What Causes Shortness of Breath?

Question: What Causes Shortness of Breath?

Answer: There are two parts to breathing:

1. Moving air in and out of the lungs
2. Moving oxygen and carbon dioxide back and forth between the bloodstream and the lungs

Blocking either of these functions can result in feeling short of breath. Shortness of breath also comes from a sudden demand for oxygen in the body due to exercise or stress. High school coaches are rather fond of running "wind sprints" until players are gasping for air, unable to talk. In fact, feeling "winded" is another way to say short of breath.

Anything that interferes with breathing leads to too little oxygen and too much carbon dioxide in the blood. The body needs some of each of these gases in our blood to function properly, but levels need to be kept in balance. There's quite a bit of extra oxygen in the blood, so a short-term lack of oxygen isn't that big of a deal. (We need that emergency reserve in case a bear decides to chase us through the cul de sac, or we have to teach a teenager how to drive.)

Carbon dioxide, on the other hand, builds up pretty fast, and we need to get rid of it in a timely manner. In fact, it's the accumulation of carbon dioxide that makes you feel like you desperately need to inhale when you hold your breath.

The best way to fix shortness of breath is to figure out what's causing it. Things that interfere with moving air in and out of the lungs are:

• Choking
• Asthma
• COPD
• Collapsed lung (pneumothorax)
• Penetrating injury to the chest (gunshot wounds or stab wounds)

Things that interfere with the transfer of oxygen and carbon dioxide between the lungs and the bloodstream are:

• Too little oxygen in the air
• Blood clot in the lungs (pulmonary embolism)

Some causes of shortness of breath interfere with both moving air and transferring gases:

• Pneumonia
• Congestive heart failure (pulmonary edema)
• Drowning

_Sources:

Henry, Mark C., and Edward R. Stapleton. EMT Prehospital Care. 3rd Ed. 2004. Mosby/Jems