Vascular Access Procedures
Maintaining major, primary access to the circulatory system
Treatment for many kinds of conditions requires access to the blood vessels of the body, and interventional radiology doctors and nurses are an important part of the medical team that establishes this vascular access. Because providing catheter access to the arteries and veins of the body - and using imaging guidance to do so –– is so fundamental to what interventional radiology does, specialty physicians and nurses in this area are highly skilled at setting up and maintaining vital access to blood vessels for a range of different therapies, treatments, and other care.
Modern medicine depends on use of primary catheters and ports into the body, and imaging makes their location and mainte.ance easier and more accurate.
In addition to the vascular access required for a variety of different procedures in interventional radiology, these team members also provide services to establish access that other members of the healthcare team will use for other aspects of care. These are types of access that go beyond routine intravenous (I.V.) lines; although, the principle in many cases is the same or similar to I.V.'s or I.V. drip lines, but with a longer indwelling time for catheters and ports, usually with lines providing central venous access. Forms of access include:
• midline catheter. This type of access has characteristics of both a standard I.V. and a primary access line. The nurse or physician inserts this line through a vein near the elbow and advances it into an large vein in the upper arm. This type of line is useful for infusing certain types of medication.
• central catheters. These types of catheters allow access to large or primary vessels for purposes of infusing medications or nutrition. Such catheters also permit the care team to measure vascular pressure, which assists in monitoring patient status, in assessing heart function, and in other aspect of care. One frequently used type of central catheter is the PICC (peripherally inserted central catheter) line, a catheter that has its entrance in an arm vein but the tip of which lies in large, central vein. Though it is temporary, the team may use it, and leave it in place, for weeks or months at a time. If placement of a central line requires imaging guidance, by ultrasound or any of various forms of angiography, a member of the interventional radiology team will usually be needed to place it.
• tunneled catheter. These catheters, including Hickman or Broviac catheters, are larger catheters meant for frequent use and intended to remain in place for many months. The medical team will normally insert these catheters in large vessels that return blood to the heart, such as the internal jugular vein in the neck or the sublcavian vein below the collarbone. The catheter is tunneled under the skin and left in place, with an external cuff for access.
• subcutaneous port. When the medical team needs only occasional access to a vascular port, spaced out over a period of time (such as for chemotherapy), the team may place a catheter into a vein and attach a small silicon reservoir to it. The entire device is implanted under the skin. When the doctors or nurses need to administer drugs to the patient, they inject them into the reservoir with a needle placed through the skin at the bulge marking the site of the reservoir. The filled reservoir will slowly infuse the medication into the blood stream.
• dialysis port. Patients undergoing kidney dialysis (hemodialysis) need to have vascular ports in the forearm to provide long-term, regular, weekly access for purposes of removing blood, dialyzing it, and returning it to the patient. This access needs to provide high volumes of blood flow continuously during treatments, and this type of access needs to be established weeks or months before dialysis starts. Dialysis ports are a major focus in the vascular-access area. Hemodialysis vascular access can take one of a number of configurations (including creating a fistula, using a synthetic tube graft, or placing a catheter directly into a vein). A surgeon, usually a vascular surgeon, creates the fistula or places the graft in the operating room. The interventional team assists in maintaining the access or in placing needed catheters. Interventionalists use angiography to image the arteries and veins involved, and angioplasty and blood clot treatments to open blocked grafts.
Millions of patients each year undergo these central venous access procedures. Depending on the type of access required and the patient's condition, some of these procedures may be performed at bedside and some in the interventional radiology procedure room - and they may require team collaboration of the interventional physician or nurse with a medical oncologist, nephrologist, internist, or other specialist. Placing such access in the interventional suite, though, is usually more cost- and time-effective than doing so in the operating room.
For the procedures, patients normally receive a local anesthetic and a sedative but may remain awake for some of the procedure. The team will assess the access with x-ray imaging to make sure that it is functioning correctly. The necessary incisions around the access will need to be closed and will require some days to heal. The medical team will give the patient specific instructions on how to maintain the access line, which may include flushing and other steps.
Vascular access devices often need maintenance. Interventional radiologists are experts in imaging, declotting, and opening vascular access. They can also insert new devices, revise old devices, and help to repair and treat access when it becomes blocked or infected.
Vascular access of the types described here keep patients from needing the repeated venous punctures, and in some cases hospital stays, that would otherwise be necessary to deliver the types of treatments made possible by these lines. The approach is also essential for some patients who have difficult I.V. access, due to body type, blood or vascular conditions, or other factors. The catheters and ports permit a large variety and amount of various therapeutic products and medications - including antibiotics, chemotherapy, and other drug treatments, as well as nutrition and blood products - to be delivered into circulation. The medical team can also readily sample blood through these types of access. The lines are immediately usable after placement and easy to remove when they are no longer needed.