[Corrado]

I doubt that you can completely deflate your lungs by exhaling; even if you try your hardest to exhale as deeply as you can. There would always be some air in the lungs so that the pressure difference generated by this device would almost certainly be enough to pop the blockage out of your trachea.

[jxramos]

That's exactly right, something called Residual Volume (https://en.wikipedia.org/wiki/Lung_volumes#Values)