Port implantation

Mykhaylo Burbelko1 and
Hans-Joachim Wagner2
1Department of Diagnostic Radiology,
Philipps University Hospital, Marburg, Germany
2 Department of Radiology, Vivantes Hospital
Friedrichshain, Berlin, Germany
Address for correspondence:
Hans-Joachim Wagner MD, PhD
Department of Radiology
Vivantes Hospital Friedrichshain, Landsberger Allee 49
10249 Berlin, Germany
Phone: +49-30-4221-1441 Fax: +49-30-4221-1652
Email: joachim.wagner@vivantes.de


Abstract
Subcutaneous ports are advantageous for long-term central venous access, especially in patients who receive chemotherapy for malignancy or undergo an intravenous therapy over several weeks. They are generally associated with fewer infectious complications in comparison with external catheters and allow patients unrestricted mobility and greater freedom in choice of activities.

Radiologists have the unique advantage of combined, real-time sonographic and fluoroscopic guidance to place port catheter systems. Sonography is used to guide internal jugular vein puncture and fluoroscopy enables visualisation of both the course and the position of the catheter. Image guidance virtually eliminates the risk of several complications reported with unguided placement: pneumothorax, haematoma attributed to arterial puncture, superior vena caval laceration and catheter malposition.

Use of the subclavian vein as access site is associated with complications such as upper extremity deep vein thrombosis, subclavian vein stenosis and pneumothorax. Transjugular port placement is associated with lower complication rates than the subclavian vein route. Anatomically, the right internal jugular vein follows a relatively straight course to the superior vena cava and is the preferred site for port insertion.

The endovascular approach is also highly feasible, safe, and effective for the management of mechanical complications of ports.

Introduction
Venous port systems (Figure 1) are of benefit in patients undergoing long-term infusion therapy, especially chemotherapy, in whom peripheral venous access often becomes increasingly difficult during the course of therapy [1-4]. The systems allow excellent comfort as the patients can perform their usual daily activities.
There are two different designs of catheter tip: closeend valved catheters and open-end catheters. However, rates of infection, thrombosis and device survival are similar between the groups(Ref: 5]. There is currently no proven advantage of one port catheter system over another. Port choice should be based on local experience.

Different types of port chambers
Port catheter and port reservoir
Figure 1. Port-catheter system. (a) Different types of port chambers;(b) Port catheter and port reservoir.

Access site
Ports can be implanted centrally (chest) or peripherally (arm). The advantage of the arm port is a smaller profile and improved cosmetic appearance. The disadvantage is a significantly higher rate of upper extremity deep venous thrombosis (2% versus 8% respectively, for chest and peripheral ports) [6] and malfunction rates (up to 29% and 2% respectively, for chest and peripheral ports) [7]. In addition, arm ports are more difficult to access, more prone to needle dislodgement and allow less flow rate. Therefore, chest ports should be viewed as preferable to peripheral ports, especially for patients with an underlying malignancy.

The preferred site for insertion of a port catheter system is the right internal jugular vein because of the relative direct path to the superior vena cava and the right atrium. The second choice is the left internal jugular vein. The subclavian veins should be chosen as access veins only if the internal jugular veins are not patent.

Imaging
The use of real-time sonographic and fluoroscopic guidance allows decreased access time, failure rates, and insertion-related traumatic complications, such as pneumothorax, haematoma attributed to arterial puncture, and superior vena cava laceration, even in patients with complete central venous occlusion [7-12].

Implantation
Placement of the port requires a maximum barrier protection. The insertion site and surrounding areas should be cleansed with surgical scrub and draped appropriately. During catheter insertion, aseptic technique should be used [13].

Patients receive a broad-spectrum antibiotic as a singleshot dose one hour before the procedure. The insertion site should be examined by ultrasound to identify the course of the vein. The area is infiltrated with local anaesthesia. Conscious sedation and analgesia are achieved with drugs such as midazolam and fentanyl.

Ultrasound is used to select the vein and to guide the needle puncture. Venepuncture should be undertaken with real-time ultrasound guidance and a 21-gauge micropuncture needle following administration of local anaesthetic. A 1-cm incision is made in the skin, laterally to the needle. The subcutaneous tissue is then exposed with blunt dissection making a subcutaneous pocket so that the catheter bend will not kink. By using fluoroscopy, a peel-away sheath should then be inserted into the superior vena cava over the guide wire.

After subcutaneous administration of local anaesthetic, a pocket is created by making a 4- to 5-cm incision on the ipsilateral chest wall, approximately 3-4 cm caudal to the clavicle. Blunt and sharp dissections should be performed to enlarge the pocket so that the port can be easily inserted into the subcutaneous tissues. A tunnel is made from the puncture site to the pocket with the tunnelling device. The catheter should be pulled through the tunnel and then advanced into the peel-away sheath. To prevent air aspiration, the sheath should be pinched between the index finger and thumb to occlude the sheath. Air embolism can occur when the occlusion is incomplete. A humming or Valsalva manoeuvre helps to prevent this potential complication [14].

The sheath should then be peeled away. Direct pressure over the venotomy site is used to control haemostasis. The use of fluoroscopy allows a precise placement of the catheter tip in the middle of the right atrium, or alternatively in the vena cava-atrial junction during deep inspiration (Figure 2) [15]. The catheter should be cut to the appropriate length, and attached to the port. The port is secured to the chest wall in the pocket with two sutures. The venotomy site and the pocket are then closed by using non-resorbable sutures.

After insertion, but before the patient leaves the procedure room, the port function may be evaluated by using the so-called ‘3 T’ test [16]. The tip should be checked using fluoroscopy to ensure that it is in the right atrium. Then, the top should be checked to ensure that the catheter makes a smooth curve without any kinks. Finally, the tug test should be performed to check flow. If problems are identified, they should be solved before the patient leaves the procedure room.

A digital image should be obtained to document port and catheter position and to exclude pneumothorax (Figure 3). Post-procedural chest radiographs are unnecessary with image-guided placement [7,9]. The ports can be used immediately. The sutures should be removed 10 days later. Ports have to be flushed with heparin with each use or once a month when not in use: 3 ml of heparin solution (100 IU/mL) is usually sufficient.

Catheter tip placement in the right atrium under fluoroscopy guidance.
Figure 2. Catheter tip placement in the right atrium under fluoroscopy guidance.

Port-catheter tip position in the right atrium immediately after placement with the patient in a supine position on the angio table.
Figure 3. Port-catheter tip position in the right atrium immediately after placement with the patient in a supine position on the angio table.
























Complications
 The most frequent port-related complications are infection and obstruction of the catheter by a fibrin sheath [17,18]. In case of infection, the port should be removed. Fibrin-sheath obstruction should be suspected in case of low flow during perfusion and the absence of reflux during aspiration. Fibrin sheaths display a typical phlebographic appearance: the contrast medium flows backward from the distal hole along the catheter, until exiting into the venous circulation upstream. Fibrin-sheath stripping using a nitinol loop snare from a transfemoral venous access is a method of choice. The reported success of this procedures ranges from 92-100% [17,19,20].

Conclusion
Port implantation with use of ultrasound guidance for venous puncture and the use of fluoroscopy for placement of central venous catheters is a safe and reliable technique for patients requiring a longterm central venous access. Compared with surgical placement techniques, the described interventional radiological method is associated with fewer complications. Interventional radiologists should become familiar with the technique and offer it to patients at their institutions.
Key Learning
  • The preferred access site for insertion of a subcutaneous port catheter is the internal jugular vein
  • Venous puncture should be done under real-time ultrasonographic guidance in order to reduce complications such as pneumothorax or inadvertent arterial puncture
  • Catheter placement should be done under real-time fluoroscopic guidance in order to reduce complications such as vessel damage or tip malpositioning
  • To prevent long-term complications such as catheter thrombosis or infection, it is important that patients and medical staff dealing with the port are properly infor
References
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10-2006 BUY1145315/JB2356/MB002264/CMC 12th edition