By Matt Gephardt
(KUTV) Good Question from Lynn King: “I have a silly question. We all know the air we breathe OUT of our bodies is poison, right? Well how is it that when we do mouth to mouth with someone, it does not hurt them?”

At the Sandy City Fire Department headquarters, the classroom was full Wednesday with people eager to learn the life saving techniques of cardio-pulmonary resuscitation.

With chest compressions, CPR will pump blood when someone's heart has stopped and air blown into the lungs can provide oxygen.

It is training that Sandy City Firefighter/Paramedic Ryan Schroeder says he was glad he had when on vacation last spring.

“I found a 43 year old male, unconscious, not breathing and not alert,” Schroeder said.

The man is Paul Rushing. He had suffered a heart attack. Schroeder and another man jumped into action, and began CPR. It was action that saved a Paul's life.

As a trained paramedic, Schroeder's experience was certainly familiar, but he admits, different.

"Not wearing a shirt, that's different,” Schroeder said. “Being in shorts poolside, that's definitely different."

If responding to a 9-1-1 call, Schroeder would have been better clothed, sure, but he also would have had paramedic tools like a bag/valve mask than can pump 100% oxygen right into a victims lungs.

That’s certainly more efficient than mouth to mouth because our bodies inhale air, rich with oxygen and exhale carbon dioxide.

So why then in CPR is exhaling carbon dioxide into someone's lungs helpful?

Sandy City Battalion Chief Derrick Maxfield says it is important to note that very little of the air we breathe is actually oxygen. Air is composed of about 21% oxygen. And likewise, when we exhale, we don’t breathe out 100% carbon dioxide.

"Exhaled air is about 16% oxygen,” Maxfield said. “Even though it's not a real high concentration, we still have oxygen in the air that we exhale."

For someone who is not breathing, 16% oxygen is better than nothing.

To someone not officially trained in CPR, the amount of oxygen exhaled is becoming moot. The American Heart Association changed the CPR guidelines two years ago and now they say to a layman, don't do mouth to mouth. The AHA says there is enough oxygen in our blood cells to keep our bodies alive even without the breaths. In a study, the AHA found that often people would waste valuable time trying to clear an airway when they should be doing chest compressions.

(Copyright 2012 Sinclair Broadcasting Group)
Good Question: We Exhale Carbon Dioxide, So Why Does CPR Work?