Plasma exchange for patients with thrombotic thrombocytopenic purpura (TTP)

Information for patients undergoing plasma exchange (plasmapheresis)

This leaflet has been specially written for patients who are about to undergo, or are undergoing plasma exchange. We hope this leaflet together with a discussion with the medical and nursing staff will help you and your relatives or carers to understand this safe, simple and routine procedure and what it involves.

What is thrombotic thrombocytopenic purpura (TTP)?

In acquired autoimmune-mediated TTP (iTTP), patients develop antibodies against the enzyme ADAMTS13 leading to blood clots (thrombosis) caused by clumping which result to reduction in platelets (thrombocytopaenia). Platelets are one of the most important components of blood which main function is to form blood clots when bleeding occurs This causes the small blood vessels to leak, allowing blood to pool under the skin (purpura). This is called thrombotic thrombocytopenic purpura.

Normally, your immune system produces antibodies and immune cells to attack invading viruses and bacteria. It is your body’s defence against infection and illness. But if the immune system malfunctions (this is called autoimmune disease), it fails to recognise healthy cells, tissues, and organs and instead attacks them.

What is plasma?

Plasma is a straw-coloured liquid. It is the part of the blood that transports the blood cells (the red blood cells, white blood cells and platelets) through the body together with proteins, nutrients and antibodies.

What is plasma exchange?

Sometimes called plasmapheresis, simply stated, it is ‘the removal of old plasma and replacement by new plasma’.

In acquired TTP, the first line of treatment is plasma exchange therapy (PEX). This is a procedure that involves the separation of plasma from other blood components by a blood cell separator machine. It spins the blood very quickly using a centrifuge to separate plasma from the other cells of the blood.

Blood is removed from one vein into the blood cell separator, which extracts and discards the defective plasma. The cellular components of the blood (red cells, white cells and platelets) are returned to the body alongside the plasma replacement fluid called solvent detergent fresh frozen plasma (SDFFP).

The procedure will take approximately two hours and is usually repeated every day until your platelet count is back to normal. This may take several days of treatment. You will also receive additional treatment as well as PEX.

The benefits of this procedure include the removal of antibodies that block the ADAMTS13 enzyme and replacing the levels of ADAMTS 13 from donated SDFFP.

What are the side effects?

Plasma exchange is a safe procedure with few side effects. Most people tolerate plasma exchange well, but if you experience any of the side effects, it is important that you inform your nursing staff immediately. These can be treated quickly and your nurse is trained to respond to these. You will be monitored throughout the procedure.

• During plasma exchange, your blood pressure is lower than usual. This can make you feel weak, dizzy, or nauseous. If this happens, your nurse will monitor your condition. You may need to lie flat until you feel better.
• You may develop a rash or high temperature if you react to replacement fluids/blood products.
• The anticoagulant used to prevent your blood from clotting may cause a sour taste in your mouth, or a tingling sensation around your lips, fingers or toes. This is due to a drop in your calcium level. You will be given a calcium replacement if you need it.

Before your plasma exchange

We want you to be involved in the decisions regarding your care and treatment. We normally ask patients to sign a consent form to go ahead with the procedure. This shows that you have understood what is involved and agree to it. However, during acute episodes of your illness, you may be too unwell and in this case, the form will be signed by your medical team for your best interest.

A good flow of blood from your body to the machine and back is essential. This is usually obtained by the insertion of a special catheter into one of your neck or groin veins. This will be done by an experienced member of the medical staff.

During plasma exchange

Your procedure is performed by one of the specially trained apheresis nurses based on Ward E10. You will be closely monitored throughout the procedure for any side effects so that appropriate interventions can be given.

The machine will take your blood out from one of your veins and spin it very quickly to separate it into its components. Your old plasma will be pushed into the collection bag by the machine for disposal and the new donated plasma together with the other blood cells will be returned to you through another vein. Only about 200mls of your blood will be out of your body at one time and you will not feel it. The procedure does not normally make you unwell.

You will be asked to remain on your bed to ensure a smooth exchange of blood products. You are allowed to sit up on the bed and can read, eat, drink, watch TV and have conversations while attached to the machine.

After the procedure

We will ask you to stay in bed for few more minutes and if you need to get up, do this very slowly after completion of the procedure to avoid fainting or feeling dizzy.

Your progress will be monitored by regular blood tests during your hospital stay and later in the clinic as an outpatient.

Contacts/Further information

If you have any questions or concerns about plasma exchange, please contact the apheresis unit on tel: 01223 256272, Monday to Friday 08:00-15:30.

Paul Boraks
Senior clinical nurse / Apheresis manager
Apheresis unit, Ward E10

If you have any queries or need support regarding your treatment, you can contact:

Dr William Thomas
TTP lead consultant
Cambridge University Hospitals

Dr Martin Besser
Lead consultant
Non-malignant Haematology

Ruth Jolley/Vivian Garcia
Specialist nurses
Non-malignant Haematology
Tel: 01223 217717

Out of hours, please telephone the hospital switchboard on 01223 245151 and ask for the haematology registrar on call.