The Difference Between Respiratory Arrest and Cardiac Arrest

One Almost Always Leads to the Other

woman calling 911
Cardiac arrest will only survive with CPR. Bicek Photography

Question

What is the difference between respiratory and cardiac arrest?

In the medical world, the term arrest is used often to describe a condition where something that should be happening has stopped. That's fine for a textbook, but what is the real difference between respiratory arrest and cardiac arrest?

Answer

Basically, the difference is a pulse.

During respiratory arrest, breathing stops. During cardiac arrest, blood flow stops.

Technically, cardiac arrest suggests that the heart has stopped beating, but it's really about the fact that blood flow is no longer detectable.

How to Tell the Difference

In both respiratory arrest and cardiac arrest, the patient will be unconscious and not breathing. However, respiratory arrest patients still have a beating heart that is pushing blood around the body. Cardiac arrest patients do not.

Without fancy equipment, the only way to tell if the blood has stopped flowing is to feel for a pulse. The way to feel that beating heart is through the blood pulsing through the arteries. It's not a perfect procedure and there is a possibility of getting it wrong, even if you're a trained healthcare provider. Indeed, when the patient doesn't have a pulse, rescuers take longer trying to find it rather than treating the patient.

As far as CPR is concerned, you should treat respiratory arrest and cardiac arrest exactly the same way: call 911 and push on the chest.

Respiratory Arrest Leads to Cardiac Arrest

These two conditions are absolutely linked. Respiratory arrest will always lead to cardiac arrest if nothing is done to treat it. When a patient has respiratory arrest, two things happen:

  1. Carbon dioxide is not removed properly from the bloodstream, leading to a buildup of carbonic acid. The excess acid can cause problems in the brain and in the heart.
  1. Eventually (much slower than the buildup of carbon dioxide), oxygen levels in the bloodstream will diminish. The lack of oxygen will also lead to problems in the brain and heart.

Without treatment, respiratory arrest always leads to cardiac arrest. Sometimes, however, it can take several minutes.

Cardiac Arrest Always Includes Respiratory Arrest

Cardiac arrest means the heart is no longer moving blood through the body. It might be beating or not, but either way there isn't any blood pulsing around.

Without blood, the brain cannot survive. A constant supply of fresh blood is required to keep the brain alive and functioning properly. When blood supply stops, the brain shuts down, including its respiratory center. So, when the heart stops, so does breathing, usually within a minute or less.

Source:

Eberle B, Dick WF, Schneider T, Wisser G, Doetsch S, Tzanova I. Checking the carotid pulse check: diagnostic accuracy of first responders in patients with and without a pulse. Resuscitation. 1996 Dec;33(2):107-16.

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