Introduction to Apheresis

By Kelli Rosenthal, MS, RN, BC, CRNI, ANP, APRN, BC

Apheresis consists of removing whole blood from a patient or donor, separating it into its different components by running it through an apheresis machine that is essentially a centrifuge, and reinfusing the remainder after drawing off the desired component. More than a quarter of a million patients undergo apheresis each year for donation (i.e., plasmapheresis, where a donor donates plasma); for the treatment of certain neurological, immunologic, hematologic and oncologic disorders; or for harvesting the small number of circulating bone marrow stem cells found among white blood cells for stem cell transplantation.

When therapeutic apheresis is performed, surgically placed multi-lumen apheresis catheters are most commonly placed in the patient’s internal jugular or subclavian veins, as therapeutic apheresis will usually require repetitive treatment. Apheresis catheters are large-bore, dual- or triple-lumen tunneled catheters. Brand names frequently used in the United States are Perm Cath^®, Tesio^®, and Quinton^®. Catheter tips are then advanced into the central vasculature (most commonly the lower 1/3 of the Superior Vena Cava, near the junction of the right atrium) where blood flow around the catheter tip is most rapid with the least resistance to flow. In donor apheresis, donors will generally have two large bore peripheral IV catheters placed, because there is no need to maintain vascular access after donation.

Permanent apheresis catheters, which are inserted similarly to other central venous access devices (CVADs), are used for both aspiration of blood from the body and its reinfusion after selected cellular components are removed from it by the apheresis machine. Because it’s crucial to both rapidly aspirate and return blood quickly (200 – 300 ml/min.), these CVADs have larger and more rigid lumens than CVADs intended strictly for infusion purposes. Thus, maintaining apheresis catheters is generally similar to maintaining other CVADs, but there are some differences.

In an inpatient setting, the majority of care of apheresis catheters will be done by the apheresis nurses. Since it may be several days or even weeks between therapeutic apheresis procedures, you may need to provide some routine care for these catheters, as well as guarding against complications, such as occlusion, air embolism, thrombosis, and infection. Things to watch for when caring for a patient with an apheresis catheter include assuring that:

You may also be asked to flush the catheter between apheresis procedures and re-lock it with heparin to maintain patency and freedom from thromboses within the lumen. Because of their large diameters to accommodate the flow rates necessary for apheresis, flushing volumes will be greater than other for tunneled, implanted catheters. They are usually maintained with higher heparin concentrations, since greater care must be taken to avoid the development of intraluminal thromboses. Heparin volumes and concentrations vary, but many manufacturers’ instructions recommend the use of 1000 U/ml. heparin flush solutions. Review the policy for apheresis catheter care in your institution to determine what concentration and volume of flush solutions should be used. Specific flush and locking concentrations and volumes must be documented in the physician’s orders.

Because of the risk of complications like heparin-induced thrombocytopenia and systemic anticoagulation, heparin locking solutions are withdrawn from the catheter lumen prior to flushing and relocking. A small-bore syringe (usually 5 ml.) is used for this purpose. Smaller syringes exert less pressure on the walls of the catheter during aspiration, and are less likely to cause the catheter walls to collapse during this procedure.

The general procedure for flushing an apheresis catheter is:

Frequency of locking procedures varies from manufacturer to manufacturer, with most apheresis catheters flushed and relocked at least every 72 hours. Follow your institutional policy for scheduling apheresis catheter care.

Apheresis catheters that will no longer used for apheresis procedures may be left in place to offer easy access for laboratory sampling and infusion administration. If this is the case with your patient’s apheresis catheter, it will usually be maintained and flushed like any other tunneled CVAD. Refer to your institutional policies for tunneled CVAD maintenance. Apheresis catheters should not be used for routine infusions or laboratory sampling without physician orders.

Apheresis catheters are usually dressed similarly to other tunneled CVADs. Some catheter materials may be damaged by prolonged exposure to alcohol, tincture of iodine, and ointments. Be aware of any restrictions on which prepping solutions are right for the brand of catheter in use in your institution, but in general, follow strict sterile technique for dressing change procedures, including masks for both nurse and patient throughout the procedure. Transparent semipermeable membrane (TSM) dressings may be preferable to tape and gauze dressings, as they allow site visualization and may be changed less frequently than tape and gauze dressings. TSM dressings must be changed whenever they are no longer clean, dry, or adherent on all sides; at a minimum of once every seven days. Tape and gauze dressings (including if gauze is used in conjunction with a TSM dressing) must be changed at a minimum of every 48 hours, per recommendation of the Centers for Disease Control and Prevention and Infusion Nursing Standards of Practice.

All catheter care must be performed using standard precautions, according to the policies of your institution. With these tips, you can safely care for apheresis catheters like a pro. To learn more about apheresis, visit the website for the American Society for Apheresis.

References

American Association of Blood Banks. Standards for Blood Banks and Transfusion Services, 19th ed. Arlington, VA, 1999.

Infusion Nurses Society: "Intravenous Nursing Standards of Practice," Journal of Infusion Nursing. Vol. 29, No. 1(S), Jan./Feb. 2006.

CDC. Guidelines for the prevention of intravascular catheter-related bloodstream infections. MMWR 2002;51:1-29.