Central venous catheter

A central venous catheter, also known as a central line , central venous line, or central venous access catheter, is a catheter placed into a large vein. It is a form of venous access. Placement of larger catheters in more centrally located veins is often needed in critically ill patients, or in those requiring prolonged intravenous therapies, for more reliable vascular access. These catheters are commonly placed in veins in the neck, chest, groin, or through veins in the arms.
Central lines are used to administer medication or fluids that are unable to be taken by mouth or would harm a smaller peripheral vein, obtain blood tests, administer fluid or blood products for large volume resuscitation, and measure central venous pressure. The catheters used are commonly 15–30 cm in length, made of silicone or polyurethane, and have single or multiple lumens for infusion.

Medical uses

The following are the major indications for the use of central venous catheters:

Difficult peripheral venous access – central venous catheters may be placed when it is difficult to gain or maintain venous access peripherally.
Delivery of certain medications or fluids – medications such as vasopressors, chemotherapeutic agents, or hypertonic solutions are damaging to peripheral veins and often require placement of a central line. Additionally, catheters with multiple lumens can facilitate the delivery of several parenteral medications simultaneously.
Prolonged intravenous therapies – parenteral medications that must be delivered for extended periods of time such as long-term parenteral nutrition, or intravenous antibiotics are administered through a central line.
Specialized treatment – interventions such as hemodialysis, plasmapheresis, transvenous cardiac pacing, and invasive hemodynamic monitoring require central venous access.

There are no absolute contraindications to the use of central venous catheters. Relative contraindications include: coagulopathy, trauma or local infection at the placement site, or suspected proximal vascular injury. However, there are risks and complications associated with the placement of central lines, which are addressed below.

Complications

Central line insertion may cause several complications. The benefit expected from their use should outweigh the risk of those complications.

Pneumothorax

The incidence of pneumothorax is highest with subclavian vein catheterization due to its anatomic proximity to the apex of the lung. In the case of catheterization of the internal jugular vein, the risk of pneumothorax is minimized by the use of ultrasound guidance. For experienced clinicians, the incidence of pneumothorax is about 1.5–3.1%. The National Institute for Health and Care Excellence and other medical organizations recommend the routine use of ultrasonography to minimize complications.
If a pneumothorax is suspected, an upright chest x-ray should be obtained. An upright chest x-ray is preferred because free air will migrate to the apex of the lung, where it is easily visualized. Of course, this is not always possible, particularly in critically ill patients in the intensive care unit. Radiographs obtained in the supine position fail to detect 25–50% of pneumothoraces. Instead, bedside ultrasound is a superior method of detection in those too ill to obtain upright imaging.

Vascular perforation

Perforation of vessels other than the intended target is a feared and potentially life-threatening complication of central line insertion. Fortunately, the incidence of these events is exceedingly rare, especially when lines are placed with ultrasound guidance. Accidental cannulation of the carotid artery is a potential complication of placing a central line in the internal jugular vein. This occurs at a rate of approximately 1% when ultrasound guidance is used. However, it has a reported incidence of 0.5–11% when an anatomical approach is used. If the carotid is accidentally cannulated and a catheter is inserted into the artery, the catheter should be left in place and a vascular surgeon should be notified because removing it can be fatal.

Catheter-related bloodstream infections

All catheters can introduce bacteria into the bloodstream. This can result in serious infections that can be fatal in up to 25% of cases. The problem of central line-associated bloodstream infections has gained increasing attention in recent years. They cause a great deal of morbidity and deaths, and increase health care costs. Those who have a CLABSI have a 2.75 times increased risk of dying compared to those who do not. CLABSI is also associated with longer intensive care unit and hospital stays, at 2.5 and 7.5 days respectively when other illness related factors are adjusted for.
Microbes can gain access to the bloodstream via a central catheter a number of ways. Rarely, they are introduced by contaminated infusions. They might also gain access to the lumen of the catheter through break points such as hubs. However, the method by which most organisms gain access is by migrating from the skin along the portion of the catheter tracking through subcutaneous tissue until they reach the portion of the catheter in the vein. Additionally, bacteria present in the blood may attach to the surface of the catheter, transforming it into a focus of infection.
If a central line infection is suspected in a person, blood cultures are taken from both the catheter and a vein elsewhere in the body. If the culture from the central line grows bacteria much earlier than the other vein site, the line is likely infected. Quantitative blood culture is even more accurate, but this method is not widely available.
Antibiotics are nearly always given as soon as a patient is suspected to have a catheter-related bloodstream infection. However, this must occur after blood cultures are drawn, otherwise the culprit organism may not be identified. The most common organisms causing these infections are coagulase negative staphylococci such as staphylococcus epidermidis. Infections resulting in bacteremia from Staphylococcus aureus require removal of the catheter and antibiotics. If the catheter is removed without giving antibiotics, 38% of people may still develop endocarditis. Evidence suggests that there may not be any benefit associated with giving antibiotics before a long-term central venous catherter is inserted in cancer patients and this practice may not prevent gram positive catheter-related infections. However, for people who require long-term central venous catheters who are at a higher risk of infection, for example, people with cancer who at are risk of neutropenia due to their chemotherapy treatment or due to the disease, flushing the catheter with a solution containing an antibiotic and heparin may reduce catheter-related infections.
In a clinical practice guideline, the American Centers for Disease Control and Prevention recommends against routine culturing of central venous lines upon their removal. The guideline makes several other recommendations to prevent line infections.
To prevent infection, stringent cleaning of the catheter insertion site is advised. Povidone-iodine solution is often used for such cleaning, but chlorhexidine appears to be twice as effective as iodine. Routine replacement of lines makes no difference in preventing infection. The CDC makes many recommendations regarding risk reduction for infection of CVCs, including:

The preferred site of insertion, from an infection prevention point of view, is in the subclavian vein, and to generally avoid the femoral vein if possible.
There is no clear recommendation for a tunneled catheter site in the guidelines.
Selection of catheters should include those with minimal ports to accomplish the clinical goal.
Sterile gloves are required for CVC
Full body sterile drapes, cap, mask, gloves are required for placement of CVCs
The catheter site should be monitored visually and with palpation on a regular basis to assess for infection.
It is, however, acceptable to use clean, non-sterile, gloves for changing the dressing of intravascular catheters.
Both chlorhexidine and povidone-iodine are acceptable skin cleansers, though chlorhexidine is preferred.
For short-term CVC sites, dressings must be changed at least every 7 days for transparent dressings, and every 2 days for gauze dressings.
For long-term implanted or tunneled catheters, dressings are to be changed no more than once weekly unless soiled or loose.
Routine removal and replacement of a central venous catheter is not recommended. While central line catheters should be removed as soon as they are no longer necessary, scheduled removal and replacement, whether over a guidewire or with a new puncture site, has not been shown to be beneficial in preventing infections.
Medication impregnated dressing products can reduce the risk getting catheter-related blood stream infection.
There is inconclusive evidence whether longer interval of changing dressings for central venous access devices is associated with more or less infections.
It is unclear whether cleaning the skin with antiseptics or without skin cleansing can reduce the rate of catheter-related bloodstream infections. The lack of clarity is due to the low quality of some of the studies used in the meta-analysis.

Using checklists, which detail the step by step process of catheter placement has been shown to reduce catheter related bloodstream infections. This is often done with an observer reviewing the checklist as the operator places the central catheter. Having central line catheter kits, which carry all of the necessary equipment needed for placing the central venous catheter, has also been shown to reduce central line related bloodstream infections.
Patient specific risk factors for the development of catheter-related bloodstream infections include placing or maintaining a central catheter in those who are immunocompromised, neutropenic, malnourished, have severe burns, have a body mass index greater than 40 or if a person has a prolonged hospital stay before catheter insertion. Premature infants also have a greater risk of catheter-related bloodstream infections as compared to those born at term. Provider factors that increase the risk of catheter-related bloodstream infections include inserting the catheter under emergency conditions, not adhering to sterile technique, multiple manipulations of the catheter or hub, and maintaining the catheter for longer than is indicated.