Apheresis Matthew L. Paden, MD Assistant Professor of Pediatric Critical Care Director, Pediatric...

Apheresis

Matthew L. Paden, MDAssistant Professor of Pediatric Critical CareDirector, Pediatric ECMO

Children’s Healthcare of Atlanta | Emory University

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– Leukopheresis– Erythrocytopheresis– Plasmapheresis– Plateletpheresis

• Common methods include– Centrifugation– Membrane filtration

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Apheresis Methods

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Separation by centrifugation

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• 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


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


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

trials14

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• Description of the disease• Current management and treatment• Rationale for therapeutic apheresis


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– 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 24


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 26


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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Apheresis Matthew L. Paden, MD Assistant Professor of Pediatric Critical Care Director, Pediatric...

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