Hi Rumpled,
Plasmapheresis is not a long term treatment, it helps overcome a crisis and acts after 3 to 10 days and up to 6 weeks but it doesn't work for about 20 % of the patients.
If you need that kind of treatment, try to show your vein condition to the team who would perform the plasma exchanges in order to avoid any unnecessary surgery (like SHELDON for ex).
Maurice.