For which of the following conditions is therapeutic plasmapheresis most likely indicated?
Plasmapheresis may be used to remove pathologic intra-vascular components (e.g., immune complexes, immunoglobulins, hormones). The technique is useful only when the offending agents are present in the circulation. (It is not effective, for example, in patients with rheumatoid arthritis or lupus nephritis, in which the immune insult is localized to peripheral tissues.) The American Society for Apheresis has established guidelines for the management of many disease states using plasmapheresis, some of which occur in the perioperative period.
Myasthenia gravis: Most patients with myasthenia gravis have autoantibodies to acetylcholine receptors. Some will have anti-muscle-specific receptor tyrosine kinase antibodies. Plasmapheresis removes these autoantibodies, and its use is associated with rapid improvement in muscle strength in patients with myasthenic crisis. The beneficial effect often disappears after two weeks, so concomitant administration of corticosteroids and other immunosuppressants is required.
Thrombotic thrombocytopenic purpura...