Vascular Access

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Vascular access

Definition

Vascular access is the use of flexible tubes (catheters) that remain inserted into blood vessels for weeks or months, and provide a means of infusing antibiotics , chemotherapy , pain medications, or nutritional support into patients, and enable blood samples to be taken from patients.

Purpose

Cancer patients may require a variety of treatments over extended periods of time. Many of these treatments are infused directly into the bloodstream (intravenous or IV therapy). For example, a cancer patient may need chemotherapy given through a vein, as well as blood tests requiring frequent samples to be taken from their veins. Indwelling catheters, which stay in place for weeks or months, save the patient the discomfort of undergoing frequent needle sticks (venipuncture), and prevent veins from the trauma of repeated punctures and accidental release of harsh chemical agents into skin and subcutaneous tissues. The catheters are used for continuous, as well as intermittent, treatments and procedures.

Description

The two types of indwelling catheters are external and internal. These devices have been in use since the 1970s.

When deciding which catheter to use, the physician looks at the:

patient's age and size
length of time the catheter will be in place
purpose of the catheter
patient's previous history with indwelling devices
condition of the blood vessels

Physicians also consider their own preferences, as well as the treatment team suggestions and any special needs the patient may have.

External catheters are usually made of polyurethane for short-term use, and silicone for long-term use. Long-term devices have an internal cuff surrounding them to prevent catheter movement and infection. They have one to three openings, called lumens. One may be used for chemotherapy, a second for nutritional support, and the third for drawing blood samples. The catheters may be inserted into a central vein in the neck or chest, or an arm vein, called a peripheral vein.

External central catheters

External central catheters are divided into the types designed to stay in place for just a week or so, and the long-term devices commonly known as Broviac, Groshong, and Hickman, which can remain in place for months. The short-term devices are placed directly into a vein, while the long-term catheters are tunneled under the skin to the point where they enter a central blood vessel, such as the cephalic, jugular or subclavian vein. Central catheters are inserted using sterile, surgical technique.

External peripheral catheters

A peripherally inserted central catheter, or PICC, is inserted through the arm, and threaded into a central vein. With proper insertion and care, a PICC can remain in place for months. It may be inserted in the patient's room by a specially trained nurse. A PICC may limit arm movement, and is usually placed in the patient's least dominant arm. For example, the left arm would be the ideal PICC insertion site for a right-handed person. However, if a procedure such as breast surgery has been performed on one side, the PICC will most likely be inserted into the arm on the other side.

Internal catheters

An internal catheter, such as a Portacath or Pasport, is commonly called an implantable mediport because the catheter connects to a pocket, or reservoir, located under the skin, either in the chest or arm. While the system is entirely internal, the pocket is located near the surface and can be felt through the skin. The range of catheter materials includes plastic and titanium. Over the years, these devices have gotten smaller in size, making them more comfortable for patients. An implantable port is inserted and removed in a surgical or radiology setting using sterile technique. Functionality can be determined by injecting contrast material into the port, a procedure referred to as a port-o-gram. Fluid flow is regulated by a pump located on the outside or implanted internally during a surgical procedure. External pumps are usually portable so patients can move around.

Preparation

External long-term indwelling catheters, such as Hickmans, and internal catheters, such as Portacaths, are inserted in a surgical setting. Patients are positioned with their legs elevated during the procedure and are usually given a local anesthetic to help them relax. Some pediatric patients are given additional anesthesia.

Aftercare

After a long-term external or internal catheter is in place, patients have a chest x ray to assure that it is in the proper position, and that the procedure has occurred without complications.

Special concerns

Catheter Care

Indwelling catheters require frequent care so that they work properly and stay clean. The devices must be cleaned daily and handled carefully. They are flushed with heparin or saline, usually every day or every other day, depending on the device. Care techniques vary with the different catheters.

Risks

There are certain complications that may occur during catheter placement. Pneumothorax (air in the pleural cavity) or hemothorax (blood in the pleural cavity) rarely occurs during insertion, and is uncommon after the catheter is in place.

The catheter may leak due to a defect or as a result of being pinched between the collarbone and rib. More commonly, a blockage in the tubing may occur. The first sign of this problem is usually difficulty withdrawing blood, and the blockage can be confirmed with a chest x ray. Flushing will sometimes clear the blockage.

Another problem is that a catheter can move over the course of time. To get a dislodged catheter back into place, patients are sometimes instructed to raise their arms or attempt other maneuvers. If catheter movement recurs, the device will repeatedly malfunction, and may need to be removed.

Another risk over time is that of a vein thrombosis, commonly called a blood clot. The treatment varies for each patient. It may be as simple as changing the arm position or, in more serious cases, may involve removing the catheter. This condition may or may not have symptoms, but is important to diagnose because blood clots that break loose (emboli) can travel around the bloodstream and become potentially fatal.

Infection presents another risk, and may occur on the surface or internally, along the tubing itself. An infection at the surface is usually red, tender to the touch, and may contain discharge. A gram-positive bacteria, such as staphylococcus, is the most common culprit, although other bacteria have been found in these infections. Treatment is determined by the seriousness of the infection, the site of the problem, and the type of catheter involved. A minor infection may clear up with a topical antibiotic applied to the skin. In more severe cases, such as infections along the tubing, in the bloodstream, or in an implantable port, a course of antibiotics will be prescribed.

Resources

BOOKS

Dorland, I., and W. I. Newman, Dorland's Illustrated Medical Dictionary, 29th ed. Philadelphia, PA: W. B. Saunders Company, 2000.

Gajewski, James L., and Issam Raad. "Vascular Access Catheters and Devices." In Cancer Treatment, 5th ed. Philadelphia, PA: W.B. Saunders, 2001, pp. 225-29.

Libutti, Steven K., and Horne K. McDonald III. "Vascular Access and Specialized Techniques." In Cancer: Princi ples & Practice of Oncology, 6th ed. Philadelphia, PA:Lippincott, Williams & Wilkins, 2001, pp.760-67.