Central lines come packed with a long introducer needle (pink arrow) to feed the guidewire through AND a long angiocatheter (yellow arrow). Most people cannulate the vein by using the syringe and the introducer needle. What’s the angiocatheter for?

In ACEP News, Dr. Taku Taira and I wrote about a Trick of the Trade on using the angiocatheter as part of a manometer trick when trying to differentiate venous from arterial vessel cannulation. In brief, the angiocatheter can be fed over the guidewire after finding the vein. It can then be connected to IV tubing as a rough manometry measurement.


Trick of the Trade

Use the angiocatheter INSTEAD of the long needle from the beginning of the procedure

  1. Cannulate the desired central vein using the angiocatheter while applying negative pressure on the syringe.
  2. After puncturing the vein, feed the angiocatheter into the vessel WITHOUT a guidewire.
  3. Remove the needle and syringe, leaving the angiocatheter in place.
  4. If necessary, check whether the blood is venous or arterial in origin using the manometer trick.
  5. Continue the rest of the Seldinger-based technique per routine by feeding the guidewire into the angiocatheter.

Caution: The angiocatheter is a few millimeters shorter than the introducer needle and may not work for those with excessive soft tissue thickness or with long tunneled tracks (e.g. subclavian line). 

This trick removes the extra step of needing to feed the angiocatheter over a wire and into the vessel. Thanks to Dr. Jeff Wiswell (EM resident at Mayo Clinic) for submitting the modification to this trick!


Michelle Lin, MD
ALiEM Founder and CEO
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD


Professor of Emerg Med at UCSF-Zuckerberg SF General. ALiEM Founder @aliemteam #PostitPearls at https://t.co/50EapJORCa Bio: https://t.co/7v7cgJqNEn
Michelle Lin, MD