In doing some research on CPAP I am coming across some information on the use of NIPPV for Asthmatics as well as the fact that COPD is as similar pathology as Asthma. My question is why can we administer CPAP for COPD exacerbation but not for Asthma? It seems to pose an equal risk for both but also has the same benefits.
Thank you for your inquiry. We ran this concept by the Associate Medical Director who offers the following:
Positive pressure can increase air stacking in asthmatics as they have narrowed airways secondary to spasm. Air goes in, but not out (easily). While individuals with COPD do have some narrowing of the airways, most at the stage that require CPAP have 'floppy' lungs - like an old balloon you let the air out.. you need some positive pressure to keep the 'sacs' from collapsing.
In asthma, the lung parenchyma is 'relatively' normal, but with COPD, it is not.
While CPAP can be used in Asthma, it is only a bridge, as eventually the lungs will become over inflated (ie barotrauma), as inspiratory rate is normal and expiratory rate is very slow (1/3 or 1/5)... this is similar in COPD but their lungs are not normal and can tolerate this"
You may find this link helpful, as it outlines the risk of barotrauma