Understanding perineural catheter designs: Which one is right for your practice?

Perineural catheters are vital tools in regional anesthesia, providing continuous postoperative pain relief. However, selecting the right catheter design can be challenging due to the variety of options available. In this post, we’ll discuss the key differences between the two primary perineural catheter designs—catheter over needle (CON) and catheter through needle (CTN)—and explore which might be best suited for different clinical scenarios.

Why focus on perineural catheter design?

• Skill-intensive procedure: Perineural catheters require greater expertise compared to single injection nerve block techniques.
• Technological advances: Recent advancements have simplified catheter insertion, making it more accessible to a broader range of clinicians.
• Clinical impact: The choice of catheter design can influence patient outcomes, including leakage rates, catheter dislocation, and overall effectiveness.

Two main designs

1. Catheter over needle

This design involves placing a single-shot injection with the indwelling catheter, removing the needle, and then threading the catheter into the indwelling catheter, offering greater stability and kink resistance.

• Advantages:
  • Easier placement: This design mimics the process of placing an intravenous (IV) line, making it more intuitive, especially for those familiar with IV access.
  • Reduced catheter kinking: Less likely to kink during insertion, which can be a significant advantage in ensuring correct placement.
  • Reduced leakage: Less likely to leak, improving its therapeutic effect.
  • Better for teaching: This design is often preferred in training environments where clinicians learn the technique due to its simplicity.
• Disadvantages:
  • • Limited depth: The catheter may not thread as deeply into the nerve sheath, which could sometimes impact its effectiveness. But slightly longer CONs are available if threading is desired.

2. Catheter through needle

In this design, the catheter is threaded through the needle, allowing it to be placed deeper into the nerve sheath.

• Advantages:
  • Deeper placement: The ability to place the catheter deeper can reduce the risk of dislocation and improve the duration of analgesia.
• Disadvantages:
  • Higher skill requirement: This design can be more challenging to master, particularly for those new to the technique.
  • Increased risk of kinking: There is a higher risk of the catheter kinking during placement, which can lead to complications.

Poll: Clinician preferences

In a recent NYSORA community poll, 52% of clinicians preferred the catheter through needle design, likely due to its long-standing use and familiarity. Conversely, about 20% favored the catheter over needle design, citing ease of use and recent technological improvements. Interestingly, another 20% had no preference or were unfamiliar with the differences.

Step-by-step guide to catheter insertion

Regardless of the design chosen, the basic steps for perineural catheter insertion remain consistent:

1. Place the needle in the perineural space: Accurately position the needle where you intend to infuse the local anesthetic.
2. Confirm needle tip placement: Inject a small amount of local anesthetic to confirm that the needle is in the correct position.
3. Insert the catheter: Depending on your chosen design, either thread the catheter through the needle or into the indwelling catheter into the desired location.
4. Remove the needle: Carefully extract the needle, leaving the catheter in place.
5. Secure the catheter: Fix the catheter to the skin to prevent dislocation and ensure it remains in the correct position.

Clinical considerations

• Leakage resistance: The catheter over needle design typically shows less leakage, which can improve patient satisfaction.

• Placement accuracy: The catheter over needle design offers more precision, reducing the chance of primary failure.
• Reliability: While both designs are effective, catheter over needle may offer better long-term reliability, especially with limited experience placing perineural catheters.

Conclusion: Which catheter design should you choose?

Both catheter designs have their merits, and the best choice often depends on the specific needs of your practice. If you are introducing perineural catheter analgesia for the first time, the catheter over needle design may be more user-friendly and easier to integrate into your practice. However, if your clinical setup requires more extended duration analgesia or you have the expertise, the catheter through needle design may offer better outcomes, particularly when long-term analgesia is required.

Q&A: Addressing common questions

Q: Is one catheter design more cost-effective than the other?

• A: While cost can vary depending on the manufacturer, the catheter over needle design may be more cost-effective due to its simpler technology and reduced complication rates.

Q: Which design is better for teaching purposes?

• A: The catheter over needle design is generally preferred in educational settings due to its resemblance to IV placement, making it easier for trainees to learn.

Q: How do I decide which catheter design to use?

• A: Consider your clinical environment, the expertise available, and the specific patient needs. If you require a design that minimizes dislocation and offers deeper placement, the catheter through needle may be better. If simplicity and ease of use are paramount, consider the catheter over needle.

By understanding each design’s strengths and limitations, you can make an informed choice that enhances patient care and aligns with your practice’s capabilities.

For more info about the differences between these two designs, check our YouTube Video on the topic.