Correspondence (reply): In Reply

Using special port cannulas is essential for infusions through port systems. In general port cannulas have a Huber tip, which is mostly regarded as punch-free. These standard port cannulas have been used in routine clinical practice for more than 20 years and are associated with very few complications. New developments such as port needles with trocar tips with a side opening make punching out silicone particles from the port membrane during puncture unlikely. However, this is currently a niche product from a small manufacturer, which has not yet become widely accepted.

Meaningful randomized controlled studies that justify regular flushing of port systems with heparin in general for all patients who have had a port implanted as a means of preventing port catheter thrombosis have thus far not been published. The risk of developing heparin induced thrombocytopenia exists in principle. In our clinical practice we do not use so called “heparin blocks,” and we flush exclusively with 10 mL 0.9% saline. No evidence exists for regular flushing of port systems during therapeutic intervals.

If the port catheter lumen is occluded any flushing should avoid applying pressure, in order to avoid rupture of the port catheter or damage to the port capsule. Connecting a three-way stopcock on the port needle enables producing suction in the occluded port catheter by aspiration with a syringe. A second syringe filled with urokinase or recombinant tissue plasmonigen activator (rtPA) can be used to attempt lysis as a result of the subsequent vacuum in the occluded port catheter or port capsule. No guidelines exist regarding the use of sterile gloves when implanting a port cannula. However, to avoid port infection, sterile measures should be adhered to as much as possible. Port infections still present common and severe late complications and will result inevitably in explantation of the port (1).

The term high-pressure port systems describes systems that are licensed for use in the application of intravenous contrast medium in computed tomography (CT) and magnetic resonance imaging (MRI). Flow rates of up to 5 mL/second are possible in such high-pressure port systems (2). Special high-pressure cannulas need to be used to apply contrast medium. Such specialized high-pressure port systems are currently available from only very few manufacturers. Any port system implanted should be identified by means of a “passport”, which should also be handed to the patient after the port has been implanted. Any port system can be used to draw bloods and administer blood products. However, the port should be flushed with saline after a blood infusion, in order to prevent coagulated blood from remaining in the port chamber or catheter.

The use of port systems made from synthetic materials has increased in recent years. The problem with such systems lies in their poor visibility in traditional radiographs. However, such port systems do not show artifacts on CT or MRI. The latter fact, combined with their reasonable price, has persuaded us to prefer port systems made from synthetic materials. The port catheter is usually made from radiopaque material and is visible on a thoracic radiograph.