Transcript Children`s Healthcare of Atlanta

Apheresis
Matthew L. Paden, MD
Assistant Professor of Pediatric
Critical Care
Director, Pediatric ECMO
Disclosures
• Funded by NIH/FDA for CRRT/ECMO device
development
– Pending grant for pediatric apheresis device
• Much of this talk is stolen from others.
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Objectives
• Review the technique of apheresis
• Discuss common evidence based indications
• Few notes on technical aspects of concomitant
ECMO/Plasma Exchange
– Things I have learned the hard way
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Apheresis – what is it?
• Separation of blood into individual components based
on density or molecular size
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Leukopheresis
Erythrocytopheresis
Plasmapheresis
Plateletpheresis
• Common methods include
– Centrifugation
– Membrane filtration
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Apheresis Methods
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Separation by centrifugation
• Milk separator
• Hand cranked
• Heavy milk goes to
the side of the bowl
• Lighter cream stays
in the middle
• Separate pathways
for each to drain
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Separation by density
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Membrane Filtration
• Semi-porous
membrane
• Appropriate pore
size for what you
are trying to
remove
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The 5 “Whats” of Apheresis
• What am I doing this for?
• What am I replacing with?
• What else am I removing?
• What is my anticoagulation?
• What is my extracorporeal volume?
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What am I doing this for?
• Plasmapheresis / Plasma exchange
– Most common apheresis procedure at our center
• Usually for removal of auto-antibodies (IgG)
– Only about 45% of your IgG is intravascular
– Need for repeated therapies
• One plasma volume (~45 mL/kg) removes about 63%
of intravascular IgG
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What am I doing this for?
• Category I: primary/standard therapy
• Category II: adjunctive therapy
• Category III: last-ditch effort (insufficient evidence to
prove efficacy)
• Category IV: lack of efficacy in controlled trials
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• Description of the disease
• Current management and treatment
• Rationale for therapeutic apheresis
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Common Indications
• Category I
– Thrombotic thrombocytopenic purpura
– Guillian Barre Syndrome
– Wegener’s/Goodpasteur’s (dialysis dependence or
pulmonary hemorrhage at presentation)
– Myasthenic crisis
• Category II
– Devic’s syndrome
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Common Indications
• Category III
– Treatment of cardiac transplant antibody mediated
rejection
– Sepsis with multiple organ failure
– Thyroid storm
• Category IV
– Diarrheal associated HUS
– SLE nephritis
– Schizophrenia
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What am I replacing with?
• Albumin or plasma?
• Depends on indication and patient condition
– Auto-antibody removal – almost always albumin
– Use FFP when you need replacement of factors
• Thrombotic thrombocytopenic purpura
• Liver failure
• Wegener’s granulomatosis with pulmonary hemorrhage
• Complication rate is higher with plasma
– Allergic, infectious, TRALI
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What else am I removing?
•
•
•
•
Coagulation factors ~25-50%
Fibrinogen ~60%
Bilirubin ~45%
Platelets ~30%
• Usually recover in 48 hours in HEALTHY patients
• Drugs – low volume of distribution, small molecular
size
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What is my anticoagulation?
• Citrate
– Alkalosis – less than CRRT, because not continuous therapy
– Symptomatic hypocalcemia
• Serial monitoring of ionized calcium and patient symptoms
• If present, treat.
• Consider reduce citrate infusion rate, adding calcium drip,
STOPPING THE PROCEDURE
– Hypomagesemia
• Some centers measure ionized magnesium levels as well
• Heparin rarely
• None
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What is my extracorporeal volume?
• Be aware of extracorporeal volume
– The disposables are made for adults not kids
– Current devices range from 250-400 mL
– We blood prime if > 12% of TBV is extracorporeal
• Blood prime
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125 mL pRBC
15 mL THAM
25 mL 25% Albumin
300 mg Calcium gluconate
10 mEq NaHCO3
50 units heparin
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Erythrocytopheresis
• Removal/replacement of RBC
• Commonly used for complications of sickle cell disease
– Acute stroke
– Acute chest syndrome
– Prevention of iron overload
• Rare other indications
– Babesiosis / Malaria
– Hereditary hemochromotosis
– Polycythemia vera
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Leukopheresis
• Removal of WBC
• Typically used for acute hematogenous cancers with
evidence of end organ disease
• Thresholds are not well defined in pediatrics
– Range of 200-800 WBC count in textbooks
– Differential range based on disease (AML, ALL, CML)
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Photopheresis
• Remove buffy coat
• Treat with a photoactive compound (psoralens)
• Expose to UVA light and reinfuse into patient
• Most commonly used with GVHD / T cell lymphoma
• Less commonly with
– Cardiac transplant rejection
– Pemphigus
– Nephrogenic systemic fibrosis
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Lipopheresis
• Selective removal of lipoproteins in patients with
familial hypercholesterolemia
– Common to have CAD by teenage years with AMI in 30’s
• Specific column
• Treatment for life or until liver transplant
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Concomitant use with other extracorporeal
therapies
• ECMO
– Circuit is already
anticoagulated with
heparin
– Some devices still
mandate citrate
• 10:1 is usual
blood:citrate ratio
• Can increase to 50:1
• Don’t need a calcium
infusion
– Duration of procedure
can be shortened
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Things I have learned the hard way
• People are scared of this
– Analogies to milk separation,
platelet donation
– Usually an outpatient procedure
• Anaphylaxis kit
– Benadryl, Epinephrine, Steroids
– Calcium
• Need for central oversight
– Plasma exchange for autism?
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