Therapeutic Apheresis

Blood is made of cells, red cells, white cells and platelets, suspended in a fluid called plasma, which also carries proteins, antibodies, cholesterol particles and clotting factors. In apheresis, blood is drawn from a vein into a machine that separates it, usually by spinning it in a centrifuge or by passing it through a filter, and the component causing harm is removed while the rest is returned. In therapeutic plasma exchange, about one to one and a half times your plasma volume is removed in a session and replaced with albumin solution, or with donor plasma when clotting factors or a missing protein must be restored. LDL apheresis, also called lipoprotein apheresis, removes LDL cholesterol and lipoprotein(a) particles selectively, returning the rest of the plasma. Cytapheresis removes cells: red cell exchange replaces sickle-shaped red cells with donor cells, leukapheresis lowers extremely high white cell counts, and extracorporeal photopheresis treats white cells with light before returning them, used in some skin lymphomas and graft-versus-host disease.

Apheresis is recommended when a harmful substance in the blood drives a disease and removing it quickly helps, usually alongside medicines that stop it from being made again. Plasma exchange is used for Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, myasthenia gravis during a crisis or before surgery, neuromyelitis optica spectrum disorder and severe relapses of multiple sclerosis that do not respond to steroids, and some forms of autoimmune encephalitis. In blood and kidney disease it is used for thrombotic thrombocytopenic purpura, where it is lifesaving, anti-glomerular basement membrane disease, some forms of vasculitis, high blood viscosity from abnormal proteins, antibody-mediated rejection of a kidney transplant and to prepare for transplants across blood group or antibody barriers. LDL apheresis is used for inherited high cholesterol that remains very high despite maximum medicine treatment, especially when heart disease is present. Red cell exchange is used in sickle cell disease for stroke prevention, acute chest syndrome and before some operations.

Each session takes place in an apheresis unit with a specially trained nurse and a doctor available. You lie or sit in a reclining chair or bed. Blood is drawn through a needle or catheter, passes through the machine and is returned, usually through a second line, in a continuous circuit. If the veins in both arms are large enough, two needles can be used. Otherwise a temporary central venous catheter, similar to a dialysis line, is placed in a large vein in the neck or groin under local anaesthesia and ultrasound guidance; for long-term treatment a fistula or port may be created. An anticoagulant, usually citrate, is added to stop blood clotting in the machine. During the session, which usually lasts about two to three hours for plasma exchange and up to about four hours for LDL apheresis, your blood pressure, pulse and symptoms are monitored. Plasma exchange is typically given daily or every other day, often about five sessions, while TTP may need daily sessions until blood counts recover.

Apheresis is considered after a specialist has confirmed a diagnosis for which it is known to help, often a neurologist, haematologist or nephrologist working with the apheresis team. Before starting, the team checks blood counts, clotting, calcium and other blood chemistry, blood group and kidney function, and assesses your veins. You need to be stable enough to tolerate shifts in fluid and blood pressure, so heart problems and severe infection are taken into account. Some blood pressure medicines, called ACE inhibitors, are usually paused about a day beforehand because they can cause flushing and low blood pressure during treatment. Plasma exchange removes some medicines from the blood, including immunoglobulin and some antibodies used as treatment, so their timing is planned. Eat a light meal and drink fluids before an outpatient session. International patients should send specialist letters, test results and antibody reports in advance, so the course, line and accompanying treatment can be planned before arrival.

Most people feel tired after a session and some feel lightheaded, so rest for the remainder of the day and avoid driving if you feel unwell. Outpatients usually return to normal activities by the next day. If you have a central line, keep it dry and covered and report fever, redness or pain at once. The time a course takes shapes the plan: a plasma exchange course usually needs one to two weeks, plus a few days for assessment and line placement, so a stay of about two to three weeks is typical. Acute conditions such as Guillain-Barré syndrome or TTP are emergencies treated where the patient is, not planned trips. LDL apheresis continues every one to two weeks for years and must be arranged near home. For conditions that need repeated courses, such as some neuropathies or myasthenia gravis, agree a written plan covering the next steps, medicines and when to return or continue near home.

Therapeutic apheresis is generally well tolerated, and serious complications are uncommon in experienced units. The citrate anticoagulant binds calcium and can cause tingling around the lips and fingers, muscle cramps or nausea; this is common and settles with calcium given by mouth or into a vein. Low blood pressure, lightheadedness and fainting can occur, especially in smaller people. Donor plasma can cause allergic reactions, from hives to, rarely, severe reactions, which the team is equipped to treat. Albumin replacement temporarily lowers clotting factors and antibodies that protect against infection. Central lines carry risks of infection, clotting and bleeding. How well apheresis works depends on the condition. In TTP it is a core part of treatment. In Guillain-Barré syndrome and myasthenia gravis it speeds recovery or helps in a crisis, often over days to weeks. Because it removes antibodies but does not stop their production, treatment of the underlying disease is continued alongside.