Anatomy
The catheter tip of most CVCs terminates at the junction of the superior vena cava (SVC) and the right atrium (RA). The venous path each catheter takes to get to the central circulation depends on the type of device. Tunneled, externalized catheters are usually inserted in the subclavian, external jugular, or cephalic vein, while implanted devices are usually inserted in the subclavian or internal jugular vein (Figure 5.1. CHOP Family Information Line Drawing w/anatomy). Externalized catheters are tunneled from the point of venous access to an exit point in the patient's chest, where a Dacron cuff stimulates tissue adherence, thereby discouraging both catheter migration and microbial infiltration (Figure 5.2). Fully implanted catheters (ports) are tunneled from their point of venous access to a subcutaneous pocket in the chest wall, where they terminate in a reservoir that is sutured in place for stability. The reservoir of the port communicates with the catheter portion of the device and is topped by a silicone self‐sealing septum that is accessed through the skin with a noncoring needle (Figure 5.3). PICC lines, which have no tunneled component, are generally inserted in the upper arm through the basilic, brachial, or cephalic vein from which they are advanced into the SVC.
Routine Management and Use
The overarching principles of routine management for CVCs in the ED is similar for all devices. As none of these indwelling catheters is initially placed in the ED, routine CVC use in the emergent setting consists primarily of accessing and de‐accessing the device for blood drawing and/or medication infusion. In all cases, a sterile field and meticulous sterile technique should be maintained when accessing or caring for a CVC. Forceps with teeth should not be used to clamp externalized lines, as these increase the risk of catheter breakage; if only toothed forceps are available, the teeth should be wrapped in sterile gauze prior to using the forceps to clamp the line. While povidone‐iodine may be used to sterilize both externalized catheter hubs and the skin overlying implanted CVCs, neither tincture of iodine nor acetone should be used to clean an externalized line, as it may dry the catheter and increase the risk of line breakage. When flushing fluids or drawing back blood from a CVC, a 10 cc syringe or larger should be used; smaller syringes may cause excessive pressure in the catheter, leading to rupture. Practitioners should have all specimen tubes for blood‐drawing, all fluids to be infused, and all heparin and saline flushes ready prior to accessing the line. Fluids should never be infused into a line that does not draw back blood after flushing. To avoid instilling an air embolus, externalized catheters should always be clamped whenever a cap, syringe, or intravenous (IV) tubing is not attached to the distal end of the device. The specifics of accessing and de‐accessing each device type are described below.
Figure 5.1 Schematic of CVC anatomy. (a) Externalized indwelling CVC and (b) implanted port.
(Source: ©2020 The Children’s Hospital of Philadelphia, CHOP Family Information Line Drawing w/anatomy, (a): https://www.chop.edu/treatments/tunneled‐catheter‐placement; (b): https://www.chop.edu/treatments/implantable‐venous‐port.)
Figure 5.2 Schematic of externalized indwelling CVC.
Figure 5.3 Schematic of fully implanted CVC.
(Source: Image courtesy of Macmillan Cancer Support, UK.)
Accessing and Drawing Blood from an Externalized CVC (Broviac, Hickman, PICC)
As noted above, the procedure for accessing an externalized CVC must follow strict aseptic technique. ED personnel should have all necessary equipment open and ready prior to accessing the line. Table 5.1 describes the steps necessary to access an externalized CVC. If blood samples are to be drawn from the catheter, an attempt should be made to use the CVC's largest lumen of the for this purpose. If blood cultures are needed, a sample should be drawn from each lumen of the catheter and labeled carefully to indicate its lumen of origin. In general, blood samples withdrawn from a CVC should be labeled as such, so that any erroneous or unusual lab results may be interpreted in the context of the line's usual use (e.g. an extremely high blood glucose level drawn from a line ordinarily used to infuse parenteral nutrition).
Table 5.1 Procedure for accessing an externalized central venous catheter.
| Identify the patient and explain the procedure to the patient and family.Position the patient safely. Supine positioning is preferred; women and adolescent girls should have their brassiere removed on the side of the catheter.Perform hand hygiene and don sterile gloves. Some institutions will also require practitioners to wear a mask and/or sterile gown.Prime all tubing and connectors to be used in the procedure to purge them of air.Place a sterile towel or drape under the externalized portion of the catheter.If the patient's CVC does not have its own clamp, clamp the line at least 3 in. proximal to the cap using forceps without teeth.Remove the catheter cap and scrub the hub with alcohol, allowing it to dry fully (at least 5–10 seconds).Attach a 10 cc syringe of normal saline; unclamp the catheter and slowly inject up to 5 cc of saline. If the line flushes easily, aspirate the instilled fluid and check for blood return.If there is resistance to fluid infusion or no blood return with aspiration, the line is likely occluded (see the section on troubleshooting an occluded CVC). Recap the line and do not inject fluids or medications into the occluded line.If there is successful blood return with aspiration, instill the remaining saline in the syringe. Clamp the line and remove the syringe.If the line is needed for blood drawing, aspirate 3–5 cc from the line prior to clamping, as in Step 10. Discard this saline‐and‐blood mixture, and attach a new, empty syringe to the catheter cap. Unclamp the catheter and withdraw the needed volume of blood. Reclamp the catheter, attach a second 10 cc syringe of saline, unclamp the catheter, and flush the line to clear blood from the line. Clamp the catheter after flushing and remove the syringe.If the line is needed for infusion of medications or fluids, connect primed IV tubing to the catheter hub, unclamp the catheter, and administer fluids or medications as care dictates. |
Accessing and Drawing Blood from a Fully Implanted Catheter (“Port”)
Accessing an implanted CVC requires puncturing the skin overlying the device; therefore, if line access is not required emergently, practitioners may wish to numb the skin over the port with a topical, lidocaine‐containing anesthetic. Care must be taken to access the port with a noncoring (Huber©) needle, as standard hypodermic needles will damage the septum of the port and prevent it from resealing properly when the line is de‐accessed. While the closed system of the implanted port boasts a decreased infection rate than that of externalized CVCs with routine use, it is critical to maintain proper aseptic technique when accessing these lines in the ED to avoid introducing infection at the access site. The skin overlying the implanted device should be cleansed with povidone‐iodine or chlorhexidine (for patients older than two months) prior to attempting access.