Connectors for intravenous catheters without needles

How to avoid the pitfalls inherent in diverse theories and approaches.

OVERVIEW: In the early 1990s, needleless connectors for N catheters, administration sets, and syringes were developed to reduce the incidence of needlestick accidents among health care personnel.

While needleless connections do this, their usage has been linked with an increase in catheter-related bloodstream infection and catheter lumen blockage. Complications may be caused by design traits, user knowledge gaps, ineffective behaviors, or a combination of the three.

The author discusses the connections now in use, their design and function differences, the possible difficulties related with different models and practices, and the nursing interventions that may help mitigate these risks.

Since the introduction of needleless connections for intravenous administration in the early 1990s, a number of these devices have been available. Although these devices are often referred to as “end caps,” “injection caps,” “luer-activated devices,” “injection ports,” and “mechanical valves,” the phrase “needle-less connection” is the most appropriate, since it is the only name that encompasses all kinds and designs in this category. Numerous needleless connect- ors may be used within a same health care system, each with a distinct design and purpose. While needleless connections have significantly decreased the likelihood of needlestick injuries among health care personnel, they have also been linked to an increase in complications such as catheter-related bloodstream infection (CRBSI) and catheter lumen blockage.'” This article discusses the numerous needleless connectors available for use in intravenous systems, the differences in their design features and function, the potential complications that can occur if the nurse using and assessing the devices is unaware of the differences, and nursing interventions that can help mitigate any associated risks.


Needleless connections vary in appearance and function.

External features. The needleless connector’s exterior housing may be opaque and colored or transparent. External connection surfaces might be angled in the center can be almost flat, concave, or indented.

An IV set or syringe may be connected in one of two ways: the male luer tip of the IV set or syringe, or a blunt cannula attached to it, may be manually pushed through a split septum or (2) immediately luer-locked onto the mechanical valve. While certain split-septum devices accept needles, they should never be used in a needleless system.

Characteristics internal. Although they may seem to be identical on the outside, needleless connections contain underlying variances that impact how they operate.

Simple vs. complicated. The majority of needleless connections are classified as either simple connectors with no internal moving elements, such as those with an external split septum, or complicated connectors having internal moving components, such as a mechanical valve, that regulate the flow of fluid inside the device. The internal properties of the connections dictate both the manner in which the devices manage fluid displacement and the fluid channel.

Manufacturers specify whether fluid displacement inside the needleless connection is negative, positive, or neutral. Negative displacement connectors enable blood to be drawn back into the catheter lumen or to reflux into it during connection, disconnection, or attachment of the administration set. Positive displacement connectors include a tiny reservoir of fluid, which is forced into the catheter lumen when the iv set or syringe is unplugged, overcoming intraluminal blood reflux. When the catheter is connected or disconnected, neutral fluid displacement keeps blood out of the catheter lumen.

To determine the fluid displacement of a needleless connection, refer to the product’s documentation and use instructions. Connectors with positive or neutral displacement often emphasize this property in their labeling information; connectors with negative displacement seldom do so. Although the word “pressure” is often used to refer to positive displacement connections, these devices do not produce pressure but rather transfer fluid ahead inside the catheter lumen. Pathway for liquids. Due to the lack of internal moving elements, split-septum connections create a “straight fluid channel,” allowing fluid to flow directly through the lumen. However, the blunt cannula or male luer tip used to access split-septum connections may be rather big, resulting in negative fluid discharge (or reflux) when it is withdrawn from the split septum.

Mechanical valve connectors contain center-pieces that open on the connection’s exterior surface. When the male luer end of the IV set or syringe presses downward on the valve’s centerpiece, fluid may enter. If the mechanical valve has a negative displacement, fluid flows through the centerpiece’s mid-dle; if the valve has a positive displacement, fluid flows between the outer housing and the moveable centerpiece. Certain mechanical valves, referred known as neutral displacement valves, feature a reversed internal blunt cannula that connects to the male luer of an intravenous set or syringe, allowing fluid to flow through its center. (This design is not used on all neutral displacement connections.)

Another method for achieving neutral displace- ment is a pressure-sensitive, cupped, slit silicon disk that may be utilized with split-septum connections or mechanical valves. When the infusion pressure declines, the disk automatically shuts, preventing blood from recirculating into the catheter lumen.


Complications related with needleless connections may be caused by a variety of circumstances, including device design, user knowledge deficiencies, inattention to the overall iv administration system’s management, and the frequency with which the connectors are replaced.

Conception of the device. Contamination might be caused by a variety of connection design characteristics. For example, opaque or colored exterior housing obscures any remaining blood or particle debris within a needleless connection, while transparent external housing allows for such viewing. Simultaneously, the design of the connecting surface may have an effect on both the ease of connection and cleaning. A smooth surface may make it more difficult to connect the IV set or syringe, since the male luer tip may get contaminated if it brushes against the surface. A concave or depressed surface may facilitate connection by guiding the male luer tip of the intravenous set or syringe into the center. The indented center, on the other hand, is difficult to clean sufficiently prior to connection.

The area between the exterior housing and the moving core of mechanical valves may trap germs and other environmental material, yet it is practically hard to clean.

 Once within the device, organisms may populate the collapsed folds of the centerpiece or the space between the fluid channel and the connection housing, which is prone to fluid leakage. To reduce the danger of infection, several manufacturers have coated a number of interior surfaces with antimicrobial chemicals such as silver or silver plus chlorhexidine. Two in vitro studies demonstrated that needleless connectors containing silver may significantly reduce both microorganisms and downstream biofilm (the slimy substance that protects and surrounds organisms), although prospective, randomized clinical trials are required to determine the effect on CRBSI.

Although no particular design or type of needleless connector has been associated with an increased risk of infection, the 2011 Centers for Disease Control and Prevention (CDC) Guidelines for the Prevention of Intravascular Catheter-Related Infections recommend that split-septum needleless connectors be preferred over mechanical valves due to the “increased risk of infection with mechanical valves.”

At the moment, the US Food and Drug Administration does not recommend any adjustments to products. Notably, facility-level product modifications have significantly raised incidence of CRBSI, prompting several hospitals to revert to their original needleless connections. Blood refluxes into the catheter lumen is governed by many elements, including the connector’s operation and the syringe’s design. Except for the pressure-sensitive, cupped slit silicone disk, when an iv set is connected to the catheter, all needleless connections provide an open channel for blood to reflux into the catheter lumen. Blood reflux is caused by compression of the rubber gasket on the plunger rod in typical syringes filled by the nurse or pharmacist. When the plunger rod is released, the gasket expands into the catheter lumen, drawing blood into it. Numerous types of prefilled syringes are now available that are specifically intended to avoid this form of reflux. (Syringes are single-use products and should never be attached to a needleless connection or an intravenous administration set.)

Deficits in user knowledge. While it is critical for the user to understand the proper procedure for cleaning and clamping the needleless connection being utilized, staff training is often insufficient. Additionally, few studies have been conducted to determine the most effective ways for cleaning and sanitizing needleless connections. According to self-reports, between 3% and 4% of ICU and medical–surgical nurses do not regularly clean needleless connections with an antiseptic solution prior to access.

According to a 2011 survey of 4,000 health care workers in clinical practice, 132 (25.4 percent) of the 554 respondents were unfamiliar with the specific type of needleless connector they used with short peripheral catheters and 114 (21.9 percent) were unfamiliar with the type they used with central venous catheters.

And over half of respondents were unaware of the proper manner to flush and clamp a catheter equipped with a needleless connection, despite the fact that it is critical for de- vice efficacy. Although self-reported practices are not the optimal way for assessing clinical procedures, no other data on these activities available.

Inattention to system administration. System management include adhering to stringent hygiene requirements for handwashing and access, restricting manipulation of IV sets and components, and adhering to current practice guidelines for connection replacements. Maintaining proper hand hygiene. A review of hospital policies revealed that whereas 80 percent of institutions in eleven midwestern states had written rules requiring hand cleanliness before to installing a vascular access device (VAD), only 36% had similar written policies requiring hand hygiene prior to accessing a VAD. 

Access devices that are not sterile. Needleless systems are bipolar in nature; one side has the needleless connector’s connecting surface, while the other features the male luer end of an IV set or syringe. Even if the connection is perfectly clean, bacteria may enter through a contaminated IV set or syringe. The CDC recommends that only sterile instruments be used to access the needleless connection.

While it is required to maintain the male luer end of an intermittent iv set from contamination between usage, a number of unsupported techniques continue to be used. These options include leaving the luer end completely exposed, covering it with the alcohol pad’s foil packaging, covering it with the flush syringe’s tip cap, or connecting it to the needleless connection higher on the same set (a process known as “looping”). The alcohol pad package and syringe tip cap are single-use components and are not intended for reuse on the set’s male luer end. There have been no studies undertaken on the safety of looping.

Manipulation is frequent. The primary purpose of managing intravenous administration sets with needleless connections is to minimize manipulation. When using iv administration sets for continuous infusion, they should never be detached from the catheter hub until the set has to be changed. The intravenous set should be luer-locked directly to the catheter hub; do not utilize a needleless connection. Regrettably, it has become widespread practice to connect a needleless connection to the catheter hub and then a continuous administration set to the needleless connector. This adds an unneeded luer-locking link to the system, increasing the possibility of organisms or air entering the system if the connection is broken. Additionally, the availability of a needleless connector in a continuous-infusion system may facilitate the disconnection of infusion fluids when the patient is toileting, bathing, or ambulating. Disconnection on a frequent basis raises the danger of contami- nation and impedes the patient’s progress toward therapeutic objectives (since while the system is disconnected the patient is not receiving prescribed fluids).

Secondary piggyback medication sets should remain linked to the primary continuous medication set at all times. When there are no pharmaceutical incompatibilities, the backpriming approach may be utilized to employ a single secondary set for several medicines (in which the nurse flushes the secondary administration tubing with the primary iv solution to remove any residual from the first admin- istered medication). 

With each medicine dosage, intermittent iv medication sets are controlled on both ends. Clinical trials on intravenous administration sets either did not specify whether they included intermittent medication sets or clearly indicated that they did not. This implies that no data exist on the results associated with the usage of intermittent medication regimens. The Infusion Nursing Standards of Practice propose that an intermittent administration set be adjusted every 24 hours in the absence of data.  The 2011 CDC recommendations say that the change interval for an occasionally used intravenous injection set remains an unsolved problem, given the dearth of evidence on such sets. 

Additionally, the delay between connection modifications is perplexing. Numerous manufacturers have tested their needleless connections for a period of no more than seven days or for the greatest number of activations that may possibly be conducted in that time period. According to the Infusion Nursing Standards of Practice, there is no proven ideal timing for replacing needleless connectors. However, the CDC recommends that needleless connections be replaced at the same frequency as continuous iv setups (that is, no more often than every 96 hours). 8 Within five days, biofilms reach a steady state in needleless connections, at which time they grow at about the same pace as they break apart—when clumps of cells detach and float into the circulation, where they might cause CRBSI. 


Infection. Needlesless connections were connected with an increase in CRBSI rates shortly after their debut in the early 1990s. Even within the last several years, complaints of CRBSI have been made in connection with the use of needleless connections in hospitals and one long-term care institution. In comparison, six randomized controlled clinical trials done in Europe between 2000 and 2007 found no increase in CRBSI rates linked with needleless connections, and in three of those studies, CRBSI rates were lowered. However, there is a substantial difference between US behavior and that shown in European research. The second study contrasted a “conventional open system” (a stopcock attached to the end of each catheter hub) to connections equipped with mechanical valves with either negative or positive displacement. Patients were assigned randomly to utilize the stopcock alone or to have a needleless connection installed on each stopcock aperture. Stop-cocks are seldom used in the United States, save for brief durations during anesthesia and critical care, when they are contained inside continuous infusion iv administration systems and are not directly connected to a catheter hub.

In the United States, it seemed as if infection was becoming less common as nurses acquired expertise and conquered the problems associated with the new needle-free methods. In 2002, the CDC said that when “[needleless connections] are used according to manufacturer’s recommendations, they have no appreciable effect on the incidence of CRBSI.” However, there were several instances of CRBSI outbreaks in needleless systems-using institutions. The American Society for Healthcare Epidemiology published a compendium of measures for preventing CRBSIs in hospitals in 2008. They suggested that prior to using needleless connections, a detailed risk-benefit analysis be conducted, as well as instruction about the correct usage of “positive-pressure needleless connectors with mechanical valves.”

Disinfection technology advancements. Recently, a new technology for cleaning needleless connections was introduced: the Site-Scrub isopropyl alcohol device (Bard Access Systems). The device is a stiff plastic cap that contains little finger-like sponges soaked with 70% isopropyl alcohol. It may be placed on top of a needleless connection, stopcock, or catheter hub. The cap’s rotation enables the sponges to clean all surfaces, including the stopcock or catheter hub’s intraluminal surfaces. Clinical trials for this device are currently underway, and results are not yet available.

Another device that falls within this category is the anti-infective or protective cap. The SwabCap (Excelsior Medical), the Curos Port Protector (Ivera Medical), the EffectIV-Cap (Hospira), and the DualCap (Catheter Connections) are all hard plastic caps that contain a circular sponge wet with 70% isopropyl alcohol. After usage, they are put over the needleless connection and left in place until the next use. The alcohol saturates the surface, killing any organisms that come into contact with it. Between usage, the cap is left in place to avoid soiling of the surroundings. A recent clinical trial demonstrated that when protective caps were utilized in conjunction with peripherally inserted central catheters (PICCs), they significantly reduced intraluminal contamination and bacteria density. A 2012 study using these protective caps shown a substantial decrease in CRBSIs. Infection rates decreased from 2.3 infections per 1,000 catheter days during the manual scrub phase to 0.3 infections per 1,000 catheter days during the protection cap era.

These protective caps clean the needleless connection surface, obviating the requirement for initial cleaning, but they are not designed to completely eliminate the need for scouring of the needleless connection surface. Three or four connections and disconnections may be required for a single medicine. While the first cleaning may be omitted, a thorough surface cleanse should precede the installation of any set or syringe attachments. Occlusion of the catheter lumen. Initially, nurses suspected that the increased use of thrombolytic medicines in patients receiving intravenous treatment was related to the use of big blunt cannulas and the moving internal components of mechanical valves. There is little evidence of catheter lumen blockage linked with needleless catheters in sequential cohort studies4, 11 and two randomized clinical trials (see Table 2 at http:// Although positive displacement connections were created to address the problem of occlusion, their effectiveness in decreasing occlusion has been shown primarily in laboratory testing conducted by device makers.

Disagreements around flushing and locking techniques.

Occlusion of the catheter lumen may be caused by poor cleansing and locking methods. After each usage of a VAD for intermittent infusions, it must be flushed and secured. To ensure catheter patency and to avoid interaction between incompatible drugs, catheters should be flushed with 0.9 percent sodium chloride (normal saline) solution. When a catheter is locked, a column of fluid is created inside the lumen to preserve patency. Manufacturers of positive and neutral displacement needleless connections advise doctors to lock the catheter with regular saline rather than heparin. However, clinical data supporting this strategy is limited to two recent investigations that demonstrated greater lumen occlusion when normal saline was employed as the locking solution. In one of these studies, the 6% occlusion rate associated with the normal saline lock (compared to the 0% occlusion rate associated with the heparinized saline lock) rendered it financially unfeasible for the hospital to discontinue using the heparinized saline lock, given the $1,900 cost of each PICC replacement. A comprehensive systematic analysis of the literature examined the results of clinical trials in which central venous catheter patency was maintained using heparin, saline, or urokinase flushes; continuous heparin; heparin-coated catheters; or “pressure caps” (needleless connectors with positive displacement). The authors found that published trials comparing therapies to avoid occlusion were of “poor quality,” and that the available data does not support any specific method of preserving patency.

Due to the incompatibility of heparin with a wide variety of medications, all VADs necessitate the use of normal saline between doses to avoid interaction and the development of intraluminal precipitate.

Two meta-analyses of trials employing short peripheral catheters found that catheter results were almost same whether normal saline or a heparin-locking solution was utilized.For these reasons, the 2011 Infusion Nursing Standards of Practice suggest that such catheters be locked with normal saline. However, because to the hazards associated with central venous catheter insertion, a greater degree of support is necessary before a new standard for their usage can be created. According to the 2011 Infusion Nursing Standards of Practice, locking all central venous catheters using a heparin lock solution (10 units per mL) maintains the national standard of practice.

Although in vitro research have shown that heparin promotes biofilm formation, no clinical investigations have established a relationship between heparin usage and an increased risk of CRBSI.

Prior to discontinuing the use of heparin-locking solutions, further outcome data are required. Alternative locking solutions that combine antiinfective and anticoagulant characteristics are being studied, but are not commercially accessible in the United States at the moment.


To minimize the danger of infection and occlusion, it is critical that employees get training on how to properly utilize needleless connections and syringes. Written rules and procedures should cover the particular connection types used at the institution and include hand hygiene for all operations involving injection or infusion through any form of VAD. Because it may be confusing for doctors and result in unfavorable results, it is discouraged to employ various brands or kinds of con- nectors in the same institution. 20

Although needleless connections are delivered in sterile packaging, removing them from the packaging and connecting them to a catheter hub contaminates the exterior surface of the connector. This implies that even recently connected connections will need a thorough cleaning. The Joint Commission now demands that a methodology for cleaning catheter hubs and injection ports prior to access be implemented. 42 In vitro investigations have shown that increasing the scrub duration reduces the microorganism load on the connection surface. A three- to five-second scrub with isopropyl alcohol is insufficient to prevent pathogens from entering the system with the majority of needleless connections. 43 A thorough 15-second scrub of the connecting surfaces with a swab pad coated with 70% isopropyl alcohol significantly decreases but does not remove the quantity of germs in the majority of needleless systems. 41 Although there are few clinical studies examining the effect of cleaning agents or manual techniques on CRBSI reduction, these in vitro studies emphasize the critical nature of cleaning the connector prior to each IV set or syringe connection, which requires the use of up to four swab pads per medication.

It’s worth noting that a recent study of one needleless system (Baxter’s Interlink IV Access System) discovered that a vigorous five-second scrub was sufficient to clean the exterior split-septum needleless connections.

New connections were either constructed in vitro or attached to catheters from critically ill patients and then cultured either without scrubbing or after a five-, ten-, fifteen-, or thirty-second vigorous scrub with a 70% isopropyl alcohol swab pad. Only one (1.4%) of the 71 connections removed from patient catheters and cleaned for five seconds revealed microscopic growth. After roughly five seconds of scrubbing, connectors infected in vitro with 103 or 105 colony-forming units (CFUs) of Staph- ylococcus epidermidis were likewise determined to be sterile. Two (20%) of ten connections infected with 108 CFUs remained contaminated after a five-second scrub but were sterile following a ten-second scrub.

The intermittent iv set is typically in touch with linens, clothes, and other environmental material for 30 to 60 minutes. Following each separation, blood-tinged fluid may remain on the connection surface. Both of these factors need repeated cleaning.

Although clinicians often replace needleless connectors immediately after collecting a blood sample, this practice is not supported by data. Before each dosage of medicine is provided, blood is sucked to determine catheter patency; this may result in blood entering the needleless connection. False-positive blood cultures have been produced in studies where blood is taken from central venous catheters through contaminated connections. This recommends that needleless connections should be replaced before to, not after, drawing blood.

Clinicians should determine the maximum pressure that a needleless connection can withstand before utilizing it for rapid-flow infusion (3 to 5 mL per second), which may be necessary in urgent operations or radiology. If something obstructs the flow of fluid, fast infusion may generate pressures that exceed the connector’s capacity. The product information for the connection should include the maximum amount of pressure it can withstand.


Health care institutions must offer needleless connections significant consideration and establish policy decisions that are acceptable for their patient groups, staff, and IV procedures. Product selection should be based on an in-depth examination of the risks and advantages. When product modifications are implemented, it is critical to monitor infection and occlusion rates, since product changes are often linked with an increase in the incidence of CRBSI.

While the degree of risk associated with each type of needleless connector cannot be determined based on available evidence, we can significantly reduce known complications such as infection and catheter lumen occlusion by becoming knowledgeable about and developing the skills necessary to safely use available connectors. This requires facilities to monitor worker compliance with specified processes. Clinical trials with an appropriate design are required to further inform practice.

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