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How does asthma lead to cyanosis?

  1. Feb 13, 2011 #1
    As title suggest. Thanks :smile:
  2. jcsd
  3. Feb 14, 2011 #2
    Through lack of oxygen in the blood I believe! Skin and mucous membranes begin to look bluish!
  4. Feb 14, 2011 #3
    Thanks for the reply but I think people with ashtma have less problem in inhaltion, but more problem in exhalation. So it is the resultant increase in carbon dioxide shifting the hameoglobin dissociation curve to the right that causes this. I posted this topic to clarify?
  5. Feb 14, 2011 #4
    No asthma has problem with inhalation also (due to narrowing of bronchi). So there is hypoxia which is why there is cyanosis.
  6. Feb 14, 2011 #5
    But when you breathe in don't bronchi dilate, but practically I can see what you are saying is right.
  7. Feb 14, 2011 #6
    There are more problems associated with exhalation but of course if bronchial muscle tone is high then inhalation rates will also be slowed. But the additional exhalational effects come from the relationship between lung volume and airway diamater.
    Incidentally asthmatics are generally not oxygen limited - it is a sign of severe ER requiring asthma if you see a change in blood PO2.
    Again - most asthmatics are not hypoxic. This is a severe life threatening situation when an astrhmatic does develop low PO2.
  8. Feb 14, 2011 #7
    The bottom line here is very simple: hypoxic leukocytes = cynanosis. It doesn't really matter if it's from the binding of cyanide, someone holding a bag over your head, or some fashion in which your breathing is restricted. Unless it's peripheral vasoconstriction... see what mtc1973 said. Oxygenated air being displaced by panic-gasps and poor exhalation can lead to a rapid crisis, but it's uncommon. More often you pass out, and your breathing is still labored, but not smothering.
  9. Feb 15, 2011 #8

    This is not correct . Asthmatics , during an attack of asthma are hypoxic (depending on severity).

    most of the cases are mild to moderate form and are usually reversible by drugs
    Last edited: Feb 15, 2011
  10. Feb 15, 2011 #9
    This is exactly what our teacher drummed into our heads today. If you were in class teacher would have been very impressed :smile:

    PS: Why didn't you tell this yesterday?
  11. Feb 15, 2011 #10
    I think you need to do 2 things.

    1.) Consider what is meant by hypoxia in this thread, given that it's in the context of cyanosis.
    2.) Tell me if you understand that "PO2" is "oxygen saturation"... pulse oxygen, "pulse ox", that little cute red light thing they put on your finger? Yeah, the "Pulse Oximeter".
  12. Feb 15, 2011 #11
    Po2 is partial pressure of oxygen.

    oxygen saturation is the not same and yes its read by a pulse oximeter.

    i would like to clarify that cyanosis develops only in severe life threatening cases of asthma or acute severe asthma
    Last edited: Feb 15, 2011
  13. Feb 15, 2011 #12
    re bold: That is EXACTLY what mtc said, and you argued with.

    Lovely, we all agree then.
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