Error Proofing Single-Use Systems: Adopting Three Strategies from the Medical Device Industry

person in a hospital bed

In a typical hospital setting, patients often have numerous lines connected to them to deliver a variety of medicines, gases and nutrients, as well as suction and drainage lines. Many of those devices and systems utilize universal luer lock connectors with male and female tapered fittings to form leak-proof connections. Though the design was implemented with good intentions, its widespread overuse across multiple applications has contributed to misconnections and sometimes tragic results. Using lessons learned in the medical device industry when designing single-use systems, there are demonstrated error-proofing steps to take to eliminate risk or potential misconnections.

Preventing misconnections

The ISO 80369 series of standards was developed to prevent misconnections between small-bore connectors in liquid and gas healthcare applications and provide strict guidelines for manufacturers to produce connectors that can only be used between devices intended for the same clinical application.

Because the medical device industry serves millions of patients each year, there is a high potential for fatal consequences due to human error; therefore, error proofing designs is crucial. The Japanese principle of “poka-yoke,” or mistake-proofing, is a key principle of product design across many industries. The goal is simply to remove product defects by preventing human errors on the front end of a process, correcting them during the process, or drawing attention to them after a process is completed, to reduce the chance of part failure, insufficient performance or most importantly, user/operator safety.

Single-use bioprocessing is also susceptible to human errors and misconnections, and while the consequences may not be as grim, the single-use bioprocess industry can learn from the medical device industry on error prevention.

Many connection types in the single-use industry are of proprietary design and are not yet ready for a dimensional standardization effort like ISO 80369. End users, however, often have their own internal standards for specific connectors to be used in their designs. How can they evolve their design standards to error proof their designs?

Connector selection

Connectors used in single-use systems are available in different styles and size formats, and can be gendered and genderless. Gendered quick connects and aseptic connectors may be implemented with a design standard for a defined flow direction, preventing connection errors. Genderless aseptic connectors and sanitary flanges are offered in more than one size format with common hose barb sizes, allowing for the use of different connector body sizes for different applications and preventing a misconnection. Ideally, a different connector could be used for every connection on a single-use system.

¾” Mini sanitary flange
1½” maxi sanitary flange, each with ½” hose barbs

¾” Mini sanitary flange and 1½” maxi sanitary flange, each with ½” hose barbs

quick connector inserts, each with 3/8” hose barb
quick connector inserts, each with 3/8” hose barb

Two different size quick connector inserts, each with 3/8” hose barb

Genderless aseptic connector with different non-interconnectable body size
Genderless aseptic connector with different non-interconnectable body size
Genderless aseptic connector with different non-interconnectable body size

Genderless aseptic connectors with different non-interconnectable body sizes

Gendered aseptic connector
Gendered aseptic connector

Gendered aseptic connectors

Tubing line length

Single-use system design standards may be developed to prevent misconnections by using different tubing line lengths for different functions or flow direction. Flow direction can be defined from short line length to long line length. Two short lines are physically impossible to connect to one another, preventing inadvertent misconnections.

Color coding for product or application identification

Color coding is the systematic, standardized application of a color system to classify and identify products. Throughout medical devices, and even within the ISO 80369 standards, color is widely used to distinguish different lines or connectors from one another, ensuring safe delivery of nutrients or medication and preventing misconnections. When one looks at a typical single-use system, most of the components are either translucent or white. To minimize the contribution to leachables, colorants are generally unwelcome in process contact materials; however, a significant potential for usage of color in non-process contact materials exists to help with visual identification of different lines. Examples of non-process contact components include cable ties, pinch clamps, luer lock rings and sampling syringes.

The potential for misconnection is clear; the principal goal is to improve ease of use to reduce human error. By implementing simple error-proofing techniques of selecting the appropriate connector, tubing line length and color identification, single-use systems can be designed to prevent connection errors to improve reliability and ensure product quality.