Is There a Limitation of the Inspiratory Airflow?

i'm not aware of a certain flow rate at which the patient's head will explode. So i don't know, but i think it brings up the same problem with like, non re breather face masses. It's flow limiting. And i've absolutely seen patients fere. They'll be on high flo nasal canula, and they're on a hundred%. But there's no way they're truly getting a hundred %. The second part is the dead space wash out that you alluded to.