain cells die rapidly. If enough brain injury occurs, the patient might never wake up or be independent, even if we can get the heart beating again.  

If pauses in compressions are so bad, why do we pause every two minutes (or at all)? 

While chest compressions are critical, defibrillation for a shockable rhythm is equally important. This is because every minute a shock is delayed, it is associated with a ~10% greater chance of death. We need to balance shocking as early and often as possible with wanting to minimize compression pauses.  

What are ways that we can minimize pauses in compressions? 

1. Bystander CPR: This is debatably the single most important aspect of out-of-hospital cardiac arrest care. If this is not present, most of the damage might have already occurred prior to EMS arrival on the scene. Emergency medical dispatchers play a pivotal role if they can identify cardiac arrest over the phone and get the caller (or another bystander) to perform chest compressions, which can absolutely save a life. While many in EMS are not directly involved in dispatch, we still play an important role in bystander CPR. This is because local leaders lean on fire and EMS for expertise in prehospital care. We should use this as an opportunity to promote policies that can increase rates of bystander CPR. 

2. Do not pause compressions for placing advanced airways: if unable to place an endotracheal tube through compressions (which is not easy), place a supraglottic airway. 

3. Practice placing a mechanical CPR device in under 10 seconds. 

4. Pre-charge the monitor: this allows us to shock the patient the moment we confirm that the patient has a shockable rhythm. If we have not pre-charged the monitor, we should continue compressions while the monitor is charging and only pause to deliver the shock if doing manual CPR. As a reminder, we can defibrillate patients while mechanical CPR devices are running and should not pause them to shock. 

Understanding why pauses in compressions are so harmful helps us understand our specific priorities in cardiac arrest care. We should always focus on ways to further minimize pauses in compressions to achieve the best possible outcomes for our patients. 

Be safe and keep up the awesome work!

Jordan Singer, MD

EMS Medical Director, UH EMS Training and Disaster Preparedness Institute

Emergency Physician, UH Cleveland Medical Center

Emergency Physician, UH Elyria Medical Center

Assistant Professor, CWRU School of Medicine