Home / EQ Academy / Resources / Closed systems vs CSTDs
While all CSTDs are classified as closed systems, not every closed system is a CSTD. The National Institute for Occupational Safety and Health, (NIOSH) defines them as follows:
A closed system is a device that does not exchange unfiltered air or contaminants with the adjacent environment.
Primary engineering controls and some supplementary engineering controls such as CSTDs are closed systems.
Engineering controls isolate people from the hazard by ensuring they are manufactured and used in a closed system. They protect the preparation from cross-contamination and microbial contamination.
A closed system transfer device, or CSTD, is a drug transfer device that mechanically prohibits the transfer of environmental contaminants into the system and the escape of hazardous drug or vapor concentrations outside the system.
Learn more about EQUASHIELD CSTDs here
Examples of each include:
Primary engineering controls: Biological safety cabinets (BSCs), Compounding Aseptic Containment Isolator (CACI), Restricted Access Barrier System (RABS)
Secondary engineering controls: Negative Pressure Room, Cleanrooms, HEPA filters
Supplementary engineering controls: CSTDs
A closed system transfer device, or CSTD, is a drug transfer device that mechanically prohibits the transfer of environmental contaminants into the system and the escape of hazardous drug or vapor concentrations outside the system.
/CSTDs are used in compounding and administration
/CSTDs prevent exposure throughout the hazardous drug lifecycle
/ CSTDs are designed to prevent drug aerosolization, leaks, and drips
/ CSTDs are designed to prevent accidental disconnections
Multiple Layers of Protection Close the Gaps
USP <800> recognizes that engineering controls are divided into 3 category levels of control including:
 / Primary Engineering Controls A ventilated device designed to minimize worker and environmental HMP exposure when directly handling HMPs
 / Secondary Engineering Controls The room in which the Primary Engineering Control is placed
 / Supplementary Engineering Controls Containment supplemental engineering controls, such as CSTDs, provide adjunct controls to offer an additional level of protection during compounding and administration.
USP <800> recognizes that engineering controls are divided into 3 category levels of control including:
Engineering controls that qualify as closed systems
/ According to USP <797> primary engineering controls are required to protect the preparation from cross contamination and microbial contamination
/ According to USP <797> primary engineering controls are a closed system
/ Primary engineering controls for containment include BSCs (biological safety cabinets), and isolators, also known as compounding aseptic containment isolators (CACIs)
/ Don’t protect from contamination that can leave residue within the primary engineering controls
/ Don’t protect contamination throughout lifecycle
/ USP <800> defines supplemental engineering controls as controls that offer an additional level of protection during compounding & administration
/ According to NIOSH CSTDs are a closed system
/ Closed System Drug-Transfer Devices (CSTDs), are the only engineering control designed to prevent vapor release, spills, leaks, and needlesticks
/ NIOSH defines CSTDs as systems that mechanically prevent environmental contaminants from entering and hazardous drugs from escaping
/ CSTD components include needle free syringe units, IV tubing sets, spike adaptors, vial adaptors, female connectors, luer lock adaptors, and additional accessories
/ Peer-reviewed studies confirm that mechanical-based technologies are more effective in preventing drug aerosolization
/ According to USP <797> primary engineering controls are required to protect the preparation from cross contamination and microbial contamination
/ According to USP <797> primary engineering controls are a closed system
/ Primary engineering controls for containment include BSCs (biological safety cabinets), and isolators, also known as compounding aseptic containment isolators (CACIs)
/ Don’t protect from contamination that can leave residue within the primary engineering controls
/ Don’t protect contamination throughout lifecycle
/ USP <800> defines supplemental engineering controls as controls that offer an additional level of protection during compounding & administration
/ According to NIOSH CSTDs are a closed system
/ Closed System Drug-Transfer Devices (CSTDs), are the only engineering control designed to prevent vapor release, spills, leaks, and needlesticks
/ NIOSH defines CSTDs as systems that mechanically prevent environmental contaminants from entering and hazardous drugs from escaping
/ CSTD components include needle free syringe units, IV tubing sets, spike adaptors, vial adaptors, female connectors, luer lock adaptors, and additional accessories
/ Peer-reviewed studies confirm that mechanical-based technologies are more effective in preventing drug aerosolization
Contamination remains a frequent issue with Isolators and BSCs. In an HMP contamination study, 75% of pharmacy area samples were wipe sampled and found to be contaminated.1
Using a CSTD in the isolator cut HMP contamination by more than half compared to a needle and syringe2
A study was conducted comparing CSTDs to traditional compounding devices (syringe and spike) using 10 antineoplastic agents to assess the effectiveness of CSTDs in reducing HMP contamination on the surfaces of Aseptic Isolators in real-world practice. Over a six-month period, 686 surface samples were collected from gloves, the inner surface of the Aseptic Isolators window, and the worktop. Results showed that average contamination rates in standard Aseptic Isolators was 26.39%. Introducing a CSTD reduced average contamination to 12.24%. The contamination rate was lower with CSTDs compared to standard devices.
In both groups, gloves were the most contaminated surface. With standard devices, average contamination rates were 33.1% for gloves, 24.2% for windows, and 21.9% for worktops. The rates were drastically reduced with the introduction of CSTDs – 16.0%, 10.4%, and 10.0%, respectively. With a p-value of <0.0001, this study is highly statistically significant and confirms that CSTDs significantly decrease the chemical contamination of Aseptic Isolators compared to standard compounding devices.
A study was conducted comparing CSTDs to traditional compounding devices (syringe and spike) using 10 antineoplastic agents to assess the effectiveness of CSTDs in reducing HMP contamination on the surfaces of Aseptic Isolators in real-world practice. Over a six-month period, 686 surface samples were collected from gloves, the inner surface of the Aseptic Isolators window, and the worktop. Results showed that average contamination rates in standard Aseptic Isolators was 26.39%. Introducing a CSTD reduced average contamination to 12.24%. The contamination rate was lower with CSTDs compared to standard devices.
In both groups, gloves were the most contaminated surface. With standard devices, average contamination rates were 33.1% for gloves, 24.2% for windows, and 21.9% for worktops. The rates were drastically reduced with the introduction of CSTDs – 16.0%, 10.4%, and 10.0%, respectively. With a p-value of <0.0001, this study is highly statistically significant and confirms that CSTDs significantly decrease the chemical contamination of Aseptic Isolators compared to standard compounding devices.
All surfaces sampled during baseline, including external surfaces of infusions and syringes, were contaminated with each marker drug. During the intervention phase, isolator surfaces were free from detectable contamination and the contamination measured on gloves, preparation mats and surface of infusions was markedly reduced. The frequency of contamination on syringe and infusion surfaces was also lower.
Surface contamination from cytotoxic infusion preparation in a pharmaceutical isolator was significant and could transmit cytotoxic residues to patient and public areas via infusion surfaces. The frequency and amount of contamination were reduced by the CSTD.
A significant difference in levels of contamination for all drugs was observed, bringing contamination levels to a safe standard. (cyclophosphamide: p <0.05; ifosfamide: p <0.01; 5-fluorouracil: p <0.0001).
Using a CSTD in the isolator drastically cut HMP contamination.3
Â
Â
All surfaces sampled during baseline, including external surfaces of infusions and syringes, were contaminated with each marker drug. During the intervention phase, isolator surfaces were free from detectable contamination and the contamination measured on gloves, preparation mats and surface of infusions was markedly reduced. The frequency of contamination on syringe and infusion surfaces was also lower.
Surface contamination from cytotoxic infusion preparation in a pharmaceutical isolator was significant and could transmit cytotoxic residues to patient and public areas via infusion surfaces. The frequency and amount of contamination were reduced by the CSTD.
Using a CSTD in the BSC drastically cut median values for surface HMP contamination compared to standard syringes.4
Â
Â
Â
Median values for surface contamination with cyclophosphamide, ifosfamide, and 5-fluorouracil were reduced by 95%, 90%, and 65%, respectively.
CSTDs are the only engineering control designed to prevent spills, leaks, and needlesticks in addition to providing extra vapor protection.
CSTDs are the only engineering control designed to prevent spills, leaks, and needlesticks in addition to providing extra vapor protection.
1. In combination with BSCs (biological safety cabinets), this is an effective way to protect workers from potential exposure to HMPs
Chief Pharmacists chose a solution that includes CSTDs as the safest method to prevent exposure to HMPs
2. In combination with CACIs (compounding aseptic containment isolators), this is an effective way to protect workers from potential exposure to HMPs
Chief Pharmacists chose a solution that includes CSTDs as the safest method to prevent exposure to HMPs
3. An effective way currently used in this institution to protect workers from potential exposure to HMPs
Chief Pharmacists have identified CSTDs as the most effective safety solution in their institutions.
However, a significant disparity exists between the number of Pharmacists who recognize the safety benefits of CSTDs and the facilities that actually implement them. With effective advocacy, it is possible to drive meaningful change and create safer work environments for healthcare professionals.
1. In combination with BSCs (biological safety cabinets), this is an effective way to protect workers from potential exposure to HMPs
Chief Pharmacists chose a solution that includes CSTDs as the safest method to prevent exposure to HMPs
2. In combination with CACIs (compounding aseptic containment isolators), this is an effective way to protect workers from potential exposure to HMPs
Chief Pharmacists chose a solution that includes CSTDs as the safest method to prevent exposure to HMPs
3. An effective way currently used in this institution to protect workers from potential exposure to HMPs
Chief Pharmacists have identified CSTDs as the most effective safety solution in their institutions.
EQUASHIELD CSTDs are clinically backed to be the most closed 6
A study found that implementing the EQUASHIELD CSTD significantly reduced surface contamination compared to using a conventional syringe with a BSC. Wipe samples taken from common high-contact areas, such as dispensing counters, door handles, and floors, frequently showed contamination levels above safe concentrations. However, the introduction of the EQUASHIELD CSTD effectively eliminated cytotoxic agent contamination in both preparation and administration areas within the ambulatory cancer chemotherapy infusion center. This study demonstrates that using CSTDs effectively minimizes contamination throughout the lifecycle.
A study found that implementing the EQUASHIELD CSTD significantly reduced surface contamination compared to using a conventional syringe with a BSC. Wipe samples taken from common high-contact areas, such as dispensing counters, door handles, and floors, frequently showed contamination levels above safe concentrations.  Â
            Â
However, the introduction of the EQUASHIELD CSTD effectively eliminated cytotoxic agent contamination in both preparation and administration areas within the ambulatory cancer chemotherapy infusion center. This study demonstrates that using EQUASHIELD CSTDs effectively minimizes contamination throughout the HD lifecycle.
  Â
Pharmacists and nurses can safeguard their health by ensuring they are using the appropriate closed systems
Protect yourself with safer practices by empowering yourself with the facts. Where procedures mandate the use of closed systems, CSTDs must be used alongside primary and secondary engineering controls. They each serve distinct purposes, working together to ensure the safe handling of HMPs.