Minimally Invasive Tumor Therapy (MITT)

Department of Radiology, Charité – Universitätsmedizin Berlin

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References

  1. O'Grady NP, Alexander M, Burns LA, Dellinger EP, Garland J, Heard SO, Lipsett PA, Masur H, Mermel LA, Pearson ML, Raad II, Randolph AG, Rupp ME, Saint S; Healthcare Infection Control Practices Advisory Committee. Guidelines for the prevention of intravascular catheter-related infections. Am J Infect Control. 2011 May;39(4 Suppl 1):S1-34. doi: 10.1016/j.ajic.2011.01.003.
  2. O'Grady NP, Alexander M, Dellinger EP, Gerberding JL, Heard SO, Maki DG, Masur H, McCormick RD, Mermel LA, Pearson ML, Raad II, Randolph A, Weinstein RA. Guidelines for the prevention of intravascular catheter-related infections. Centers for Disease Control and Prevention. MMWR Recomm Rep. 2002 Aug 9;51(RR-10):1-29.
  3. Moureau N. Vascular safety: it's all about PICCs. Nurs Manage. 2006 May;37(5):22-7; quiz 50. Review.
  4. Teichgräber UK, Kausche S, Nagel SN, Gebauer B. Outcome analysis in 3,160 implantations of radiologically guided placements of totally implantable central venous port systems. Eur Radiol. 2011 Jun;21(6):1224-32. doi: 10.1007/s00330-010-2045-7
  5. Gebauer B, Beck, Wagner HJ. Zentralvenöse Katheter: Diagnostik von Komplikationen und therapeutische Optionen. Radiologie up2date 2008; 8(2): 135-154 DOI: 10.1055/s-2007-995703

Implantable Port

 

An implantable port is a venous access system that consists of a flexible tube or catheter, made of polyurethane or silicone, and a small chamber or reservoir, made of polyurethane or titanium. Port is from Lat. porta (a door, gate, or entry). The catheter typically has a diameter of 6 - 9 French (2 - 3 mm). One end is inserted into a vein and the other end is connected to the reservoir, which is implanted under the skin (subcutaneously) in the chest or arm. Port-catheter systems have several advantages. First, the device is placed completely under the skin and is typically not visible when not in use. Second, a port system can be left in the body for a very long time, up to several years. Ports are often implanted for long-term treatment like chemotherapy or for artificial feeding (parenteral nutrition). In addition, the port can be used for repeated blood sampling. Finally, there is a special type of port, known as a power-injectable port, that allows rapid high-pressure injection of contrast agents (up to 5 ml/s at a pressure of up to 300 psi) for imaging exams like computed tomography (CT) or magnetic resonance imaging (MRI).

 

Figure 1: Drawing and X-ray image of an implanted port system. The device consists of a reservoir/chamber and a catheter (flexible tube) connected to it. In this example, the port reservoir is located under the skin in the right chest, the catheter tube enters the internal jugular vein (the major deep vein of the neck), and the catheter tip rests at the entrance of the heart. The corresponding X-ray image shows the port reservoir and a part of the catheter tube.

 

How is a Port Placed?

 

A port system is implanted under local anesthesia. The interventional radiologist uses ultrasound and X-ray guidance to observe the procedure. First, the radiologist inserts a cannula into the internal jugular vein (deep neck vein) or the subclavian vein (the vein under the collar bone). Next, the flexible catheter is advanced into the venous system by means of a guide wire (a technique known as the Seldinger technique). The other end of the catheter is connected and secured to the port chamber implanted in the chest. Both the catheter tube and the reservoir are placed completely under the skin. All that may be palpable or visible from the outside is a small bulge in the skin. The port system provides easy access to the bloodstream. Repeated access is possible with a special type of needle that is inserted through the skin into the port chamber.

 

What are the Risks of Port Implantation?

 

The combined use of ultrasound to guide venous puncture and X-ray images to guide advancement and positioning of the port catheter allows interventional radiologists to reduce the risks associated with port implantation to a very low level. This is the safest method for placing a port system. Possible risks of central venous catheterization include bleeding and hematoma (bruise), accidental puncture of the cervical or subclavian artery, infection or abscess formation, thrombosis of the vein or catheter, escape of air into the pleural cleft (pneumothorax), and injury of neighboring organs.

 

How is a Port Taken Care of?

 

An implanted port system should be flushed regularly with 0.9% saline solution. A needle inserted into the port chamber can be left in place for up to a week. To prevent port infection, needles are always inserted and removed under sterile conditions. If a port system is not used for a longer period of time, it has to be rinsed with 1,000 IU heparin in 10 ml of saline solution to prevent clotting. With proper care, a port system can be left in place for several years.

 

Case Example

 

 

 

 

Figure 2: The photograph shows the stitched skin incisions in the neck (where the catheter has been inserted into the vein) and in the chest (where the port reservoir has been implanted) immediately after the procedure, which is performed in an outpatient setting.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3: The small skin incisions in the neck and chest take only a few weeks to heal, leaving inconspicuous scars. Depending on the amount of body fat present, the implanted port and tunneled catheter tube may be barely visible. Insertion of the needle into the port is typically painless. After removal of the needle, a small bruise may develop at the site but, in most cases, will resolve within a few days.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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