Applied Radiology

Peripherally inserted central catheters (PICCs) have become an important means of central venous access. PICCs originally were designed to be placed at the bedside, into visible antecubital veins.1 Today, they often are placed by a radiologist in patients without any visible arm vein.2,3 As radiologists become more involved in the placement of PICCs, they should be aware of the indications and proper technique for PICC placement, knowledgeable of the pitfalls to be avoided, familiar with the various characteristics of the multiple PICCs that are available, cognizant of the complications associated with PICCs, and able to manage patients once they have had a PICC placed. With these skills, radiologists will be able to provide safe, comfortable, and reliable venous access for a very large population of patients.

Venous anatomy

The veins of the upper extremity are grouped into superficial and deep components (figure 1). The two main superficial veins of the upper arm are the cephalic and basilic veins. The cephalic vein is a superficial vein which extends from the radial side of the wrist along the lateral aspect of the upper arm, traversing the pectral-deltoid groove to insert into the axillary vein. The basilic vein arises along the ulnar side of the forearm and extends to the shoulder, where it is joined by the deep brachial veins to form the axillary vein. The large superficial antecubital vein connects the cephalic and basilic veins at the elbow.

The brachial vein is the main deep vein in the upper arm and it is often paired. These veins course in a common fascial sheath with the brachial artery. The brachial vein is formed from the confluence of the radial, ulnar, and interosseous veins of the forearm. Normal brachial veins usually are small, as most of the blood flow is via the superficial veins.

Indications

The indications for placement of a PICC are broad (table 1). PICCs greatly improve patient comfort by avoiding the need for frequent vein punctures to maintain peripheral IV access or to draw blood.

Referring physicians appreciate the reduced risk of placing a PICC compared to placing a temporary subclavian or internal jugular line. PICCs are safe, reliable, and easy to care for, making them ideal for home IV therapy.

Contraindications

Though almost every patient is able to have a PICC, alternative access becomes necessary when a patient has no continuous arm vein, or has extensive burns or a diffuse dermatological disorder involving the upper extremities (table 2). Acute upper extremity deep venous thrombosis also is an important contraindication to PICC placement. Placement of a PICC in a paralyzed extremity or in the arm ipsilateral to a mastectomy is associated with an increased risk for developing severe thrombophlebitis. Chronic central venous occlusion is only a relative contraindication to placement of a PICC. Although superior vena cava (SVC) or subclavian vein occlusion may be present, a PICC can still be placed with its tip positioned just peripheral to the level of the occlusion.

Many patients referred for vascular access suffer from severe thrombocytopenia or anemia. In these patients, PICC placement may be the only reasonable option for venous access. Because most PICCs are placed into superficial veins in the arm, these catheters can be placed safely despite a moderate anemia or coagulopathy. However, a prothrombin time within 3 seconds of control, a hematocrit of 30%, and a platelet count of 100 K/uL is preferred.

Whenever possible, avoid using an upper extremity vein as an access site in patients with end-stage renal disease. Damaging an upper extremity vein may reduce the number of sites available for creation of hemodialysis fistulas.

All central lines can be a source of cellulitis, sepsis, or air embolization. These serious complications are less likely to occur if patients have a good support system at home. Therefore, it is important to determine who will be caring for the PICC prior to its placement.

Pre-procedure preparation

A good history and a directed physical examination are essential prior to PICC placement. A recent complete blood count, serum chemistries, prothrombin time, partial thromboplastin time, and electrocardiogram are helpful prior to placement of any central line, including PICCs.

The most important part of the pre-procedure evaluation is determining the indication for line placement and the planned duration of use. Choosing the correct type of line also is a very important component of the preparation process.

Types of PlCCs

There are a wide variety of PICCs available. No single design has been found to be clearly superior; rather, the catheter selection must be tailored to each individual patient.4

The catheter tips have two basic designs: end-hole and valved (Groshong-type) (figure 2). The most common style of catheter tip is the end-hole design. Its primary advantage is that it can be advanced coaxially over a guidewire. A staggered-tip, dual lumen end-hole catheter has one lumen exiting the catheter proximal to the catheter tip. This design allows for simultaneous infusion of incompatible substances. However, these catheters cannot be trimmed without sacrificing the staggered-tip.

The Groshong valve-tip (Bard, Salt Lake City, UT) has no end-hole but rather a slit near its tip that functions as a valve to prevent spontaneous back-flow of blood into the catheter. This design only requires saline to flush the catheter, thereby simplifying line care.5 Groshong-tip catheters also are valuable for patients with a known heparin allergy or heparin-induced thrombocytopenia.

One of the most important considerations in selecting a PICC is the minimum number of lumens required. Single lumen catheters are easier to maintain and provide a larger lumen, which allows for more rapid infusions or infusion of more viscous solutions (i.e., blood products). Whenever possible, a single lumen catheter should be placed. However, most of the PICCs placed are dual lumen because of the requirement for multiple, simultaneous infusions.

The larger the catheter, the better the flow rates; however, larger catheters are more difficult to place and more likely to occlude small arm veins. Sizes for pediatric patients typically vary from 2 to 4 French (F), while most adults receive either a 4 to 5-F single lumen or a 5 to 6-F dual lumen PICC.

Almost all the PICCs available today are made from either silicone or polyurethane (PU). Each of these materials has distinct advantages. PU provides a stronger, thinner-walled catheter. Thus, a 5-F PICC made of PU has a bigger inner diameter (ID) than a 5-F PICC made from silicone (figure 3). The potential disadvantage to PU is that it is stiffer, and there is a theoretical concern that PU catheters are more likely to cause vascular injury. There are also some formulations of PU that have been known to become brittle on long-term exposure to blood. Despite these concerns, many patients have had PU PICCs in place for over a year without any clinical problems.

Silicone is biocompatible, non-thrombogenic, and is associated with a low infection rate.6 Silicone is not as strong as PU, which necessitates silicone catheters having thicker walls to provide adequate rigidity and resistance to rupture. Their thicker walls mean smaller IDs and lower flow rates than for PU catheters of the same outer diameter.

One of the greatest drawbacks to PICCs is their limited flow rate, due to their small inner diameters. Whether the catheter is single or dual lumen, silicone or PU, or 4, 5, 6, or 7-F will greatly affect the ID of the catheter lumens. PICC flow rates also are limited by their long length (typically 50 to 60 cm). These factors together make PICCs unreliable for infusing blood products.4 The viscosity of packed red blood cells (PRBCs) varies greatly from one unit to the next. Therefore, one unit of PRBCs may infuse well, but another may not infuse at all. Because a unit of PRBCs must be completely infused within four hours or the remaining blood must be discarded, placement of a PICC in a patient that needs frequent transfusions is not recommended. If these patients must be infused through a PICC, a single lumen PU catheter is recommended.

The pressure required to generate the 1 to 3 cc/sec of contrast injection for chest and abdomen computed tomography (CT) is too great for most PICCs. Single lumen PU catheters are the most reliable to use for power injection.4,7 The flow rates, at a given pressure, are better for a shorter catheter than a longer one. Therefore, trimming the PICC to remove excess catheter length prior to its placement will improve flow rates.

Overall, the single lumen catheters are easier to manage, provide better flow rates, and appear to plug less frequently. For these reasons, placement of a single lumen catheter should be encouraged whenever possible.

Placement technique

For PICC placement, the patient is situated with the arm positioned at about 45 degrees of abduction. Careful sterile preparation and draping of the arm is the key to achieving a low infection rate.8 A 10 minute betadine scrub is performed, followed by application of a betadine solution. Once this is dry, alcohol should be used to remove all the residual betadine. Sterile drapes are placed to provide a sterile field centered on the upper arm.

Placement of a PICC into the forearm or antecubital fossa requires a catheter that is unnecessarily long and is exposed to kinking caused by flexion at the elbow and, therefore, placement in the upper arm is preferred. Patients also find it more comfortable to have their catheter placed in the upper arm.

There are 4 different methods for visualizing the arm veins during PICC placement: (1) direct visualization or palpation; (2) IV contrast; (3) IV carbon dioxide (CO2); and (4) ultrasound. A number of manufacturers package PICCs in a kit that provides the components needed to place the line using the Seldinger technique (table 3).

A small percentage of patients have a visible or palpable basilic or cephalic vein in the upper arm. In these cases, a tourniquet, placed high on the upper arm, allows direct puncture of the vein using a 22 G angiocatheter (Johnson & Johnson Medical, Arlington, TX). Once the angiocatheter is in the vein, an 0.018" guidewire is advanced, as described below.

Unfortunately, the large majority of patients referred for a PICC have no visible or palpable superficial vein. However, an upper arm vein can easily be opacified by injecting one-third strength iodinated contrast into a more peripheral IV line. This method requires some type of peripheral IV access; a small gauge IV in the forearm or hand usually can be introduced in most patients. The excellent opacification provided by IV contrast allows most of PICCs to be placed using less than 10 cc of contrast material. A tourniquet should not be used when using IV contrast, as there is marked leakage of contrast at the puncture site when the vein is distended. In patients with a contrast allergy or renal insufficiency, intravenous CO2 also can be administered in order to visualize the veins (figure 4). The patient is given a slow injection of approximately 10 to 20 cc of CO2 via a peripheral IV. It is best to use a tourniquet to slow the passage of the gas. The image contrast may be poor and, thus, several punctures may be needed to gain access into the vein.

The majority of PICCs can be placed using ultrasound guidance. Use of a 5 to 7.5 MHz linear array transducer and a tourniquet facilitates visualization of arm veins. Many of our patients have had multiple peripheral IVs and their superficial veins are sclerosed, making access via the brachial vein necessary. However, when the brachial vein is punctured using IV contrast guidance, the needle may inadvertently traverse the brachial artery.

An important advantage of ultrasound guidance is that it allows clear location of the arteries. When using ultrasound, a puncture site that keeps the vein superficial to, or beside, the artery can be chosen. The needle is then advanced into a suitable vein using real-time imaging (figure 5). If needed, the arm can be rotated internally or externally to facilitate the vein puncture.

Following localization of the vein and prior to the puncture, 1% lidocaine, without epinephrine, is used to raise a dermal wheal at the intended site of puncture. The 25 G needle should not be advanced so deep as to enter the vein of interest and cause spasm of the vein or a perivenous hematoma. When using fluoroscopic or ultrasound guidance, a 7 cm, 21 G needle is used to puncture the vein. This needle is large enough to accept an 0.018" guidewire.

The veins are compliant, thus a double wall puncture is frequently performed when using fluoroscopic guidance. It also is helpful to have the orientation of the needle parallel to the course of the vein (figure 6). The technique for ultrasound guided puncture is similar, but often a single wall puncture of a distended vein is sufficient because a tourniquet is in place. Once the ultrasound-guided puncture into the vein is made, fluoroscopy is used to visualize passage of the guidewire.

Whatever method is used to access the vein, the remaining portion of the procedure is always performed in a standard fashion. The 0.018" guidewire is gently advanced through the needle. If it does not pass easily into the vein, the needle is slowly withdrawn during fluoroscopic visualization. The vein is then gently probed with the guidewire, which should advance easily once the needle tip is in the vein. After guidewire access into the vein is gained, a small incision with a number 11 blade and blunt dissection of the puncture site greatly facilitates the advancement of the peel-away sheath and the PICC. A peel-away sheath should then be advanced over the guidewire. Once the sheath is in the vein, the guidewire and dilator are removed. Some manufactures provide a long 0.018" guidewire that can be used to size the length of PICC that will be needed. The catheter is then advanced through the peel-away sheath, without a guidewire, into the SVC. The tip of the PICC is positioned in the SVC at the caval-atrial junction (figure 7). As with most conventional central lines, retraction of the catheter tip can be expected after placement.9 The position of the catheter is documented using a tightly collimated chest radiograph. All PICCs have adequate radiopacity to identify the tip of the catheter.4

Next, the catheter is affixed to the skin, sutured in place with 2 to 4 stitches of a non-resorbable material (3-0 Prolene, Ethicon Inc., Somerville, NJ), as tape is not reliable for fixation. Although the ideal dressing is debatable, we prefer to place a clear plastic adhesive dressing over the PICC site. Both ports are flushed with heparinized saline (2 cc of 100 units/cc heparin), clamped, and then capped. Instructions for catheter care are reviewed with, and a copy given to, the patient. A copy of the instructions are also placed in the chart. These instructions include a phone number to call should any questions arise.

Pitfalls

The most common pitfall encountered is the inability to puncture the vein of interest or an inability to advance a guidewire into the vein. If the first pass of the 21 G needle is unsuccessful, intense spasm of the vein often will occur. Administration of 100 ug of nitroglycerin through the peripheral IV, with simultaneous compression of the other outflow veins may be helpful for relieving the venospasm. If the spasm persists, or a hematoma develops, then a more central puncture in the same vein, or puncture of a different vein is often necessary.

Central venous stenoses or occlusions are other common pitfalls. The small size of PICCs allows them to be advanced into the SVC in almost all patients-even those with central venous stenoses. However, if the catheter cannot be advanced into the SVC, an upper extremity venogram should be performed. If the subclavian vein is occluded in one arm, the PICC should be placed in the contralateral arm. In patients with bilateral central venous occlusions, the PICC tip can be positioned peripheral to the occlusion and still be a valuable venous access site.

While advancing the PICC, the veins usually are not opacified. Rarely, the catheter will exit the main venous channel and pass into a small parallel collateral channel. When this occurs, it may be necessary to pull the catheter back and perform a contrast injection. Advancing a small torqueable guidewire through the PICC may be necessary on occasion to facilitate placement of the line in the main venous channel, or to successfully advance it into the SVC.

A PICC should not be placed in a persistent left SVC (figure 8) because the left SVC drains into the coronary sinus, and pericatheter thrombosis can lead to coronary sinus thrombosis. The left SVC may be mistaken for the descending aorta and the operator may pull out the PICC assuming it has inadvertently been placed into the brachial artery. A contrast injection should be made to confirm the PICC position prior to removing it.

Complications

Overall, the complication rates associated with PICCs are similar to or less than those associated with other central lines. PICC complications can be generally divided into early (less than three days) and late (greater than three days) types.

Early complications include bleeding, hematomas, nerve or arterial injury, acute thrombophlebitis, and arrhythmias. Puncture site problems are the most common early complications. Using a peel-away sheath for PICC placement can lead to pericatheter bleeding immediately after catheter placement and sheath removal. This oozing of blood around the catheter at the insertion site can persist for minutes or hours. Light pressure for 10 minutes usually will control the bleeding. Otherwise, a gelfoam sponge can be placed on the puncture site.

If bleeding is persistent and coagulopathy is not present, an arterial injury should be suspected. Arterial injury is often due to inadvertent through-and-through puncture of the brachial artery when performing brachial vein puncture using fluoroscopic guidance. It also may occur when the brachial artery is mistaken for the brachial vein while attempting an ultrasound-guided puncture. However, ultrasound guidance usually allows continuous visualization of the artery during puncture of the brachial vein. A color duplex examination also can be performed prior to the puncture to insure that the vein is correctly identified.

If there is any question about the possibility of a transarterial venous puncture, a pull-back test can be performed. After the peel-away sheath is introduced over the guidewire, the dilator is removed. The sheath is then slowly withdrawn over the .018" guidewire. If the needle traversed the artery, a sudden flash of arterial blood from the peel-away sheath will be seen. If no flash of arterial blood is seen, the dilator and peel-away sheath can then be re-advanced over the 0.018" guidewire, and the PICC is placed.

Nerve injury is rare and is most likely to occur during brachial vein punctures. Symptoms of nerve injury include immediate pain or numbness radiating to the hand. If these symptoms occur, the puncture needle or the catheter (if the PICC has already been placed) should be removed immediately. A new line should then be placed in the other arm. The symptoms usually will resolve within several hours.

Arrhythmias are associated with advancing the PICC into the right heart. These will usually resolve when the catheter is withdrawn into the SVC.10

Acute superficial thrombophlebitis is another complication. It usually is associated with pain and tenderness, and perhaps mild erythema, along the course of the accessed vein. This problem usually resolves within 24 to 48 hours following conservative therapy with arm elevation and moist local heat. If symptoms persist despite adequate conservative therapy, a superimposed infection should be excluded, and it may be necessary to remove the line.

Late complications include line plugging, catheter dislodgement, line fracture, venous thrombosis, exit site infection, and sepsis. Line plugging is the most frequent late complication and is best prevented by meticulous maintenance flushes using heparinized saline. The second most common late complication is catheter dislodgement, which can occur despite suturing the catheter to the skin. Dislodgement is common in uncooperative patients, and for them, a port may be preferable. Fortunately, almost all the line fractures occur in the portion of the catheter external to the puncture site, and are seen more frequently with silicone catheters.

Thrombophlebitis occurs in approximately 1 to 10% of patients with PICCs.11,12 There are 2 distinct presentations. Most cases of phlebitis appear in the first few days after placement, as previously discussed. These cases are probably due to the manipulation of the veins with catheters and guidewires, or to the presence of a PICC in a relatively small arm vein.

Late presentations (greater than 3 days) are related to either a line infection or significant venous thrombosis. Infected lines usually are removed immediately, and the catheter tip is

then cultured. Patients with severe thrombophlebitis symptoms should be systemically heparinized. Fortunately, instances of central venous thrombosis are rare (approximately 1%) with PICCs. This is an important difference from conventional chest-wall venous access catheters, where symptomatic central thrombus forms in up to 8% of patients.13 The rate of sepsis associated with PICCs is similar to that of tunneled central lines (1 to 3%).11-14 Approximately 2% of patients with PICCs develop local cellulitis.11

Findings will include insertion site erythema, tenderness, induration, purulent drainage, and fevers. These lines should be removed and cultured. If venous access is still needed, a new PICC should be placed in the opposite arm and antibiotics initiated pending results of the catheter tip culture. The main differential diagnosis for exit-site erythema is an allergic reaction to the tape used on the dressing or the catheter itself.

Post-procedure care

Starting a PICC service means a large investment of personnel and time into care of these lines. The following instructions are given to a patient or their care providers in order to minimize the occurrence of problems: (1) The lumens should be flushed after the completion of any infusion; (2) for end-hole catheters, each lumen must be flushed at least once every 12 hours (the flush consists of 10 cc of saline followed by 2 cc of 100 unit/ml heparin); (3) the dressing must be changed every 3 days; and (4) the catheter is to be kept sutured to the skin with non-resorbable sutures.

Another potential care issue is preventing contamination of the lumen of the line and preventing entry of air into the line. Most of the manufactures of PICCs include a clamp on the catheter near the hub, which is used in addition to an injection cap on the hub.

When a patient presents with a plugged PICC, the external portion of the catheter is inspected for kinks or occlusive sutures. Clearing the plugged PICC using a 10 cc syringe filled with saline should be attempted. The small size of PICCs makes them prone to plugging, and the thin wall of these lines also makes them easy to rupture. About

9 ATM of pressure can be generated with a 10-cc syringe, whereas a 3-cc syringe can generate about 21 ATM.15 Generally, the catheters made from PU are stronger than the silicone catheters. Silicone catheters have been shown to rupture or leak with pressures of 3 to 11 ATM, whereas the pressure required to induce rupture or leakage in PU catheters is at least 19 ATM. Therefore, with plugged PU catheters, a 3 or 5-cc syringe can be used when attempting to clear these lines. If simple flushing fails, an attempt will be made to clear the line with 5000 units of urokinase (UK) (Abbott Laboratories, Chicago, IL). If the line is completely plugged, it can be difficult to get the UK into the catheter. In this situation, a three-way stopcock and a 60-cc syringe on the side-arm of the stopcock should help get the UK into the catheter. The three-way stopcock is connected to the PICC. The syringe containing the UK (5000 units in 2 cc of saline) and an empty 60-cc syringe are attached to the 2 side-arms of the three-way stopcock. By generating a negative pressure in the PICC with the 60-cc syringe and then turning the stopcock handle open to the UK syringe, some of the UK will be drawn into the plugged PICC. It may be necessary to repeat this maneuver several times to facilitate transfer of the full 5000 units (2 cc) of UK into the plugged PICC lumen. The UK should be left in place for 10 minutes, and the catheter is then flushed with saline. This process should be repeated if needed. PICCs with a leak or only one plugged lumen can often be safely rewired over a 0.018" Teflon-coated guidewire.

Results

One of the main advantages of having PICCs placed in the interventional suite is the greater than 99% technical success rate. This compares with bedside insertion success rates of approximately 74%.11 The average duration of catheter usage is extremely variable, ranging from a day to greater than a year. In a study by Cardella et al, the catheters remained in for an average of 72.7 days.11 In 73.4%, catheters were removed because they were no longer needed. In 22.6% of the patients, the lines were replaced at least once to allow completion of the planned therapy. These line exchanges occurred when the PICC became partially dislodged, fractured, or partially plugged. In the remaining 4%, a new line had to be placed at a different site to complete the therapy, due to site infection, phlebitis, or suspicion of systemic infection.

Alternatives

Although the number PICCs placed is increasing, there are several important alternative venous access devices to consider (table 4). As interventional radiologists, we must provide a good venous access service, of which PICCs are just one component. Consultation should be provided to the referring physicians regarding the most appropriate type of access device for their patients.

Peripheral IVs -Peripheral IVs, although certainly cheaper in the short term, require frequent replacement, are inappropriate for infusions of vein-sclerosing infusates, and do not allow for blood draws.

Conventional central lines -Conventional central lines introduced through the subclavian or jugular vein have a higher infection rate than PICCs. Traditional temporary central lines also carry the additional risks of pneumothorax or arterial injury.

Permanent central lines -Tunneled central lines with a dacron cuff that becomes incorporated into the subcutaneous tissues are considered a permanent type of venous access. These lines are more costly to place than PICCs, but they are still the most practical choice if long-term therapy is needed. Patients who have had multiple central lines or who have bulky mediastinal disease may have central venous stenoses or occlusions. Tunneled catheters are large diameter catheters and are more prone to inducing venous thrombosis if the central veins are narrowed significantly. The small diameter of PICCs allows placement in many patients with central venous stenoses in whom a tunneled central line may be hazardous.

Other cuffed silicone catheters -A Hohn catheter16 is a non-tunneled silicone catheter with an antimicrobial cuff (Bard Access, Salt Lake City, UT or Cook, Inc., Bloomington, IN). Use of these catheters is an important alternative to conventional central lines, tunneled central lines, and PICCs. These

5-F single or 7-F dual lumen catheters are placed via the subclavian or jugular vein and are designed for intermediate-term access. They are introduced through a peel-away sheath, and have a cuff attached to the catheter near the hub which is advanced into the subcutaneous tissue at the puncture site. Infection rates are similar to those of tunneled lines but the placement procedure is easier.16 Unfortunately, patient satisfaction is not high when this line is placed in the neck.

Arm ports -Arm-port catheters are similar in size and length to PICCs but are particularly intended for long-term (greater than 6 month) usage. Placement is similar to PICCs, except that a pocket is made for the port at the puncture site in the upper arm.17 The initial cost for placement of an arm port is significantly more than that of a PICC.

Cost-effectiveness

PICCs have all the capabilities of a multi-lumen, tunneled central line (blood sampling, simultaneous infusions of incompatible agents, and delivery of infusates directly into the central venous system) except for infusion of blood products. Placement of PICCs is an outpatient procedure and can be performed in about 20 minutes. There is no need for a prolonged recovery time. Placement of PICCs by interventional radiologists provides the safety of fluoroscopic guidance and a technical success rate that is approximately 100%. Immediate complications are rare when PICC placement is performed in the interventional suite.

The success rate for bedside insertion of PICCs is approximately 74%. The lower cost of bedside insertion by nurses has created a two-tier system at some institutions: patients who fail bedside insertion are then sent on to the interventional radiologist. Unfortunately, what is lost in this two-tier system is the concept of a venous access consultation service. A PICC is not for everyone (i.e., the dialysis patient). In addition, the added cost of having a PICC placed in the interventional suite is more than offset by the savings associated with the potential delays in starting intravenous therapy and higher complication rates associated with bedside insertion. Just as important is the continuity of care that occurs after line placement when all PICCs are placed by one service center.13,18

The placement of PICCs in the radiology suite has been found to be more reliable and more comfortable. This is because the antecubital fossa is a common insertion site for lines placed at the bedside. These lines can be uncomfortable and are prone to fracture, dislodgement, and kinking, when compared to PICCs placed in upper arm veins.

Calculating the actual expense of placing and maintaining a PICC is difficult, and the true cost-effectiveness of providing a PICC service remains uncertain.

Conclusion

There are many indications for PICC placement, and the radiologist can provide successful placement in nearly all patients referred for the procedure. PICCs are associated with a very low morbidity rate. Procedure planning must include a careful selection of the appropriate type of venous access device for the clinical situation. Perhaps most important to creating a viable PICC service in the department of radiology is the development of an effective post-placement care system. With appropriate organization and attention to detail, creating a PICC service can be a rewarding and productive activity. AR

References

1. Hoshal VL: Total intravenous nutrition with peripherally inserted silicone elastomer central