You need to treat lots of blood continuously, so you have to cut a bypass into the largest, irreplaceable blood vessels, unlike smaller operations like kidney d

You need to treat lots of blood continuously, so you have to cut a bypass into the largest, irreplaceable blood vessels, unlike smaller operations like kidney dialysis where you can just "plug into" an arm. Mechanical pumping of blood is a problem as it damages blood cells. Infection is a severe risk. Any break in the operation or a temporary "plumbing issue" where the machine connects with the body can be fatal. So you need 24/7 monitoring capable of really rapid response.