A central venous access port, often called an implanted port or port-a-cath, is a small medical device placed completely beneath the skin to allow long-term, repeated access to a major vein for various treatments. This device is particularly useful for patients requiring frequent intravenous therapy over an extended period. While many patients use a single lumen port, some require the specialized “double lumen” variant to manage complex treatment regimens. Understanding the access procedure for this dual-chamber device is essential.
Understanding the Double Lumen Design
The double lumen port is engineered with two distinct internal reservoirs, each connected to its own separate channel, or lumen, within a single catheter. These two channels travel side-by-side through the catheter, but they remain entirely non-communicating until they reach the central vein near the heart. This physical separation allows two different substances or procedures to occur simultaneously without any risk of mixing inside the device.
The port body reflects this dual design by having two separate self-sealing septums, which are the rubber injection sites. Each septum serves as the entry point for one of the two lumens. The triangular or dual-chamber shape of the port housing helps healthcare providers differentiate it from a single lumen device.
Clinical Scenarios Requiring Dual Access
A double lumen port is chosen over a single lumen port primarily to administer two incompatible substances simultaneously. Certain medications, such as some chemotherapy agents and specific supportive drugs, cannot be mixed in the same line because they can neutralize each other or form dangerous precipitates. The dual channels allow each incompatible agent to be infused separately, ensuring the full effectiveness and safety of both treatments.
This dual capacity is also beneficial for patients receiving simultaneous treatments, such as continuous intravenous hydration or total parenteral nutrition alongside chemotherapy. It allows laboratory blood samples to be drawn from one lumen without having to pause an ongoing infusion in the other. The dual port can also support high-flow procedures like apheresis or certain types of dialysis, which require both an inflow and an outflow line.
The Access Procedure and Routine Usage
Accessing a double lumen port requires a trained healthcare professional. The first step involves careful palpation of the port body to locate the two distinct septums and to stabilize the device beneath the skin. The skin over the port is then thoroughly cleansed with an antiseptic solution, such as chlorhexidine, and allowed to air dry completely.
A specialized, non-coring Huber needle is used to puncture the septum. This needle is designed with a deflected tip to slice through the silicone septum without removing a core of material, which helps the septum self-seal and prolongs the life of the port. The needle is inserted firmly at a 90-degree angle into the center of each septum until it makes contact with the port’s back plate.
Once the needles are in place, patency is confirmed by gently withdrawing a small amount of blood, often referred to as obtaining a brisk blood return. After the treatment or blood draw is complete, both lumens must be flushed with sterile saline and then locked with a solution, such as diluted heparin or a concentrated saline solution, to prevent clotting. This flushing is performed using a positive pressure technique, which helps prevent blood from flowing back into the catheter tip as the needle is withdrawn.
Maintenance and Recognizing Potential Issues
When the double lumen port is actively being used, the Huber needles remain in place and are secured under a sterile dressing that should be changed every seven days. When the port is not in use, it is a completely internal device, allowing the patient to bathe and swim without specific restrictions. To maintain the patency of the lumens when unaccessed, the port must still be flushed, typically on a monthly basis, to ensure the locking solution prevents blood clot formation inside the catheter.
Patients and caregivers should be vigilant for signs of potential complications to ensure the device’s safety. Localized infection is indicated by redness, swelling, warmth, or pain at the port site, or a generalized fever. Occlusion, or blockage, is a common issue signaled by the inability of the healthcare provider to draw blood or flush the port easily. Any discomfort, difficulty with access, or visible changes to the skin over the port should be reported immediately to the medical team.