TFA says that they're currently working on a portable (external) lung replacement[0]. I see no reason that it couldn't be installed in the chest cavity with a port for the O2 bottle connection.
Even if "they're currently working on" meant "it's available now or practical in the near future" (it doesn't), that doesn't affect what I said about the immense costs involved.
The portability of the device is not the core issue here. It's a bit like arguing that you can build a quantum computer today, so therefore we'll all have one on our desktop soon.
Extracorporeal livers were being explored in the 1960s. It was advanced enough that it was included in a contemporary Time-Life book. Unfortunately, experimental success was not observed and the idea was shelved.
The portability of the device is not the core issue here. It's a bit like arguing that you can build a quantum computer today, so therefore we'll all have one on our desktop soon.