Venous access for blood sampling, hemodialysis, hydration, medication administration, and nutritional support is essential for the management of many chronic diseases.1,2 A variety of indwelling central venous access devices have been developed to avoid frequent venipunctures and permit direct access to the central circulation. Approximately 150 million intravascular devices are currently in use in the United States.3 These devices may be partially or completely embedded under the patient’s skin (Figures 66-1 and 66-2). The Emergency Physician must be able to access these devices to administer medications and withdraw blood samples without causing catheter damage or catheter thrombosis. Familiarity with this process can be potentially lifesaving if the need for resuscitation becomes imminent in a patient with an indwelling line. The necessary procedures for successfully accessing indwelling devices are described in this chapter.
Indwelling central venous lines. A. The partially implanted central venous line. The distal end of the line emerges from the chest wall. Contamination of the implanted portion is prevented by a subcutaneous tunnel and a Dacron cuff around the catheter. B. The fully implanted central venous line. The catheter is connected to a reservoir that is contained in a subcutaneous pocket.
Indwelling subcutaneous fully implanted devices are used to access the body cavities and veins. (Courtesy of Smiths Medical, Dublin, OH.)
ANATOMY AND PATHOPHYSIOLOGY
Indwelling central venous lines allow access to the central venous circulation from a peripheral site.4,5 This is accomplished through the end of a partially implanted catheter or through the skin into a subcutaneous reservoir of a fully implanted catheter (Figures 66-1 and 66-2). The proximal tip of the central venous line may lie in the superior vena cava or in the right atrium. Catheters designed for right atrial placement are made of softer and more pliable material than catheters used for short-term transcutaneous central venous access. These catheters are less likely to erode through or perforate the thin wall of the right atrium or veins.
The internal jugular, subclavian, and femoral veins can all be used as a route for a central venous line to access the vena cava or right atrium. Subclavian veins are most commonly used to maximize patient comfort and mobility. The vein is punctured transcutaneously when the line is initially inserted. The catheter is inserted into the vein, and its distal segment is tunneled under the skin. The distal end of the catheter is pulled through a small puncture at the skin exit site if the line is partially implanted (Figure 66-1A). Its distal end is connected to a subcutaneous reservoir if the line is fully implanted (Figures 66-1B and 66-2).