Tubing connectors for medical applications come in an almost endless variety, but the recent thrust in their design is to prevent accidental connections. For instance, by one estimate a hospital room could have nine different fluids in use, making the possibility of a misconnection too high.
That makes it important to have a simple and repeatable process for selecting the best connector. The process requires an analysis of the application to ensure connectors will be compatible with the physical, chemical, and biological environment, and be easy to use as well as help prevent misconnections. Concerns over the wider use of Luer connectors has prompted a series of new, small-bore medical connector standards from the International Standards Organization (ISO) and the International Electrotechnical Commission (IEC). The ISO 80369 series of standards will define non-interchangeable connectors that affect connector selections for a range of medical-device applications.
In addition to design standards, the following factors should be part of a process that selects a fluid connection:
The tubing ID should be a connector’s first consideration. Pressure drops across connectors and valves vary greatly by manufacturer. Some designs exhibit less turbulence and resistance to flow than others. Compare CV factors for various connectors to determine the pressure drop across them.
Many valve styles mean flow rates and pressure drops will vary. Connectors with built-in valves prevent spills when disconnected, and prevent air from entering the system. Connectors with integral precision flush-face valves are considered “dry-break” connectors and should be selected when there is a critical need to avoid any spills, contamination, or the introduction of air upon connection.
Find the range of temperatures and pressures and those the connectors might encounter in storage or shipping.
Connectors and O-rings should be compatible with the anticipated media. Start with a review of published data in chemical-compatibility charts to understand what materials will work acceptably with the range of chemicals, media, or reagents in the application.
A connector’s manufacturing quality affects its performance and aesthetics. Parting lines and mold defects on couplings should be minimal on the connector body and absent from the first hose barb.
In addition, the FDA, the international standards community, and the medical device industry are taking action to reduce the likelihood of tubing misconnections. This includes the development of standardized connectors for specific medical applications that cannot be interconnected with devices for other medical applications.
Briefly, the FDA recognizes the AAMI provisional American National Standards AAMI/CN3(PS) 2014 “Small-bore connectors for liquids and gases in health care applications” – Part 3: Connectors for enteral applications and AAMI/CN20:2014 – Part 20: Common test methods.