Medical Design Briefs - November 2021 - 22

TECHNOLOGY LEADERS Gas/Fluid Handling/Pumps
Suppliers Keep Pace with
Changing Dialysis Needs and Fast-Moving
Regulatory Environment
W
ith global populations ex -
panding and aging, the
demand for advanced medical
therapies like dialysis
continues to grow, as do patients' expectations
for convenient access to the procedure,
shorter dialysis time frames,
lower infection risks, and better medical
outcomes. Dialysis equipment builders
have steadily met these expectations,
building hospital-quality hemodialysis
machines that shorten clinic-based
hemo dialysis sessions from 12 hours to 4
hours and make home-based " in your
sleep " peritoneal dialysis not only a reality
but a preferred option.
But every advance in making dialysis
technology safer, faster, more portable,
and more effective for the patient has
been hard-won. Dialysis equipment
builders and their suppliers must not
only manage the medical side of the
process - a precise blood filtration and
purification process made possible by
physics - but also implement the technology
through components and products
that meet ever-higher regulatory
standards while simultaneously improving
process consistency, reliability and
cost-effectiveness.
The European Union's
(EU) new
Medical Device Regulation (MDR) went
into effect in May 2021. To meet stringent
requirements, not only of Europe's
MDR but also those of the U.S. Food and
Drug Administration (FDA) and other
global bodies, dialysis equipment manufacturers
must rely on fluid-system
automation and control suppliers that
can help them meet these regulatory
requirements, such as strict change controls,
and offer the range of necessary
valves and fluid controls.
Hemodialysis Challenges
Because the fluid pathways of hemo -
dialysis machines directly handle human
blood and related bodily fluids, MDR
and FDA rules require every wetted
22
Cov
The ASCO Series 283/383 miniature fluid isolation
valves are often used in dialysis equipment because
they provide complete, hermetic isolation of the
fluid path to reduce the risk of contamination.
(Credit: Emerson)
surface of these pathways to be made of
thoroughly tested biocompatible materials
- subject to source-to-end-use
change controls to ensure their consistency
and purity. In addition, any
mechanical flow-control components,
such as pumps or valves, must incor -
porate biocompatible materials while
ensuring complete isolation - a hermetic
separation between their power/
control/actuation mechanisms and the
fluid path that carries the blood being
purified. This isolation prevents the risk
of contamination due to metallic particles
or external pathogens.
Other key requirements include superior
reliability and configurability. Re -
liability is essential since clinic-based
hemodialysis machines are subject to
constant use. In this context, improved
reliability means flow-control valves that
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can realistically deliver life of 5 million to
6 million cycles over a three- to four-year
period of use. Another requirement is
configurability, since a large hemodialysis
machine can require 20 or 30 valves,
enough to run three or four identical
dialysis/filtration circuits simultaneously.
Configurability means anything from
modifying individual valve bodies to combining
multiple valve flow paths - and
associated actuators/controls/printed
circuit boards (PCBs) - into compact
manifolds that meet dimensional requirements.
It can also mean modifications to
controls, wire leads and connections, or a
valve's noise output, since dialysis valves
are typically actuated using pneumatics
and must operate in a relatively quiet hospital
or clinical environment, or even
while a patient sleeps at home.
Only after a valve meets all of the
above requirements - regulatory, materials,
isolation, design, manufacturability,
and assembly - does its actual function
come into play. Within the hemo -
dialysis process, the pressure and flow of
fluids must be carefully and consistently
managed through a series of dialyzing
circuits. These circuits expose a volume
of blood to physical filtration and a
process of diffusion/osmosis, where
wastes are transferred from blood to a
dialysate fluid.
For analytical and medical specialists,
the process of making better dialysis
valves and ensuring their continued regulatory
compliance never ends. Yet
beyond engineering, quality, and regulatory
requirements, these valves must also
meet customer requirements: performance,
configuration, flow rate, reliability,
and ease of installation. For example,
the ASCO 283/383 Series miniature
solenoid valves met requirements for
durability and biocompatibility, with
valve bodies and fluid paths made of
polyetherimide (PEI). However, a pro -
spective customer and dialysis equipment
builder asked Emerson to modify
Medical Design Briefs, November 2021
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Medical Design Briefs - November 2021

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