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I am confused about the initial sequence of events in an asthma attack. I've been reading about how you don't see hypercarbia in the ABG until things are very severe. I understand that hyperventilation would cause low CO2 but what I don't get is why the patient is hyperventilating in the first place.
I thought that CO2 is the main drive of respiration. Thus I would think that the patient would first start to feel the anxiety/effects of an asthma attack (and thus start to hyperventilate) when the CO2 rises. I would also think that it would be the CO2 driving hyperventilation during the attack. (Thus, if CO2 normalizes due to hyperventilation, why don't patients stop hyperventilating? Why does it seem that oxygen is the main issue here?)
Additionally, I thought that asthma is primarily an air trapping disorder, and like COPD, is mostly an issue with high CO2 (at least early in the disease course, I understand that if you can't move any air you'll obviously get low oxygen then as well). This unfortunately leads me to a whole other issue of trying to figure out why Bronchitis is "blue bloater" and Emphysema is "pink puffer" since I thought both of those have the same ABG.
Anyways...if anyone can try to help me with this I'd greatly appreciate it. Thanks in advance!
I thought that CO2 is the main drive of respiration. Thus I would think that the patient would first start to feel the anxiety/effects of an asthma attack (and thus start to hyperventilate) when the CO2 rises. I would also think that it would be the CO2 driving hyperventilation during the attack. (Thus, if CO2 normalizes due to hyperventilation, why don't patients stop hyperventilating? Why does it seem that oxygen is the main issue here?)
Additionally, I thought that asthma is primarily an air trapping disorder, and like COPD, is mostly an issue with high CO2 (at least early in the disease course, I understand that if you can't move any air you'll obviously get low oxygen then as well). This unfortunately leads me to a whole other issue of trying to figure out why Bronchitis is "blue bloater" and Emphysema is "pink puffer" since I thought both of those have the same ABG.
Anyways...if anyone can try to help me with this I'd greatly appreciate it. Thanks in advance!
