8 minute read

Needleless Connectors: New Standards, Still Confusing

Matt Gibson, Chief Executive Officer for Vascular Access Consulting, LLC

How exciting it is to have the new Infusion Therapy Standards of Practice (SOP). One area of interest is needleless connectors (NC). Many clinicians find differentiating NCs and how to use them confusing.1 A common question I hear is, “What is the difference between neutral and anti-reflux NCs?” The way the SOP discusses these labeled connectors seems to be nearly the same. However, the labels come from the manufacturer’s marketing descriptions2 , and there are no established quantitative criteria from device regulatory agencies that determine which device belongs to each category. The neutral NC is described in the SOP glossary3 as, “Contains an internal mechanism designed to reduce blood reflux into the vascular access device (VAD) lumen upon connection or disconnection.” This definition is different from the 2016 SOP4, where the term described as “internal mechanism to prevent blood reflux” which both definitions, 2016 and 2021, more closely describes the anti-reflux NC. Neutral, antireflux as well as negative connectors have a straight fluid pathway, but the anti-reflux is the only one that has an internal mechanism to reduce or prevent blood reflux.

The differences between the anti-reflux technology and other NC categories are the volume of reflux (see Table 1) and bidirectional flow control5. When the vein’s pressure is higher than in the infusion system, the dome-shaped silicon diaphragm closes independent of the clinician dependent clamping. It will prevent the retrograde flow of blood into the catheter lumen and infusion system. More confusion with the glossary terms is with positive displacement NCs. The new SOP definitions tell us that the positive displacement NCs, having a complex fluid pathway, “Allows blood reflux on connection and disconnection.” This statement is a little confusing for the reader. As written, it implies that this type of connector refluxes, both when connection and disconnection occur. However, all NCs will only reflux during one phase of the connection-disconnection cycle6-8 . Look at Table 1 (on following page). It is clear that all NCs reflux blood. The difference is when and how much occurs. Negative displacement, neutral and anti-reflux NCs reflux on disconnection, and positive NC reflux on connection. Generally, the neutral label connectors list less reflux than other first-generation negative connectors.

Why is this so important, you ask? Because up to 32 percent and 36 percent of catheters, PIVCs and CVCs, respectively, have occlusions9,10 leading to delays of treatment, increase risk of infection, catheter failure, and device replacement9,11-13. The SOP (36 B 1) states for neutral and anti-reflux connectors, “no specific sequence required” 3. This author’s opinion is that, this direction is not the best recommendation for connectors labeled as “neutral” considering the reflux volume listed for each NC (see Table 1). By not clamping the neutral NCs prior to disconnection will allow blood to reflux into the catheter.

My recommendation is for end-users is to forget the idea that anything about the needleless connector is neutral. In the simplest of terms, all negative, neutral, and anti-reflux needleless connectors will reflux blood on disconnection. The difference is the volume. Clinicians will minimize reflux by engaging the clamp before disconnection occurs. CONTINUED ON NEXT PAGE


Positive needleless connectors will reflux on connection. Clinicians will minimize reflux by assuring the clamp is engaged before connection, apply slight plunger pressure when unclamping, then re-clamp after the syringe is disconnected. Remember, all devices should be flushed thoroughly prior to disconnection regardless of type of NC is use.

Consider this definition of anti-reflux NCs to help you better understand. I have combined the definitions from neutral and anti-reflux to clarify the definition of anti-reflux.


Anti-reflux NCs contains a straight fluid pathway with a 3-position pressure-activated silicone diaphragm (anti-reflux definition) designed to reduce blood reflux into the VAD lumen upon connection or disconnection (neutral definition). The diaphragm opens and closes based on infusion pressure (antireflux). However, the sequence of flushing, clamping, and disconnecting the syringe may improve patency (neutral definition).



Table 1 describes the volume of reflux and when it occurs based on three published articles. Gibson8, Hull6, and Eli7 . (*NOTE: If more than one volume listed from the articles, the author averaged the volumes.)

Brand/ Model Volume of reflux Gibson, Hull and Eli Connector Label2,6,8 Reflux occurs on connection or disconnection

Nexus TKO-6P

BD Neutra-Clear

ICU Medical Neutron



Nexus NIS

RyMEd Invision

0.09 µL 0.33 µL 0.60 µL 1.24 µL 2.38 µL 2.79 µL 4.05 µL Anti-reflux Disconnection

Anti-reflux Disconnection

Anti-reflux Disconnection

Neutral* Disconnection

None Disconnection

Neutral* Disconnection

Neutral* Disconnection

Baxter One Link

ICU Medical Clave

ICU Medical Microclave


BD MaxZero

Baxter Interlink

BBraun Caresite

BD MaxPlus

BBraun Ultrasite

6.14 µL 7.98 µL 8.29 µL 9.36 µL 12.87 µL 13.18 µL 14.98 µL 24.85 µL 36.63 µL Negative Disconnection Negative Disconnection Neutral* Disconnection

Neutral* Disconnection Zero Reflux, neutral*, anti-reflux Connection Negative Disconnection Positive Connection

Positive Connection

Positive Connection

BD Q Syte

BD Smartsite

38.34 µL 41.10 µL Negative Disconnection Negative Disconnection

Baxter Clearlink 118.98 µL Negative Disconnection *NOTE: When reflux occurs on disconnection, the clamp should be engaged prior to disconnection. When reflux occurs on connection, clamp should be engaged prior to connection with positive pressure on syringe plunger prior to unclamping.


The neutral NC becomes a part of the definition of negative displacement NC because both refluxes in the same way. The rationale behind the recommendation is related to the management of the device. Despite what the industry has told the clinicians, neutral NCs have reflux and would benefit by clamping before disconnection. This is the same care needed for negative NCs. Clinicians can provide excellent patient care with any type of needleless connector through precise flushing techniques and timely clamping every connection-disconnection sequence, every time! No matter what connector you are using in your facility, make it a priority that every person knows the right way to flush and clamp your device. REFERENCES

1. Hadaway L. Needleless connectors: improving practice, reducing risks. Journal of the Association for Vascular Access 2011; 16(1): 20-33. 2. Hadaway L, Richardson D. Needleless connectors: a primer on terminology. Journal of Infusion Nursing 2010; 33(1): 22-31. 3. Gorski l ea. Infusion Therapy Standards of Place 8th edition. 2021. 4. Gorski L HL, Hagle ME, McGoldrick M, Orr M, Doellman D. Infusion therapy standards of practice. J Infus Nurs 2016; 39 (suppl 1): S1-S159. 5. Gibson m. In Vitro Evaluation of Needleless Connectors: Testing Bi-directional Flow Control and Quantifying Reflux. 2020. 6. Hull GJ, Moureau NL, Sengupta S. Quantitative assessment of reflux in commercially available needlefree IV connectors. The Journal of Vascular Access 2018; 19(1): 12-22. 7. Elli S, Abbruzzese C, Cannizzo L, Lucchini A. In vitro evaluation of fluid reflux after flushing different types of needleless connectors. The Journal of Vascular Access 2016; 17(5): 429-34. 8. Gibson SM, Primeaux J. Do Needleless Connector Manufacturer Claims on Bidirectional Flow and Reflux Equate to In Vitro Quantification of Fluid Movement? Journal of the Association for Vascular Access 2020. 9. Helm RE, Klausner JD, Klemperer JD, Flint LM, Huang E. Accepted but unacceptable: peripheral IV catheter failure. J Infus Nurs 2015; 38(3): 189-203. 10. Ernst FR, Chen E, Lipkin C, Tayama D, Amin AN. Comparison of hospital length of stay, costs, and readmissions of alteplase versus catheter replacement among patients with occluded central venous catheters. Journal of hospital medicine 2014; 9(8): 490-6. 11. Thakarar K, Collins M, Kwong L, Sulis C, Korn C, Bhadelia N. The role of tissue plasminogen activator (alteplase) use and systemic hypercoagulability in central line-associated bloodstream infections. American journal of infection control 2014; 42(4): 417-20. 12. Rowan CM, Miller KE, Beardsley AL, et al. Alteplase use for malfunctioning central venous catheters correlates with catheter-associated bloodstream infections. Pediatric Critical Care Medicine | Society of Critical Care Medicine 2013; 14(3): 306-9. 13. Jones RK. Short Peripheral Catheter Quality and Economics: The Intravenous Quotient. Journal of Infusion Nursing 2018; 41(6): 365-71.

Disclosure of relevant financial relationships: 1. Consultant for: B Braun, Nexus Medical,

Interrad Medical, PICC Excellence, The Clinician

Exchange, Ethicon, Access Vascular, Adhezion

Biomedical LLC, Eloquest 2. Grant/Research support from: Beaumont

Hospital Research Institute Royal Oak Michigan,

Deaconess Clinic Research Institute, Evansville,


3. Honoraria from Association for Vascular Access (AVA)

Since 1993 Matt Gibson has worked in nursing vascular access was both a primary and essential skill, including emergency department, ICU/telemetry, house supervisor, home infusion and long-term care vascular access team. Gibson currently works with multiple organizations as a vascular access consultant and speaker. He is certified registered nurse infusion, vascular access board certified and certified PICC ultrasound user. He has served on the AVA PIV task force, is a past-president and founder of the Kentucky Indiana Vascular Access Network, current president of Michigan Association of Vascular Access Network and presidential advisor for the InndiVAN.

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