Medical Design Briefs - January 2024 - 18

TECHNOLOGY LEADERS Electrical Connectors/Wires/Cables
ISO 80369-7:
Changing the
Standard
for Luer
Connectors
I
SO 80369 Part 7, the long-awaited replacement
to ISO 594, introduced a
number of changes to the standard
governing dimensions and performance
requirements of Luer connectors.
Its publication in October 2016 capped
a monumental change in the fundamental
thinking surrounding devices that
transfer liquids and gases in healthcare
settings. Despite the Technical Committee's
desire to disrupt as little as possible
surrounding the current practices with
Luer connectors, ISO 80369-7 still makes
many significant changes.
This article highlights the changes
that most significantly affect how one
should construct a design verification
plan. Those changes include:
* Stricter requirements on dimensional
and mechanical specifications.
* Testing against slip and lock reference
connectors.
* Modifications to assembly and test procedures.
*
Addition of guidance for performance
of variable tests.
As should be expected with changes
of this magnitude, there are many nuances
in the new standard that require
some interpretation.
18
Why the Change? Prior to ISO 80369,
every small-bore connector was a Luer
and, under ISO 594, there was a lot of
design leeway on what those Luers
looked like. ISO 80369 aims to reduce
variation in order to prevent errors in
connecting to the patients; errors that
were sometimes fatal.
What Is the Difference Between ISO
594 and ISO 80369? Compliance to ISO
594 requires two things: gauging (for
which failures could often be justified
away) and meeting performance requirements.
ISO 80369-7 requires three
things: full compliance with materials,
dimensional requirements, and performance
requirements. All three are required
in order to maintain the assumption
of non-interconnectability.
Stricter Requirements on Dimensional
and Mechanical Specifications
Prior to the implementation of ISO
80369-7, the ubiquitous use of Luer
connectors made it possible for two incompatible
devices to be accidentally
connected, which could lead to patient
injury. The principal goal of ISO 80369
is to reduce the likelihood of these adverse
events by introducing unique conwww.medicaldesignbriefs.com
nector
designs for different medical
applications whose geometry makes it
extremely difficult to make these harmful
connections.
One consequence of using the geometry
of the connectors to preclude misconnections
is that the connectors now
need to be measured to ensure that they
meet the dimensions and tolerances of
the prints in the standard. This differs dramatically
from ISO 594, where as long as
connector performance could be proven
against a reference standard, the dimensions
of the connector largely did not need
to precisely match the standard. This is by
far the most burdensome new requirement
resulting from the standards change
and many in industry are incredulous to
learn that their thread design that has performed
adequately must now be changed.
In addition to stricter dimensional requirements,
there are also new restrictions
on what materials may be used to
construct Luer connectors. The elastic
modulus of the materials must be greater
than 700 MPa when tested in either tension
or flexure per standard ASTM methods.
Some polymers commonly used as
Luer connectors do not meet this requirement,
including many polyethylenes.
Medical Design Briefs, January 2024
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Medical Design Briefs - January 2024

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