Central Venous Access

Fig. 6.1

B-mode image of oval internal jugular vein (IJV) and round carotid artery (CA). (Courtesy of Srikar Adhikari, MD)

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig2_HTML.png — Fig. 6.2

Color Doppler image of internal jugular vein and carotid artery demonstrating the differences in the direction of flow. (Courtesy of Srikar Adhikari, MD)

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig3_HTML.png — Fig. 6.3

Spectral Doppler image of internal jugular vein showing phasic flow. (Courtesy of Srikar Adhikari, MD)

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig4_HTML.png — Fig. 6.4

Spectral Doppler image of common carotid artery showing pulsatility. (Courtesy of Srikar Adhikari, MD)

Indications

Providing medications that are caustic to smaller vessels, i.e., vasopressors, certain antibiotics, and long-term electrolyte replacement
Large volume resuscitation (Cordis line)
Hemodynamic monitoring
Transvenous cardiac pacing
Hemodialysis/plasmapheresis
Difficult venous access

Contraindications

A CVC should not be placed in an area with overlying cellulitis or where it will be difficult to maintain site sterility. A CVC should not be placed in a clotted or stenotic vein or if there is known or suspected venous injury. Coagulopathic and obese patients should be approached with great care as there is an increased risk of complications. If a patient is in need of dialysis or is to have an arteriovenous (AV) fistula placed, the central line should not be placed in the vein that the AV fistula or temporary catheter will be placed.

Equipment and Probe Selection

Probe Selection

A high-frequency linear probe (Fig. 6.5) should be used as it provides the best resolution for superficial structures such as the veins that require cannulation as well as the needle tip. Typical modern broadband transducers now range from approximately 15–6 MHz, but exact frequencies and bandwidth can vary widely. While attempting a supraclavicular subclavian line, the endocavitary probe (Fig. 6.6) or other small footprint high-frequency probe can be used as this provides better access to the supraclavicular fossa.

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig5_HTML.png — Fig. 6.5

High-frequency linear array probe

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig6_HTML.png — Fig. 6.6

Endocavitary probe

Equipment

Antiseptic (chlorhexidine gluconate, betadine, etc.)
Local anesthetic (1% lidocaine)
Gauze
25 gauge needle for anesthetic infiltration
18 gauge introducer needle
Syringes (3 cc, 10 cc)
Needles for anesthetic (18 gauge, 25 gauge)
Sterile drapes, gown, gloves, mask, and hat
Sterile ultrasound probe cover
J-shaped guidewire
Dilator
11 blade scalpel
Large Tegaderm
Biopatch
Catheter

Preparation and Preprocedure Evaluation

The site and choice of catheter depends on the clinical scenario. The subclavian or internal jugular veins are typically preferred because of lower infection rates and thrombosis, but a femoral CVC is appropriate in many situations. For certain procedures or when large volume resuscitation is required, a large bore 8.5 french (2.8 mm) introducer (Cordis) (Fig. 6.7) may be required. When central access is required to give specific medications or provide central venous pressure monitoring, a multilumen CVC (Fig. 6.8) may be more appropriate. (It is important to note that a multilumen CVC is typically inferior to large bore peripheral IV access for rapid volume resuscitation due to the resistance to flow caused by the longer catheter length.) Informed consent should be obtained and the benefits and risks explained. In emergent settings, if the patient or a next of kin is unable to provide timely consent, implied consent may be necessary.

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig7_HTML.png — Fig. 6.7

Cordis catheter with dilator in place

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig8_HTML.png — Fig. 6.8

Triple lumen catheter

Prior to setup, anatomic landmarks should be assessed by ultrasound. First note the location of the target vein and its corresponding artery. Veins will appear to have thin walls versus the thicker walled and pulsatile artery. Note that the artery should not be easily compressible, while the vein should compress with gentle probe pressure. The use of color Doppler may also demonstrate the pulsatile flow of the artery and the steady flow of the vein. Scan up and down to visualize the course of the vein, while also taking note of surrounding structures. It is important to identify surrounding vessels, nerves, lymphatics, or evidence of lung tissue as these structures should be avoided while placing the line.

There are two ways that ultrasound can be utilized to guide the placement of CVCs. The static approach describes when ultrasound is used to confirm the location of the target vein and its trajectory and to assess the surrounding anatomy, but is not used during the procedure itself. The site of needle insertion over the vein must be marked on the skin prior to sterilization. The dynamic approach is when ultrasound is used to provide real-time visualization during needle insertion and help guide needle advancement into the target vessel. It has been found that the static approach has superior first-attempt success rates than the landmark technique (also known as the “blind” technique) alone. It can be done quickly if the practitioner is unable to place the line with the ultrasound probe remaining stable or if a sterile cover is not available. However, the same study found the dynamic approach to be superior to both static and landmark techniques [4]. The dynamic approach is strongly recommended as there is potential for the alignment and orientation of vessels to change with movement (particularly for the internal jugular vein with head and neck movements).

After scanning the vessel, the room should be set up appropriately with ultrasound machine and equipment in locations that permit the operator to easily access equipment and visualize the screen. The patient should be prepared and draped in normal sterile fashion. Clean the patient’s skin with chlorhexidine gluconate or a comparable antiseptic solution. The operator should gown and then drape the patient. It is important to have an assistant to aid the operator in handling equipment and the ultrasound probe.

When using a dynamic approach, the ultrasound probe must be placed in a sterile sleeve. A sheath of at least 6 feet in length is important to cover enough cable length to avoid contaminating the sterile field with uncovered cable. However, some radiology procedural sterile sheaths can be so long as to be unmanageable when it comes to dressing a standard ultrasound transducer. Sterile ultrasound sleeves are typically packaged with sterile ultrasound gel. A copious amount of gel should be placed directly in the sleeve prior to inserting the probe to ensure that the entire footprint of the ultrasound probe is covered. The ultrasound probe can then be lowered into the sleeve by the assistant (Fig. 6.9). Rubber bands provided are used to keep the sterile sleeve in place. When applying the rubber band, try to make sure there is a layer of gel in between the transducer footprint and the sterile sleeve free of air bubbles.

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig9_HTML.png — Fig. 6.9

Lowering the probe into the sleeve when an assistant is present

In the event that an assistant is not available, a single-operator technique can be used to cover the probe. The probe should be placed in a holder on the ultrasound cart, and gel should be applied prior to the operator gowning. After the operator has put on sterile gloves and gown, the operator will place his hand inside the sterile ultrasound cover sleeve and grasp the nonsterile probe as demonstrated in Fig. 6.10. The operator can then grab the corner of the sleeve and pull the cover over the probe and cord as shown in Fig. 6.11.

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig10_HTML.png — Fig. 6.10

The single operator with a sterile glove can invert the end of the probe cover and grasp the probe

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig11_HTML.png — Fig. 6.11

The practitioner then grabs the bottom of the probe cover and pulls it down over the cord

All equipment should be inventoried and inspected prior to starting the procedure. When using a multilumen CVC, the lumens should be instilled with normal saline to assess for integrity and/or malfunction.

Procedure

The previously determined site of needle entry should be anesthetized using local anesthesia. Always make sure to aspirate prior to instilling the lidocaine to ensure the needle is not inside a vessel. The dynamic approach for ultrasound guidance can be performed using three different needle visualization techniques: in-plane, out-of-plane, and oblique (Table 6.1).

Table 6.1

Advantages and disadvantages of the in-plane, out-of-plane, and oblique needle visualization techniques for dynamic ultrasound-guided central venous catheter placement

	Advantages	Disadvantages
In-plane	Constant needle tip and vessel visualization without any need to move the probe	Potential for cylinder tangential effect May be difficult to keep the vessel and needle within the plane of the beam Cannot see adjacent structures
Out-of-plane	Able to simultaneously view the vessel, and surrounding structures	The probe must be moved with the needle tip to keep it in view Loss of needle tip visualization can result in complications
Oblique	Hybrid approach allowing partial view of vessel and surrounding anatomy with constant needle visualization	May be conceptually more difficult Potential for needle to travel out of plane

Advantages

Disadvantages

In-plane

Constant needle tip and vessel visualization without any need to move the probe

Potential for cylinder tangential effect

May be difficult to keep the vessel and needle within the plane of the beam

Cannot see adjacent structures

Out-of-plane

Able to simultaneously view the vessel, and surrounding structures

The probe must be moved with the needle tip to keep it in view

Loss of needle tip visualization can result in complications

Oblique

Hybrid approach allowing partial view of vessel and surrounding anatomy with constant needle visualization

May be conceptually more difficult

Potential for needle to travel out of plane

Out-of-Plane Approach

In the out-of-plane approach , the ultrasound beam is insinuated perpendicular to the target vessel causing it to appear as a circle. Once the needle is inserted through the skin, the practitioner should translate the ultrasound probe both proximally and distally to identify the location of the needle tip. The needle tip is seen as a bright, hyperechoic dot with reverberation artifact (Fig. 6.12). Because the needle will also be perpendicular to the ultrasound beam, or “out-of-plane,” the practitioner must actively translate the ultrasound probe as the needle is advanced to maintain constant needle tip visualization . If the needle tip is not adequately visualized, the operator can move the needle side to side to create a jiggling effect of the needle tip to aid in its identification. The needle should be slowly advanced toward the vessel while relocating the tip after each manipulation until the needle tip indents and punctures the anterior wall of the target vein. Once the needle tip is properly positioned within the vein, it should appear as a target sign. Again, the ultrasound probe should be moved distally to ensure that the needle does not pass through the back wall of the vein. Once you see the “target sign” fan the probe distally the “target sign” should disappear, and when you fan the probe back proximally the “target sign” should reappear. This indicates the needle tip is in the vessel and is known as the “vanishing target sign” [5].

../images/323313_1_En_6_Chapter/323313_1_En_6_Fig12_HTML.png — Fig. 6.12

Echogenic needle tip is visualized inside a vein in out-of-plane approach (known as the “target sign”)

An advantage of the out-of-plane approach is it allows for simultaneous visualization of the vessel and surrounding structures (artery, nerves, etc.). A common drawback is for the operator to mistake the shaft of the needle for the needle tip, which can result in advancing the needle too far and potentially puncturing the posterior wall of the vein or other nearby structures.

In-Plane Technique

In the in-plane approach , the beam is parallel to the long axis of the target vessel causing the vessel to appear as a rectangle on the screen. The needle is inserted and advanced toward the vessel in this same plane (also known as an “in-plane” approach). The benefit of the “in-plane” technique is the operator does not need to move the probe as the needle is advanced; the needle tip will always be visible so long as the needle remains in the plane of the beam. This minimizes the chances of advancing the needle tip past the posterior wall of the target vessel. Figure 6.13 shows an example of a needle in the vessel in long axis. A disadvantage of the in-plane approach is it requires that the sonographer be able to maintain alignment of the vessel and needle in the beam of the ultrasound probe, which may be difficult in some patients. If the operator swings the syringe either left or right, the needle may move out of plane and become only partially visualized. If the operator accidentally translates or fans the probe, the beam will go from cutting through the main sagittal portion of the vessel to a parasagittal portion which may prevent successful cannulation. This latter issue is often termed the cylinder tangential effect.