Catheter Implantation

Author:  Dipl.-Biol. Maria Yiallouros, Gesche Tallen, MD, PhD, Editor:  PD Dr. med. Gesche Tallen, Reviewer:  Prof. Dr. med. Dr. h.c. Günter Henze, English Translation:  Hannah McRae, Last modification: 2017/10/26 https://kinderkrebsinfo.de/doi/e67773

The treatment of cancer is associated with various procedures that require access to a vein. These include, for example, taking diagnostic blood samples regularly, administration of fluids, blood products, parenteral (that means bypassing the digestive tract) nutrition, antibiotics and other medications, as well as the anticancer agents themselves. There are very few drugs that can be taken orally and get passed through the mucus membranes of the mouth, stomach, and intestines (enteral).

Before a cancer treatment can be started, certain blood tests are necessary, and sometimes also the administration of medicines. The physicians usually do this by puncturing a vein on the back of the hand or in the elbow with a hollow needle attached to a cannula. The cannula is usually left in place for a short period of time, so it can be re-used when needed. This type of venous access is called a peripheral intravenous (IV) catheter.

However, veins in the hand or arm are usually small and not sufficient for administering larger fluid volumes, as required for chemotherapy. Also, a peripheral catheter is generally not stably inserted, thereby being susceptible to displacement or mechanical catheter damage with the child moving around.

Damage or malposition may cause inflammation of the vein (phlebitis) or even accidental distribution of the cancer drug within the surrounding tissue (a so-called paravasat), which may cause irreparable tissue damage. Hence, a peripheral catheter is not feasible for a patient who must experience several months of intravenous therapy.

Therefore, most children and adolescents with cancer will have a central venous catheter (called central or IV line) inserted before the treatment is started [BOD2004‎]. Under general anesthesia, central lines are inserted by a surgeon who will always explain the details to you and your child prior to the procedure. After surgery, a chest radiograph (chest x-ray) is done to confirm the catheter tip is in the correct position.

Types of central venous catheters

The following types of central lines are frequently used for childhood cancer treatment:

Subcutaneous Catheter

A subcutaneous catheter is also called "port". It usually consists of a small round metal chamber (portal) with a rubber top (septum) and a flexible tube (catheter). It is placed completely under the skin on the right side of the chest. A catheter threads under the skin from the metal chamber into a large vein near the collarbone, then into or near the right atrium of the heart.

Intravenous Catheter

An intravenous catheter is a long, hollow tube made of soft, rubber-like material called silicone, with an opening called a lumen. It is usually inserted into the large vein leading directly into the heart (Vena Cava). There is a cuff around the catheter, which is used to anchor the catheter under the skin so there is less danger of the catheter slipping out. The cuff also blocks bacteria.

Benefits of central lines

The use of central lines in cancer therapy is advantageous for many reasons:

They they can stay in the vein for a long period of time. Therefore, they reduce major discomfort, because all intravenous (IV) chemotherapy, blood products and supportive care medication, such as antibiotics, antiemetics or pain medication can be given and blood samples can be taken without poking the patient with a needle every time.

Central lines are anchored. Therefore, the risk that they are displaced and thus leak while being used is much less compared to peripheral venous punctures, for example of a vein in the elbow. This safety advantage is particularly relevant when cytostatic drugs are administered, because these can destroy more than cancer cells: they can cause severe tissue damage (called necrosis) if they get into contact with the surrounding healthy skin.

Directions after insertion of a central line

Like any other foreign body, central venous lines carry the risk of infection. Therefore, the treatment team to analyze each situation carefully in order to determine in which patients the advantages mentioned above outweigh the risks of infection. In order to avoid an infection, the sterility of the catheter during insertion, as well as regular maintenance with disinfectants, is of principal importance. The nursing staff will comprehensively instruct the patient and his or her parents how to manage the catheter care.

If a catheter infection occurs during the course of treatment, particularly in times of neutropenia, antibiotic therapy is generally indicated and successful. If the infection does not subside after the patient receives medication or if the infection is proven to be bacterial or fungal, the catheter is sometimes removed and later on replaced.