Plasmapheresis- Techniques, Types, Complications And Indications

Introduction

Plasmapheresis means the pheresis of the blood is done and plasma is removed. Blood contains- 55% plasma and 45% cells (RBC). Plasma has water, plasma proteins (albumin, globulin, and immunoglobulin), coagulation factors and cytokines. Removal of large molecular weight substances from the plasma. It can be pathogenic antibodies, cryoglobulins, lipoproteins. Most common renal indication - TTP, HUS→ TMA (thrombotic microangiopathy).

Techniques

Two types of techniques- Centrifugal cell separation and Hollow fiber membrane plasma filtration.

1. Centrifugal Cell Separation Technique

Blood from the patient is taken into port, anticoagulant is added (mostly citrate). Blood goes to the centrifugal cell separation machine. Cells go peripherally and plasma remains in the center. Plasma goes into the plasma collector. Cells are sent back to the patient's body and replacement fluid is given.

2. Hollow Fiber Membrane Plasma Filtration

This technique is used in the dialysis machine. Blood drawn from the patient mixed with anticoagulant (heparin). Blood passed through a hollow fiber plasma filter. Plasma is filtered off and plasma is collected and discarded. Cells along with colloid replacement forms new blood. New blood is given back to the patient's body.

Difference Between Techniques

Replacement Fluid

• Removal of plasma- 50 ml/kg/body weight. Plasma volume is replaced with crystalloid or Human albumin/colloid and FFP (Fresh Frozen Plasma). Crystalloid - normal saline, Hypoproteinemia and hypotension occur if normal saline alone is used as replacement fluid.
• Colloid – albumin. Depletion coagulopathy occurs if albumin alone is used as replacement fluid. Can be used in all exchanges except TMA.
• Fresh Frozen Plasma- To replenish coagulation factors fresh frozen plasma is given, given at the end of the cycle. To be used when bleeding risk is high. Each session depletes- 60% of immunoglobulins. 5 sessions deplete 90% of immunoglobulins. Always plasmapheresis must be combined with immunosuppression to control disease progression.
• Plasma volume= total blood volume × (1-hematocrit). Total blood volume is 75% of body weight in males and 65% of body weight in female. Plasma to be removed= plasma volume/body weight.

Also Read: PSORIATIC AND REACTIVE ARTHRITIS

Other types of Plasmapheresis

Double filtration Plasmapheresis 

Double filtration plasmapheresis, membrane filtration to separate cells from plasma, separation of cells from plasma. Second plasmapheresis to remove solutes from plasma. Most solutes are removed and plasma is returned along with replacement

Cryofiltration

Filtrate exposed to 4 degrees C, leads to precipitation of cryoglobulins. Precipitate is removed from the blood. Blood sent back to the patient's body

Protein A Immunoadsorption

Adsorptive columns remove only immunoglobulins. Filter can be used 30 times for one patient, so cost-effective.

Complications

Complications are more in the membrane technique than in the centrifugation technique. Citrate in Fresh Frozen Plasma).  and centrifugation can cause Hypocalcaemia (as citrate binds to calcium in the blood). Metabolic alkalosis (citrate metabolized to bicarbonate), Coagulopathy, Prothrombin time increases by 30%. APTT increases by 100%. Fresh Frozen Plasma).  replenishment is done if there is an increased risk of bleeding. Dilutional hypokalemia. Infection- sepsis secondary to AV access. Removal of immunoglobulins. Hypotension- Extracorporeal circuits, Sepsis, Only saline is used as replacement fluid.

Mechanism of action

Clears antibodies and cytokines. IgM removed effectively because it is present wholly intravascular. Rebound synthesis counteracted by immunosuppression.

Investigations were undertaken before Plasmapheresis

Indications for Plasmapheresis

In Anti-GBM disease, Fresh Frozen Plasma is used as replacement fluid if there is a risk of bleeding. In HUS/TTP (Thrombotic Thrombocytopenic Purpura), increased platelet count is indicated as a positive outcome of plasmapheresis.

Strong indications for Plasmapheresis

Some evidence for performing plasmapheresis

Circulating factor called SUPAR acts on podocytes and destabilizes them and leading to FSGS. Plasmapheresis removes SUPAR, thus FSGS is avoided. TMA has two components- Thrombotic Thrombocytopenic Purpura and HUS. Eculizumab is the preferred treatment in HUS. In Thrombotic Thrombocytopenic Purpura plasmapheresis is the only option.

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Hope you found this blog helpful for your NEET SS Nephrology Preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.