Staying Connected - December 2013

The Role of the Cable Jacket for Medical Cables

Often, the first impression of the quality of a medical cable comes from how it looks and feels to the user.  Regardless of the components contained within the cable jacket, it is the exterior of the cable that is the most observable indication of the quality of the product.

Besides the appearance, the tactile feel of a cable and is how it is perceived by the user is largely influenced by the jacket material and also by the overall flexibility of the cable.



Comparison of a new cable jacket to
one that is well used suggesting that
white may not be the best color option
for some intended uses

The Appearance of the Cable

In most instances, the look of the cable jacket does not affect the mechanical or electrical performance of a cable assembly.  However, the appearance of the cable may be important for several reasons:

  • A specific cable color is required to match device maker’s color scheme
  • The cable color may help differentiate a specific cable from others
  • The color may hide dirt or debris if it is deemed to be harmless for the intended use
  • The color may accent dirt or debris and indicate that cable requires cleaning

While white is often considered an appropriate color for medical devices, a white cable jacket will show marks or dirt which may detract from the “clinical look” of the cable assembly.

Other than white, neutral colors are most commonly used and include light grey, darker greys and black.  But, in addition to neutral colors, cable jacket can be extruded in almost any custom color.


Neutral colors, such as white, grey,
dark grey and black are often chosen
for cable jackets

Cable jacket can be extruded
in almost any custom color

Light grey is by far the most common color for cable jackets.  This neutral color compliments equipment by not being prominent.  Darker greys or black are often recommended for cables that will be prone to be becoming dirty or scuffed in use.

Colors are commonly specified by Pantone number in the U.S. or RAL numbers in Europe.  When the cable jacket must match the color of an existing product it is highly recommended to match the resin color to a sample rather than depend upon either a Pantone or RAL number.

The Feel of the Jacket and Cable Flexibility


Silicone jacketed cable assemblies
are typically soft and flexible


In addition to the appearance of the cable jacket, the feel to the user often implies a great deal about the quality of the cable assembly.  Different materials offer a different tactile feel and more significantly softer grades of even the same material feel different.

Silicone is typically the softest and most flexible material used for medical cable jackets.  In addition to being soft and flexible, it can withstand a high number of sterilization cycles by autoclave.  However, uncoated silicone cables are “tacky” and easily accumulate dirt.  Because of this, it is common to add a coating over the cable jacket such as Parylene.  The coating gives the cable jacket a silky texture and makes the cable easy to clean.

Rubberized polyvinylchloride is available as a very soft material.  Contrary to some views, it is available in medical grades meeting FDA and ISO biocompatibility requirements as well as being RoHS compliant.  A cable jacket made of PVC will be more durable than one made of silicone for the same wall thickness, can be very flexible and is a lower cost material.



Polyurethane is commonly used for
cable components where high tear
strength is desirable

Thermoplastic elastomers, such as Santoprene®, are more durable than either silicone or PVC and are available in soft grades that are quite flexible.  TPE cable jackets typically have a “velvety” feel and which is thought to convey the feeling of higher quality.

Thermoplastic polyurethane (TPU) is the most durable of materials commonly used to jacket medical cable.  It has excellent abrasion resistance, tensile strength and high tear resistance.  And, while it is available in softer grades, it is typically not as flexible as the three previously listed materials.

Protection of Conductors

The primary function of the cable jacket is to enclose the various components together and protect them from damage during use, cleaning and sterilization. 

For maximum protection of the cables internal components during use, polyurethane is typically recommended.  Polyurethane is often the recommended jacket and overmold material for cables used by first responders or for used outside of a clinical setting such as Holter monitoring.

For cables that will be subject to a high number of sterilization cycles, a silicone jacket offers the maximum protection.


Increasing cable jacket wall thickness
increases strength but reduces flexibility


Durability the Cable Jacket

The durability of a cable jacket is a function of the type of material, as described previously, but also of the hardness of the material and wall thickness of the jacket.  Increasing the wall thickness of the cable jacket increases the durability, but conversely reduces the flexibility of the cable, irrespective of the material.

Provides Additional Strength

Additional strength and protection of cable terminations can be achieved by employing a robust cable jacket that is mechanically clamped to the internal components.  If this method is used, the stronger and thicker the cable jacket, the greater the protection of terminations is.

Polyurethane is the most durable material commonly used for medical cable jackets and can add significant strength to the cable assembly.  Silicone, while having other advantageous properties, offers the least amount of added strength or protection.  A thermoplastic elastomer, such as Santoprene®, is stronger than silicone and typically more flexible than polyurethane.
 
Skin Contact and Material Selection

ISO 10993 and FDA regulations call for materials used in medical devices which come in contact with the body to be biocompatible.  Dorland’s Medical Dictionary defines biocompatible as “The quality of not having toxic or injurious effects on biological systems.”

By their nature, most patient cables come in contact with the body and therefore should employ medical-grade, biocompatible materials.  Because all of the common materials used for medical cable jackets are available in medical grades, meeting biocompatibility requirements does not limit material selection.

Cleaning and Disinfection

The cable jacket plays a large role in determining what methods can be used to clean and disinfect a cable.

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 with the following solutions:

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

In addition, because it is commonly found in clinical settings, alcohol based solutions are often used.  The following table offers guidance in the selection of both cable jacket and overmold resins based on how the cable assembly will be cleaned or disinfected:

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



Silicone jacketed cables can withstand
hundreds of sterilization cycles

When the elimination of all micro-organisms by sterilization is required, the selection of a suitable cable jacket material becomes even more significant.  Of the three most common methods: steam autoclave, low-temperature hydrogen peroxide (Sterrad®) or peracetic acid (Steris®), steam autoclave is the most challenging for many materials used for cable jackets and overmolding.

Of the materials commonly used for medical cable jackets, only silicone can withstand hundreds of autoclave cycles.

The following table may assist in the selection of both cable jacket and overmold material based on which common sterilization method will be employed:

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

Summary

The Affinity engineering team has decades of experience designing medical cable assemblies, including recommendations for cable construction and jacket material.  Our team can help match your mechanical and electrical performance requirements with an ascetically pleasing appearance and tactile feel.

If you would like to take advantage of Affinity’s experience and expertise in providing robust, long lasting cable assemblies, we welcome you to contact us at +1 949-477-9495 or via email to CustomerCare2@Affinitymedical.com.

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Meet Laura Ramirez – Affinity Engineering Assistant


Laura Ramirez, Affinity Engineering Assistant


When a new product development project is started at Affinity Medical there are many steps and procedures that need to be followed before production begins.  Laura Ramirez, an Engineering Assistant, plays an important role in this process.

As an Engineering Assistant, Laura is involved managing Engineering Change Notices, updating engineering drawings, maintaining Affinity’s parts master file and reviewing customer drawings to ensure that what we manufacture fully meets the customer’s requirements.

“Because Affinity is both an FDA registered Medical Device Manufacture and is also ISO 13485 certified, documentation is very important,” said Laura. “As Affinity has grown, so has the amount of documentation.  Even though we are handling a much larger volume of documents – drawings, ECN’s, BOM’s – we have do to everything accurately.  There is no room for errors.”

Laura joined Affinity Medical in 2001 as a Manufacturing Associate.  She soon joined the Quality Department as an inspector.  In 2007, Laura was promoted to Engineering Assistant and moved into the Engineering Department.  She now reports to Matt Pathmajeyan, Affinity’s Engineering Manager.



Laura Ramirez updates Affinity
documents as part of Engineering
Change Notice (ECN) procedure

During her career at Affinity, Laura received certification in soldering in addition to a great deal of job specific training.  Laura took advantage of other training opportunities completing English as Second Language and Lean Manufacturing.  Her experience in manufacturing and quality has helped her in her role in the engineering group.  She is now training for and is involved with Affinity’s conversion next year to SAP.

When asked what she likes most about her job at Affinity Medical Laura replied, “I have had many opportunities to learn new skills and advance in the company.  I continue to receive a lot of support from all of the managers, engineers and other team members here at Affinity.  It is also exciting to see how much the company has grown since I started working here twelve years ago.”

When asked about Laura, Affinity General Manager Bob Frank commented, “I have worked with Laura since she started at Affinity in 2001.  She is one the most dedicated, hardworking people I know.  She has a very long commute, but is here each day without fail.  She is an excellent Mom to her family, a great coworker and friend to her peers.  It is a pleasure to have her on our team.”

Soon after moving from Mexico to California, Laura met her husband and they settled near Los Angeles.  Laura and her family now live in Montclair.  She stays busy with four children - most of them teenagers.  Her oldest child is now studying at the University of California in Irvine.  Laura says that she enjoys helping her kids with their school projects, hiking with the family and during the winter, going to the mountains for sledding in the snow.  “I like to work with arts and crafts and create mosaics out of various materials,” said Laura.  “I like to cook my kid’s favorite’s food.  I love my family!!!”

When Laura takes time away from work, she likes to visit her parents and siblings still living in Mexico in order to keep the family connected.  “I want to keep close ties with my family and want my children to know their cousins.

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Multi-channel Cable Systems


Common jumble of wires in ICU


Hospital patients are typically monitored simultaneously for multiple physiological parameters. This generally means that there are three or more cables connected between the patient and monitors.  Add to these an IV line and possibly an oxygen line there can be a “tangle of wires” as nurses often described it.

One option to reduce the number of lines running to the patient is to use a cable management system where one cable carries signals from different sensors on the patient to the monitor.  The typical configuration is one trunk cable with multiple monitor connectors on one end and multiple sensor connectors on the patient end.

Affinity Medical has developed and manufactured variations of multi-channel cable systems including bifurcated, trifurcated and quad versions.



A trifurcated cable carries three discrete
signals on a single trunk cable reducing
the number of wires going to the patient

Depending upon the nature of signals to be carried, the raw cable material may be simple, meaning a number of conductors within an outer jacket or complex meaning there are multiple discrete cables, typically shielded or isolated, within the outer jacket; “cables within a cable.”

The Affinity engineering team can assist with design of cable management systems.  Contacting us early in your product development cycle allows you to take maximum advantage of our experience and expertise in cable design.

If you would like to see a sample of an Affinity bifurcated or trifurcated multi-channel cable, contact Affinity Medical Customer Care at +1 949-477-9495 or email to customercare2@affinitymed.com.

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Announcements, Information and Trivia

Christmas and New Year’s Holidays

Affinity Medical will be closed Tuesday and Wednesday, December 24th and 25th to allow our team members to celebrate and enjoy the Christmas holidays.

We will also be closed Wednesday, January 1st to celebrate New Years Day.

The entire Affinity Medical team thanks you for your continued partnership.  We hope that your holidays are sweet and your new year is happy!



Kinara, the candle holder,
is one of the seven
symbols used to
celebrate Kwanzaa

Holiday Trivia

Kwanzaa

Dr. Maulana Karenga established Kwanzaa in 1966 as a week-long festival celebrating “family, community and culture.”  Kwanzaa, which means "first fruits of the harvest" in the African language Kiswahili, has gained tremendous acceptance and is now celebrated around the world, especially in the U.S., Africa, and the Caribbean. 

Kwanzaa is neither political nor religious and is not celebrated as a substitute for Christmas.  Kwanzaa begins on December 26th and continues until New Year’s Day, January 1st.



Winter solstice in the
northern hemisphere

Winter Solstice – Northern Hemisphere

This year, 2013, on December 21st at 17:11 GMT the sun will be at its southernmost point in the sky.  For those in the northern hemisphere, this will be the shortest day of the year while in the southern hemisphere it will be the longest day of the year.

The Twelve Days of Christmas

The “Twelve Days of Christmas” are the festive days that 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.


New Year’s Baby

The tradition of a baby signifying the “birth” of a New Year is believed to have started around 600 BC by the Greeks.  To honor Dionysus, the God of Fertility, a baby was carried around in a basket at the start of the New Year.