Needleless Injection Site -Working Anatomy Of Needleless Connector Structure


External characteristics. The housing of the pinless co […]

External characteristics. The housing of the pinless connector can be opaque, colored or transparent. The external connection surface may have an angled center, or may actually be flat, concave or concave.

There are two ways to connect an IV set or syringe: the tip of the male Luer connector of the IV set or syringe or the blunt-ended cannula attached to it can be done in the following ways:

(1) Manually push through the split diaphragm or

(2) Directly lock the Luer connector to the mechanical valve. Although some septum separation devices will accept needles, never use needles in needleless systems.

Internal characteristics. Although their appearance may be similar, internal differences in pinless connectors affect how they work.

Simple and complex. Most pinless connectors are one of two types: simple connectors that do not have internal moving parts, such as those with external split diaphragms; and complex connectors, which rely on internal movements such as mechanical valves Components to control fluid flow within the device. The internal characteristics of the connector determine how the device handles fluid displacement and the fluid path

The manufacturer describes the fluid displacement in a needleless connector as negative, positive or neutral. A connector with a negative displacement can pull blood back into the catheter lumen when connecting, disconnecting, or connecting a drug delivery device. The positive fluid displacement connector can hold a small amount of liquid, so when the IV set or syringe is disconnected, the liquid will be pushed into the lumen of the catheter to overcome the backflow of blood in the lumen. When connected or disconnected, neutral fluid displacement prevents blood from entering the catheter lumen.

To determine the fluid displacement of a needleless connector, you must refer to product information and instructions. Connectors with positive or neutral displacement usually highlight this feature in their label information; devices with negative displacement rarely discuss this quality. Although the term "pressure" is commonly used to describe a connector with positive displacement, such devices do not actually generate any pressure, but merely move the fluid forward within the catheter lumen.

Fluid channel. Because the septa connectors have no internal moving parts, they provide so-called "DC channels", which means that they allow fluid to flow directly through the lumen (see Figures 1a and 1b). However, the blunt sleeve or male luer tip used to enter the separation septum connector may be relatively large, but when drawn out of the separation septum, a negative fluid displacement (or backflow) may occur.


The center piece of the connector with a mechanical valve opens on the external connection surface. When the male luer end of the IV set or syringe pushes down the center part of the valve, it means that the IV set or syringe is connected. If the displacement of the mechanical valve is negative, the fluid flows through the middle of the center piece; if the displacement is positive, the fluid flows between the housing and the movable center piece. Some mechanical valves that are said to have a neutral displacement include a reversed internal blunt-ended cannula that is connected to the male luer of an IV set or syringe, allowing fluid to flow through its center. (Not all neutral displacement connectors have this design.)

Another device designed to achieve neutral displacement is a pressure-sensitive cup-shaped slit silicone disk that can be used with septum connectors and mechanical valves. When the infusion pressure drops, the intervertebral disc closes automatically, preventing blood from flowing back into the catheter cavity

The potential risk factors for complications associated with needle-free connectors can be divided into several categories, including device design, insufficient user knowledge, negligence of the management of the entire IV system, and frequency of connector replacement.

Equipment design. Potential contamination may be related to several connector design features. For example, the opaque or colored housing makes it difficult to see any residual blood or particles inside the needleless connector, and the transparent housing makes this visualization possible. Similarly, the configuration of the connection surface may affect the ease of connection and cleaning. A flat surface may pose a challenge for the installation of intravenous infusion sets or syringes, because if the tip of the male luer is swept across the surface, it may be contaminated. A concave or concave surface may simplify the connection because it guides the male luer of the IV set or syringe to the center. However, it is difficult to fully clean the dent center before connecting.


In a connector with a mechanical valve, the space between the housing and the active centerpiece of the valve can trap microorganisms and other environmental debris, but it is practically impossible to clean. 12Once the organic matter enters the device, they can settle at the fold of the center piece. 5.13 In order to reduce the associated infection risk, some manufacturers have produced needleless connectors with antimicrobial agents on various internal surfaces, such as silver or silver plus chlorhexidine,. Two in vitro studies have shown that silver-containing needleless connectors can significantly reduce microbes and downstream biofilms (the viscous material that protects and surrounds organisms), although prospective randomized clinical trials are required to determine this reduction in CRBSI influences. 14, 15

No specific design or type of needleless connector is associated with a higher risk of infection, but the 2011 Guidelines for the Prevention of Intravascular Catheter-Related Infections developed by the US Centers for Disease Control and Prevention (CDC) recommends the use of septa Pinless connector. Compared with "mechanical valves", "mechanical valves" are more popular because they "increase the risk of infection of mechanical valves." 8 At present, the US Food and Drug Administration does not recommend product changes. 16 It is worth noting that the product changes in the facility greatly increased the incidence of CRBSI, which led to the hospital's return to the original needleless connector.

Whether blood flows back into the catheter lumen depends on the function of the connector and the design of the syringe. 17 Except for the pressure-sensitive cup-shaped slit silicone disk, all needle-free connectors have an open blood return channel. When the intravenous infusion set is connected to the catheter, the catheter enters the catheter cavity. For traditional syringes filled by nurses or pharmacies, blood backflow is created by compressing the rubber gasket on the plunger rod. After releasing the plunger rod, the gasket expands and draws blood into the lumen of the catheter. Several brands of pre-filled syringes are now designed to prevent this type of backflow. (All syringes are disposable items, do not reconnect them to the needleless connector or intravenous drug delivery kit.)

The user has insufficient knowledge. Although it is essential that the user must know the correct method to flush and clamp the needleless connectors used, employee training is often inadequate. In addition, few studies have investigated the most suitable method for cleaning and disinfecting needleless connectors. Self-reports of nurse practices indicate that 3% to 4% of ICU and medical surgical nurses use disinfectant to clean needleless connectors from time to time before entering


Inattentive to system management. System management involves following strict hygiene practices regarding hand washing and contact, restricting the operation of IV sets and components, and following current connector replacement practice standards.

Hand hygiene. A survey of the hospital policies of 10 hospitals in the Midwest found that 80% of the written policies required hand hygiene before inserting the vascular access (VAD), but only 36% of the written policies required hand hygiene before entering VAD Ministry of Health.

Non-sterile access equipment. The needle-free system is two-sided, one side is the connection surface of the needle-free connector, and the other side is the male luer end of the intravenous infusion set or syringe. Even if the connector is completely clean, it is possible to introduce organisms from a contaminated intravenous infusion set or syringe. The CDC guidelines require that only sterile equipment be used to access the needleless connectors.

Although the male luer end of the intermittent intravenous infusion set must be protected from contamination between uses, various unsupported methods are still being used. These measures include fully exposing the Luer end, covering it with an aluminum foil wrap on an alcohol pad, covering it with the tip cover of a flush syringe, or connecting it to a higher needleless connector on the same set (this practice is called "circulation" ). 20, 22 alcohol pad packaging and syringe tip cover are disposable items, not suitable for repeated use of the male luer end of the kit. No research has been conducted on cyclic safety.

Operate frequently. The most important goal of managing intravenous infusion sets and needleless connectors is to minimize the amount of operation. When intravenous infusion sets are used for continuous infusion, do not disconnect them from the catheter hub before replacement. set. The IV set should be directly luer-locked on the catheter base. Pinless connectors should not be used. Unfortunately, it has become common practice to attach a needleless connector to a catheter hub and then attach a continuous drug delivery kit to a needleless connector. This adds unnecessary Luer lock connection, if the connection is disconnected, organic matter or air may enter the system. In addition, the presence of a needleless connector in the continuous infusion system will facilitate the disconnection of the infusion solution when the patient goes to the bathroom, takes a bath or walks. Frequent disconnection increases the risk of contamination and slows the patient's progress toward the treatment goal (because the patient did not receive the prescribed infusion when disconnecting the system).

The secondary piggy-type drug group should maintain a connection with the primary continuous group. If there is no drug incompatibility, you can use the reverse perfusion method to apply a set of auxiliary drugs to multiple drugs (in this method, the nurse flushes the secondary drug delivery tube with the main IV solution to remove the first Drug residues)


Each dose of medication is intermittent intravenous medication at both ends. Clinical studies on intravenous administration either did not state that they included intermittent drug therapy, or specifically pointed out that these drugs were excluded from the study. This means that there is no data on the results of intermittent drug therapy. In view of the lack of data, the Infusion Care Practice Standard recommends that the intermittent dosing group be changed every 24 hours. The 232011 CDC guidelines pointed out that the change interval of the intermittent intravenous administration group is an unresolved problem, and therefore recognized the lack of data sets used in this way.

The interval between connector changes is also a confusing issue. Many manufacturers have tested their pinless connectors for up to seven days, or the number of activations that can be reasonably performed within seven days. The Infusion Care Practice Standard states that the best time to replace a needle-free connector has not been determined. 23 However, according to the CDC guidelines, the frequency of replacement of needle-free connectors should be the same as that of continuous intravenous infusion devices (ie, the frequency of each replacement should not exceed 96 hours for each group). 8 Research shows that the biofilm reaches a stable state in the needleless connector within five days, at which time the biofilm grows at the rate of rupture of the clumps, because the clumped cells are separated from it and float into the blood, they can produce CRBSI .twenty four


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