An implanted port (Port-a-Cath) is a medical device placed completely beneath the skin, providing long-term access to a patient’s bloodstream for therapy. This system consists of a small reservoir, or port body, connected to a catheter threaded into a large central vein. Accessing this reservoir requires a specialized Huber needle. Using the correct size and type of Huber needle is crucial for patient safety, comfort, and ensuring the port’s silicone septum remains intact for proper function over many uses.
Understanding the Huber Needle and Access Port
The implanted port features a self-sealing silicone septum that allows for repeated needle punctures for administering medications, fluids, or drawing blood. The unique design of the Huber needle makes repeated access possible without compromising the port’s integrity. Unlike a standard hypodermic needle, the Huber needle has a deflected, or non-coring, tip.
This specialized tip pushes the silicone fibers of the septum apart instead of cutting out a small piece (coring). Coring creates silicone fragments that could enter the bloodstream or clog the catheter, leading to complications and port failure. The non-coring design minimizes damage to the septum, significantly prolonging the port’s functional life. The needle is typically angled at 90 degrees to lie flat against the skin once inserted, providing stability during continuous infusions.
Criteria for Selecting the Correct Needle Size
Selecting the right Huber needle involves considering both the needle’s diameter (gauge) and its length, determined by the patient’s anatomy and the type of therapy. Needle gauge follows an inverse relationship: the higher the gauge number, the smaller the outer diameter. Huber needles commonly range from 19-gauge (19G) to 22-gauge (22G) for most clinical applications.
The choice of gauge is primarily dictated by the required flow rate and the viscosity of the fluid being administered. The 19G needle has the largest diameter and allows for the fastest flow, suitable for rapid infusions like blood transfusions or high-volume hydration. Conversely, the smaller 22G needle has a slower flow rate but is preferred for long-term, continuous, low-volume infusions or for pediatric patients. The 20G needle is often considered a standard, versatile size for general medication administration and routine blood draws.
The appropriate needle length, typically ranging from 0.5 inches to 1.5 inches, is determined by the depth of the port under the skin. The needle must be long enough to pass through the skin and subcutaneous tissue and fully penetrate the port’s septum. It must firmly rest against the back wall of the reservoir. If the needle is too short, it may not reach the reservoir, leading to extravasation (fluid leaking into the surrounding tissue).
For patients with more subcutaneous fat or a deeply implanted port, a longer needle (e.g., 1.5 inches) is necessary for secure access. A needle that is too long can be unstable, potentially causing the port to wobble or spin, which may damage the septum and increase infection risk. Healthcare providers aim to use the shortest possible length that securely ensures the needle tip reaches the bottom of the port chamber.
The Access Procedure: Key Steps and Safety
Accessing the port is a sterile procedure requiring meticulous technique to prevent infection. Before beginning, the healthcare professional performs hand hygiene and dons a mask, offering one to the patient. A sterile field is established, and the port site is scrubbed with an antiseptic solution, such as chlorhexidine. The site is scrubbed using a back-and-forth motion for the recommended duration (typically 30 seconds), and then allowed to air dry completely.
The port body is located by palpation and stabilized firmly between the thumb and forefinger to prevent movement during insertion. The Huber needle, pre-attached to saline-primed tubing, is inserted straight down at a 90-degree angle to the skin. Insertion continues in one smooth motion until a distinct change in resistance is felt, indicating the tip has contacted the port’s solid backplate.
Once the needle is seated, the provider confirms correct placement by gently pulling back on the syringe plunger to check for blood return. The presence of blood confirms the needle is correctly positioned within the port reservoir and the catheter is patent. The line is then flushed with sterile saline using a turbulent or “push-pause” method before administering any medication.
Needle Maintenance and Preventing Complications
Once the port is accessed, the needle is secured with a sterile dressing that must be kept clean, dry, and intact. This specialized dressing is typically a transparent, semipermeable film. It is changed at least every seven days, or sooner if it becomes wet, soiled, or loose. An antimicrobial disk may also be placed beneath the needle hub to reduce the risk of infection at the insertion site.
While the needle is in place, the port system requires regular flushing with saline to maintain patency and prevent clot formation. A locking solution, such as heparin, may be instilled into the line after flushing to minimize the risk of blood reflux and occlusion when the port is not in active use. Improper technique or insufficient flushing can lead to complications like catheter occlusion or infection.
To remove the needle, the port is flushed one final time, often maintaining positive pressure during the final moments of the flush. The provider stabilizes the port and withdraws the needle straight out in a single, smooth motion. Maintaining positive pressure during withdrawal prevents blood from being drawn back into the catheter tip, which can lead to clotting and dysfunction.