Chapter 93: Central Venous Access

Central venous catheterization is a commonly performed procedure and is an essential skill for critical care physicians. Common indications for placement of a central venous catheter (CVC) include hemodynamic monitoring, lack of peripheral venous access, administration of vasoactive agents, nutritional support, and long-term vascular access. Although traditionally performed by emergency and critical care physicians, anesthesiologists and surgeons, it has been shown that with proper training, this procedure can be safely performed by advanced practice practitioners such as nurse practitioners and physician assistants.¹

Central venous catheter placement can be attempted via two methods: surface landmark approach or using real-time ultrasound guidance. While the landmark method is the traditional approach taught, real-time ultrasound guided CVC placement has emerged as the preferred and recommended practice, and is endorsed by majority of quality assurance agencies and professional societies. Knowledge of surface and deep anatomy is crucial in minimizing complications related to placement of internal jugular, subclavian, and femoral venous catheters.

Internal Jugular Vein

The internal jugular (IJ) vein is formed by the inferior petrosal sinus and sigmoid sinus. It forms the brachiocephalic vein after it runs under the clavicle at the level of the sternum. The IJ vein, internal carotid artery and vagus nerve form the carotid sheath which runs under the sternocleidomastoid muscle. The IJ vein runs anterolateral to the common carotid artery, however it may be directly anterior to the common carotid artery on the right side in 26% and in 20% on the left side.² The right IJ vein follows a direct course to the superior vena cava (SVC) joining the right subclavian vein and forming a short and steeply angled right brachiocephalic vein. The left IJ vein forms a longer and shallow angled left brachiocephalic vein as it joins the left subclavian vein. The right IJ vein is larger than the left IJ vein given its direct relationship with the right ventricle.

Subclavian Vein

The subclavian vessels are a valveless continuation of the axillary veins. Similar to the IJ veins, the path of the right and left subclavian veins is not symmetrical. The right subclavian vein forms an angled arc as it merges with the right IJ vein forming the right brachiocephalic vein which enters the SVC, whereas the left subclavian vein merges into the left brachiocephalic vein along a shallow trajectory. The subclavian vein lies posterior to the clavicle after crossing the first rib. This isolated region is the only area where the subclavian vein directly communicates with the clavicle. The subclavian artery runs superior and posterior to the subclavian vein. The subclavian artery and vein are separated by the anterior scalene muscle. The phrenic nerve also runs over the lateral aspect of the anterior scalene muscle. The apices of the lungs may reach as far as the first rib.

Femoral Vein

The femoral vein is located in the femoral triangle (of Scarpa). The femoral triangle is a subfascial space secured superiorly by the inguinal ligament, medially by the medial border of the adductor longus muscle, and laterally by the medial border of the sartorius muscle. The femoral vein lies medial to the femoral artery. The femoral nerve travels down the leg lateral to the femoral artery. The pneumonic NAVEL (nerve, artery, vein empty space, and lymphatics) is commonly used to remember the location of the femoral structures from lateral to medial. Cannulation of the femoral vein is performed below the inguinal ligament. Femoral anatomy is the least complex when compared to the neck and the subclavian spaces especially as the course of the femoral veins is symmetric unlike the locations mentioned above. It is important to note that as the femoral vein progresses distally, the artery and vein may rotate on each other and the femoral artery may lie anterior to the vein.

General Considerations

Successful placement of a CVC requires careful pre-procedure setup and patient assessment. A recent complete blood count and coagulation profile should be available to ensure that the platelet count is > 50,000 and the prothrombin time/International Normalized Ratio (INR) is < 2.0 and the activated partial thromboplastin time (aPTT) is < 50 seconds. Consent must be obtained from the patient or a healthcare agent and discussion of the risks, benefits and alternatives to CVC placement must be documented.

Equipment

Typically central venous catheters are available in a prepacked sterile kit (Figure 93–1). “Bundling” has demonstrated a reduction in central line-associated bloodstream infections (CLABSI).³ It is important to choose a catheter that has the correct lumen size to deliver medications, blood products, and length to reach the cavoatrial junction. Remember to “know your kit” and the structure of the catheter.

After pre-procedure laboratory values, consent, and ultrasound (US) imaging have been reviewed, the site of cannulation must be selected. The insertion site must be tailored to the patient’s anatomy and clinical scenario. It is advisable to choose insertion sites with easily identifiable anatomical landmarks. If an ultrasound is available, we recommend performing a pre-procedural bedside US survey or reviewing previously obtained US images to evaluate the selected site’s anatomy and vessel patency. Sites with anatomical defects, infections, masses, or areas of recent surgery or trauma should be avoided. Table 93–1 lists the advantages, disadvantages, and complications associated with each anatomical site.

Position the patient to gain optimal access to the vessel. In all cases, the patient should be placed at a height and position comfortable for the operator.

Internal Jugular Vein

The patient should be placed in a flat supine Trendelenburg position (lower extremities higher than the head) in order to engorge the vein and create a larger target. Additionally, this decreases the risk of an air embolism. The head should be turned to the contralateral side to expose the neck and landmarks. Too generous contralateral rotation of the neck can impede cannulation as the sternocleidomastoid muscle may move into an anterior position over the IJ vein hindering cannulation.⁴ Rotation beyond 40° increases the risk of arterial puncture as overlapping of the IJ vein with the carotid artery occurs.⁵ Generally rotating the neck by an angle of 15° to 30° to the contralateral side allows for optimal vessel access and does not increase the risk for arterial cannulation. Pillows should be removed from under the head in order to extend the neck.

Subclavian Vein

The patient should be placed in a flat supine Trendelenburg position with the head in a neutral position. Many authors have argued that a roll placed between the scapulae in order to elevate the subclavian vessels anteriorly and widen the sternoclavicular angle. However, magnetic resonance imaging studies have demonstrated that placing a roll between the scapulae leads to compression of the subclavian vein between the first rib and clavicle hindering cannulation. The arm should be placed adducted to the torso.

Femoral Vein

The patient should be placed in a flat supine reverse Trendelenburg position with the targeted side’s leg slightly abducted and rotated laterally at the hip.

Maximal sterile barriers should be used when central venous cannulation is attempted to decrease the risk of CLABSI. These include using a cap, mask, sterile gown, gloves, and a sterile full-body drape. Chlorhexidine has been shown to be the most efficacious antiseptic.⁶ The exposed cutaneous surface should be coated with chlorhexidine thoroughly prior to cannulation.

Prepare the catheter by flushing each lumen it with sterile saline. Anesthetize the cannulation site using 1 to 2 ml of 1% lidocaine or equivalent with a 25-gauge needle. Attach a 10-ml syringe to the finder/introducer needle and puncture the skin applying constant negative pressure approaching the target vessel (ultrasound or landmark-guided). As the needle enters the vessel lumen, blood enters the syringe. Ensure that blood is aspirated with good flow. Sluggish blood flow with aspiration suggests that the needle tip is not optimally positioned in the vessel lumen. Stabilize the hub of the needle and remove the syringe. Ensure that the blood flow from the needle is nonpulsatile. Bright red pulsatile blood flow suggests arterial cannulation; however, in states of hemodynamic compromise arterial cannulation may mimic venous cannulation (dark red nonpulsatile blood). Place your thumb over the needle hub to minimize the risk of air embolism before passing the guidewire.

If arterial cannulation is suspected, send a blood gas and compare the results with a confirmed arterial blood gas. Alternatively, introduce the flexible distal end of the guidewire into the cannulated vessel and directly visualize the guidewire in the vein with the ultrasound. Placing a single lumen 18-gauge angiocatheter over the guidewire and then connecting the catheter to a pressure transducer can also confirm venous cannulation in the presence of a transduced venous waveform and pressure. A simpler method of transducing venous pressure can be achieved by using standard IV tubing or the guidewire sheath as a manometer. Connect the IV tubing or remove the connectors of the guidewire sheath and uncurl the plastic guidewire sheath. Attach the IV tubing or uncurled guidewire sheath directly to the hub of the angiocath. The operator should hold the IV tubing or sheath vertically and wait for a blood column to rise in the sheath. If the angiocath is in the vein, the blood column will rise and correspond to the central venous pressure and variate with the respiratory cycle. If the angiocatheter is in the artery, the blood column will fill the entire tubing.⁷ Venous cannulation must be confirmed prior to dilation of the soft tissue and vessel. Once venous cannulation is confirmed, introduce the soft end of the guidewire through the needle hub. The guidewire should thread smoothly without resistance. If resistance is met, do not force the wire, but remove it and attach the syringe to the introducer needle and aspirate blood and confirm that the needle tip is in the lumen of the targeted vessel. Retracting the needle slowly and changing the angle of entry may facilitate passing the guidewire. Ultimately, if the guidewire cannot be passed, new cannulation of the same vessel can be attempted or a new site should be chosen. Maintain control of the guidewire throughout the entire process.

Once the wire is placed in the vessel, make an incision at the level of the guidewire entering the skin to ease placement of the tissue dilator. Ensure that the incision completely enters the dermis and is about the width of the catheter. Firmly thread the dilator over the guidewire with a turning motion several centimeters into the vessel, as the dilator does need to be “hubbed.” Again, maintain control of the guidewire at all times. Remove the dilator and expect bleeding around the guidewire. Thread the central venous catheter over the guidewire and grasp the guidewire once it emerges from the distal port of the catheter. Advance the catheter into the vessel and remove the guidewire once the catheter has been placed at the correct depth. Remember to cover the open port with the thumb to minimize the risk of air embolization. Next aspirate and flush all ports of the catheter and suture securely into place using non-absorbable silk. Finally clean the skin around the entry site of the catheter, place a Biopatch^® and a simple transparent dressing. In the nonemergent setting for internal jugular and subclavian approaches, always confirm line placement with a chest X-ray and evaluate for immediate complications.

Internal Jugular Vein

Anterior Approach

Insert needle at an angle of 30° to 45° along the medial border of the sternocleidomastoid muscle 2 to 3 fingerbreadths above the clavicle aiming towards the ipsilateral nipple. Palpate the carotid artery during cannulation and direct the needle away from the carotid pulse.

Central Approach

Insert the needle at angle of 30° at the apex of the triangle formed by the sternocleidomastoid muscle. Direct the needle towards the ipsilateral nipple. Palpate the carotid pulse; the vein lies lateral to the artery.

Posterior Approach

Insert the needle at a 45° angle at the lateral border of the sternocleidomastoid muscle at the midpoint between the mastoid process and the clavicle. The operator should aim towards the suprasternal notch; note that the vein is accessed at a depth of approximately 7 cm.

Subclavian Vein

Infraclavicular Approach

The aim of this approach is to access the subclavian vein as it passes the first rib and travels under the clavicle. The operator places the index finger in the suprasternal notch and places the thumb at the costoclavicular junction. The skin is punctured approximately 2 cm below the junction of the medial two-thirds and the lateral third of the clavicle aiming towards the index finger. The operator “walks the needle” under the clavicle with vessel entry occurring at 3 to 4 cm. Note that entering the skin close to the clavicle makes it difficult to maneuver the needle tip below the clavicle. Prior to puncturing the skin, ensure that the bevel of the needed is pointed inferomedially as this will facilitate directing the guidewire towards the brachiocephalic vein rather than the opposite vessel wall or IJ vein. During cannulation, the risk of pneumothorax is highly dependent on the angle needle. Keeping the trajectory of the needle “parallel to the floor” decreases the risk of hitting the pleural dome and causing a pneumothorax.

Supraclavicular Approach

This less traditional approach to subclavian vein catheterization aims to access the subclavian vein as it meets the internal jugular vein superior to the clavicle. The clavisternomastoid angle is formed by the junction of the lateral head of the sternocleidomastoid muscle and the clavicle. The needle is inserted 1 cm posterior to the clavicle and 1 cm lateral to the lateral head of the sternocleidomastoid muscle and aimed towards the contralateral nipple at an angle. The needle tip is angled posteriorly 5° to 15° relative to the coronal plane, following this trajectory the vein is accessed between the clavicle and the anterior scalene muscle. Note the right-sided approach is often preferred given the absence of the thoracic duct and the direct route to the superior vena cava. Additionally the dome of the pleura is lower on the right.⁸

Femoral Vein

The aim of this approach is to access the femoral vessel below the inguinal ligament. The operator palpates the femoral artery pulse 2 fingerbreadths inferior the inguinal ligament and punctures the skin at 45° angle in a cephalad direction 1 cm medial to the femoral pulse. Alternatively, a line can be drawn between the anterior superior iliac spine and midpoint of the pubic symphysis. The femoral artery lies at the midpoint of this line with the corresponding vein 1 cm medial to it. Note that pressure on the femoral artery may distort the anatomy impeding cannulation. The depth of accessing the femoral vein is dependent on body habitus. In a normal sized adult, the vein can be reached at a depth of 2 to 3 cm.

In recent years, there has been a significant increase in the use of real-time ultrasonography as a safety-enhancing adjunct during CVC placement. With US guidance, anatomical variations that cannot be readily visualized and pathologies such as vessel stenosis and thrombosis can be detected. The two approaches in US guidance for CVC placement are the short-axis (SA) approach and long-axis (LA) approach. In the SA approach, the operator’s US probe is placed perpendicular to the target vessel with the indicator dot pointed to the left, in line with the position of the indicator dot on the US screen. The advantage of the SA approach is that the surrounding structure of the target vessel can be clearly visualized. The disadvantage of the SA approach is that the central line needle shaft can be mistaken for the needle tip on the US screen and as a result, the needle tip can advance beyond US visualization and cause posterior wall puncture. In contrast, in the LA approach, the operator places the US probe parallel and above to the target vessel with the indicator dot cranially. Thus, on the US screen, the left of the screen would represent the cephalic direction and the right would be caudal. The advantage of the LA approach is that the needle tip can be better visualized. However, the surrounding structure cannot be visualized since the US beam is only in line with the vessel. The SA approach is associated with shorter cannulation time while the LA approach is associated with decrease in incidence of posterior wall puncture.⁹ With either approach, a standard CVC placement technique such as sterile preparation and Seldinger technique as previously described should be employed.

Prior to sterilization of the site, the operator should examine the target area with US to determine the size and patency of the target vessel. Alternative target vessel should be selected if pathologies such as thrombosis or stenosis are noted (Figure 93–2). The US machine should be positioned at the ipsilateral side and across from the operator so that direct visualization of the US screen is maintained throughout the procedure (Figure 93–3). The operator should also scan the patient’s lung on the ipsilateral side of the procedure for lung sliding prior to procedure to establish the baseline condition (Figure 93–4). In the SA approach, the needle tip should be visualized at all time using the “creep” technique where the US probe is fanned ahead of the needle trajectory to maintain visualization.¹⁰ In the LA approach, the operator must secure the US probe so that the entire target vessel in a sagittal plane can be visualized. Visualization of the entire needle shaft and tip should be maintained during cannulation. The target vessel should be centered on the US screen in either approach and proper adjustments should be made to the depth and gain in order to optimize visualization under US.

Internal Jugular Vein

The internal jugular vein is beneath the sternocleidomastoid muscle and is lateral to the trachea and medial to the carotid artery (Figure 93–5). However, anatomical variations exist and the relative position of the vessel may vary. With US guidance, the carotid artery and internal jugular vein can be easily differentiated using direct visualization or with the aid of color flow and Doppler.¹¹ The needle should be inserted directly beneath the needle guide on the US probe and would appear as a hyperechoic object on the US screen. The US probe should be advanced as the needle is advanced so that the needle tip does not advance beyond the US beam and cause inadvertent posterior wall puncture. Once the needle tip is visualized within the vessel, the operator can release the US probe and proceed with the cannulation. After the guidewire is inserted into the vessel, the operator can use US to visualize the guidewire within the vessel to confirm placement prior to dilation of the vessel (Figure 93–6). After the completion of the procedure, lung sliding on the ipsilateral side can be evaluated using US to look for pneumothorax.

Subclavian Vein

Subclavian vein cannulation using US guidance is difficult technically due to the position of the clavicle in relation to the target vessel.¹² There are two potential approaches to cannulation: supraclavicular approach and infraclavicular approach. Concern for mechanical complications has limited the use of the supraclavicular approach.¹³ Although the US-guided infraclavicular approach is technically difficult, it has been shown to be safer than landmark approach in the hands of an experienced operator. Both the short axis (SA) and long axis (LA) approaches can be used. The US probe can be placed over the clavicle perpendicularly with indicator dot directed cranially, and the probe should be moved laterally. As the probe move towards the axilla, the subclavian vein and artery can be visualized to extend beyond the shadow created by the clavicle (Figure 93–7). Color flow and Doppler can be used to differentiate between the artery and vein. After identification of the target vessel, the vessel should be centered on US screen and the SA or LA approach can be utilized to cannulate the vessel. Due to the proximity of the lungs to the subclavian vein, extra attention should be paid to keep track of the needle tip since losing track can inadvertently result in a pneumothorax.

Femoral Vein

With US guidance, direct visualization of the femoral vein can facilitate CVC placement. The US probe should be placed transverse to the target vessel right below the inguinal crest. The common femoral vein should be in the medial position with the common femoral artery laterally positioned (Figure 93–8). Ideally, the CVC placement should be in the common femoral vein since it is proximal to the branching points and is largest in diameter. Compression of the vessel prior to cannulation attempt should be conducted to evaluate for common femoral vein thrombosis and an alternative site should be selected if there is a positive finding.

Immediate complications are of mechanical nature and related to operator technique and experience. It is important to know, recognize, and manage the immediate complications as they can become rapidly life-threatening in nature. Risk factors for immediate complications include operator inexperience, number of needle passes, and larger catheter size. Mechanical complications include puncture of adjacent artery, hematoma, air embolism, arrhythmia, pneumothorax pericardial tamponade, catheter/wire embolus, arteriovenous fistula, vessel obstruction, vessel perforation, pseudoaneurysm formation, catheter malposition, and catheter knotting.^{14,15,16,17,18,19} Subclavian vein catheterization has been associated with the highest risk of pneumothorax.

Major delayed complications include infection and catheter related thrombosis.^16,17,18,19 Some of the rarer late complications include delayed pneumothorax, and vascular and ventricular erosion or perforation, leading to hemothorax or pericardial tamponade. The incidence of delayed pneumothorax occurs around 0.5% to 2%. Time of onset can occur as late as 6 hours after the procedure. The type of damage caused by vascular erosion or perforation depends on the anatomical location of the vascular catheter tip. Erosion leading to pericardial tamponade can occur up to 0.2% of patients and erosion without pericardial tamponade occurs in 0.4% to 1% of patients.

Infectious complications from CVC placement is a significant cause of increased morbidity and mortality in hospitalized patients. The most common bacterial agents causing catheter-related infections are Staphylococcus aureus and Staphylococcus epidermis, both of which are natural skin flora. Infection can be caused by catheter contamination from skin flora, contamination from access port or hematogenous spread from other sites. The rate of infection is highest in the femoral site, followed by internal jugular, and finally the subclavian vein.¹⁹ Multiple attempts at CVC are associated with an increased incidence of CLABSI; this can be reduced with US guidance. Thus, professional societies recommend US guided CVC as the preferred method because of the lower incidence of CLABSI.

CVC-related thrombosis after 1 week range from 33% to 67%. There are 2 types of thrombosis: the first type forms as a fibrin sheath around the catheter resulting in the occlusion of the cannulated vessel, whereas the second type forms at the tip of the catheter. Cannulated vessels are at higher risk for thrombosis due to the disrupted endothelium resulting activation of the coagulation cascade. Platelet aggregation subsequently forms at the site of damaged endothelium forming thrombus. Risk factors for thrombus formation include small diameter of the target vessel, site of the cannulation, and difficult cannulation. Less common risk factors include external compression of the target vessel due to mass or tumor. The treatment of choice for catheter-related thrombosis is removal of the catheter and infusion of heparin or injection of low-molecular weight heparin. Instillation of fibrinolytics (eg, tissue plasminogen activator) can also be considered if the thrombus is suspected to be within the catheter lumen.