Asthma

[NightNurseRN13]

Is asthma an airway obstruction or reduced alveolar capillary diffusion.

My book says obstruction, my instructor says capillary diffusion.

[nurseprnRN, BSN, RN]

your book is correct. by definition, the prime symptom of asthma is tight airways, sometimes to the point of complete obstruction. the most terrifying person in the er, for my money, is the asthmatic who, when you listen to her chest, has no chest sounds at all. some people think it's great when an asthmatic isn't wheezing, and stop worrying right there. however, wheezing is better than no air movement at all, which is what "no breath sounds" means. some of these people die right in front of you and there's not a damn thing you can do about it.

however, because the airways are so constricted (and there can be lots of secretions), there could be a lack of functioning alveolar units, in which case there will be a decrease in gas diffusion into the capillary bed. that may be what your instructor is thinking of, though it's a secondary effect. or s/he might be thinking of the generalized edema that comes with an allergic response, which would cause airway constriction and wheezing, but also thicken the alveolar walls and decrease efficient gas exchange. why not ask him/her to define his/her terms?

[guest042302019, BSN, RN]

Simply, airway obstruction/narrowing leads to decreased alveolar gas exchange.