Abstract
Centrally inserted central venous catheters, or “central lines,” are a common and useful tool in the Neuro-ICU. Here the following topics related to insertion of central lines are discussed in detail: relevant anatomy and physiology, indications/contraindications, equipment, technique, complications, and expert suggestions.
8 Central Line
8.1 Introduction
Securing central venous access is a fundamental skill essential to the care of critically ill patients. In the United States, over 5 million central venous access catheters are placed annually 1 and on average remain in place for 7 to 10 days. Centrally inserted central venous catheters (CICVCs), or “central lines” as they are commonly known, may be placed in the subclavian, internal jugular, or femoral vein. 2 3 The concept of central line placement was first introduced by Dr. Werner Forssmann when he self-inserted a ureteric catheter through his cubital vein into his right heart. 7
8.2 Anatomy/Physiology
Central venous access catheters are placed into a large vein in the body, terminating in the veins within the thorax. The three most common types of central lines placed are subclavian, internal jugular, and femoral. The catheter tip of a central line terminates in the superior vena cava for subclavian and internal jugular vein (IJV) central lines, and inferior vena cava for femoral central lines.
8.2.1 Subclavian Vein Anatomy
The subclavian vein is an extension of the axillary vein that originates at the outer border of the first rib. The vein runs under the clavicle, where it connects to the IJV to form the innominate, or brachiocephalic vein. The subclavian vein measures between 1 to 2 cm in diameter; however, it can be smaller or larger depending on the individual. The subclavian vein follows the subclavian artery and is separated from the subclavian artery by the insertion of the anterior scalene. Thus, the subclavian vein lies anterior to the anterior scalene while the subclavian artery lies posterior to the anterior scalene and anterior to the middle scalene. 11 The anatomy of the subclavian vein and surrounding structures is depicted in ▶ Fig. 8.1.
8.2.2 Internal Jugular Vein Anatomy
The IJV is formed by the confluence of the inferior petrosal sinus and the sigmoid sinus. The IJV descends in the carotid sheath with the internal carotid artery. The vagus nerve (CN X) lies between the two. After receiving tributaries from the face and neck, the IJV continues to descend into the thorax, usually between the heads of the sternocleidomastoid muscle, before uniting with the subclavian vein to form the brachiocephalic vein. 11 The anatomy of the jugular vein and surrounding structures is depicted in ▶ Fig. 8.2.
8.2.3 Femoral Vein Anatomy
The femoral vein is the main deep vein of the lower limb, and travels next to the superficial femoral artery and common femoral artery. The femoral vein forms the continuation of the popliteal vein at the adductor opening, and becomes the external iliac vein as it ascends posterior to the inguinal ligament. In the distal adductor canal, the vein is posterolateral to the superficial femoral artery. Proximally in the canal, the vein lies posterior to the artery in the distal femoral triangle and medial to the artery at the base of the triangle. In the upper thigh, the vein is between the common femoral artery and femoral canal and therefore occupies the middle compartment of the femoral sheath. 12 The anatomy of the femoral vein and surrounding structures is depicted in ▶ Fig. 8.3.
8.3 Indications
There are a few generally agreed upon indications for placing a central line. These include:
Inadequate peripheral venous access
Rapid fluid resuscitation (requires an introducer sheath or other large bore catheter)
Special drug administration such as vasopressors or hypertonic saline
Need for total parenteral nutrition administration
Invasive hemodynamic monitoring
Pulmonary artery catheter placement
Transvenous pacing
Renal replacement therapy 8
Intravascular cooling
8.4 Contraindications
The following are relative contraindications to central line insertion:
Coagulopathy, platelet dysfunction, and thrombocytopenia
Local infection at site of placement (i.e., cellulitis)
Thrombosis or stenosis of vein to be accessed
Traumatized or burned site of insertion
The following are relative contraindications specific to subclavian central line insertion:
Hemothorax or pneumothorax contralateral to the insertion site
Tenuous pulmonary status
8.5 Equipment
To begin with, each intensive care unit (ICU) should have a central line “kit” that should be available at any time. Specific equipment will vary depending on the type of catheter being inserted. The following equipment is used for the insertion of a nontunneled triple lumen central line:
Sterile gown
Sterile gloves
Ultrasound probe cover/gel
1% lidocaine with two syringes and needles (22 and 25 gauge)
18-gauge introducer needle with 5 mL syringe
Guidewire
Triple-lumen indwelling catheter 7 French, 20 cm
Tissue dilator
Sterile flushes
End caps
Catheter clamp and fastener
Antibacterial patch
Scissors
Needle driver
Occlusive dressing
Gauze
3.0 silk suture
8.5.1 Catheter Types
Central venous catheters may be tunneled or nontunneled. Tunneled catheters are used when it is anticipated that the catheter will be needed for longer than 3 to 4 weeks. Tunneled catheters have a lower rate of infectious complications 9 because of the distance between the skin entry site and the venotomy. Although they provide reliable long-term access, their complications include thrombosis, occlusion, and infection. 10 Nontunneled catheters are primarily used for short-term access in the emergency department, operating room, and ICU. These types of catheters are generally easier to place than tunneled catheters. 9 Nontunneled catheters have a higher rate of infectious complications and should generally be removed or exchanged after 5 to 7 days. 11
There are many different models of central venous catheters, including single, dual, and triple lumen catheters, as well as introducer sheaths. Triple lumen catheters are generally preferred for ICU patients requiring multiple ports of access for medication administration. Introducer sheaths are required for rapid fluid resuscitation, transvenous pacing, or insertion of a pulmonary artery catheter. Specialized catheters with at least two large diameter ports are required for renal replacement therapy.
8.6 Technique
The steps below pertain to the insertion of a nontunneled triple lumen central venous catheter.
General steps for ultrasound-guided placement:
Connect ultrasound machine to a power source.
Select a linear vascular probe and confirm orientation (i.e., tap the left side of the probe and this should correspond with left side of the screen).
Examine target vein. Make sure vein is compressible, easily visualized, and centered on the screen.
Start with the short-axis view (probe perpendicular to the path of the vessel), as depicted in ▶ Fig. 8.4. Introduce the needle at a 45-degree angle and advance toward the vessel under direct visualization while applying gentle negative pressure to the syringe, as depicted in ▶ Fig. 8.5.
Once the vessel is entered blood will fill the syringe. At this point the probe can be rotated 90 degrees so that it is parallel to the path of the vessel to obtain the longitudinal view, as depicted in ▶ Fig. 8.6. This view can help confirm the location of the needle and visualize the guidewire entry into the lumen of the vessel, as depicted in ▶ Fig. 8.7.
8.6.1 Subclavian Vein Technique
Numerous landmarks have been described for determining the needle insertion site, as depicted in ▶ Fig. 8.8. 13 , 14 , 15 The following are some of the options mentioned, any of which will work:
1 cm inferior to the junctions of the middle and medial third of the clavicle
Inferior to the clavicle at the deltopectoral groove
Just lateral to the midclavicular line, with the needle perpendicular along the inferior lateral clavicle
One finger breadth lateral to the angle of the clavicle
In general ultrasound guidance is not necessary for subclavian vein cannulation, although it may be helpful to inspect the vein with ultrasound prior to insertion to confirm that it is not stenotic or otherwise anatomically aberrant.
Place the patient in Trendelenburg position and place a shoulder roll under the shoulder on the side of insertion. This will help elevate the chest area.
Turn the patient’s head to the contralateral side.
Open the central line kit and confirm that all needed equipment is easy to reach for each step.
Retract the curved J-tip wire into the plastic loop sheath to facilitate placement into the introducer needle.
Flush the catheter and place caps on all lumens except the distal-most port which will need to remain open for passage of the guidewire.
Sterilize the insertion site. The sterile area should be wide including the neck, chest, and shoulder.
Don sterile mask, gown, and gloves.
Drape the patient in a sterile fashion, with the insertion site exposed.
Draw up the lidocaine 1% and infiltrate the skin, subcutaneous tissue, and the clavicular periosteum. It is especially important to anesthetize the periosteum as needle contact with the clavicle is the greatest source of pain during the procedure.
Position the bevel of the introducer needle in line with the numbers on the syringe. While inserting the needle and syringe, orient the bevel upwards.
Insert the introducer needle at the predetermined and chosen landmark; this is done while gently withdrawing the plunger of the syringe throughout the advancement.
Once the needle makes contact with the clavicle, carefully depress the needle to slide it underneath the bone.
Once under the clavicle, the needle should be carefully reoriented toward the suprasternal notch, aspirating on the syringe.
A flash of venous blood indicates entry into the subclavian vein.
When venous blood is freely aspirated, disconnect the syringe from the needle, and observe for steady, nonpulsatile flow of blood.
If pulsatile arterial blood flow is observed, remove the needle and manually compress the infraclavicular fossa.
If there is any uncertainty as to whether the vein or artery has been punctured, the needle can be connected to intravenous (IV) tubing in order to visually estimate or transduce the hydrostatic pressure in the vessel.
After confirming puncture of the vein, insert the guidewire through the needle into the vein with the J-tip directed caudally.
Advance the wire by approximately 30 cm (often indicated by three hash marks on many wires).
The operator or an assistant should observe the patient’s heart rhythm at this point in the procedure and the wire should be slightly withdrawn if there are premature ventricular contractions.
Holding the wire in place, withdraw the introducer needle and place it in a safe location.
One hand should remain on the wire at all times until it is withdrawn after placement of the catheter.
Use a scalpel to make a small stab incision just against the wire to enlarge the catheter entry site.
Thread the dilator over the wire and through the skin and subcutaneous tissue to a depth of several centimeters with a gentle twisting motion.
Remove the dilator and thread the catheter over the wire until it exits the distal-most port.
Grasp the wire and continue to thread the catheter to the desired depth. Generally, if entering the right subclavian vein, the length of catheter inserted should be 15 cm, and for the left subclavian vein it should be 18 cm.
Once at target depth, remove the wire and place a cap on the distal-most port.
Attach a syringe to each port and confirm that blood can be readily aspirated.
Flush each port with saline.
Suture the catheter in place and apply a sterile dressing.
A chest X-ray should be obtained to confirm appropriate placement and to rule out pneumothorax.
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