Therapeutic apheresis (TA) is an extracorporeal procedure for various diseases as primary treatment or as an adjunct therapy in which large quantities of plasma are removed and replaced by FFP (Fresh Frozen Plasma), albumin and saline.
Requirement of replacement fluid during therapeutic apheresis is to prevent hemodynamic instability due to volume depletion and decreased oncotic pressure with removal of plasma.
Replacement fluids used during plasma exchange include FFP, albumin (5 percent), combination of albumin and normal saline or normal saline.
Deciding which replacement product to be used is based on the underlying condition and the risks and benefits associated with each replacement product. In general, albumin is the most common replacement product because of its low side-effect profile and broader availability, on the other hand normal saline is used for hyperviscosity and some combination of albumin and normal saline if cost is a consideration.
1. FFP(Fresh Frozen Plasma)
Fresh Frozen Plasma replaces coagulation factors, other beneficial factors and immunoglobulins proteins removed by apheresis so that significant depletion of coagulation factors or immunoglobulins does not occur with multiple or consecutive daily procedures.
Administering plasma as a replacement fluid at the beginning of a TA results in exposure of the patient to blood products without benefit as the majority will be removed.
Advantages and Specific Indications
- TTP/HUS
TA works in TTP both by removing von Willebrand factor (VWF) multimers and autoantibodies against ADAMTS13. FFP as a replacement fluid has a therapeutic role by providing ADAMTS13 and because in the presence of thrombocytopenia with TTP/HUS, it helps to decrease risk of bleeding.
- Pre-existing defects in haemostasis
To treat coagulation factor deficiencies, and to prevent dilutional coagulopathy in patients with active bleeding or who are pre or post-surgery.
- Serum fibrinogen <125 mg%
Disadvantage
- Hepatitis B Virus (HBV) & Hepatitis C Virus (HCV) transmission
There is a small but measurable incidence of transmission via FFP of hepatitis B (0.0005% per unit), hepatitis C (0.03% per unit), and HIV (0.0004% per unit). Although these infectious risks are now much smaller with pre-donation and post-donation testing, it should be kept in mind that with each plasmapheresis treatment where 1.5 to 3 L of plasma is replaced with FFP, and for that 7–15 units of plasma coming from an equal number of donors are required. Detergent-treated plasma is available from a number of manufacturers.
- Allergic reactions
Minimal reactions -urticaria, paresthesias, nausea, dizziness, and leg cramps. Moderate reactions-hypotension, chest pain, and ventricular ectopy.
All are usually brief and without sequels.
Severe reactions- noncardiogenic pulmonary edema caused by transfusion of leukoagglutinins occur in <3% of treatments and are mainly related to anaphylactoid reactions associated with FFP administration. Another cause of anaphylaxis is infusion of IgA-containing FFP to a patient with selective IgA deficiency.
The patients getting FFP should be premedicated with intravenous diphenhydramine, and intravenous steroid and subcutaneous epinephrine should be kept ready at the bedside.
- Citrate load
FFP contains citrate, and use of FFP increases the risk of citrate-mediated low ionized calcium reactions.
- Requirement of ABO compatibility
Because FFP may contain appreciable amounts of anti-A and anti-B isoagglutinins, ABO compatibility between donor and recipient is necessary.
- Monitoring problem
FFP as the replacement fluid makes measurement of levels of IgG and other immunoglobulins difficult. Also, FFP may replace some factors removed during plasmapheresis that could participate in the inflammatory process.
2. ALBUMIN
Albumin as replacement fluid is slightly hyper oncotic compared with FFP and may therefore expand intravascular volume.
Specific Indications
Anti-GBM disease
Cryoglolulinemia
Post-transplant antibody mediated rejection
Advantage
No risk of Hepatitis B Virus (HBV) & Hepatitis C Virus (HCV) transmission
No concern of ABO Blood Group matching
Depletion of inflammatory mediators
It markedly lowered risks of pathogen transmission and anaphylactic reactions.
No disease transmission and transfusion reactions related to FFP transfusion (eg, transfusion-related acute lung injury).
Can be preserved at room temperature.
Disadvantage
The main disadvantage of albumin is its expense relative to plasma.
No coagulation factors-In general, because plasmapheresis also depletes coagulation factors, replacement by albumin and crystalloid alone may result in no replacement of these factors like FFP and place the patient at increased risk of bleeding. This coagulation factors depletion occurs after one or two plasma exchanges, particularly if they are performed daily, because the half-life for most clotting factors is approximately 24–36 hours.
Net loss of immunoglobulins can occur.
We prefer 5 percent albumin or albumin-normal saline combination as the replacement fluid, rather than normal saline alone. Albumin 20 percent should not be used unless it is diluted to 5 percent concentration by normal saline.
Preparations
- Five percent albumin
5% albumin is isosmotic, and its oncotic pressure is close to plasma. The most commonly used replacement fluid is 20% human albumin in physiologic saline. When preparing 5% albumin solution from 20% human albumin, 0.9% saline must be used as the diluent(100ml 20% albumin to be diluted in 400 ml 0.9% NS; use of water for injections as a diluent has resulted in severe hyponatremia and haemolysis.
- Albumin-saline combination
When colloid (albumin) and crystalloid(normal saline) solutions are to be used in combination, the amount of colloid should not be less than 50 percent of the total infused. Many centres use a combination of crystalloids and colloids, such as normal saline for 25%–30% of the exchange volume at the beginning followed by 5% albumin for the rest of the procedure when exchange volume is equal to one plasma volume and in the absence of hypoalbuminemia. This method would result in a final concentration of albumin in the vascular space of approximately 3.5 g/dL (35 g/L), sufficient to maintain oncotic pressure and avoid hypotension. The approach should not be used in patients with hyperviscosity, patients with neurologic diseases, and patients with other causes of hypotension.
When this is done, the albumin and saline are alternated, with the majority of the albumin being given at the end of the procedure to avoid hypovolemia from redistribution of the crystalloid. It should be noted that the use of albumin and saline has been associated with a greater frequency of hypovolemic reactions compared with using albumin alone.
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Normal saline
Normal saline alone provides insufficient oncotic pressure and tends to lead to significant edema and/or hypotension. Thus, 5 percent albumin or an albumin-normal saline combination is preferable over saline except when albumin is not available or for complications such as allergies occurring with albumin or plasma or hyperviscosity.
Dr. Jigar Shrimali
About him:
Dr. Jigar Shrimali has completed his DM (Nephrology – Gold Medalist) from I.K.D.R.C. – ITS, BJ Medical College, Ahmedabad, Gujarat. He is currently working as a consultant Nephrologist and Transplant Physician in Renus kidney hospital, Ahmedabad, Nadiad, Gujarat. He is also keen on academic programs for which he has conducted several workshops for resident doctors, physicians and dialysis technicians covering 40+ topics on Dialysis Therapies alone. He is author of TEXTBOOK OF DIALYSIS THERAPY.
