Staying Connected - May 2014

Cleaning, Disinfection and Sterilization Design Considerations for Medical Cables

Unless designed for single use, medical cable assemblies and leads will almost certainly require cleaning, disinfection and possibly sterilization.  Depending upon the intended use, cleaning may range from a wipe down with soap, to the elimination of all micro-organisms by sterilization, or something in-between.

The recommended method to clean medical cables and connectors, and equally important, how they are likely to be cleaned should be addressed early in the design process so that the most appropriate materials and manufacturing processes will be used.



Most medical cables only
contact unbroken skin and are
classified as non-critical for
cleaning and disinfection


Risk-based Classification

Based on the risk of contamination spreading from a device to a patient, three levels of disinfection are defined based on a strategy developed by Dr. Earle Spaulding in the 1960’s.  (Dr. Spaulding was the Chair of the Department of Microbiology and Immunology at Temple University School of Medicine between 1949 and 1972.)

When considering disinfection or sterilization, both Spaulding and the EPA classify medical cables and leadwires as “non-critical”.  Most medical cables and leads typically come in contact with unbroken skin and do not normally come in contact with mucous membranes.  Non-critical devices typically require only cleaning and low-level disinfection.  If cables or wires come in contact with broken skin or mucous membranes, a higher level disinfection is required.

Cleaning and Disinfection Standards


Cleaning and disinfection standards for medical cables
are included in ANSI/AAMI EC53

In 1995, ANSI/AAMI EC53 established minimum standards for cleaning and disinfection of ECG Cables and Leadwires.  Section 4.3.1 of the standard details cleaning and disinfection requirements:  “The trunk cable and patient leadwires shall be capable of being cleaned and disinfected 15 times with the following materials per section 5.3.1:

  • Green soap or alcohol-free hand soap
  • 2% glutaraldehyde solution (such as Cidex Plus)
  • Sodium hypochlorite (bleach) solution 10% in water


Glutaraldehyde disinfectants such as
Cidex Plus are a recommended for
disinfecting agent for medical cables


Alcohol based solutions or other solvent based cleaners are not recommended for cleaning medical cables because they may dry out the jacket causing it to become brittle and fail prematurely.  However, engineered plastics such as Santoprene® offer good to excellent resistance to isopropyl alcohol or other alcohol based cleaners.

Additionally, ANSI/AAMI EC53 section 4.4 establishes sterilization exposure requirements.  If no sterilization method is specified by the cable manufacturer, the standard provides an ethylene oxide (EO) sterilization cycle that is repeated ten times.  After ten cycles, “all labeling and performance requirements of this standard shall be met after sterilization.”

Cable Jacket Material Specification



Autoclave is the most common
sterilization method and is not suitable
for cables made of PVC or polyurethane


The material used for the outer jacket is one of the considerations when designing a medical cable assembly or lead.  The jacket material is not only the part of the cable or wire that is most visible; it plays a large role in the performance of the finished cable assembly.  A cable jacket offers mechanical, chemical and environmental protection to the conductors and components within the jacket.

Because the cable jacket is exposed, the conditions the cable will be used under and how it will be cleaned or disinfected should be considered early in the design stage.

The following tables offer guidelines as to the suitability materials based on various cleaning, disinfection and sterilization methods.  These materials are commonly used for cable jackets and molded assemblies.

1 50 Autoclave Cycles = Good, 250 Autoclave Cycles = Fair

Common Cable Jacket and Overmold Materials

  • PVC is one of the lower cost materials used in cable assemblies.  It is commonly used to insulate conductors, as cable jacket material and also for molded components.  PVC offers good resistance to alcohols, most solvents and alkalis, but is not suitable for steam sterilization by autoclave.
  • TPE/TPR (Thermoplastic Elastomer or Thermoplastic Rubber) - These materials are often referred to by the trade name of Santoprene®.  TPE/TPR materials have excellent chemical resistance and are suitable for cleaning and disinfection by most methods.  With suitable design and manufacturing processes, TPE/TPE cable assemblies can withstand up fifty or more steam autoclave cycles.
  • TPU – Thermoplastic Polyurethane offers excellent mechanical properties including abrasion resistance and tear strength.  Disadvantages of polyurethane material include poor resistance to some common cleaning agents and high temperatures making them unsuitable for steam sterilization by autoclave.
  • Silicone – Silicone is both very flexible and offers very high flex life.  It is the most common choice where a high number of steam sterilization cycles are required.  Silicone cables can also be disinfected with most common solutions.  However, silicone is less durable than other materials used for wire and cable jackets.  It is easily cut and offers lower tear resistance materials.

Cleaning and Disinfection Issues


Unless specifically designed to be
submerged – an IPX7 rating - soaking
cables is not recommended and can
lead to premature failure


When used at higher than the recommended concentrations, cleaning and disinfection agents can damage medical cables and leads.  An all too common error is that disinfection solutions such as glutaraldehyde or sodium hypochlorite (bleach) are used at much higher concentrations than recommended, causing damage to medical devices such as cables and leads. 

Unless the cable assembly, including connectors, is specifically designed and manufactured to be submersible, having an IP rating of X7 or higher, it should not be cleaned or disinfected by submersion in a liquid.  And, unless designed to have an ingress protection rating of X3 or higher, cables and connectors should not be subject to being sprayed or saturated with liquid cleaning agents.  Even if the cleaning agent is compatible with the material used to manufacture the device, ingress into contacts or terminations may cause unseen corrosion or shorting resulting in poor performance or failure.



Quaternary compounds are formulated to
disinfect hard surfaces such as tile and
stainless steel and can damage the plastics
used in medical cables


Because they are commonly found in healthcare facilities, cables are often cleaned with wipes saturated with quaternary ammonium compounds containing didecyl dimethyl ammonium chloride.  While these wipes are very efficient for cleaning and disinfecting, they are specifically designed to be used on “hard, non-porous surfaces.”   With continued use these cleaning agents will degrade many plastics, including cable and wire jackets, leading to reduced service life.  Common trade names of wipes designed to disinfect hard surfaces are “CaviWipes” and “Sani-Cloth.”

Summary

The service life of a medical cable assembly can be significantly affected by cleaning, disinfection and sterilization.  How the product will be cleaned and disinfected should be considered at an early stage of product development so that the most appropriate materials are selected.

If you would like more information, or if you would like to take advantage of our experience in designing cable systems to withstand cleaning and sterilization, contact us at +1 949-477-9495 or via email to custcare2@molex.com.

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Affinity’s 17th Year Anniversary



Mary Phillipp, Kevin Kom and Bob Frank in 1998

Affinity Medical celebrated its 17th Anniversary on May 19th.  The company was founded by Mary Phillipp and Bob Frank on May 19th, 1997.  Mary and Bob had worked together at medical cable manufacturer Tronomed before that company was acquired and relocated out of state.  Affinity’s fist employee was Kevin Kom who is now Affinity’s Manager of Manufacturing and Facility.

Affinity started with a single employee in 1997, grew to eight in 1998 and had more than 50 in 2003.  On the company’s tenth anniversary, in 2007, there were 82 employees.  2011 saw the number of employees jump to more than 230 and then surpass 270 this year.

The company was located in Irvine California until 2011 when it relocated to its current and larger facility in nearby Costa Mesa.  Continued growth caused the company to expand into adjacent space earlier this year.


Affinity General Manager Bob Frank
address the group at All Employee Meeting


Speaking at an All Employee Meeting in April, company founder and General Manager Bob Frank commented, “It is hard to believe how large the company has grown. Your hard work and dedication to quality have set Affinity apart.  We are fortunate to be working together and fortunate to have so many wonderful OEM customers that want us to manufacture their cables.”

“As part of Molex, we have even more opportunities to grow,” said Bob.  “Molex has invested in additional people, expanded our facility and added to our capabilities.  Molex Sales Engineers around the world are bringing us new opportunities every week.  I feel like our growth has just started.”

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Announcements, Information and Trivia



Ecuador is one of
13 countries located
on the Equator


World Map with the
Equator marked -
public domain CIA
World Fact book image

The Equator Trivia

On the Equator - There are 13 countries located on The Equator: Sao Tome and Principe, Gabon, Republic of Congo, Democratic Republic of The Congo, Uganda, Kenya, Somalia, Maldives, Indonesia, Kiribati, Ecuador, Colombia and Brazil.

Republic of Ecuador - or in Spanish, República del Ecuador, which literally translates as "Republic of the Equator"

Imaginary Line - The Equator is an imaginary line circling the surface of the Earth equal distance from both the North and South poles.

Latitude - The latitude of The Equator is 0º (zero degrees)!

Circumference of Earth - The circumference of the Earth at the Equator is 24,901.55 miles or 40,075.82 kilometers.  If the circumference is measured through the poles, it is 768.27 miles shorter showing that the Earth is not a perfect sphere.

Consistent Day - The length of a day at the Equator – sunrise to sunset – is nearly constant throughout the year.