Pathophysiology
Clinical meaning
Therapeutic plasma exchange (TPE/plasmapheresis) removes the patient's plasma containing pathogenic autoantibodies, immune complexes, paraproteins, or toxins and replaces it with donor plasma or albumin solution. Each standard exchange removes approximately one plasma volume (40 mL/kg), eliminating roughly 63% of the target substance. Blood is drawn through a central venous catheter or large-bore peripheral access, separated by centrifugation or membrane filtration, the plasma is discarded, and cellular components are returned with replacement fluid. Category I ASFA indications (first-line therapy) include Guillain-Barré syndrome (anti-ganglioside antibodies), myasthenic crisis (anti-AChR antibodies), thrombotic thrombocytopenic purpura (TTP — removes anti-ADAMTS13 autoantibodies and replenishes ADAMTS13 enzyme), and anti-GBM disease (Goodpasture syndrome). Category II indications include acute demyelinating encephalomyelitis (ADEM), neuromyelitis optica (NMO), and severe lupus nephritis refractory to conventional therapy.