Pediatric emergency medicine trisk 1166

INDWELLING VENOUS ACCESS DEVICES
Background
In 1973, Broviac designed the first Silastic-tunneled, cuffed central venous
catheter (CVC). In 1983, the first totally implanted central venous access device,
often referred to as a chest port, was developed and introduced. These devices
provide children with relatively permanent and secure venous access during
chemotherapy, total parenteral nutrition, or other prolonged IV therapy. Clinicians
must be familiar with the procedures for establishing patency, drawing blood,
dealing with catheter occlusion or breakage, and assessing for infection.

Pathophysiology
The distal tip of tunneled cuffed CVCs is most often located at the junction of the
right atrium and the superior vena cava for lower body CVC insertion sites, the
tip should be located in the inferior vena cava above the level of the diaphragm.
The site of venous entry is usually the subclavian or internal jugular vein;
however, access is occasionally obtained through the external jugular, cephalic,
and brachiocephalic veins. For lower body insertions, access is obtained via the
femoral vein. The catheter is tunneled under the skin to a site in the chest away
from the venous entry site and then externalized. For implanted ports, the catheter
is connected to a subcutaneous reservoir.

Equipment
Tunneled CVCs come in various brands, such as Broviac, Hickman, Leonard,
Raaf, Hermed, Groshong, and Corcath ( Fig. 135.7 ). The original catheters were
made of Silastic elastomers and are tunneled under the skin a few centimeters
before externalization. Newer versions of tunneled, cuffed CVCs are made of
polyurethane materials, which can be manufactured in smaller gauge sizes with
multiple lumens to serve the neonatal/pediatric populations. A Dacron cuff,
located around the catheter, anchors the catheter after it stimulates fibrosis of the
surrounding tissue. This also serves to inhibit migration of bacteria into the
catheter tract. The most proximal portion of the catheter contains a female Luer

lock tip, which is usually covered with a removable needleless cap, allowing a
direct and solid connection to most syringes and IV tubing. A clamp is present
just before this tip, under which a reinforced sleeve protects against catheter
breakage. The catheters can vary in length, diameter, and number of lumens and
access ports. The Groshong-type catheter is valved at the distal tip to keep blood
out of the lumen and therefore requires only saline flushes and does not require


clamping. Kits are available that contain the equipment necessary to repair broken
external catheters (Bard Access Systems, Inc., Salt Lake City, UT; Invacare Inc.,
Holliston, MA).
Totally implantable venous access devices are internalized under the skin ( Fig.
135.8 ). Like the tunneled CVCs, they use a Silastic or polyurethane catheter with
the distal tip located in the distal SVC. However, the proximal end is tunneled
and connected to a subcutaneous reservoir chamber, which is implanted in a
pocket under the skin. The reservoir has a self-sealing silicone septum and a hard
metal or plastic back surface, with suture holes to secure it to the muscle wall.
The chamber is accessed by inserting a tapered 20- or 22-gauge Huber noncoring
needle through the skin over the port. The noncoring needle is angled at 90
degrees for ease of insertion and stabilization. If emergency access is required, a
straight needle can be used, although this may core a portion of the device’s
septum.


FIGURE 135.7 Partially implantable (“tunneled”) venous catheter.


Specific equipment is available for accessing tunneled and totally implanted
indwelling CVCs ( Table 135.5 ). The medical office or ED that occasionally sees
these children should have a prepared kit containing these items at hand.

FIGURE 135.8 Totally implantable venous access device.

TABLE 135.5
EQUIPMENT NEEDED TO ACCESS CENTRAL VENOUS CATHETERS
Clamp or hemostat without teeth, possibly with rubber tips
T-extension tubing with clamp
10-mL syringe of normal saline
10-mL syringe of heparin 10 unit/mL; 100 unit/mL
Needleless injection caps
70% Alcohol or Chlorhexidine/Alcohol
Procedure gloves for accessing a capped line; Sterile gloves to change the caps
of access a port
Dressing gauze and tape
Transparent semi-permeable sterile dressing
For implanted ports: Two tapered Huber noncoring needles, 20- and 22-gauge,
in the appropriate length for the patient (3/4 in most commonly used).