Optimizing Catheter Tip Positioning

This new chronic hemodialysis catheter combined with precise technique execution improves retrograde tunneling.

By John R. Ross, MD

Tunneled chronic hemodialysis (HD) catheters continue to play an important role in vascular access for HD.1 Between 1995 and 1999, the percentage of patients receiving dialysis through an HD catheter increased from 13% to 22%,2 while the insertion rate for permanent catheters increased by 71% between 1996 and 1999.3 During the last 3 months of 2001, 26% of adult HD patients received dialysis through a catheter.4 Despite this growth, based on the Kidney Disease Outcomes Quality Initiative (K/DOQI) Vascular Access Guideline 30, catheters are not recommended as a permanent chronic dialysis access because of the many disadvantages associated with catheters relative to native arteriovenous (AV) fistulas and dialysis grafts.5 However, in instances in which catheters are required as a permanent access, the catheter must provide optimal performance.

Good catheter outcomes depend on proper positioning.6 Conversely, improper positioning of the catheter tip can lead to insertion complications such as pneumothorax, hemothorax, and cardiac tamponade,7-12 as well as poor blood flow rates, poor clearances, and long-term complications such as catheter dysfunction and fibrin sheath formation.5,13 Precise positioning of the catheter can be challenging with conventional tunneling techniques because antegrade tunneling makes it difficult to secure exact tip placement once the tunnel has already been created. With conventional antegrade tunneling, cuff and exit site placements also tend to be suboptimal, and bleeding from the venotomy site can cause prolonged oozing or subcutaneous hematoma formation along the tunnel.14,15 Moreover, antegrade tunneling and typical tunnel dilation through the exit site often results in a loose catheter exit site that may allow catheter migration and promote bacterial spread through the exit site into the tunnel.

To overcome the risks of malpositioning, a new modular design catheter (Arrow Cannon Catheter II Chronic Hemodialysis Catheter, Arrow International, Inc., Reading, PA) with a unique coupling mechanism was developed that allows retrograde tunneling, which facilitates complex placements and permitting optimal positioning of the catheter tips as well as the cuff and exit site. A retrograde tunneling technique for placement of this “new-generation” cuffed, tunneled dialysis catheter is described. This technique allows the operator to optimally place the catheter tip first, then tunnel back to the exit site, offering reliable and consistent tip placement with optimal cuff positioning and exit site location.

The Cannon Catheter II set includes a 15-F, radiopaque, polyurethane dual-lumen catheter with nonfused arterial and venous ends with side holes. The V-tip design minimizes the risk of recirculation and occlusion, while maximizing blood flow rates. Furthermore, the catheter design allows the use of a guidewire weave insertion technique, which facilitates difficult placements such as those in the left internal jugular vein (IJV). The integral tunneling connector simplifies and facilitates the process of attaching the tunneler to the catheter. The compression sleeve and threaded compression cap preloaded on the tunneler make connecting to the catheter hub assembly rapid and easy. This attachable hub assembly allows retrograde tunneling with precise positioning of the tips, cuff, and exit site; it also permits replacement of the catheter hub assembly for catheter repair during extended use.

The surgical field is prepared and draped in the usual manner and local anesthesia is administered. The catheter is prepared according to manufacturer’s instructions by attaching the irrigation tube to the proximal end of the catheter, flushing both catheter lumens, and clamping the irrigation tube. Sonographic guidance is used to identify and directly cannulate the left IJV with an 18-g needle attached to a syringe. After the vein is cannulated, the syringe is removed and a .038-inch, hydrophilic, angled-tip guidewire is threaded through the needle and passed down through the left IJV, medially through the left brachiocephalic vein, and down through the superior vena cava into the inferior vena cava. To avoid potentially lethal cardiac arrhythmias or perforation, the guidewire is left in the inferior vena cava during catheter placement and positioning. The guidewire should not be placed in the right atrium of the heart. After proper placement of the guidewire is verified by means of fluoroscopy, a small incision using a #11 scalpel blade is made in the neck for the catheter pocket. A small hemostat is used to develop the catheter pocket using blunt dissection. The catheter pocket minimizes the risk of catheter kinking in the neck and makes it easier to feed the cuff segment through the tunnel.

Serial dilators (12 F and 14 F) are used over the guide wire to dilate the vein, using visualization to ensure that the dilators follow the trajectory of the wire. A 16-F, peel-away split sheath introducer is advanced over the guidewire only to the point where the sheath enters the IJV. The dilator is removed and the sheath is occluded to prevent air embolism or blood loss. Using the weave technique, the Cannon Catheter II is threaded onto the guidewire (Figure 1). In this technique, the guidewire is threaded through the distal tip of the venous limb, out the most proximal side hole of the venous limb, and then passed straight through the arterial limb of the catheter, effectively tying the split tips together to allow even advancement of both catheter limbs during insertion over the guidewire.

The catheter is then advanced over the wire through the introducer sheath and passed—with the aid of fluoroscopic guidance—into the right atrium of the heart with the arterial lumen facing medially. The guidewire is removed and the introducer sheath is split and removed. Proper placement and separation of the catheter tips in the right atrium should be verified by fluoroscopy. It should be noted that the catheter could also be placed using the weave technique without the peel-away split sheath introducer. However, experience has shown that the catheter can be passed into position more easily and consistently with the introducer in place.

In preparation for optimal placement of the tunnel and exit site, the proximal end of the catheter is laid on the chest wall with a gentle curve to avoid kinking and the location of the exit site (approximately 6 cm lateral to the venotomy site) determined (Figure 2). Because the catheter is tunneled in a retrograde fashion, the exit site can be positioned to accommodate the patient’s body habitus and to ensure optimal placement of the cuff (approximately 2 cm from the exit site). A small incision is made at the exit site with a #11 scalpel blade; the metal tunneling tool is bent to follow the curve of the planned tunnel path and passed from the exit site medially to the catheter pocket that was previously developed in the neck (Figure 2).

A tunnel dilator is placed over the metal tunneling tool and pulled back into the tunnel, dilating the tract to accommodate passage of the cuff. The tunnel tract is dilated only as far as the cuff position; it is not pulled through the exit site. After the tunnel has been created, the catheter is compressed between the thumb and forefinger to prevent air embolism and blood loss while the irrigation tube is removed. The catheter is snapped onto the metal tunneling tool and gently pulled from the catheter pocket through the tract in a retrograde fashion and out the exit site (Figure 3A,B), positioning the cuff approximately 2 cm from the exit site.

A threaded compression cap and sleeve coupling mechanism are located on the tunneling tool, which is still attached to the catheter. The operator simply slides the cap and sleeve onto the catheter beyond where the catheter will be cut. The catheter is then pinched and cut. The cannulas of the hub connection assembly are inserted into the catheter lumens, with a “red-to-red” match for the draw (arterial) lumens and a “blue-to-blue” match for the return (venous) lumens. The threaded compression cap is slid over the compression sleeve and securely threaded into the hub connection assembly. Blood is aspirated to test flow and heparin locks are instilled before the catheter is sutured into place at the exit site (Figure 4). As a final step, proper placement and separation of the catheter tips in the right atrium should be verified once again by fluoroscopy (Figure 5). This insertion technique differs slightly from the manufacturer’s instructions for use, but has been highly successful for both left- and right-sided placements.

The Cannon Catheter II optimizes tip placement in the right atrium, providing more accurate placement of the tip with less kinking and high blood flow rates, while avoiding the complications of poor cannula placement such as myocardial damage, conduction problems, and poor flow rates.

The weave insertion technique and retrograde tunneling of the catheter allow the operator to consistently position the cuff 2 cm proximal to the tunnel tract exit site, an optimal placement that seems to reduce the rate of catheter infections. By this technique, the exit site can be kept small and the distal tunnel tract remains the same diameter as the tunneler because neither the tunnel dilator nor the catheter cuff passes through the exit site. The resultant snug fit around the catheter cuff segment helps secure the catheter in the tunnel—minimizing catheter kinking and migration—and reduces retrograde bleeding through the tunnel tract from the venotomy site.

The weave insertion technique over a guidewire to place a Cannon Catheter II in the left IJV allows very precise placement of the split catheter tips in the right atrium, regardless of anatomical aberrations or damage due to previous catheter placements in the central venous system. Retrograde tunneling allows the operator to optimally position the catheter tip before the catheter is tunneled. Because the exit site is identified after the catheter tips are positioned, the cuff and exit site can also be optimally placed in relation to tip location in the right atrium and in consideration of the patient’s body habitus. The result is ideal catheter position in what would otherwise be a difficult catheter placement into the left IJV. Finally, the unique coupling mechanism makes the connection process quick and convenient, and it is easy to repair or replace the attachable hub assembly during conditions of extended use.

The technical advantages to the operator placing the device are combined with the favorable clinical results in patients receiving dialysis with the device. By optimizing tip positioning and blood flow—even among challenging patients and anatomical placements—the Cannon Catheter II Chronic Hemodialysis Catheter represents a significant advancement in vascular access options that promises to enhance the clinical outcomes and care of patients requiring chronic vascular access for hemodialysis. 

John R. Ross, MD, is Chief of Surgery, Bamberg County Hospital, Bamberg, South Carolina. He is a consultant for Arrow International, Inc. Dr. Ross may be reached at (803) 245-4435; jrrsurgery@aol.com.

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