Dyspnea vs. Shortness of breath??

Do-over, ASN, RN · Mar 14, 2014

They are the same thing.

SwansonRN · Mar 14, 2014

Dyspnea and SOB can essentially mean the same thing. If anything, dyspnea can mean painful/difficult breathing whereas shortness of breath is the sensation of not getting enough air.

As far as your second question, I don't really know what you mean. Can you elaborate?

tokebi · Mar 14, 2014

I don't think you can say they're the same thing.

Dyspnea is difficulty breathing, or labored breathing.

Shortness of breath is... just feeling of short of breath, like when you just did a two-mile run. You can feel short of breath but not necessarily have difficulty breathing.

As for your second question, if a new-onset dyspnea is not addressed, the result would manifest in altered tissue perfusion and hypoxia, not slowing of respiration -- that would be... death!

Tachypnea might progress to respiratory alkalosis as a result of hyperventilation.

Bradypnea... the only case I can think of is opiate overdose.

tokebi · Mar 14, 2014

It might help to think of it this way:

Shortness of breath is brought on by the body's need for more oxygen, such as in physical exertion or inadequate cardiac output.

With dyspnea, there is something that's preventing the normal mechanical process of breathing. Think what happens in the lungs in COPD, asthma, pleural effusion, pulmonary edema, PE... Any pain problems will also hinder diaphragm movement and cause dyspnea.

When someone has dyspnea, it will lead to hypoxia due to ineffective breathing/gas-exchange, which will then lead to shortness of breath due to the need for more oxygen. That's why those two conditions seem like the same thing. But remember what is causing what. That'll help differentiating the two.

nurseprnRN, BSN, RN · Mar 15, 2014

It might help to think of it this way:
Shortness of breath is brought on by the body's need for more oxygen, such as in physical exertion or inadequate cardiac output.
With dyspnea, there is something that's preventing the normal mechanical process of breathing. Think what happens in the lungs in COPD, asthma, pleural effusion, pulmonary edema, PE... Any pain problems will also hinder diaphragm movement and cause dyspnea.
When someone has dyspnea, it will lead to hypoxia due to ineffective breathing/gas-exchange, which will then lead to shortness of breath due to the need for more oxygen. That's why those two conditions seem like the same thing. But remember what is causing what. That'll help differentiating the two.

Not exactly. But a common misconception weaves in and out of these.

To clarify, your body increases its minute volume (the volume of air it moves in and out of your chest in one minute) in response to higher levels of CO2, as in when you have been carrying something heavy up two flights of stairs. You deep breathe not because you are short of oxygen, but because your muscles have put out a lot of CO2, this has made you acidotic, and your respiratory center tells the diaphragm and other things to hustle it up and get rid of that. In this case, you might feel short of breath, but you are not dyspneic. That is, there is nothing standing in the way of breathing as deeply and as rapidly as you need to until you reach homeostasis.

Dyspnea is difficulty breathing, difficulty moving air in and out. Asthmatics have tight airways --- dyspnea. Congestive heart failure makes heavy wet lungs --- dyspnea. Rib fractures or primary muscular weakness (like ALS or high SCI) --- dyspnea. Please try hard to notice the difference.

Either shortness of breath or dyspnea can result in a higher respiratory rate. However, dyspnea, because of the implied difficulty in moving air in and out, will move less air per breath. Even if one of these folks is breathing as rapidly and feels as if he's breathing as hard as you are after your stair-climb, he isn't getting the most bang for his buck, respiratory-effort-wise. :) You will feel better soon; he won't. (And if his respiratory rate is decreasing after a period of untreated dyspnea, it's because he's dying right before your eyes.)

Dyspnea may lead to hypoxia and hypercarbia, if inadequate gas exchange is occurring. The O2 will be affected first, because the lungs' prime directive is moving CO2 to maintain acid-base balance over a wide range of physical activity; oxygenation is actually a secondary chore. This is why people with pulmonary emboli or pneumocystis pneumonia have low oxygen levels AND low CO2 levels. They are dyspneic because they are hypoxic, and the lower CO2 is a byproduct of their rapid respiratory rate (their pathology, alas, prevents them from absorbing more oxygen for all that work).

tokebi · Mar 16, 2014

^ So thoroughly and eloquently put. I see I was barely scratching the surface. You're a natural teacher, GrnTea.

I realize I overlooked the fact that the increasing CO2 is what drives the respiration. But when we exert physically, isn't the increased metabolic demand (i.e. the need for oxygen to generate energy) also a driving factor? Hence, "shortness of breath?"

nurseprnRN, BSN, RN · Mar 16, 2014

Not really, because if you have decent lungs your PaCO2 will go up enough to increase respiratory drive, as expected, but your PaO2 won't drop so far as to make an hypoxic drive kick in. Remember that the lungs' prime directive is pH balance, because that can be tuned so rapidly by changes in CO2 via minute volume (rate-dependent in most people).

As a matter of fact, people who drop their PaO2 (most easily tracked by watching continuous SpO2) with minimal exercise (like turning in bed :eek: ) are the ones with really bad lung disease, even though they aren't generating much CO2. They just have so little O2 on board (and remember, again, lungs are always better at excreting CO2 than they are at taking in O2) that the least bit of consumption just drops 'em.