Central Venous Access

Vascular access in critically ill patients often involves the insertion of long, flexible catheters into large veins entering the thorax or abdomen. This type of central venous access is the focus of the current chapter.

I. Infection Control

The infection control measures recommended for central venous cannulation are shown in Table 1.1 (1,2). When used together (as a “bundle”), these five measures have been effective in reducing the incidence of catheter-related bloodstream infections (3). The following is a brief description of these preventive measures.

A. Skin Antisepsis

Handwashing is recommended before and after palpating catheter insertion sites, and before and after glove use (1). Alcohol-based hand rubs are preferred if available (1,4); otherwise, handwashing with soap (plain or antimicrobial soap) and water is acceptable (4).
The skin around the catheter insertion site should be decontaminated just prior to cannulation, and the preferred antiseptic agent is chlorhexidine (1).
- The advantage of chlorhexidine is its prolonged antimicrobial activity, which lasts for at least 6 hours after a single application.
- Antimicrobial activity is maximized if chlorhexidine
  it is allowed to air-dry on the skin for at least two minutes (1).

Table 1.1 The Central Line Bundle

Components	Recommendations
Hand Hygiene	Use an alcohol-based handrub or a soap and water handwash before and after inserting or manipulating catheters.
Barrier Precautions	Use maximal barrier precautions, including cap, mask, sterile gloves, sterile gown, and sterile full body drape, for catheter insertion or guidewire exchange.
Skin Antisepsis	Apply a chlorhexidine-based solution to the catheter insertion site and allow 2 minutes to air-dry.
Cannulation Site	When possible, avoid femoral vein cannulation.
Catheter Removal	Remove catheter promptly when it is no longer needed.
From the Institute for Healthcare Improvement (2).

B. Sterile Barriers

All central venous (and arterial) cannulation procedures should be performed using full sterile barrier precautions, which includes caps, masks, sterile gloves, sterile gowns, and a sterile drape from head to foot (1).

C. Site Selection

According to published guidelines (1) femoral vein cannulation
should be avoided to reduce the risk of catheter-associated septicemia. However, clinical studies indicate that the incidence of septicemia from femoral vein catheters (2–3 infections per 1000 catheter days) is no different than the incidence of septicemia from subclavian or internal jugular vein catheters (5,6).

II. Catheters

A. Catheter Size

The size of vascular catheters is expressed in terms of their outside diameter. Size can be expressed in a metric-based French size or a wire-based gauge size.
- The French size is a series of whole numbers that increases in increments of 0.33 millimeters (e.g., 1 French = 0.33 mm, 2 French = 0.66 mm).
- The gauge size (originally developed for solid wires) has no definable relationship to other units of measurement, and requires a table of reference values (like the one in Appendix 3).

B. Central Venous Catheters

The term central venous catheter (CVC) refers to catheters inserted into the internal jugular, subclavian, or femoral veins and advanced into one of the vena cavae.
Modern CVCs have multiple infusion channels, like the popular triple-lumen catheter shown in Figure 1.1. This catheter has an outside diameter of 2.3 mm (French size 7), and is available in lengths of 16 cm (6 in), 20 cm (8 in), and 30 cm (12 in). (Dimensions may vary by manufacturer.)

FIGURE 1.1 Triple-lumen central venous catheter, showing the gauge size of each lumen and the position of the outflow ports at the distal end of the catheter.

C. Antimicrobial Coating

CVCs are available with two types of antimicrobial coating: (a) chlorhexidine and silver sulfadiazine (available from Arrow International), and (b) minocylcine and rifampin (available from Cook Critical Care). Each of these coatings can reduce the risk of catheter-related bloodstream infections (7).
According to published guidelines (1), antimicrobial-coated catheters should be considered if the expected duration of catheterization is >5 days and if the incidence of catheter-related infections in an ICU is unacceptably high.

D. Peripherally-Inserted Central Catheters

The term peripherally-inserted central catheter (PICC) refers to long catheters that are inserted into the basilic or cephalic vein in the arm (just above the antecubital fossa) and advanced into the superior vena cava.
PICCs are available with multiple infusion channels, like CVCs, but they are narrower than CVCs (typically 5 French or 1.65 mm in diameter), and are considerably longer than CVCs. PICCS are available in lengths of 50 cm (19.5 in) and 70 cm (27.5 in).
As a result of the smaller diameter and longer length of PICCs, flow through PICCs is considerably slower than flow through CVCs. (See Appendix 3 for charts showing the flow rates through PICCs and CVCs.)

III. Cannulation Sites

The following is a brief description of central venous cannulation at four different access sites: i.e., the internal jugular vein, the subclavian vein, the femoral vein, and the veins emerging from the antecubital fossa.

A. Internal Jugular Vein

1. Anatomy

The internal jugular vein (IJV) is located under the sternocleidomastoid muscle (see Figure 1.2), and runs obliquely down the neck along a line drawn from the pinna of the ear to the sternoclavicular joint. In the lower neck region, the vein is often located just anterior and lateral to the carotid artery, but anatomic relationships can vary (16).
At the base of the neck, the IJV joins the subclavian vein to form the innominate vein, and the convergence of the right and left innominate veins forms the superior vena cava.
The right side of the neck is preferred for cannulation of the IJV because the vessels run a straight course to the right atrium. The distance from cannulation site
to the right atrium is about 15 cm, so the shortest CVCs (∼15 cm) should be used for right-sided cannulations (to avoid advancing the catheter tip into the right atrium).

FIGURE 1.2 The large veins entering the thorax.

2. Positioning

A head-down body tilt to 15° below horizontal (Trendelenburg position) results in a 20–25% increase in the diameter of the IJV (8). Further increases in the degree of body tilt has no incremental effect (8).
A head-down body tilt of 15° can be used to facilitate IJV cannulation, particularly in hypovolemic patients, but is not necessary in patients with venous congestion, and is not advised in patients with increased intracranial pressure.
The head should be turned slightly in the opposite direction to straighten the course of the vein, but turning the head beyond 30° from midline is counterproductive because it stretches the vein and reduces its diameter (16).