Staying Connected - December 2009

Cable and Leadwire Cleaning and Sterilization Considerations

Unless designed for single use, medical cables and leads will be cleaned.  Depending upon the use, cleaning may range from a simple wipe down with soap to the elimination of all micro-organisms by sterilization.  Cleaning and disinfection requirements must be considered along with functional attributes in the early product design so that appropriate materials and production processes will be specified.


EN980 symbol
for sterilization
by autoclave

Non-critical Classification

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

Both Spaulding and EPA classifications establish medical cables and leadwires as non-critical when considering disinfection or sterilization.  Medical cables and wires typically only come in contact with normal 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.


Minimum standards for cleaning,
disinfection and sterilization of
medical cables is established
by ANSI/AAMI EC53

Minimum Standards Defined

Minimum standards for cleaning and disinfection of ECG Cables and Leadwires are established by ANSI/AAMI EC53.  Section 4.3.1 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)
  • Sodium hypochlorite (bleach) solution 10% in water

Alcohol based solutions or other solvent based cleaners have not been recommended for cleaning medical cables because they may dry out the cable or wire jacket causing it to become brittle and shorten the life of the product.  However, engineered plastics such as Santoprene® offer good to excellent resistance to isopropyl alcohol or alcohol based cleaners.


Common
glutaraldehyde
disinfectant

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 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

When designing a medical cable assembly or leadwire, one of the considerations is the jacket material.  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 within the jacket.


Autoclave is the most common
sterilization method and is
unsuitable for cables with made
of PVC or polyurethane

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

The following table offers guidelines as to the suitability of common cable materials based on various cleaning, disinfection and sterilization methods.  These materials are commonly used for both cable jackets and molded assemblies.


Cleaning and Disinfection

Material Sodium Hypochlorite (bleach 10%) Isopropyl
Alcohol
Glutaral-dehyde (Cidex)
PVC Good Good Fair
TPE/TPR Excellent Excellent Excellent
TPU Poor Poor Good
Silicone Good Excellent Good

Sterilization

Material Autoclave Gamma Ethylene oxide (ETO) VHP1
(Sterrad)
Paracetic Acid (Steris)
PVC Poor Excellent Excellent Good Good
TPE/TPR Fair/Good Excellent Excellent Good Good/ Excellent
TPU Poor Excellent Excellent Good Good
Silicone Excellent Excellent Good Excellent Good/ Excellent

1 Vaporized Hydrogen Peroxide

Common Cable Jacket and Overmold Materials

  • PVC – PVC is one of the lowest cost cable materials.  It is commonly used for both the outer cable jacket and molded connectors.  PVC is now available in RoHS compliant forms.  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.  When designed properly, cable assemblies made of these materials can be sterilized by autoclave up to several hundred times.
  • 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 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 sterilization cycles by autoclave are required.  Silicone cables can also be disinfected with most common solutions.  Silicone cables are typically more costly than those made of thermoplastic materials.  This is due to both the higher cost of silicone materials and the methods to mold and extrude silicone.

Cleaning and Disinfection Issues


Unless specifically designed to
be submerged, do not soak
cables or leadwires

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

Unless the cable assembly, including connectors, is specifically designed and manufactured to be submersible, it should not be cleaned or disinfected by submersion in a liquid.


Quaternary compounds, such as didecyl
dimethyl ammonium chloride, which are
commonly used as surface disinfectants
in hospitals, are not suitable for
cleaning cables and lead sets

Quaternary ammonium compounds such as didecyl dimethyl ammonium chloride are used in a variety of disinfectants commonly used in medical facilities.  The most common trade name is Sanimaster.  While these agents offer a high degree of disinfection, they are harmful to most plastics and should not be used to clean medical cables or leadwires.

Summary

Cleaning, disinfection, and sterilization requirements of medical cables and leads should be considered at an early stage of product development.  Involving the Affinity engineering team early in the design stage can help achieve your design goals, including cleaning and sterilization requirements.

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Happy Holidays

At the end of 2009, we thank our many OEM partners for their continued business and support.  We’re very thankful that we continue to grow and hire rather than have to lay off people.


One of the secrets to
Affinity’s high quality

We wish all of our OEM partners, suppliers, friends and Affinity team members Happy Holidays and a prosperous New Year!

As usual, the Affinity elves have been busy building cables.  They’re happy that they will be enjoying a four-day break for Christmas!

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Announcements, Information, and Trivia


Twelve drummers drumming
from the popular holiday song
The Twelve Days of Christmas

The Twelve Days of Christmas

The Twelve Days of Christmas begin on December 25th, Christmas Day, and end on January 5th, the day before the Feast of the Epiphany.  The popular song by the same name was first published in England in 1780 and is a cumulative song.  If you received all of the gifts listed in the song, “The Twelve Days of Christmas,” you would receive 364 gifts


Lighting a candle each
night of Chanukah

Chanukah

Chanukah is also known as the Festival of Lights.  It is an eight-day Jewish holiday commemorating the rededication of the Temple in Jerusalem.  Chanukah is observed for eight nights starting on the 25th day of Kislev according to the Jewish calendar.  This year, Chanukah is celebrated December 11th through 19th.

According to the Talmud there was only enough consecrated olive oil to fuel the flame in the temple for one day.  Miraculously, the oil kept burning for eight days, until fresh olive oil could be prepared and consecrated.  During Chanukah, a single light is lit each night, for eight nights.


Kinara candles used to
celebrate Kwanzaa

Kwanzaa

In 1966, Dr. Maulana Karenga established Kwanzaa as a week-long festival celebrating African American people, their culture, history and community. Kwanzaa, which means "first fruits of the harvest" in the African language Kiswahili, has gained tremendous acceptance and is now celebrated all over the world--especially in the U.S., Africa, and the Caribbean. Kwanzaa is neither political nor religious in nature and is not celebrated as a substitute for Christmas. Kwanzaa begins on December 26th and continues until New Years Day, January 1st.

Affinity Holiday Schedule

Affinity will be closed on Thursday, December 24th and Friday, December 25th as well as Friday, January 1st to allow our employees to enjoy the holidays.



Suzann Sitka, Cesar Jara and Candy Golding
- the Affinity Customer Care Team

Affinity Customer Care -
Hours of Operation

Affinity Medical Technologies customer care specialists are available to assist you from 7:00 A.M. until 4:00 P.M., U.S. Pacific Time, except holidays.

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Affinity Medical Technologies

1732 Reynolds Ave
Irvine, CA 92614  USA
Phone: +1 949 477 9495
Fax: +1 949 477 9499
Email: CustomerCare2@affinitymed.com
Website: www.affinitymed.com