Error in Goljan?

[Dwindlin]

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So I'm reviewing for a Resp. test Monday and I noticed that in Goljan he lists the changes to the ABG in emphysema as a "normal to decreased" PCO2. That's mistake right, wouldn't the PCO2 be increased due to air trapping? Or did I completely misunderstand emphysema?

 

[da8s0859q]

So I'm reviewing for a Resp. test Monday and I noticed that in Goljan he lists the changes to the ABG in emphysema as a "normal to decreased" PCO2. That's mistake right, wouldn't the PCO2 be increased due to air trapping? Or did I completely misunderstand emphysema?

I'd say PCO2 goes up -- but it's not in his errata.

 

[dude1344]

The way I thought it works is that since most people with emphysema are hyperventilating, that allows them to blow off more CO2 than normal. That's why they're called "pink puffers" as they hyperventilate.

 

[Funky]

The way I thought it works is that since most people with emphysema are hyperventilating, that allows them to blow off more CO2 than normal. That's why they're called "pink puffers" as they hyperventilate.

This
Also it mentions that the patients are usually in respiratory alkalosis, probably because of hyperventilation.

 

[da8s0859q]

The way I thought it works is that since most people with emphysema are hyperventilating, that allows them to blow off more CO2 than normal. That's why they're called "pink puffers" as they hyperventilate.

Forgot all about that. Doh.

 

[MedStudentWanna]

I don't really understand the pink puffers vs. blue bloaters thing. Can someone explain it to me?

 

[Dwindlin]

Hyperventilation makes sense, I'm just having a hard time finding another source that agrees. emedicine and Robins both had increased CO2 as a finding and I even did the unthinkable (for me anyways) and drudged through my course pack and it listed CO2 as being increased.

 

[unsung]

So I'm reviewing for a Resp. test Monday and I noticed that in Goljan he lists the changes to the ABG in emphysema as a "normal to decreased" PCO2. That's mistake right, wouldn't the PCO2 be increased due to air trapping? Or did I completely misunderstand emphysema?

Not a mistake. Emphysema does not have elevated PCO2. This is because emphysema not only destroys the respiratory unit, it also destroys nearby vasculature. So there's an even loss of both ventilation & perfusion, which ensures CO2 levels are actually normal. Or decreased, if lose more perfusion (vasculature) than ventilation.

By way of comparison, in chronic bronchitis, mucous/inflammation is plugging up the terminal bronchioles... but this is more proximal to the damage that occurs in emphysema. Anyway, with chronic bronchitis, we lose more ventilation than perfusion, so we have elevated CO2 (trapped in blood, not being "ventilated out").

So the difference is where the damage occurs.

 

[unsung]

The way I thought it works is that since most people with emphysema are hyperventilating, that allows them to blow off more CO2 than normal. That's why they're called "pink puffers" as they hyperventilate.

Emphysema is an obstructive disease, and obstructive lung diseases cause HYPOventilation.

The restrictive lung diseases like lung fibrosis, etc. cause hyperventilation. Tho' I think asthma exacerbation also causes hyperventilation.

But the more I think about this, the more unsure I get. 😕

 

[Dwindlin]

But the more I think about this, the more unsure I get. 😕

lol. You're not the only one. . .

 

[ArcGurren]

I don't really understand the pink puffers vs. blue bloaters thing. Can someone explain it to me?

It's basically a way to differentiate between the two forms of COPD - chronic bronchitis and emphysema (though my understanding is they're treated almost exactly the same clinically).

Pink puffer = emphysema --> basically they're putting a lot of their accessory muscles to use during exhalation so they'll generally be blowing off a lot of CO2/hyperventilating. Hence they'll often have a reddish face and breathing hard. They also tend to be a thinner than in chronic bronchitis.

Blue Bloaters = chronic bronchitis --> basically refers to the fact that you have a bit of cyanosis due to increased PCO2 in CB because the mucus plugs make it hard to blow off extra CO2. In addition they tend to be obese hence "bloater", though I'm not actually sure of the pathophys behind that.

 

[MedStudentWanna]

It's basically a way to differentiate between the two forms of COPD - chronic bronchitis and emphysema (though my understanding is they're treated almost exactly the same clinically).

Pink puffer = emphysema --> basically they're putting a lot of their accessory muscles to use during exhalation so they'll generally be blowing off a lot of CO2/hyperventilating. Hence they'll often have a reddish face and breathing hard. They also tend to be a thinner than in chronic bronchitis.

Blue Bloaters = chronic bronchitis --> basically refers to the fact that you have a bit of cyanosis due to increased PCO2 in CB because the mucus plugs make it hard to blow off extra CO2. In addition they tend to be obese hence "bloater", though I'm not actually sure of the pathophys behind that.

Makes sense, finally. Thanks!