Therapeutic Apheresis
When is leukapheresis done w acute leukemia? With what particular kind of leukemia is this done at a lower blast count and why?
blast count > 100,000. Do with lower blast count for promyelocytic leukemia because of association with DIC
Isotonic solution definition
has the same osmotic properties as plasma
For what conditions is apheresis an ongoing need? (over years)
high cholesterol states Refsum's disease
Adverse events associated with therapeutic apheresis
hypocalcemia due to citrate hemodynamic challenges resulting from fluid shifts depletion of cellular and plasma protein elements venous access problems (infection, pneumothorax)
Risks associated with central line use w apheresis
infection, bleeding, bruising, kinking, clotting, pheumothorax, femoral lines = nonambulatory pt. Subclavian and intrajugular catheters require chest X-ray to confirm placement. = single greatest risk of apheresis.
Why is LDL removal by adsorption better than plasmapheresis? Course of treatment?
leaves behind "good" proteins including the HDL. Requires adsorption every 1-3 weeks for lifetime. Only real cure = liver transplantation
Heemolytic Uremic Syndrome
look like TTP but are not the result of deficient ADAMTS-13. See with more kidney damage than TTP presents with and symptoms usually the result of infection. Plasmapheresis less effective.
Extracorporeal Blood Adsorption goal =
remove the offending component of plasma and leave behind the other plasma proteins, eliminating the need for colloid replacement and removing depletion of coag factors.
End point for plasmapheresis in TTP
sustained normalization of platelet count and normalization of LDH levels
What measurement may be more useful than extracorporeal volume in determining whether or not to prime tubing for a apheresis procedure?
the patient's intra-procedural Hct.
Why are IgM mediated diseases more effectively treated w apheresis than IgG mediated diseases?
IgM = w/in intravascular compartment (76%). Too big to cross into extravascular area. IgG = only 45% w/in intravascular compartment. Most in extravascular space: after exchange, re-equilibrates between intravascular and extravascular compartments.
Intra-procedure hematocrit calculation:
(initial RBC vol - extracorporeal RBC vol) divided by Total Blood volume X 100
Replacement Fluids
5% albumin prepared in normal saline 25% human albumin Dextran and HES (hydroxylene starch) = syntetic colloid good for Jehovah's Witness FFP (replacement of V and VIII)
Central line blood flow requirement
60 - 150 ml/min. Most double lumen IV lines operate under positive pressure; these can collapse under the negative pressures of the draw phase of apheresis
A 1 plasma volume exchange is expected to remove what % of target plasma substance?
63.2%
A 1.5 plasma volume exchange is expected to remove what % of target plasma substance?
77.7%
A 2.0 plasma volume exchange is expected to remove what % of target plasma substance?
86.5%
Indications for RBC exchange in sickle cell patients
Acute Chest Syndrome Refractory pain crisis priapism (erect penis / clitoris) prevention of recurrent stroke prevention of pregnancy complications OR
Therapeutic apheresis vs dialysis:
Apheresis only treats intravascular volume while dialysis can also treat the extravascular volume. Apheresis is thus better at removing larger proteins while dialysis is better at removing smaller proteins. Depends upon the dialysis membrane used and the rate of equilibrium between intravascular and extravascular spaces. Dialysis leaves behind the plasma proteins (clotting factors) and does not require colloid replacement. If target molecule is protein bound, apheresis is required for removal.
TTP: description of disease process
Category I microangiopathic hemolytic anemia, thrombocytopenia, neurologic symptoms Release of extra-large von Willebrand multimers from endothelium normally broken down by ADAMTS-13 but this is lacking or neutralized by presence of an auto-Ab against ADAMTS-13. Extra-large multimers are more active and cause platelet aggregation causing thrombocytopenia and micro thrombi leading to blood flow obstruction, end orgaan damage and mechanical destruction of RBC's (causing the microangiopathic hemolytic anemia). Untreated mortality > 80%
American Society for Apheresis Categories
Category I = apheresis is primary treatment Category II = apheresis is supportive or adjunct therapy Category III = some rationale present for apheresis use Category IV = apheresis ineffective
Indications for photopheresis
Cutaneous t-cell lymphoma (only FDA approved use) Sezary syndrome, mycosis fungoides GVHD solid organ allograft rejection
Photopheresis, AKA:
Extracorporeal Photochemotherapy
What plasma protein is most effected by plasma apheresis / exchange?
Fibrinogen = 80% intravascular
Anticoagulant used in LDL Adsorption and why?
Heparin used because membrane filtration instead of centrifugation.
RBC exchange uses beyond sickle cell anemia
Severe malaria or Babesia parasitemia (>5-20% w symptoms) Processing of ABO incompatible bone marrow (RBC depletion only)
Interaction between ACE inhibitors and apheresis
The presence of ACE inhibitors in circulation at apheresis can cause an allergic-type reaction. Discontinue ACE inhibotors for 24-48 hours prior to doing apheresis.
Steps in LDL Cholesterol Removal by adsorption
1. Membrane filtration results in plasma seperation 2. Plasma run through columns containing dextran sulfate; LDL adsorbs onto column surfaces. 2 columns used: when 1 is full, instrument switches to 2nd column 3. Full column regenerated by eluting off the adsorbed LDL into a waste bag w high concentration NaCl. 4. LDL poor Plasma recombined with cellular components and reinfused to patient.
Emergency Apheresis appropriate for:
1. risk of imminent bleeding (Goodpasture/Pulmonary renal syndrome) 2. risk of stroke (hyperleukocytosis, thrombocytosis) 3. hypoxemia (sickle cell acute chest syndrome) 4. severe hemolysis (malaria/Babesia parasitemia)
Because of diminishing return on volume exchanges, most plasma exchanges do not exceed:
1.5 plasma volumes
What is the maximum donor extracorporeal volume (%BV) during an apheresis procedure?
15%
How does photopheresis work?
Patient mononuclear cells separated and inclubated with a psoralen compound. Then exposed to UV light 320 - 400 nm Then reinfused to patient. Prevents cell replication Thought to provide an immunomodulatory effect; turning on immune system
What can you do to minimize the chance of exceeding the maximum extracorporeal volume when apheresing a small volume patient (child)?
Prime the apheresis machines tubing with RBC's prior to beginning.
Who can perform apheresis procedures?
RN MD another health care degree (MT) with certification as a Hemapheresis Practitioner (HP) by ASCP.
Conditions requiring lifetime ongoing apheresis
Refsum disease (neurological disease: increase in phytanic acid) Homozygous hypercholesterolemia RBC exchange for sickle cell anemia
Treatment of TTP
Replacement w FFP or cryopoor plasma. Replaces the missing ADAMTS-13 and removes ultra-large vWF.
Hyperviscosity Syndromes
Risk of stroke or lung damage from increased protein load. See w: Multiple Myeloma, Cryoglobulinemia, Waldenstrom macroglobulinemia. Protein load = result of Ab formation but the need for plasmapheresis has to do with the excessive viscosity that results, not the direct cause of the antibodies themselves.
Cytoreduction Apheresis: What and why? Symptoms?
What = Leukapheresis (WBC removal) + Plateletpheresis Why = reduce hyper viscosity. Watch for decreased oxygenation, mental status changes.
ACE Inhibitors
angiotension-converting enzymes used for blood pressure control and heart failure Captopril Enalapril Lisinopril
Conditions most commonly treated w therapeutic apheresis
antibody mediated diseases
Conditions requiring ongoing treatment schedules (in the weeks or months):
antibody mediated diseases (Guillain Barre, myasthenia gravis) diseases treated by photopheresis TTP
Symptoms of citrate effect:
circumoral paresthesias (tingling around mouth) cramping of hands, feet, jaw chest pain or vibration nausea
How does extracorporeal blood adsorption work?
column containing antibodies to the offending substance or containing another substance that the offending substance will adhere to selectively pulls that out of circulation. Example: dextran sulfate column to remove LDL.
Theory behind use of cyropoor plasma for TTP
cryopoor plasma = deficient in vWF so thought to not "feed the fire" by adding more vWF that will cause platelet aggregation but this has not been proven to be true.
Benefits of RBC exchange over simple transfusion
maintenence of baseline Hct when increased RBC mass is not desired. (>30-33% for sickle cell pts leads to hyper viscosity) removal of abnormal RBC's to minimize iron deposition from cell destruction rapid replacement of abnormal cells with normal cells
What processes within hemapheresis must be done by an RN?
manipulation of a central venous line administration of medications
Disadvantages of using heparin as anticoagulant for therapeutic apheresis
not cleared by the body as quickly (1/2 life = 90 minutes) causes system-wide anticoagulation risk of HIT in occasional patients
Mechanism for Familial Homozygous Hypercholesterolemia
people lack receptors on their liver for LDL cholesterol therefore it backs up in system causing coronary artery blockage by teens. Meds don't help because the problem is that the liver cannot recognize and remove the LDL.
When is plateletpheresis done?
plt count > 1,000,000
When can apheresis be a curative procedure?
poisoning
Conditions only needing 1-2 exchange procedures:
poisoning or overdose RBC exchange for an urgent situation AML w blast count >100,000
Goal of apheresis used with concurrent steroid treatment, immunosuppressive treatment, immunoglobulin concentrate administration:
reduce load of antibody or WBC until other treatments can take effect.
Symptoms of citrate toxicity:
vomiting severe chest discomfort widespread cramping tetany