Donor and Therapeutic Apheresis: Eligibility, Indications, and Complications
Core concepts
Apheresis separates blood into components and returns the remainder. Donor apheresis (platelet, plasma, double red cell) has specific eligibility: platelet donors need adequate pre-donation platelet count (≥150,000/µL), interval limits (e.g., 7 days between platelet donations, 24 donations/year), and protein/calcium considerations. Therapeutic apheresis indications are graded by ASFA categories (I–IV), with category I being first-line therapy.
Common therapeutic procedures: plasmapheresis for TTP (category I), myasthenia gravis, Guillain-Barré; cytapheresis for leukostasis or sickle cell (red cell exchange); photopheresis for cutaneous T-cell lymphoma and graft-versus-host disease.
Complications include citrate toxicity (perioral tingling, tetany, hypocalcemia), hypotension from volume shifts, access-related thrombosis or bleeding, allergic reactions to replacement fluid (plasma), and coagulation factor depletion with plasma exchange. Replacement fluid choice: albumin for most; plasma when coagulopathy or ADAMTS13 replacement is needed (TTP).
Traps
Citrate reactions are managed with calcium, not with stopping unless severe. Plasma exchange removes factors but also drugs-check pharmacokinetics. Donor platelet counts and intervals are frequently tested.
Rule of thumb
ASFA category I = first-line; category III = controversial; category IV = not recommended. For TTP, plasma exchange with plasma replacement is first-line; do not give platelets unless life-threatening bleeding.