How plasma and plasma components are used

Plasma and plasma components can be removed from blood in a number of different ways, allowing them to be used to treat a variety of conditions.

The main ways plasma is used include:

• plasma transfusions
• fractionation
• plasma exchange (plasmapheresis)

Plasma components can be used to help prevent health problems occurring in conditions such as Rhesus factor disease (where antibodies in a pregnant woman's blood destroy her baby's blood cells).

They can also be used to prevent bleeding in people with haemophilia (an inherited condition that affects the blood's ability to clot).

Plasma transfusions

Fresh frozen plasma

To obtain plasma for transfusion, a donation containing all the components of blood (whole blood), including plasma, is taken from one person.

The plasma is separated from the red cells and frozen, becoming fresh frozen plasma. When needed, it's thawed and given as a transfusion to another person.

For example, a person may be given a plasma transfusion if they're bleeding after having a serious accident or major surgery, where clotting factors need to be replaced in addition to red blood cells.

Before someone is able to donate blood for transfusion, they have to comply with a strict set of guidelines about their medical, travel and sexual history. This ensures it's safe for them to donate and that their blood is safe to be transfused.

As with red blood cells, plasma is always checked for viruses to make sure it's as safe as possible to use.

Most people receiving plasma receive fresh frozen plasma. This is stored frozen at -25C for up to three years, so it needs to be carefully thawed before use.

Pathogen-inactivated fresh frozen plasma

Plasma transfused to people born after January 1 1996 comes from donors outside the UK to reduce the risk of variant Creutzfeldt-Jakob disease (vCJD) , a rare and fatal brain condition.

There are two products available.One is produced by UK blood services and has been treated with a chemical called methylene blue (an additional step to make plasma safer). The alternative is a batched mixed plasma that's been treated with solvent detergent to make it safer.

Cryoprecipitate

Cryoprecipitate is plasma that's been specially treated so it's rich in certain proteins, including fibrinogen (a special protein that helps blood clot).

For more information about the process, see blood transfusions .

Plasma products made by fractionation

Many of the components found in plasma can be separated and removed so they can be used to treat specific problems.

Some plasma donations are mixed (pooled) and subjected to a number of different heat and chemical treatments. The various proteins are then separated out in a complex process known as fractionation.

All blood donations used to make plasma pools for fractionation have to be checked for viruses to make sure they're as safe as possible to use. The pooled plasma is alsocarefully filtered and "cleaned" using heat, detergents and solvents to remove any viruses that may be present.

After the fractionation process has been completed, the plasma products are either kept as a liquid or freeze-dried as a powder for reconstitution before use. They're then packaged, ready for distribution to clinics, surgeries and hospitals.

There are numerous plasma components, but the three main ones are:

• human albumin solution
• clotting (coagulation) factors
• normal human immunoglobulin

Some of these are briefly outlined below.

Thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpurais a rare clotting disorder affecting the platelets, where microscopic blood clots form and damage organs and red blood cells.

Plasma exchange separates and removes theplasma from the rest of your blood and replaces it with solvent detergent plasma. This replenisheslevels of a vital enzyme that controls the platelet clotting and removes the antibodies responsible for the condition.

Multiple myelomaand Waldenstrm's macroglobulinaemia

Multiple myeloma and Waldenstrm's macroglobulinaemia are both rare types of bone marrow cancer where abnormal bone marrow cells create large amounts of a protein called a paraprotein (immunoglobulin).

If the protein levels in the blood become too high, the blood can thicken, which is known as hyperviscosity. The symptoms of hyperviscosity include:

• headaches
• fatigue (tiredness)
• blurred vision

Plasma exchange reduces the amount of abnormal protein in the blood, which helps relieve the symptoms.

However, the process does not prevent the production of immunoglobulin. Other treatments, such as chemotherapy , may be required to achieve this.

Plasma exchange procedure

During plasma exchange, a machine called a cell separator isused to separate the plasma fromthe rest of your blood. A needle is inserted into a vein inthe arm and theblood is removed and passed through the cell separator.

The plasma is separated from the rest of your blood and a plasma substitute is added before the blood is returned through a needle in a vein inthe other arm.

Plasma exchange takes about two hours to perform. During the process, only a small amount of blood (less than 100ml) will be outsidethe body at any one time. This is because the blood is being removed and returned atthe same rate.

The amount of plasma exchanged will depend on factors such as:

• your height
• your weight
• how viscous (thick) your blood is

The number of plasma exchanges needed will depend on your symptoms and how well you are responding to your other treatments.

Side effects

Feeling faint or lightheaded are both possible side effects of a plasma exchange. If you feel faint or lightheaded, you should tell the healthcare professional treating you.

The symptoms can usually be effectively treated by changing to a lying down position. Ensuring you have something to eat on the day of the procedure will also helpprevent these symptoms.

During a plasma exchange, you may also experience numbness or a tingling sensation around your nose and mouth and in your fingers.

This is caused by a substance called citrate, which is added to your bloodas it goes through the machineto prevent it clotting. The citrate may affect the levels of calcium in your blood.

Letthe healthcare professional treating you knowif you experience numbness or tingling sensations. They may stop the plasma exchange for a few minutes until your body adjusts to the increased citrate levels in your blood, or they may increase the level of calcium in your blood.