Transfusion medicine
Therapeutic apheresis
Leukocytapheresis
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Last staff update: 4 October 2022 (update in progress)
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PubMed Search: Leukocytapheresis therapeutic leukapheresis [title]
Table of Contents
Definition / general | Vascular access | Indications | Volume exchanged and technical details | Adverse events | Treatment | Additional referencesCite this page: Pham HP, Booth G Leukocytapheresis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/transfusionmedleukocytapheresis.html. Accessed December 1st, 2022.
Definition / general
- In this topic, we only discuss therapeutic leukapheresis as a treatment for leukostasis
- Hyperleukocytosis:
- Generally defined as white blood cell (WBC) count or blast count > 100,000/µL
- Usually due to acute or chronic leukemia
- Can lead to hyperviscosity / leukostasis syndrome
- Hyperviscosity / leukostasis symptoms:
- Cerebrovascular insufficiency (altered mentation, TIA, stroke)
- Pulmonary complications (dyspnea, hypoxemia)
- Disseminated intravascular coagulopathy
- Usually associated with:
- AML with WBC > 100,000/µL
- Incidence of AML with WBC > 100,000/µL is 12 - 18% in children and 5 - 18% in adults
- Can happen in patients with blast count < 50,000/µL if they have AML M4 or M5 variant
- ALL with WBC > 400,000/µL (< 3% of ALL patients)
- AML with WBC > 100,000/µL
Vascular access
- Usually performed emergently using femoral apheresis or a dialysis catheter, which do not require radiographic confirmation
- Central venous catheter, which requires radiographic confirmation, can be used in nonemergent situations
Indications
- For therapeutic procedure, the American Society for Apheresis (ASFA) delineates leukapheresis based on the acuity of the clinical presentation
- Symptomatic leukostasis - ASFA category I
- Prophylaxis - ASFA category III
Volume exchanged and technical details
- 1.5 - 2 blood volume is usually performed for therapeutic leukapheresis procedure
- This usually reduces the WBC count by 30 - 60% although predicting the postprocedural WBC count is difficult due to mobilization of leukocytes from extramedullary sites
- 6% hydroxyethyl starch (HES):
- May be used to enhance separation of WBC from other blood components
- Recommended to remove mature cells such as in CML
- Is a volume expander excreted via urine so must evaluate patients for cardiovascular and renal status prior to use
- For therapeutic procedures, replacement fluid is usually not indicated - usually less than 15% of the total blood volume is removed
- Normal saline can be used to maintain blood pressure throughout the procedure
- For pediatric patients or in patients where the volume removal is > 15% of the total blood volume, 5% albumin replacement can be used for fluid replacement
- RBC units may be used with caution to prime the apheresis machine in in patients with severe anemia but undiluted RBCs can increase the blood viscosity
Adverse events
- Leukapheresis is an apheresis procedure, with its typical complications
- Also complications from the underlying leukemia, hypotension, citrate related toxicity, bleeding and infection
Treatment
- Therapeutic leukapheresis is not curative; WBC reduction is short lived and only a bridging therapy to definitive treatments such as chemotherapy
- Symptomatic leukostasis treatment:
- Can be performed daily or as needed to treat leukemic patients with high WBC count with hyperviscosity syndrome
- WBC count has a poor correlation with clinical symptoms; thus defining a WBC or blast goal is not optimal
- Treatment should be continued until symptoms are resolved and WBC or blast count < 400,000/µL in ALL patients or < 50,000 - 100,000/µL in AML patients
- Chemotherapy should be given concurrently with leukapheresis to prevent the rapid reaccumulation of WBC and blasts
- Leukapheresis might decrease early death in leukemic patients with hyperviscosity but does not appear to increase overall survival
- Can be performed daily or as needed to treat leukemic patients with high WBC count with hyperviscosity syndrome
- For prophylaxis:
- Leukapheresis is not superior to aggressive chemotherapy and supportive care
- Might be useful in children with ALL and WBC > 400,000/µL (50% of these patients develop pulmonary complication from leukostasis)
- Goal:
- ALL: WBC or blast count < 400,000/µL
- AML: WBC or blast count < 100,000/µL
