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Old 04-19-2012
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Lungs Why respiratory alkalosis in retrictive lung disease?

Why is there respiratory alkalosis in Restrictive lung disease? is it due to hypoxemia-->stimulation of peripheral receptors-->hyperventilation?
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Old 04-19-2012
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You are right.

Restrictive lung disease there is decreased perfusion (unlike in Obs lung the lungs are well perfused) >> hypoxemia>> stimulates respiratory center>> hyperventilation >>more co2 is driven out>> resp alkalosis


Whereas in Obs lung disease , ther is retention of CO2 >> respiratory acidosis
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Old 04-19-2012
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Default Restricted vs Obs lung disease well explained

http://pathology-youcandoit.blogspot...ctive-and.html

Hope this helps
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Old 04-20-2012
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Hyperventilation almost always causes respiratory alkalosis due to decreased CO2 concentrations. The notable exception is COPD, where there's a lot of CO2 retention... they have an increased respiratory rate, but they're not really hyperventilating because there's so little air going into their lungs with every breath.

For Step 1 purposes, you should just know that increased RR means decreased CO2 (which means respiratory alkalosis), except in COPD.
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Old 04-20-2012
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Quote:
Originally Posted by shan564 View Post
Hyperventilation almost always causes respiratory alkalosis due to decreased CO2 concentrations. The notable exception is COPD, where there's a lot of CO2 retention... they have an increased respiratory rate, but they're not really hyperventilating because there's so little air going into their lungs with every breath.

For Step 1 purposes, you should just know that increased RR means decreased CO2 (which means respiratory alkalosis), except in COPD.
As far as I know, all obstructive diseases have a high CO2 retention. I came across a question that basically asked what the findings would be if a peanut was lodged in someone's coryna. The answer was the stereotypical obstructive picture.

I guess that the best way to differentiate the two is as to whether the airway is obstructed (by mucus in CF and COPD), or if it is interstitial (all the Restrictive Lung Diseases).
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Originally Posted by Valkoff View Post
As far as I know, all obstructive diseases have a high CO2 retention. I came across a question that basically asked what the findings would be if a peanut was lodged in someone's coryna. The answer was the stereotypical obstructive picture.

I guess that the best way to differentiate the two is as to whether the airway is obstructed (by mucus in CF and COPD), or if it is interstitial (all the Restrictive Lung Diseases).
I think CO2 retention is a feature of chronic obstructive disease... you won't find it in conditions like asthma and acute bronchitis. I'm not sure what would happen in the case of a physical obstruction, but if you've seen a question about it, then that's probably right.
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I think that the intermittent nature of asthma, and the acute nature of acute bronchitis may skew the ABGs.

In the exam, however, if they ask for the blood gasses for asthma, would you mark the option with increased CO2?
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