Closed-system transfer devices (CSTDs) are adapters that connect two medication vessels – syringes, vials or IV bags – to allow hazardous drugs (HDs) to be transferred between the vessels without leakage. The devices are intended to minimize personnel environmental exposure to HDs from the time the drugs are compounded in the pharmacy to the time they are administered to the patient.
The need to use CSTDs is detailed in a newly implemented United States Pharmacopoeia (USP) standard, USP General Chapter <800>. To help when comparing available products, the National Institute for Occupational Safety and Health (NIOSH) has spearheaded efforts to develop a test protocol that can be used to assess CSTD performance. To date, however, stakeholders have been unable to agree upon a fully satisfactory methodology. (See www.cdc.gov/niosh/topics/hazdrug/CSTD.html.)
With such uncertainty surrounding CSTD selection and use, how can health care facilities make wise purchasing decisions? ECRI Institute has been examining CSTD models in its lab to help find some answers.
The Dangers Posed by Hazardous Drugs
Some drugs that are used in health care – such as those used for cancer therapy, some antiviral drugs, hormone agents, or bioengineered drugs – are toxic or otherwise harmful by nature and must be handled in a way that minimizes exposure by health care workers involved in their preparation and administration. NIOSH notes that workplace exposures can lead to acute as well as chronic health effects, from skin rashes, to infertility or other adverse reproductive outcomes, to the development of leukemia or other cancers. (See www.cdc.gov/niosh/topics/hazdrug/.)
The agency estimates that 8 million U.S. health care workers are potentially exposed to HDs. In addition to pharmacy and nursing personnel, those at risk of exposure include veterinary care workers, environmental services workers and shipping and receiving personnel. Protecting workers from such exposures requires the use of protective equipment and a combination of administrative and engineering controls. CSTDs are a supplemental engineering control that can be used to provide some protection, but they should not be the only means used.
CSTD Form and Function
A CSTD system comprises a manufacturer-specific set of male and female adapters, which enable fluid transfer between, for example, a drug vial and a syringe or a syringe and an IV bag in a closed manner—that is, without leakage or vapor escape. CSTD adapters remain closed until connected together. A connection of male and female adapters opens a pathway enabling access for liquid transfer.
A pathway is established using either of two approaches:
- Needle-based systems: A needle protected inside the adapter punctures a septum upon connection to open a pathway; the needle then retracts upon disconnection.
- Needle-free systems: The membranes within each CSTD component are opened when the adapter connection is complete.
One important consideration when transferring fluid between different containers is that pressure equalization will need to occur; and during equalization, drug vapors that may be present in the drug vial will need to be released. Because the drug is hazardous, those vapors need to be contained. Two technologies for preventing vapor escape are dominant:
- Barrier technology: Pressue is equalized using a balloon air reservoir in the vial adapter that is intended to contain all resulting HD vapor.
- Filter technology: Pressure is equalized using a filter in the vial adapter that is intended to capture all resulting HD vapor.
For pharmacy compounding, a CSTD may be used as follows: A CSTD vial adapter is connected to a drug vial. The vial adapter is accessed using a syringe with a compatible CSTD syringe adapter attached. Required transfers are conducted (e.g., reconstitution, drawing of drug). The drug is injected into a final container or, alternatively, held in the syringe if that is the final container. IV bags or other fluid containers are accessed with appropriate adapters (e.g., IV bag adapter). The final container is labeled and sent to the care unit with CSTD adapters attached that enable administration to a patient.
For drug administration: The HD is received in a clinical area in a syringe or IV bag or other final container with CSTD adapters that enable connection to a patient administration line. A clinician administers the HD via an infusion pump, by gravity or by manual push by connecting it to the patient administration line with appropriate CSTD administration set adapters. Some types of CSTDs may require separate administration set adapters to be added by the clinician, while others connect directly to a needle-free connector.
Selection Considerations
Unresolved questions surrounding the testing of device effectiveness is a significant challenge, admits Juuso Leinonen, senior project engineer in ECRI Institute’s Health Devices Group. “But even so, there are factors that facilities can consider when assessing products for purchase.” Following are five key considerations that ECRI Institute has identified:
- Leakage and vapor containment. Any leakage of medication from a CSTD is a cause for concern, as it could lead to HD exposures. Vapor containment and/or reduction in environmental HD exposure is likewise an important factor – though it is more difficult to assess. Objective product comparisons in this regard are hampered by the current lack of agreement about what constitutes an appropriate test methodology. The availability of published peer-reviewed clinical studies that assess a device’s performance in this area are thus desirable.
- Usability/ease of use. Devices that are difficult to use – or difficult to use correctly – offer less reliable protection. Mistakes in use or, worse, decisions not to use the device at all increase the risk of HD exposures. ECRI Institute conducts significant ease-of-use testing during its product evaluations to identify potential issues. The organization has observed that opinions about a product often differ depending on the user’s role: that is, some devices favored by clinicians were not well regarded by pharmacists and vice versa.
- Number and types of components. The use of CSTDs could require stocking dozens of different components to meet the needs of expected use cases. Additional factors that warrant consideration include: the availability of components for specific applications (e.g., for use with various vial sizes); the number of components and the amount of assembly required for specific applications; and the impact that the component mix will have on workflow.
- Preventing incorrect disconnections. During use, CSTD components need to remain firmly connected to protect the clinician and other personnel from HD exposure. Incorrect disconnection—for example, disconnecting components from the wrong connection point—could compromise the closed system. Features such as binding adapters or fused adapters, which aid in preventing such accidental disconnections or component removal, are thus beneficial. Similarly, the incomplete connection of components could result in accidental environmental exposure of the HD or result in a delay in therapy. Thus, features that help users identify a complete connection are desirable.
- Cost. As an add-on technology, CSTDs represent an added cost that must be budgeted for.
This article is adapted from ECRI Institute’s “Evaluation Background: Closed-System Transfer Devices” (Health Devices 2019 Nov 20). The complete article – including model-specific test results and product ratings, along with additional guidance for purchasing and using CSTDs – is available to members of ECRI Institute’s SELECTplus, Health Devices System, and associated programs. To learn more about membership, visit www.ecri.org/solutions/evaluation-and-comparison, or contact ECRI Institute by telephone at (610) 825-6000, ext. 5891, or by e-mail at clientservices@ecri.org.