August 1, 2017 by Casey Carr
By: Casey Carr
A port is a centrally inserted catheter, whose tip is positioned at the junction of the superior vena cava and right atrium. The catheter is connected proximally to a subcutaneous reservoir. The reservoir is usually located in the anterior upper chest. “Accessing” the port is done through the reservoir.
Anatomy of a Port
The reservoir of the port is placed subcutaneously, and can be left in the body for years. It has a silicone covering (septum) that can be punctured by a special “non-coring” needle. This needle is called a Huber needle – it is designed with a hole on its side and shape that allows slicing rather than puncture. This minimizes damage to the silicone septum. Using any other needle will damage the port, render it inaccessible, and possibly dislodge silicone into circulation. The Huber needle needs to be inserted vertically in order to prevent bending it, and needs to be performed under aseptic technique. The needle can remain in place for 72 hours. By using a Huber needle, the port can be accessed over 2,000 times.
Commercially available ports have continued to evolve. There are dual-lumen ports, for the purpose of infusing incompatible fluids concurrently. Most contemporary ports are “power injectable” – meaning they can tolerate an appropriate flow rate and pressure to accommodate power injection techniques. In the ED this means these ports are compatible with CT angiography. Keep in mind however that not all ports are power injectable. If the patient does not know the model of their port, and it is unable to be determined based on their appearance on physical exam and chest x-ray, an IV may need to be placed if power contrast is needed.
Brief Review of Port Complications
Local Extravasation – occurs in 1-6% of patients with in dwelling port. While a port should be able to withstand hundreds of Huber needle insertions, if any alternative needle is used, the septum may become damaged and be prone to leaking. There are a number of antidotes available for chemotherapeutic vesicants that have extravasated – these should be given in conjunction with pharmacy and oncology. Otherwise surgical debridement may be necessary for extensive necrosis.
Pinch-off Syndrome – mechanical complication that occurs when the catheter is impinged between the first rib and the clavicle. Only occurs in infraclavicular port placement. The hallmark is positional occlusion; the port will flush easily while the patient’s arm is abducted. In these cases, the port needs to be removed, as the catheter can break and embolize to the right heart.
Upper extremity DVT – occurs in 5% of implanted ports. Diagnosed with ultrasound. Management is based on the clinical need for the port. If the port is needed, LMWH and fondaparinux are preferred over unfractionated heparin for acute management. Anti-coagulation should be continued for at least three months, or until the catheter is removed. If the catheter is not needed, this is an indication for port removal.
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