Overview of Plasmapheresis
Plasmapheresis is a treatment used by doctors that involves removing, replacing, or exchanging the plasma in your blood. Plasma is a part of your blood that contains many things your body needs, such as proteins and antibodies. This process can be done through two different methods: centrifugation or filtration.
Centrifugation is a way of separating different components in the blood by spinning it rapidly in a machine. It uses the idea that different parts of the blood have different “weights” and thus, separate differently when spun. On the other hand, filtration uses a special membrane (like a very, very tiny sieve) to separate the blood components by their particle size.
Most hospitals around the world use the centrifugation method, where the separated plasma is removed, and red blood cells are put back into your body along with some replacement fluid. This could be plasma from a donor or other substances. However, in some cases, such as certain hospitals or patients on hemodialysis (a treatment for kidney failure), filtration is used instead. This method is able to selectively remove unwanted large particles, so that the cleaned plasma can be returned back to the patient, without needing any replacement fluids.
In the rest of our discussion, we’ll be exploring when and why plasmapheresis is used, who shouldn’t have it, what kind of equipment is involved, how to prepare for the procedure, what happens during the procedure, and the possible complications that may occur.
Why do People Need Plasmapheresis
Plasmapheresis, which is a procedure that filters harmful substances from your blood, can be used as a treatment for many different diseases. When you have plasmapheresis, your blood is removed and divided into different parts so that any unhealthy substances, like excess antibodies, can be taken out. Then, your blood is returned to your body, minus the harmful elements.
The American Society for Apheresis (ASFA), a professional organization for experts in the field, groups illnesses that can be treated with plasmapheresis into four categories:
Category 1: Illnesses where plasmapheresis can be used as the primary treatment.
Category 2: Illnesses where plasmapheresis can be used alongside other treatments.
Category 3: Illnesses where the benefits of plasmapheresis are unclear, so doctors need to consider using it on a case-by-case basis.
Category 4: Illnesses where plasmapheresis either doesn’t work or could be harmful, so it is only used if a medical ethics committee gives approval.
Some specific conditions that plasmapheresis can be used to treat include Guillain-Barre syndrome, Myasthenia gravis, and acute liver failure among others. Some are placed into different categories based on the severity and specifics of each case. For example, plasmapheresis can be used as a primary treatment for severe versions of some disorders, but for less severe cases, it might be used alongside other treatments or not at all. Individuals will need to consult with their medical practitioners to understand what category their illness falls into, and if plasmapheresis is a good treatment option for them.
When a Person Should Avoid Plasmapheresis
There are several situations where therapeutic plasmapheresis, a procedure that filters the blood, may not be possible or advisable:
* If there isn’t a suitable central line access or large bore peripheral lines available. These are special tubes that doctors put into a large vein to deliver medicines or carry out certain procedures.
* If a person is experiencing hemodynamic instability or septicemia. Hemodynamic instability relates to unstable blood pressure and heart rate, and septicemia is a severe infection that has spread via the bloodstream.
* If a person is known to be allergic to fresh frozen plasma, replacement colloid/albumin, or heparin. These substances are often used in the process of plasmapheresis and in preventing the blood from clotting.
* If a person has low calcium levels in the body, known as hypocalcemia, using citrate as an anticoagulant during the procedure may be restricted. Citrate is a substance used to prevent blood from clotting.
* If a person has taken an Angiotensin-Converting Enzyme (ACE) inhibitor, a type of medication for high blood pressure and heart failure, in the last 24 hours, the procedure may not be advised. This is a relative contraindication, meaning the benefits and risks should be evaluated by a physician.
Equipment used for Plasmapheresis
For the medical procedure of plasmapheresis, doctors will either use a central venous catheter or large-line veins to access your blood stream. Certain centrifuge-based machines, produced by different companies, are used to carry out this process.
Another way to do plasmapheresis involves the use of semipermeable membrane filters, paired with a standard machine similar to one used for kidney dialysis. For this method though, the catheter must be placed into a major vein because it needs to handle a flow of 100 to 150 milliliters of blood per minute. Nowadays, two types of membrane technologies are used: hollow fiber and parallel plate.
Hollow fiber filters look like cylindrical shells and contain multiple strands of a synthetic material called polysulfone. On the other hand, parallel plate filters are made up of layered membranes that have unique designs with ridges and grooves to help with the filtration process. Both of these filters work by allowing plasma (the liquid part of the blood) to pass through based on the size of blood particles and pressure differences.
Generally, hollow fiber filters are considered to be more gentle and they are often used for children. Moreover, they use less blood, reducing the amount of citrate or heparin (substances to prevent blood clotting) needed.
One of the main benefits of using membrane-based plasmapheresis, as compared to centrifuge-based methods, is that the cleansed plasma can be put back into the patient. This eliminates the need for additional fluids or proteins to replace the cleansed plasma.
Who is needed to perform Plasmapheresis?
Plasmapheresis is a process that was usually done in places where blood is stored using machines that spin the blood to separate the components. Today, this process is commonly performed by certain medical professionals who have gone through special training. These include doctors specializing in intensive care, doctors who treat kidney diseases (nephrologists), and professionals trained to perform kidney dialysis. They are skilled in doing this procedure to help patients, and it’s done regularly in places like the intensive care unit.
Preparing for Plasmapheresis
For these types of medical procedures, typically no special preparation is required from the patient. However, when a central line is being inserted – which is a tube placed into a large vein in your neck or chest – doctors often use a local anesthetic to numb the area and make it more comfortable. They commonly use a medicine called 2% lidocaine to do this. For children, doctors might consider using a sedative to calm any anxiety and manage pain.
For the procedure called plasmapheresis, in which the liquid part of your blood, or plasma, is separated from the blood cells, patients are usually asked to lie flat on their back. But the exact position, particularly the neck, might need to be adjusted depending on where the central line is inserted to make sure blood flow is not disrupted during the procedure.
During the treatment, it’s important that the doctors closely monitor the patient’s vital signs – such as heart rate, blood pressure, and oxygen levels – to watch for possible complications. These could include low blood volume, calcium levels drop too low (hypocalcemia), and any complications that may arise from the transfusion of fresh frozen plasma, which is a blood product used in certain treatments.
How is Plasmapheresis performed
Plasmapheresis is a procedure where blood is removed from the body, separated into plasma (a part of your blood that carries cells and proteins throughout your body) and red blood cells (which transport oxygen), and then returned with the plasma replaced with a different fluid. Machines that use a centrifuge (a device that spins the blood really quickly to help separate the different components) might follow these steps:
First, about 3-5 milliliters (mL) of blood from the large vein in your body (the central venous catheter) is thrown away. This is to remove any “impure” blood leftover from a previous procedure or that might’ve been sitting in the catheter for a while.
Next, some blood is drawn so the doctors can double-check your baseline blood counts (complete hemogram) and levels of calcium and fibrinogen (a protein that helps in clotting). Once those tests are taken, the catheter is cleaned with a solution containing a small amount of the blood-thinner heparin and saline (a medical-grade salt solution).
The catheter is then connected to the machine and the machine is set up or “primed” for the procedure. The machine considers your height and weight to estimate your total body volume (TBV) and effective plasma volume (the quantity of plasma in your body, which can be calculated using your TBV and hematocrit – the proportion of your blood that is made up of red blood cells).
The medical team then decides what type of replacement fluid (usually a mix of saline, albumin or plasma) to use and the volume needed for your body size (typically around 40-60 mL/kg). Once determined, this information is entered into the machine which then calculates the speed of the centrifuge needed to separate your plasma from your red blood cells.
The machine then begins the actual plasmapheresis. It separates your plasma from your red blood cells and discards the plasma. Your red blood cells are mixed with the replacement fluid and returned to your body.
To finish up, the machine’s tubes are cleaned with the same heparin-saline mixture and any remaining replacement fluid is slowly infused into your body. Blood samples for fibrinogen and calcium are taken again to make sure your levels are okay post-procedure. The lumens (the channels inside your central venous catheter) are also cleaned out with the same heparin-salt solution.
Possible Complications of Plasmapheresis
The plasma exchange procedure, or swapping out the liquid part of the blood, can sometimes have complications, either during or after the process.
* One possibility is hypocalcemia or hypomagnesemia, which means a low level of calcium or magnesium in your body. This often happens because of the use of citrate, a substance that stops blood from clotting in the machine. Doctors can handle this by adding more calcium and magnesium through an injection into the vein.
* Hypothermia, or becoming too cold, is another potential issue.
* Transfusion reactions, or the body’s response to receiving foreign substances, might also happen. If you’re having a reaction during the procedure, doctors might give you medications like pheniramine, hydrocortisone/dexamethasone, or epinephrine to help.
* The procedure might also affect the balance of fluid and electrolytes, or essential minerals, in your body.
* Bleeding disorders could occur due to a decrease in substances that clot the blood, specifically fibrinogen and platelets.
* In some cases, low blood pressure or hypotension might happen.
* You might also experience flushing, a sudden reddening of the skin.
* Finally, you might have gastric symptoms, like feeling sick or actually throwing up. This could be related to the medications or the procedure.
What Else Should I Know About Plasmapheresis?
Plasmapheresis, a medical procedure that can filter the blood, is a helpful treatment option for a variety of sudden and long-term illnesses. Beyond just treating diseases, it can also be used to prepare patients for surgeries or other procedures, and even help speed up recovery afterwards and reduce the time a patient needs to be on a ventilator.
This process usually carries a minimal risk of side effects; the most common of these is temporary low blood pressure (hypotension) and the symptoms related to that, such as dizziness or lightheadedness.
Extensive studies have been carried out by the American Society for Apheresis on plasmapheresis as a treatment strategy. They continually update a comprehensive guideline for this treatment, based on the latest scientific evidence, to help doctors provide the best possible care for their patients. Using this resource helps to standardize the way patients are treated and encourages new and innovative approaches.