Transfusion medicine
Therapeutic apheresis
Plateletpheresis
Last author update: 1 March 2014
Last staff update: 24 April 2023 (update in progress)
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Table of Contents
Definition / general | Epidemiology | Vascular access | Indications | Volume exchanged and technical details | Adverse events | Treatment | Additional referencesCite this page: Pham HP, Booth G Plateletpheresis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/transfusionmedplateletpheresis.html. Accessed June 9th, 2023.
Definition / general
- Plateletpheresis (or thrombocytapheresis):
- Process of removing platelets using an automated machine
- Currently available instrumentations for plateletpheresis procedures are COBE Spectra and Trima Accel from Terumo and Fenwal Amicus from Fresenius Kabi
- Can be used both as a platelet collection procedure from a donor and as a therapeutic modality to quickly decrease the platelet count in a patient with thrombocytosis
- Process of removing platelets using an automated machine
- Apheresis platelets:
- Collection by apheresis machine
- Minimum platelet yield in an apheresis platelet product is 3.0 × 1011 platelets per unit
- Instrument: Fenwal Amicus (from Fresenius Kabi)
- Only for donor collection (NOT for therapeutic procedure)
- Can be single needle or double needle procedure
- Can collect:
- Single or double apheresis platelet units
- One apheresis platelet unit and one plasma unit
- Single or double apheresis platelet unit and one red blood cell unit
- Instrument: Trima Accel (from Terumo Medical Corporation)
- Only for donor collection (NOT for therapeutic procedure)
- Single needle procedure
- Can collect:
- Single or double red blood cell units
- Single, double or triple apheresis platelet units (depending on donor size, hematocrit and platelet count)
- Instrument: COBE Spectra (from Terumo Medical Corporation)
- Can use for both donor collection as well as for patient for therapeutic plateletpheresis
- Can be single needle or double needle procedure
- Can collect single or double apheresis platelet units
- Thrombocytosis:
- Usually defined as platelet count > 450,000 - 500,000/µL
- Can be caused by an underlying hematologic malignancy (primary thrombocytosis) or by a reactive process (secondary thrombocytosis)
- Primary thrombocytosis:
- Due to a myeloproliferative disorder (MPD), including polycythemia vera, essential thrombocythemia and chronic myelogenous leukemia
- Shorter platelet survival
- Increase in markers of platelet activation, such as platelet factor 4, thrombomodulin and beta thromboglobulin
- May experience hemorrhage or thrombosis
- Hemorrhage risk is greatest when platelet count > 1,500,000/µL due to acquired von Willebrand disease
- Thrombosis usually occurs when platelet count > 600,000/µL but risk does not correlate well with platelet count
- Secondary thrombocytosis:
- More common, accounting for 80 - 90% of cases
- Platelet function is relatively normal
- Carries significantly smaller risk of hemorrhage or thrombosis
Epidemiology
- Incidence for essential thrombocythemia is 1.5 cases per million persons/year
- Incidence for polycythemia vera is 1.4 cases per million persons/year
Vascular access
- For patients undergoing plateletpheresis as therapeutic procedures, a central venous catheter might be used
- For emergent procedure, a femoral apheresis or dialysis catheter should be used because it does not require radiographic confirmation
- For donors undergoing apheresis platelet or multiple component collection, peripheral access is preferred due the risk of putting in a central venous catheter
- The minimal allogeneic platelet count is 150,000/µL
Indications
- For therapeutic procedure, the American Society for Apheresis (ASFA) delineates plateletpheresis based on the acuity of the clinical presentation
- Symptomatic thrombocytosis: ASFA category II
- Prophylactic or secondary thrombocystosis: ASFA category III
Volume exchanged and technical details
- 1.5 to 2 blood volumes is usually performed for therapeutic plateletpheresis procedure
- This usually reduces the platelet count by 30 - 60%
- For therapeutic procedures, replacement fluid is usually not indicated because 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, if the volume removal is > 15% of the total blood volume, 5% albumin replacement can be used for fluid replacement
- Citrate should be used as the only anticoagulant for the procedure because heparin might cause platelet clumping in the circuit
- The anticoagulant to whole blood ratio should be between 1:6 and 1:12
Adverse events
- Plateletpheresis is an apheresis procedure
- Adverse events include but are not limited to hypotension, citrate related toxicity, bleeding and infection
Treatment
- For primary thrombocytosis, therapeutic plateletpheresis is not a curative procedure - the reduction of platelets achieved by this procedure is short lived
- It is only a bridging therapy in addition to other definite treatments, such as chemotherapy
- For symptomatic treatment:
- Can be performed daily or as needed to treat thrombosis or hemorrhage in patient with myeloproliferative disorder and thrombocytosis
- Goal is to decrease platelet count to < 450,000 - 500,000/µL until the effect of chemotherapy takes place
- Hydroxyurea should be given with plateletpheresis to prevent the rapid reaccumulation of platelets
- Can be performed daily or as needed to treat thrombosis or hemorrhage in patient with myeloproliferative disorder and thrombocytosis
- For prophylaxis treatment:
- Can be used in pregnant or preoperative patients
- Post procedure platelet count should be individualized based on history of thrombotic or hemorrhagic event at specific platelet count
- For symptomatic treatment:
- For secondary thrombocytosis, treatment of the underlying cause is indicated
