The 7+7 Day Extreme Use Microbial Challenge for the nPulse™ Neutral Connector

Thursday May 28, 2015
by Todd Chelak: Research & Development

In Part I of this two-part series, I reviewed factors that can influence the disinfection routine. The article also compared the durability associated with three designs for needle-free connectors: internal cannula system, Luer penetrating system, and the self-opening split septum (SOSS™) system used in the patented nPulse™ Neutral Connector.


In Part II, I’d like to talk about how you can be confident that the SOSS™ design maintains the integrity of the septum — meaning that it opens and closes with reliable performance even with prolonged usage.

NP Medical used a third-party testing firm to conduct a 7+7 day extreme use clinical simulation. The goal was to determine whether, after 7+7 days of extreme clinical use, our nPulse Neutral Connector would break down and allow pathogens to pass through the septum. Note: 20 test samples were used in the study, along with 3 positive control samples and 2 negative control samples.

How did we characterize extreme clinical use?

Multiple activation cycles:          168 (equates to 1 per hour for 7 days), followed by an
Extended activation period:         7 days (168 consecutive hours)

At the end of the 7+7 day extreme clinical use scenario, when it could be reasonably assumed that the septum would be prone to wear, Staphylococcus aureus was introduced upon the septum at a clinically high level of approximately 500 CFU[1]. After a brief period of incubation, the disinfection routine was conducted in accordance with the Instructions for Use. The device was then flushed with 10mL of fluid to assess whether any S. aureus bacteria were present and could be introduced into the fluid path, which would indicate a microbial barrier failure.

As the table below shows, there was zero growth of bacteria for each of the 20 nPulse Neutral Connector test samples[2]. It is important to note that this was not the average or median number of CFU for these samples, but an absolute reported number.

What does this test tell clinicians? It says that we simulated rigorous use over a longer period of time than you are likely to see in a clinical setting. Then we deposited a clinically high level of bacteria on the surface of the septum, which we were able to effectively wipe off following a routine disinfection procedure — with zero penetration of the bacteria into the fluid path in every single connector test sample. The conclusion: the SOSS™ design maintained a robust barrier with intense use and over an extended period of time.

It’s why we also say that it is all in the SOSS™.


[1] Larson EL, Cronquist AB, Whittier S, Lai L, Lyle CT, Della Latta P. Differences in skin flora between inpatients and chronically ill patients. Heart Lung 2000; 29: 298–305.

[2]  Data on file at Toxikon Corporation (Bedford, MA, USA).

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