Why would someone with emphysema have swollen ankle?

Pulm HTN: If both ankles are swollen, one should consider pulmonary hypertension. If only 1 ankle is swollen, it is unrelated to emphysema.

Emphysema: Can and does cause ankle swelling, but in both ankles. If you only have one ankle that's swollen, it usually means there is something local with that one ankle that's causing the swelling, although emphysema certainly can make a little swelling worse. I would suggest a good vascular work-up to see the state of your circulation in both legs. If the ankle swelling is painful, x-rays would be wise.