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Amy Graham
Positive Fluid Displacement Devices
I am searching for the names of any positive fluid displacement catheter end devices on the market.  I am aware of CLC 2000 and Flolink. Any help would be appreciated. Amy Graham
Tom Billings
MicroClave is neutral with a

MicroClave is neutral with a dedicated sterile internal fluid path.  Saline flush only FDA Claim.


rivka livni
MaxPlus by Verus

MaxPlus by Verus Medical.

RyMed also has one, can not remeber it's name.

Peggy McDaniel
 SmartSite Positive Bolus

 SmartSite Positive Bolus Needle Free Valve by Alaris Products.  Product #3000E

Peggy McDaniel RN BSN

Infusion Practice Manager, Western Region

Cardinal Health

Peggy McDaniel RN BSN

Infusion Practice Manager, Western Region


The InVision Plus Neutral

The InVision Plus Neutral Connector by RyMed Technologies, franklin TN is not a positive pressure device.  It is a zero fluid displacement connector.  There is zero fluid displacement with connection or disconnection.  With positive pressure devices there is fluid displacemnt with connection.


Denise Macklin

I thought the RyMed valve
I thought the RyMed valve was a negative pressure valve. I believe this because everytime I have removed a flush syringe from the device, the fluid sucks back into the catheter. What does the "zero" fluid displacement you mentioned mean?
Zero fluid displacement

Zero fluid displacement means exactly that:  zero fluid reflux upon connection to or disconnection from a syringe.

The Vygon Bionector was introduced in the early, mid-1990s and is the first needle-free IV connector to exhibit "neutral" pressure.

The RyMed InVision-Plus Neutral IV connector also exhibits neutral pressure and carries a registered trademark on the term "neutral."  Neutral Displacement is defined in their patent language as -0.000mL/+0.002mL immediately upon connection, and + or - 0.000mL immediately upon connection.

Both of these devices exhibit zero fluid displacement because neither contain dead space within the fluid pathway.  Both offer an internal fluid spike or cannula whose internal fluid path volume is not "displaced" by the luer slip during access, entry. 

The MicroClave by ICU Medical calls itself "neutral" with the subsequent caveat, "This means that there is virtually no reflux of blood into the catheter lumen either when you connect or disconnect an administration device."  This is because, while the MicroClave does offer a dedicated internal cannula, the silicone seal or "sleeve" encompassing the fluid cannula still allows for "dead" volume capture at the proximal tip of the seal.  This dead space is displaced when compressed by a luer slip.  The MicroClave claims the lowest dead space of any needlefree connector (0.04mL).  This is true.  However, in order for a device to offer truly NEUTRAL or zero displacement there must exist ZERO dead space.  Curiously, the MicroClave "Neutral" exhibits more negative fluid displacement upon disconnection than that of the original Clave.

When one performs a structured, uniform fluid displacement evaluation on all connectors, these fluid displacement phenomena are clearly identifiable and can be quantitatively measured and consistently repeated.  There should, in fact, exist THREE classifications of devices; those offering negative displacement upon disconnection requiring a clamping sequence, those with negative displacement upon connection (positive pressure valves) requiring no clamping sequence, and those with ZERO displacement at neither connection NOR disconnection where NO change to clamping practice is needed.

All blood reflux cannot be eliminated.  The IV connectors only impact that of mechanical reflux, not physiological.  When repetitive reflux episodes during routine catheter/IV connector access occur, the repetitive cycling of blood along the intraluminal surface of the catheter accelerates the deposition of protein, blood fibrin, necessarily accelerating the process of or potential for occlusion.  If the SASH method is used, 4 additional cycles of blood reflux will occur with any device carrying negative displacement.  With the SAS method 3 refluxive episodes occur.  With a 4-drug administration this equates to 16 or 12 cycles of blood in and out of the tip of the catheter respectively.  These repetitive reflux episodes can contribute to intraluminal thrombotic catheter occlusion potential and can be mitigated by flushing.  However, if these repeated episodes of intraluminal blood movement could be minimized or eliminated, it stands to reason that occlusion potential could thus be mitigated.  Reduced intraluminal thrombotic occlusions have been reported with zero displacement devices.  Conversely, "positive pressure" connectors, those displacing upon connection, generally reflux more as a device category than their "negative displacement upon disconnection" predecessors.  This largely is due to the internal valve mechanism needed to provide the fluid expulsion upon disconnection.  Luer-slip access depresses the internal "valve" into the fluid chamber, causing inner volume displacement which then fills the chamber with fluid in order to then expel or "push" the fluid outward upon disconncetion.  This is why NO clamping sequence can be employed with positive pressure devices because clamping exhibits the requisite fluid expulsion during luer-slip exit.

Also, only IV connectors that offer a dedicated internal fluid pathway with ZERO dead space, i.e. the Bionector and InVision-Plus Neutral, can be effectively flushed with 10mL saline-only flush.  Dead space cannot be effectively flushed or cleared.  So the argument that since all devices allow blood penetration, passage through the connector during aspiration therefore ALL carry the same fibrin build-up and biofilm potential is invalid.  RyMed publishes a blood clearing report at and it shows 0.00 residual hemoglobin after only a 5mL normal saline flush.  RyMed also posts an independent study correlating device priming volume as a predictor of biofilm formation.  The Vygon did not appear in the study but the InVision-Plus Neutral was logarithmically superior.  The Clave's blood clearing report is published at and shows a residual blood volume of 28% in the wash post-flush.  The study demonstrates that minimal residual hemoglobin was found in subsequent second, third or fourth flush-washes.  Therefore, the deduction can be made clearly that the residual hemoglobin resides "dead" somewhere in the fluid path or system.  No blood clearing reports are published online for the MicroClave.  Such reports for the Bionector are not published online.  However, Vygon does cite three "Laboratory Reports" relative to its device's testing.  Of all the IV connector manufacturers posting information online, RyMed offers the most comprehensive, unbiased, educational information available.

Brian Colby
Clearthemud, Fact. Rymed


Fact. Rymed Invision causes blood reflux upon luer disconnection.

Also, you're ignoring a huge question. Why do nurses access valves in the first place? They do this to aspirate blood, deliver medication, and flush with saline. This makes your spin on positive displacement as (reflux on connection) an insignificant point. The blood that will enter the catheter upon connection is no different than when a nurse is checking for flashback on the placement of the line. I know you're trying to sell some Invision valves, but telling clinicians there is no clamping protocol for your negative displacement device could be putting patients at a higher risk for occlusion, infection, and possibly worse if that valve was to accidentally come off of a central line of an unconcious patient in the icu.


Brian Colby
Maximus Medical

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