Closed System [drug] Transfer Devices
CSTDs evolved from the observation that the use of needles and vials for HD compounding results in contamination. For nurses who do not compound, a good example is what happens when a needle and syringe is used to withdraw medication from a solumedrol or hydrocortisone vial. As soon as the needle is removed, pressure in the vial typically results in drug spray. Imagine that same problem occurring multiple times when preparing a dose of chemotherapy.
Nurses are also keenly aware of what happens when tubing is disconnected from a patient: it tends to drip. Fluid dynamics tells us that liquid will go through the path of lease resistance. When tubing is disconnected, any movement of the tubing will cause liquid (chemotherapy with or without its flush) to drip from the end. Indeed, dripping IV tubing can be a significant source of HD environmental contamination (Connor, T. et al, 2010, JOEM, 52(10).
CSTDs eliminate or reduce both of these problems, and are required for the administration of antineoplastic HDs by USP <800>.
CSTD Design Types
There are essentially two CSTD designs: luer-based and membrane-based. Each design has certain advantages and disadvantages although membrane designs tend to be more effective (Eisenberg, S. 2017 Journal of Infusion Nursing, 41(1)). (See discussion on CSTD testing for more information). Membrane designs, however, do require the use of a luer adapter (see below).
There are a number of FDA-approved CSTDs on the market. The devices have different strengths and weaknesses and some devices have more published studies than others. Provided below is a brief description of these devices. (Photos © S. Eisenberg)
The first successful CSTD was Phaseal, currently made by BD. When introduced in 1999, it was a revolutionary concept; components added to the traditional vial and syringe successfully prevented the escape of droplets, vapors and aerosols.
During compounding, the vial adapter forced vapors and aerosols into an external balloon. Transfer of the drug is accomplished by compressing two membranes during a locking procedure. Only after the mechanism is engaged can a needle then be passed between the two membranes. The needle is withdrawn prior to disengaging the compressed membranes.
Original Carmel Pharma Phaseal Diagram
Four years later, Teva Medical developed the Tevadaptor which is marketed in the US as the B Braun OnGuard. While also using a membrane system, it relies upon air-cleansing technology to trap aerosols and vapors during compounding. A 0.2-micron filter allows for pressure equalization and prevents microbial ingress, while its charcoal drug-binding matrix is designed to ensure drug vapors cannot escape.
Similar to Phaseal, OnGuard uses a needle to pass between the two compressed membranes. Components push on and off without using a key-design system.
ICU Medical initially developed the ChemoClave system using a closed male luer device (Spiros) and the Genie, which used a balloon that was inserted into the drug vial. The advantage of the luer-based system is that it did not require any adapters. Although the Spiros is still marketed, the Genie has been replaced by a vial adapter using an external metalized expansion balloon (see ChemoLock below).
The CareFusion Texium system consists of a closed male luer device and the Vialshield external balloon. It also has the advantage of not requiring any adapters, and is designed to work with SmartSite connectors. CareFusion was purchased by BD and the Texium line is part of their CSTD porfolio.
Using a unique dual-chambered syringe, Equashield traps vapors and aerosols in the rear section of the syringe during compounding. It is also a membrane based device, and has 2 needles (one for drug transfer and one for rear venting). Unlike traditional syringes, the plunger on the Equashield syringe cannot be accidentally pulled out, and remains free from HD contamination. As with all membrane-based devices, a luer adapter is required.
ICU Medical's newest product line is the ChemoLock, consisting of a needleless membrane-based connector, metalized external expansion chamber, and reinforced vial spike. As with all membrane-based devices, a luer adapter is required.
The Corvida Halo uses a circumferential external balloon to trap vapors and aerosols, and relies upon a robust membrane system that transfers drug via a needle. The larger components are designed to distribute work over a larger area to decrease strain. The Halo has been available for 4 years.
The newest CSTD system is the Baxter Arisure, with components manufactured by Yukon Medical. It consists of a closed male luer and an external balloon.
CSTD Administration Options
Nurses are well-acquainted with primary and secondary tubing sets. But the arrival of CSTDs has allowed more efficient--and safer methods of administering intravenous chemotherapy.
Spiking into a bag of HD at the bedside (or removing the spike) has been prohibited in the guidelines for decades. Tubing spikes are typically sharper than they need to be and can easily puncture the side of an IV bag. Likewise, unspiking a bag has been shown to spread liquid droplets.
Fortunately, there are several safe options when using CSTDs. The oldest option is to have pharmacy prime the tubing in the BSC with neutral solution and then spike into the HD bag. This practice has several disadvantages including the need to stock hundreds of IV sets in the pharmacy, time spent priming the tubing, the presence of tubing inside the BSC had interrupt sterile airflow, and the potential exists for the tubing itself to become contaminated should any trace of HD remain in the BSC. Listed below are other practical options that mitigate these issues.
Dry spikes are reinforced plastic spikes that interface with a CSTD during compounding, and allow the nurse to spike (with normal primary tubing) directly without concern for puncturing the IV bag.
These devices also permit "circle priming", which allows for priming tubing with HD without risk of leakage.
ICU Medical ChemoLock dry spike and BD Phaseal dry spike
Another option with CSTDs is the Direct Spike. This allows pharmacy to compound the HD using a CSTD. The bag is then sent to the floor which allows the nurse to safely connect and disconnect at the bedside. This system also permits having secondary infusion sets with permanently attached (bonded) CSTD components for safe connection at the bedside.
ICU Medical ChemoLock dry spike and BD Phaseal dry spike
Pictured at the left is an example of a chemotherapy bag with a direct spike.
All of the membrane devices require the use of an adapter. Without one, the device could not interface with IV tubing ports and needleless connectors attached to central and peripheral IV catheters.
Adapters vary in size as seen in the photo below.
One consideration often overlooked by pharmacy is how the CSTD will be used for subcutaneous injections. While only a handful of chemotherapy agents are given via this route, the syringe with the CSTD and the adapter plus the needle creates a very different balance for nurses.
Practice with the device can ensure that the same technique used for SubQ injections without a CSTD can still be used even with a device that requires an adapter. It will, however, feel different.
Training and Ongoing Education
Despite all of the safety advatanges that CSTDs bring to nursing, spills can occur. This is the reason that despite their effectiveness, PPE is still required even when CSTDs are in place. While any product can malfunction, most CSTD-related spills are due to knowledge deficits and not product defects.
All of the manufacturers provide excellent education when the device is first rolled out. Unfortunately, nurses hired after "go-live" need to be given the identical education as many spills occur with new employees who may be unfamiliar with the nuances of the device and related components (e.g., adapters). Therefore, organizations must have a reliable method of ensuring all staff (including traveling nurses and float nurses) are well versed in safely using the CSTD.