Vascular Tunneled Central Catheter Access

Anatomy and Physiology

Central venous access is obtained via the internal jugular (IJ), subclavian (SC), and femoral veins. 

The internal jugular vein is a paired vessel that collects blood from the head, face, and neck and delivers it to the superior vena cava (SVC). It runs within the carotid sheath alongside the common carotid artery and the vagus nerve. The IJ begins at the jugular foramen and travels lateral to the internal and common carotid arteries, terminating at the innominate vein. The right IJ makes a straight line from the brachiocephalic vein to the SVC and is often preferred for central venous access; however, the left IJ takes a more acute angle as it joins the left innominate and again as the innominate joins the SVC. The mean diameter is 10 mm but may range between 5 mm and 35 mm. Placing the patient in the Trendelenberg position can increase the size of the IJ to allow for easier cannulation. The IJ is easily accessed at the apex of the Sedillot triangle, bordered medially by the sternal head of the sternocleidomastoid (SCM), laterally by the clavicular head of the SCM, and inferior by the clavicle.[1]

The subclavian (SC) vein is a large, paired vein that drains blood from the bilateral upper extremities. It runs from the outer border of the first rib to the medial border of the anterior scalene. At this point, it joins the IJ to form the innominate (brachiocephalic) vein. It is separated from the subclavian artery by the anterior scalene. The average diameter is 10 mm to 20 mm. Placing the patient in the Trendelenburg position also increases the diameter of this vein and minimizes the risk of a venous embolus formation. The SC vein is accessed 1 cm to 2 cm inferior and lateral to the clavicular transition point - the flat, lateral two-thirds of the clavicle.[1] The pleura and subclavian artery are in danger of puncture during this approach. As opposed to the IJ, the left SC vein is the preferred access due to its less acute angle to the SVC. 

The femoral vein is also a large, paired vein that drains the bilateral lower extremities. It travels medially to the femoral artery in the femoral sheath. The femoral vein is a continuation of the popliteal vein and begins at the adductor hiatus within the adductor magnus. It becomes the external iliac at the inferior margin of the inguinal ligament. Access for CVCs occurs at the common femoral vein, which is located halfway between the anterior superior iliac spine (ASIS) and pubic symphysis, below the inguinal ligament. The average diameter of the common femoral vein is 11 mm to 15 mm. Non-tunneled CVC femoral access is favored during emergent placement, especially during cardiopulmonary resuscitation (CPR) and intubation.[1] Traditionally, femoral access has been associated with a higher risk of central line-associated bloodstream infection (CLABSI).[2][3] However, tunneled femoral catheters are viable options in patients who have exhausted other vascular accesses.[4]

Knowledge of the surface anatomy is usually enough to cannulate the blood vessel of choice; however, the use of ultrasound has been shown to reduce complications rates, including hematoma, arterial access, pneumothorax, and central line infection.[5]

Indications

Tunneled CVCs with a subcutaneous port require cannulation of the IJ or SC veins. Because the catheter and port are entirely under the skin, they can be left in place for months with proper handling and care. They allow patients to live normal lives, including swimming and bathing, without concern for damage to the catheter or infection. It is most commonly used for infusion of medication, transfusion of fluids and parental nutrition, and long-term venous access in those with poor peripheral access.[6] The port should be placed at least two weeks before beginning chemotherapy to allow for healing at the insertion sites. Specific atraumatic needles are required for port access to prevent damage to the silicone septum. This extends the life of the port and prevents thrombosis and infection of the tunneled CVC.[6]

Tunneled CVCs without a subcutaneous port are externalized through a separate skin incision a distance from the venous cannulation site. They are used most frequently for hemodialysis (HD) with higher prevalence in those of advanced age at initiation of HD, those with comorbid vascular disease, those awaiting arteriovenous fistula (AVF) maturation, those scheduled for living donor renal transplant, and those that have not decided between HD and peritoneal dialysis.[7] The right IJ is the preferred location, followed by the left IJ. Ideally, the catheter should be placed in the side opposite the planned or maturing AVF. The common femoral vein can be used when there is stenosis or occlusion of the central veins. SC vein access should be avoided because of the increased incidence of central venous stenosis, which would compromise AVF function.[7][8]

Contraindications

Relative Contraindications

Relative contraindications for placement of tunneled CVCs on the chest wall include neoplasm, burn and/or trauma, and patients with cystic fibrosis requiring chest physical therapy. In these patients, a subcutaneous port may be placed on the upper arm (although this is associated with a greater risk of thrombosis),[6] and femoral access can be used for dialysis. Another relative contraindication includes mild to moderate coagulopathy. When possible, this should be corrected before catheter placement to prevent bleeding and hematoma formation.

Thrombosis can be considered a relative contraindication. If a CVC exists within a thrombosed vein, infused thrombolytics and/or interventional radiological procedures can be performed to break up and remove the clot.[6][7] Care must be taken when placing a new catheter within a partially thrombosed vein to prevent embolism. Placement should be performed under fluoroscopy to confirm the patency of the vessel and placement of the catheter. Catheter placement tunneled or otherwise, should be avoided in fully occluded veins. 

Absolute Contraindications

Severe, uncorrectable coagulopathies, uncontrolled sepsis, and/or bacteremia are absolute contraindications to the placement of all tunneled CVCs. In these patients, a temporary, non-tunneled catheter should be placed until the coagulopathy can be corrected or the infection clears. If a patient has a tunneled catheter and later develops sepsis secondary to bacteremia, the recommendation is to remove the CVC.[6][7]

Equipment

To decrease the risk of infection, a full sterile technique should be employed. This includes a head cap, face mask, sterile gown and gloves, and use of a full-size sterile drape, covering the insertion site and distal exit site. A skin prep of either chlorhexidine or povidone-iodine should be used to thoroughly clean and sterilize the skin. A local anesthetic is used to numb the site of venous cannulation as well as the path the tunneler will take along the subcutaneous tissues, and, if used, at the site of the skin pocket for the subcutaneous port. While the landmarks described above can be used for venous cannulation, ultrasound, with a sterile cover, is recommended for identification and cannulation of the vein. X-ray with or without fluoroscopy is also necessary to confirm the final placement of the catheter tip within the cavoatrial junction. Most tunneled catheters come as a complete kit containing an introducer needle, which has a special radiopaque tip to enable visualization on ultrasound, multiple syringes, a guide-wire, a dilator, and a peel-a-way sheath, as well as a catheter and tunneling device. A suture is needed to close the venous access site and, in the case of HD catheters, secure the catheter to the skin at the exit site. An absorbable suture is typically used to close the skin over the subcutaneous port site. Sterile saline is needed to prime the catheter before placement as well as to aspirate and flush the catheter once placed. Heparinized saline can also be used to flush the catheter. A sterile dressing of either gauze or a transparent, semipermeable dressing can be used to cover the exit site of HD catheters. Skin glue can be used to cover the incision overlying the subcutaneous ports.

Personnel

Tunneled CVCs are typically placed by general or vascular surgeons or interventional radiologists (IR). If the surgeon or radiologist is not certified in conscious sedation, then an anesthesiologist or anesthetist should be present. When performed in an operating room, a scrub technician or registered nurse should be present and scrubbed in to assist. When performed by IR, a scrubbed technician is also required for assistance. An additional registered nurse should also be present in both the operating room and IR suite to monitor patient care and ensure all equipment is available. If the operating room does not have radiographic capabilities, an X-ray/fluoroscopic technician should be present to provide the required visualization for catheter placement.

Preparation

As with all surgical procedures, a good history and physical should be obtained to identify risk factors for the procedure. Though this is considered a low-risk procedure, those patients with significant cardiac history may require cardiac risk stratification and medical optimization before undergoing surgery. It is important to identify possible coagulopathies to correct and prevent complications post-operatively.

The patient's history should be taken into account when deciding which venous access to use. If the patient has a history of kidney disease, subclavian access may not be the best choice for that patient.

An adequate physical exam can reveal sites of previous venous access, cellulitis, underlying trauma, or physical limitations that would prevent safe venous access. 

Basic laboratory work including a complete blood count (CBC), basic metabolic panel, and coagulation studies should be ordered and reviewed preoperatively. Correction of electrolytes and coagulation should occur before surgery. 

A chest x-ray and electrocardiogram should be considered preoperatively in patients with associated risks: smoker, lung cancer, chronic kidney disease or acute renal failure, electrolyte abnormalities, cardiac history. 

The chest should be mapped with the patient standing to determine the best exit site for HD catheters and subcutaneous port sites. Concurrently, body habitus should also be assessed to determine the easiest, safest, and cleanest venous access sites. 

Also, a conversation with the patient's referring clinician should occur preoperatively to determine what type of tunneled catheter and the number of lumens required by the referring clinician.

Technique or Treatment

The following technique describes an internal jugular (IJ) vein catheter tunneled to the chest wall, commonly found in dialysis patients while awaiting maturation of their AV fistula. 

As stated above, the IJ is easily accessed at the apex of the Sedillot triangle, bordered medially by the sternal head of the sternocleidomastoid (SCM), laterally by the clavicular head of the SCM, and inferior by the clavicle.[1] The patient should be placed in the Trendelenburg position to increase the size of the IJ for easier cannulization. In the posterior approach, the finder needle is placed at the posterior border of the SCM, one-third of the way from the sternoclavicular joint to the mastoid process. At this point, the external jugular vein usually crosses the SCM and can serve as a useful landmark. The needle is inserted about 1 cm to 1.5 cm beneath the skin at an angle of 30° to 40° off the skin and advanced toward the ipsilateral sternoclavicular joint. The operator should be continuously aspirating on the finder needle and syringe to prevent an air embolism and properly identify cannulization of the vein. Once venous access is obtained, the syringe is removed, leaving the needle within the IJ. A guidewire is then passed through the needle into the IJ. Fluoroscopy is used to confirm the correct placement of the wire within the IJ proximally and the SVC distally. The finder needle is then removed, leaving the wire in place.

Using a scalpel, a small, 0.5 cm incision is then made in the skin at the insertion site. Two dilators of increasing size are passed over the wire under fluoroscopy; the second dilator contains a peel-away sheath, which is left in place after the dilator is removed. At all times, care must be taken to maintain control of the guidewire. A marking pen is used to mark the catheter exit site (or subcutaneous port site), which is then incised with a scalpel. The catheter length is then measured to ensure the tip of the catheter will reside at the cavoatrial junction. Using a tunneler with a tapered tip at one end and the catheter attached at the other end, the catheter is tunneled along the subcutaneous tissue from the chest wall over the clavicle and toward the neck. The catheter is then detached from the tunneler and fed through the sheath. Care must be taken not to twist the catheter when placed through the sheath as this can cause kinking and flipping of the catheter. Afterwhich, the sheath is peeled away from the catheter with care taken not to dislodge the catheter. The location of the catheter tip is then confirmed with fluoroscopy. 

The catheters are aspirated and flushed with saline (or heparinized saline) to confirm good inflow and outflow. The catheter is then locked with heparin. The neck incision is closed with a single subcuticular 4-0 monocryl stitch. The catheter is secured with two interrupted non-absorbable stitches (this writer prefers 3-0 braided nylon). 

Post-procedure, a chest X-ray is ordered to confirm the correct position of the catheter tip at the cavoatrial junction and assess for a postoperative pneumothorax.

When using ultrasound for venous access, the IJ will typically appear overlying the carotid artery. When in the Trendelenberg position, the vein will generally appear larger than the artery. To clearly distinguish the vein from the artery, pressure should be applied to the ultrasound probe. This will result in compression of the IJ; however, the artery will stay circular and pulsatile. When cannulating the vein, the tip of the needle should be visualized at all times to prevent arterial or pleural injury. Depending upon the ultrasound device in use, color Doppler can also be used to distinguish the artery from the vein.

Complications

Immediate

Immediate complications are those occurring within the first 30 days of placement. These include bleeding, air embolism, pneumothorax, wound dehiscence, catheter migration and malposition, cardiac perforation and arrhythmias, and infections. Historically, the most common complication is arterial puncture and subsequent hematoma formation, although this has decreased significantly since the start of more routine ultrasound guidance.[6] The overall risk of pneumothorax has also improved with the increased availability of ultrasound guidance. 

Minor bleeding at the catheter exit site can be expected. Less than 0.1% of patients require transfusion secondary to prolonged oozing. Patients should be placed in an upright position to decrease central venous pressure.[7] If secondary to a coagulopathy, this should be corrected. In patients with renal disease, consider uremic bleeding and administration of desmopressin.[7] When placing subcutaneous ports, pocket hematomas should be evacuated when large as they place excess tension on the overlying skin, risking dehiscence, and skin necrosis. They can also make accessing the port difficult.[6] 

Cardiac complications occur when the catheter tip is placed incorrectly. Placement should be at the cavoatrial junction to prevent cardiac arrhythmias, cardiac rupture, catheter thrombosis, migration. If the catheter is placed too high above this junction, it can potentially flip (spontaneously redirect) into the IJ or brachiocephalic veins.[6] 

An air embolism is an extremely rare acute complication of any CVC placement. The negative pressure of the thoracic cavity during respiration has the potential to suck air into the central veins. The occurrence is roughly 0.2%-1% of patients receiving a CVC.[9] The severity varies from asymptomatic to complete cardiac collapse, depending on the size and final location of the embolism. A "millwheel" murmur can be heard on precordial auscultation. Treatment involves placing the patient in Trendelenberg and left lateral decubitus position, followed by aspiration through the CVC to decrease the amount of air within the heart and pulmonary circulation.[9]

Long Term

After 30 days, complications are usually infections or thrombosis. Infection can occur at the skin pocket (in subcutaneous ports), along the tunnel tract, or within the catheter, known as central line-associated bloodstream infection (CLABSI).

CLABSI is a diagnosis of exclusion or by differential time to positive blood cultures. In stable patients with suspected port infection, antibiotic salvage can be attempted. This consists of broad-spectrum intravenous antibiotics until a specific organism is determined on culture. An antibiotic lock can be used to augment this therapy, which entails a high concentration of antibiotic-heparin solution infused into the catheter between each use.[6]

The use of antibiotic locks has been associated with decreased rates of CLABSI.[7] Proper care should also be taken when accessing the tunneled CVCs. For subcutaneous ports, access should be performed under sterile/clean conditions, and the dressings changed in the same fashion. Dialysis catheters should also be accessed under sterile/clean conditions. Antibiotic ointment can be applied to the exit site to prevent local skin infection.[7]

Stenosis and thrombosis generally form secondary to two main processes including vein wall trauma causing stenosis or occlusion of the host vein and intravascular protein and cell wall deposition causing thrombosis of the catheter tip. The second process begins almost immediately after placement.[6] Using a "locking solution" of sodium citrate or concentrated heparin can prevent catheter thrombosis. There are no differences between the two solutions in terms of preventing thrombosis; however, bleeding rates and biofilm characteristics are lower with sodium citrate.[7] Traditionally speaking, subclavian catheters have a higher rate of stenosis.

Trauma to the venous wall can occur secondary to the medications infused through the line, chemotherapy being the most caustic, and/or from the velocity of blood traveling in and out of the vein, such as in the case of HD catheters. A cohort study completed in London followed patients undergoing HD through their entire HD career, an average of 4.7 years. Approximately 4.3% were affected by central venous stenosis. Of those with a history of tunneled CVC, the incidence rate for central venous stenosis was found to be 2.2 per 100 patient-years.[8] Only a quarter of patients were found to be symptomatic, and those noted to have bilateral disease were more likely to be symptomatic. This study also found a greater risk of stenosis with left-sided catheters likely due to the more angulated and narrower course of the left brachiocephalic vein.[8]

A Canadian cohort study of 1,041 adult patients who initiated outpatient maintenance hemodialysis therapy with tunneled CVCs demonstrated complications of catheter malfunction (15%), bacteremia (9%), and central stenosis (2%) at 1 year. Interestingly, compared to patients younger than 60 years, patients aged 70-79 and those 80 years or older experienced lower rates of CVC complications.[10]

Clinical Significance

Non-tunneled CVCs are typically used for urgent/emergent access, whether that is for hemodialysis or resuscitation. The preferred insertion site, in the setting for acute kidney injury, is the right IJ, followed by the femoral vein. However, if the patient is obese, the left IJ is generally preferred over the femoral vein as it decreases the risk of CLABSI.[7] Non-tunneled catheters should be removed immediately if there is evidence of surrounding skin infection or CLABSI. For those patients that will need chronic hemodialysis, permanent access is preferred, rather than a non-tunneled catheter. For those that require long-term infusions, conversion to a tunneled subcutaneous port or peripherally inserted central catheter should be performed sooner rather than later. 

Tunneled CVCs are commonly used for hemodialysis (HD) access. While an arteriovenous fistula (AVF) is the preferred access for HD, tunneled catheters may be used in those requiring HD for at least three weeks while awaiting maturation of an AVF, while planning peritoneal dialysis, when awaiting a living donor transplant, or when no other access is possible. Several dual-lumen, large-diameter catheters are available.[7] They may be made of polyurethane elastomers or silicone. Multiple catheter designs exist with no difference in overall performance. Sterile technique is necessary at both catheter insertion and removal. The preferred site for a tunneled CVC is the right IJ, followed by the left IJ. Ideally, that catheter should be inserted on the opposite side of the future AVF. Subclavian (SC) veins should be avoided due to the increased risk for venous stenosis. Exit-site care is extremely important in reducing CLABSI.

Tunneled CVCs with subcutaneous ports are used for those patients requiring chronic, intermittent intravenous therapies; this includes cancer patients and those requiring prolonged parenteral nutrition. When used appropriately, these ports fulfill their requirements with low rates of infection (0.1 bloodstream infections/1000 catheter days). With the routine use of ultrasound and fluoroscopy, the short-term complications of composition, hematoma formation, and pneumothorax are minimal.[6]

Enhancing Healthcare Team Outcomes

The decision to insert a tunneled CVC into a patient is not without risk, which should be discussed with both the patient and the care team. First, the interprofessional care team needs to decide whether a tunneled CVC is necessary for the patient. Then, the patient must fully understand the reason for the catheter and the challenges that can occur as a result.

On the topic of subcutaneous ports, the oncologist must first decide whether the patient will undergo chemotherapy, whether that therapy will be oral or intravenous, when the chemotherapy will start, and how long the chemotherapy will last. While not discussed in this paper, a peripherally inserted central catheter (PICC) could be an option, with less risk, if the chemotherapy is planned for a few weeks to months. 

Perhaps the patient would benefit from radiation first, as decided by the radiation oncologist, thus delaying port placement until radiation is completed. This should be determined by the patient's oncological team before a surgical or IR referral. Once it is decided to start intravenous chemotherapy, the port should be placed at least two weeks before the start of chemo to prevent a wound complication; this requires a conversation between the oncologist and the surgeon to ensure appropriate timing and placement of the correct subcutaneous port with the correct number of lumens. During pre-admission testing, any concerning medical history should be flagged for further workup by the surgeon, anesthesia, and nursing. During the procedure, the team in the operating room works to ensure patient safety and successful outcomes. The patient is instructed on appropriate post-operative care which includes keeping the wound clean and dry, protecting the port against injury, and if accessed, maintaining a clean, impermeable bandage over the access needle. 

Will the infusions occur daily, weekly, monthly? Will the patient go to the office or an infusion center? What will the patient's insurance cover? Does the patient have appropriate transportation to and from their appointment? These questions require an interprofessional team made up of doctors, nursing case managers, and social workers. Maintaining sterility and catheter function is dependent upon the infusion nurses using appropriate techniques and instruments when accessing the port. The entire team, including the patient, should be vigilant for signs of early infection to prevent significant morbidity and mortality.