Journal of Clinical Apheresis 7: 154-157 (1992)

Central Venous Apheresis

Catheters for Access

Lori Thompson

Product Manager for Medical Products, Quinton Instrument Company, Seattle

Large bore, dual lumen central venous catheters are quickly becoming the preferred means of vascular access for apheresis. Long recognized for their efficiency in dialysis treatment, the catheters provide the high flow rates and flexible design needed for apheresis treatment [ I ] . Clinical studies also confirm that the catheters have a low incidence of catheter-related infection [ 2 ] . When choosing a catheter for apheresis, the treatment needs of the patient can help determine whether a short-term or long-term catheter is preferable. The following questions should be considered:

How many treatments will the patient have'? What other treatment will the patient be having? Will treatment be completed quickly or will it be long term, occurring intermittently over a period of weeks? Will the patient be going home with the catheter in place? What is the patient's or family's ability to perform catheter care at home?

SHORT-TERM CATHETER

One of the first central venous catheters used for short- term apheresis was the dual lumen Mahurkar catheter, developed by Quinton Instrument Company in asso- ciation with Dr. Sakarham Mahurkar, a nephrologist at Cook County Hospital, Chicago. Made of temperature- sensitive, radiopaque, polyurethane tubing, the Mahurkar remains rigid during insertion, then softens once inside the vein. A cross section of the catheter shows 2 patented D-shaped lumina, the optimal design for high flows within a small outer diameter. The catheter's radiopaque tip is made of soft polyvinyl chloride to reduce the risk of vessel puncture. To maximize the efficiency of the catheter, the 3 inflow holes in the tip are separated from the 2 outflow holes, thus reducing recirculation.

The catheter is attached to a molded hub, which di- vides the external portion of the catheter into 2 exten- sions. Each silicone rubber extension has an adapter made of Ulteme:, a hard resin that can withstand temper- ature changes and repeated exposure to cold sterilizing agents. A rotatable suture wing, used to anchor the cath- eter to the patient, is incorporated into the hub. The

0 1992 Wiley-Liss, Inc.

transparent wing is constructed to angle away from the exit site so that any inflammation caused by sutures will not affect the site.

All sizes of Mahurkar catheters are available with op- tional curved extensions, designed to facilitate patient comfort and catheter care-important criteria in the overall consideration of apheresis treatment. The pat- ented 180" curve of the soft silicone rubber extensions permits the catheter to rest easily in the jugular and sub- clavian veins without interfering with the activity of the patient. Curving down away from the neck, the exten- sions are less visible and more comfortable. Catheter care is simplified, because the flexible curved extensions are easier to clean and tape. Table I compares the infec- tion and complication rates of other catheters to the Ma- hurkar.

The addition of an optional VitaCuff (@ silver-collagen cuff gives the Mahurkar the advantage of cuffed catheters in fighting catheter-related infection. Implanted under the skin at the time the catheter is inserted, the collagen cuff begins to swell upon contact with blood, acting sim- ilarly to a compress. As body tissue grows into the cuff, it forms a natural barrier against bacteria and yeast. At the same time, the silver ions in the cuff provide antimi- crobial protection directly at the exit site. Since exit-site infection is one of the major causes for catheter replace- ment, the presence of the cuff can extend the duration of the catheter implant significantly [4].

USING THE MAHURKAR CATHETER

The Mahurkar catheter is available in 2 diameters and a variety of lengths and configurations to meet the needs of a diverse patient population (10 French, in lengths of 12, 15, and 19.5 cm, and 11.5 French, in lengths of

Address reprint requests to Lori Thompson, RN, MA, ABS, Product Manager for Medical Products, Quinton Instrument Company, 2121 Terry Avenue, Seattle, WA 98121.

Ultem is a registered trademark of General Electric.

VitaCuff is a registered trademark of Vitaphore Corporation

PermCath is a registered trademark and Pull-Apart a trademark of Quinton Instrument Company.

Dacron is a registered trademark of Dupont.

~

Central Venous Catheters for Apheresis Access 155

ria. The PermCath catheter consists of soft silicone rub- ber dual lumen tubing with dual extensions. The unique staggered tip, with a 2.5 cm separation between the arte- rial lumen and the tip, is designed to reduce recircula- tion. A Dacron@ cuff, attached to the catheter, is im- planted into the subcutaneous tissue during insertion. The cuff serves to anchor the catheter as tissue grows into the area between the catheter and vessel wall, form- ing a natural barrier to microorganisms within the subcu- taneous tunnel.

In terms of longevity, several studies indicate success- ful long-term use of the PermCath, primarily in dialysis, but also in apheresis. Bour’s study of 53 catheters in 49 patients reports a mean catheter use of 84 days, with a range of 1-573 days [2]. Shusterman reports that of 22 catheters in his study, 41% were still functional after 32 months [6]. Moss studied 168 catheters placed in 131 patients and found a mean catheter survival rate of 18.5 months with a range of 1-28 months [7]. In addition to these studies performed on the PermCath catheter spe- cifically, extensive literature supports the use of silicone rubber catheters in long-term tpn and chemotherapeutic drug therapy.

In terms of complications, published studies reflect low infection rates, the majority of which are resolved with parenteral antibiotic therapy. The same studies re- late a low incidence of catheter thrombosis, most often are resolved by using urokinase [ 5 ] .

TABLE I. A Comparison of Complication Rates in Central Venous Catheters

Cath Cath Mahurkar catheter # 1 #2 (without Vitacuff)

No. of catheters 71 52 51 No. of treatments 185 253 215 No. of superficial infections 5 1 2 Septicemia 5 1 0 Clotting 9 4 0

Adapted from de 10s Angeles et al. [ 3 ] .

13.5, 16, and 19.5 cm). For optimal performance, the implant length should correspond to the distance from the catheter exit site to the patient’s right atrialisubcla- vian junction. The catheter is placed percutaneously us- ing the Seldinger method, and the tip position is con- firmed immediately after placement using x-ray. If a VitaCuff is used, the cuff should be positioned approxi- mately 3-7 mm under the skin.

To prevent occlusion, the blue adapter (blood return port) should be medial to the red, that is, nearer the midline of the patient’s body. This positions the arterial holes in the tip away from the vessel wall. If the catheter is placed in the opposite manner, the catheter tip may be sucked against the wall of the superior vena cava as blood is removed from the body, resulting in reduced flows, particularly if the patient is dehydrated. The rotat- able wing on the Mahurkar catheter enables the clinician to reposition the catheter without removing sutures.

In general, it is recommended that the Mahurkar cathe- ter be replaced every 2-3 days when used in the femoral vein and every 3 weeks when used in the subclavian or jugular vein.

LONG-TERM CATHETER

For some patients, a long-term catheter is more suit- able. These include patients receiving Interleuken I1 ther- apy for renal cell carcinoma, peripheral stem cell trans- plant patients, and Guillain-BarrC patients, for example. As suggested by Haire et al. [5], the ideal access device for these patients would meet the following criteria:

A device that could be used repeatedly for apheresis

One that would be left in place for use during the

One that would cause no more apheresis-related com-

One that would cause no complications itself

for up to several months

transplant procedure

plications than the use of peripheral veins

Quinton’s PermCathB dual lumen catheter, originally designed for dialysis, meets the majority of these crite-

USING THE PERMCATH CATHETER

The oval PennCath is available in 28 cm (oval 4.9 mm X 2.8 mm O.D. , 1.5 mm I.D.) and in 36 cm and 40 cm (oval 5.9 mm X 3.3 mm O.D., 2 mm I.D.). The 40 cm catheter permits access to the right atrium from the patient’s left side and is useful for larger patients and when the right side is thrombosed.

The catheter can be placed either surgically or percu- taneously. For percutaneous insertion, it is best to use Quinton’s Oval Pull-Apart@@ Introducer, an oval-shaped sheath and dilator that conforms to the oval shape of the catheter. Round introducers are not recommended, as air can enter the space between catheter and sheath, increas- ing the risk of air embolism during insertion. Immedi- ately after implant, the correct tip position should be confirmed by x-ray.

CHOOSING PLACEMENT SITES

Whichever catheter is used, its function and longevity can depend on the placement site. In choosing sites, the physician must consider the patient’s size and body type, previous catheterizations and duration, and the expertise of the person placing the catheter.

156 Thompson

Internal Jugular

Whenever possible, the internal jugular vein should be chosen over the subclavian because the complications are fewer. The jugular site is particularly useful in obese patients in whom landmarks are difficult to find. In the case of short-term catheters, however, unless curved ex- tensions are used, catheter care and comfort can pose a problem.

The right internal jugular is the preferred insertion site for the PermCath. For proper function in jugular and subclavian placements, the PermCath catheter tip should be placed in the right atrium rather than the junction of the superior vena cava and right atrium [8]. For this reason, it is preferable to insert the catheter on the pa- tient’s right side.

External Jugular

Although the external jugular is usually more visible and easy to cannulate than the internal vein, it is better suited to soft flexible catheters. The soft catheters pass more easily around acute bends than do rigid catheters, and the rigid catheter is more likely to perforate the vessel.

Subclavian Vein

The subclavian vein offers the advantage of a wide caliber in adults (1-2 cm) and, because it is held open by surrounding tissue, even in cases of severe circulatory collapse, it is usually easily accessible. It may also be the only vessel accessible in a patient in shock. The catheter can be placed either supraclavicular or infracla- vicular. During insertion, however, it is important to avoid injuring the first rib and clavicle. A needle punc- ture can result in fibrosis, calcification, or periostitis if the needle is contaminated. If the periostium is damaged, it can result in a clinically palpable hard mass at the anterior scalene tubercle that would preclude further ve- nous access at this site.

The disadvantage of using the subclavian vein is that it has the highest complication rate, including pneumo- thorax or collapsed lung, and long-term use may be asso- ciated with subclavian thrombosis [91. With long-term silicone rubber catheters, the pinch-off syndrome also can occur. In the pinch-off syndrome, the catheter be- comes wedged between the clavicle and the first rib. The syndrome results from the catheter being inserted while the patient is in the Trendelenberg position with a rolled towel beneath the shoulder. This position opens the angle between the clavicle and first rib, enabling the catheter to flow freely when inserted. Once the patient sits upright, however, the angle closes and flows decrease. In rare instances, the catheter can be severed by repeated com-

pression accompanying normal everyday arm movement [lo].

Femoral Veins

The femoral vein should be used only as a last resort due to the high incidence of infection and discomfort to the patient. Most femoral placements are performed on bedridden patients or when only 1 or 2 treatments are planned.

CATHETER CARE [ll]

Catheter care is similar for the Mahurkar and the PermCath catheter, and plays a critical role in using these catheters successfully.

He par inization

To maintain patency between treatments, the lumina of the catheter should be filled with the appropriate con- centration and volume of heparin. Priming volumes are imprinted on Quinton@ catheter extensions to assure proper heparinization. Implanted catheters should be heparinized using the positive pressure technique (clamping the extension immediately after infusing). The extensions should remain clamped once the catheter is primed unless attached to bloodlines or a syringe. When an extension is unclamped, the priming volume increases slightly as a result of the tube returning to its normal unclamped state. This action creates a vacuum at the tip and causes blood to be drawn into the distal portion of the catheter, ultimately forming a thrombus. Before treatment, the heparin must be withdrawn and discarded; flushing the heparin into the patient can compromise co- agulation status.

Exit Site Care

To reduce the risk of exit site infection, the site should be kept dry at all times and sterile technique should be used when cleaning the site. Loose or wet dressings should be changed immediately. The exit site should be cleaned at least 3 times weekly, using hydrogen peroxide and optional aqueous-based povidone iodine. Silicone rubber tubing should not be cleaned with alcohol, ace- tone, or tinctures, as these can change the properties of the tubing. The cleaned site should be covered by an occlusive dressing that permits access to the extensions. With cuffed catheters, a simple dry gauze, or no dressing at all, may be acceptable once the tissue has grown into the cuff, usually after 14 days.

Central Venous Catheters for Apheresis Access 157

Thrombus

An obstruction must never be flushed forcibly; rather, a thrombus should be aspirated gently with a syringe. If infusion is still slow, urokinase may be indicated.

REFERENCES 1. McLeod, Bruce C: The technique of therapeutic apheresis. J Crit

Illness 6:487-489, 199 1. 2. Bour, ES, et al.: Experience with the double lumen silastic cathe-

ter for hemoaccess. Surg Gynecol Obstet 171:33-39, 1990. 3 . de 10s Angeles, A. et al.: Comparison of coaxial and side by side

double lumen subclavian catheters with the single lumen catheter. Am J Kidney Dis 7:221-224, 1986.

4. Maki. DG, et al.: An attachable silver impregnated cuff for pre- vention of infection with central venous catheters: A prospective randomized multicenter trial. Am J Med 85:307-313, 1988.

5 . Haire, WD, et al.: Thombotic complications of subclavian cathe- ters in cancer patients: Prevention with heparin infusion. .I Clin Apheres 5:188-191, 1990.

6. Schusterman, Neil H et al.: Successful use of double-lumen. sili- cone rubber catheters for permanent hemodialysis access. Kidney International, Vol 35, pp 887-890, 1989.

7. Moss, AH, et 211.: Use of a silicone dual-lumen catheter with a dacron cuff as a long term vascular access for hemodialysis pa- tients. Am J Kidney Dis 16:211-215, 1990.

8. Schwab, SJ, et al.: Prospective evaluation of a dacron cuffed hemodialysis catheter for prolonged use. Am J Kidney Dis 11: 166- 169, 1988.

9. Peters, JL (ed): “A Manual of Central Venous Catheterization and Parenteral Nutrition,” London, Wright, PSG, 1983.

10. Aitken, DR, Minton, JP: The “pinch off sign”: A warning of impending problems with permanent subclavian catheters. Am J Surg 148:633-636, 1984.

11. Quinton Instrument Company: “Central Venous Catheter Care: A Handbook for Clinicians.” Seattle, WA: Quinton Instrument Company, 1988.

TROUBLESHOOTING

Decreased blood flow and prolonged treatment can be caused by many factors, including catheter malposition, kinking, infection, low cardiac output, or malfunctioning equipment. Flow problems should be resolved immedi- ately to prevent clotting and air embolism.

When problems occur, it is useful to check first for kinking. Bloodlines should be draped carefully without constrictions. The catheter should not bend when the patient moves or lies on the same side as the exit site. Sutures at the exit site should be secure, preventing the catheter from moving in and out of the site.

One-way Obstruction Catheter obstruction or tip occlusion is one of the

more common problems encountered with central venous catheters. In such instances, the tip may become oc- cluded against the vessel wall or a fibrin sheath may form over the tip, acting as a flap on the end of the catheter. One-way obstruction can be suspected if a lu- men can be flushed but not aspirated, if air bubbles ap- pear in the tubing set, or if the blood is foamy. Several techniques can help to remove the obstruction, including

Repositioning the patient Having the patient hold both arms above the head while coughing Flushing the catheter with saline to push the tip away from the wall Rotating the catheter to reorient the venous adapter towards the midline