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comparison and function of positive, negative and neutral needleless connectors

I am confused with the negative, positive or neutral valves for PIV's. Which are recommended and why? How is the flushing different? When to clamp? My hospital recently changed to the Braun ultrasite, which is positive.-----Thanks

Ultrasite needleless connector

First, a specific answer for the Braun Ultrasite:
It is a positive displacement needleless connector.
This means that when a syringe or other male luer lock device is removed from the Ultrasite,
a small amount of fluid is moved into the lumen of the catheter, preventing blood reflux.
However, when a syringe is connected to the Ultrasite, blood reflux into the catheter occurs.

The flushing and clamping sequence for the Ultrasite that you are using would be as follows:
Connect the syringe to the Ultrasite, flush the catheter.
Remove the flush syringe, and AFTER removing it, clamp the catheter.
If the catheter is clamped before removing the flush  syringe, that interferes with the positive displacement feature.
For more general information about all types of needleless connectors, here are some resources:

A manufacture of one of the needleless connectors has a slideshow on their website that allows you to see pictures and facts about different injection caps.

Also, there is an article in the Journal of Infusion Nursing, called Needleless Connectors: A Primer on Terminology, by Lynn Hadaway.  This article explains in more detail different features of various needleless connectors and important information for proper use.

Which device were you using before you switched to the Ultrasite?

/Tess M. Hopkins


I would like to add what I have learned from my Max Plus Clear sales rep, Brian. As stated above, positive pressure caps produce fluid displacement. Only once. When the syringe is disconnected from the cap. After that there is no more "positive pressure" activity. Clamping is still necessary (after disconnection) and blood can still reflux with gravity and other pressure changes.

Nancy Rose

Wilmington VA  Medical Center


Nancy Rose 

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