Equipment
Plasmapheresis can be accomplished through centrifuge-based platforms such the Cobe Spectra, Fenwal Aurora, and the Fresenius COM.TEC series of devices. Patients require either a double-lumen central venous catheter or two large-bore antecubital peripheral lines.
Plasmapheresis can be performed using a semipermeable membrane–based device in combination with hemodialysis equipment. Central lines, as opposed to peripheral lines, are required for membrane-based plasmapheresis because of their higher flow rates of roughly 100-150 mL/min, as compared with 50-70 mL/min for centrifuge-based equipment.
Two types of membrane-based plasmapheresis technologies exist: hollow fiber and parallel plate. Hollow-fiber dialyzers consist of a bundle of capillaries potted (glued) at both ends into a plastic cylindrical shell. Parallel-plate dialyzers contain layers of stacked membranes with ridges and grooves. Both technologies allow for the separation of plasma from the cellular components of blood based on particle size as well as pressure gradients.
The major advantage of hollow-fiber dialyzers is that they are considered more gentle than parallel-plate technology and are therefore more commonly used in pediatrics. Parallel-plate dialyzers, on the other hand, require less blood volume and therefore less anticoagulant, thereby minimizing the side effects associated with citrate or heparin. Asahi Plasma-Flo is an example of hollow-fiber technology, and Cobe TPE is an example of parallel-plate technology.
An advantage of membrane-based plasmapheresis is that multiple cycles of filtration and ultrafiltration can take place, potentially allowing for the return of beneficial plasma elements while discarding the pathogenic components. [5]
Patient Preparation
Anesthesia
Anesthesia is occasionally used during central line placement in preparation for plasmapheresis if the patient does not already have a central line. However, anesthesia is rarely used during the plasmapheresis session itself. In pediatrics, opioids such as morphine and benzodiazepines such as lorazepam are occasionally used for temporary pain relief and anxiety control, respectively.
Positioning
The patient is placed in the supine position. The head of the bed is flat or elevated to a reverse Trendelenburg position in accordance with the patient's comfort. If an internal jugular line is being used, the patient's neck may have to be repositioned to permit proper flow.
Monitoring & Follow-up
Vital signs are monitored every 15 minutes, particularly for signs of volume depletion (eg, tachycardia and hypotension). Signs and symptoms of hypocalcemia (eg, numbness or tingling of the fingers, nose, or tongue) are also checked carefully. In pediatric patients, symptoms of hypocalcemia can include abdominal pain, nausea, or vomiting.
Long-term monitoring
Delayed transfusion reactions can be seen several days after the transfusion ends, and patients should be alerted to the signs and symptoms so that they can seek medical attention.
Infection related to the use of central venous catheter is a potential complication. Sterile technique can minimize the likelihood of this possibility. Infection related to the use of blood products is another potential complication that should be raised as part of the initial consent.
