How does asthma lead to cyanosis?

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Discussion Overview

The discussion revolves around the relationship between asthma and cyanosis, exploring the physiological mechanisms that may lead to cyanosis in individuals with asthma. Participants examine the roles of oxygen levels, carbon dioxide retention, and the mechanics of inhalation and exhalation in this context.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that cyanosis results from a lack of oxygen in the blood, leading to bluish skin and mucous membranes.
  • Others argue that asthma primarily causes problems with exhalation, resulting in increased carbon dioxide levels that may shift the hemoglobin dissociation curve to the right.
  • There is a contention regarding whether asthmatics experience significant hypoxia, with some asserting that most are not oxygen limited unless in severe cases, while others maintain that hypoxia can occur during asthma attacks.
  • Participants discuss the relationship between bronchial muscle tone, lung volume, and airway diameter, noting that these factors can affect both inhalation and exhalation rates.
  • Clarifications are made regarding the definitions of hypoxia and oxygen saturation, with emphasis on the context of cyanosis and the severity of asthma attacks.
  • Some participants highlight that cyanosis typically develops only in severe, life-threatening cases of asthma.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the mechanisms leading to cyanosis in asthma. There are multiple competing views regarding the role of hypoxia, the significance of oxygen saturation, and the conditions under which cyanosis may develop.

Contextual Notes

Discussions include varying interpretations of hypoxia and oxygen saturation, as well as the severity of asthma attacks and their implications for cyanosis. Some claims about the relationship between blood PO2 and hypoxia remain unresolved.

sameeralord
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As title suggest. Thanks :smile:
 
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sameeralord said:
As title suggest. Thanks :smile:
Through lack of oxygen in the blood I believe! Skin and mucous membranes begin to look bluish!
 
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?
 
sameeralord said:
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?

No asthma has problem with inhalation also (due to narrowing of bronchi). So there is hypoxia which is why there is cyanosis.
 
thorium1010 said:
No asthma has problem with inhalation also (due to narrowing of bronchi). So there is hypoxia which is why there is cyanosis.

But when you breathe in don't bronchi dilate, but practically I can see what you are saying is right.
 
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.
 
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.
 
mtc1973 said:
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.
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
 
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mtc1973 said:
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.

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?
 
  • #10
thorium1010 said:
This is not correct . Asthmatics , during an attack of asthma are hypoxic (read oxygen saturation).

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".
 
  • #11
nismaratwork said:
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".

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
 
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  • #12
thorium1010 said:
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

re bold: That is EXACTLY what mtc said, and you argued with.

thorium1010 said:
mtc said:
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.


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

Lovely, we all agree then.
 

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