Until a few years ago, the prevailing view was that a neutral needle-free connector was impossible to achieve. Consequently, many medical device manufacturers promoted positive displacement as the best approach for preventing blood reflux into an IV catheter. However, in the last few years, neutral connectors have become a reality, and now a neutral needle-free connector with no blood reflux is the preferred technology1.
nPulse™ Neutral Connector.
The other three were the InVision-Plus® Neutral®from RyMed Technologies, the MicroCLAVE® Clear Connector from ICU Medical, and the One-Link Needle-free IV Connector from Baxter.
Achieving neutral displacement is, in reality, an engineering feat. Actually, it requires a combination of advanced engineering design, and high-precision manufacturing processes— the latter is especially important for consistent performance in high volume production.
1Jarvis W., MD. Choosing the Best Design for Intravenous Needleless Connectors to Prevent Bloodstream Infections. Infection Control Today, July 2010,
2 For an in vivo correlation, -2 microliters of blood reflux within a typical 3 Fr silicone PICC would be approximately 1 cm of length up the lumen of the catheter.
Blog Reference: http://www.npmedical.com/blog/post/how-close-zero-displacement-do-neutral-needle-free-connectors-actually-get