Laparoscopic Workshop 1997

ELECTRICAL TESTING OF LAPAROSCOPIC SURGICAL INSTRUMENTS

Convened by

• The Society for Medical and Biological Engineering (SA) (SMBE-SA)
• The Institution of Engineers, Australia - College of Biomedical Engineers (IEAust CBME)
• The South Australian Perioperative Nurses Association (SAPNA)

Background

The issue of electrical testing of insulated laparoscopic instruments used in conjunction with electrosurgery has been on the agenda within NSW since approx. 1997. An incident in that state that may have caused an injury to a patient during a laparoscopic procedure prompted the NSW Dept of Health to seek expert opinion on the matter. The NSW Biomedical Engineering Advisory Group (BEAG) and the IEAust National Panel on Clinical Engineering provided such input, the result being the release of a document discussing the matter and prompting some possible actions that health care facilities may want to take. These guidelines have undergone a couple of revisions, the latest being designated "Guide to Maintenance of Electrosurgical Accessories Revision 3f"

The South Australian Scene

There had been, at best, passing interest expressed in this whole matter in states outside of NSW, SA included. The SMBE and IEAust here in SA decided that the valuable experience gained within NSW should be shared with a wider audience and to that end convened a workshop that brought together a broad base of expertise. This included engineering, medical, nursing, sterilising and commercial interests in a forum that was planned to disseminate as much information as possible to all interested parties.

The Workshop

This was not intended to be a prescriptive exercise by which attendees would leave with all of the answers, but rather an interactive and informative session. It was planned that people attending would become well equipped with:

• A range of information on the issue
• An insight into interstate experience
• Information on the relevance of standards
• Information on the place of risk management
• Shared experiences of relevant people

and hence be able to make decision that would be most appropriate to their own work environment. Over 70 people attended representing a good mix of nursing, biomedical engineering and sterilising professionals.

The Workshop Faculty

• Mr. Bruce Morrison - Director of Biomedical Engineering, Hunter Area Health Service, NSW
• Dr David Watson - Director, The Royal Adelaide Hospital Centre for Endoscopic Surgery and Senior Consultant Surgeon
• Mr. John Robson - Director, Biomedical Engineering, Flinders Medical Centre
• Ms Kym Hepper - President - SA Perioperative Nursing Association
• Mr. Adrian Richards - Biomedical Engineering, North Western Adelaide Health Service
• Mr. Mark Littlejohn - Director, Electrolab Pty Ltd.
• Mr. David Garrett - Surgical and Medical supplies Pty Ltd.

The Workshop Programme

Workshop Summary

The following provides and overall summary of the presentations and discussion of the evening.

• Australian Standards use the wording "Reasonably Practicable"
  OHS+W Act 1996 allows us to make an interpretation on this as there has not been any legal testing of this definition as yet.
  
• Australian Standard 4360 1999 "Risk Management" provides good advice as to the definition and assessment of risk.
  
• Consider a process such as,
  1. IDENTIFY HAZARDS
  2. ASSESS THE RISK
  3. PLAN CONTROL MEASURES
  4. IMPLEMENT PLANS
  5. REVIEW AND MONITOR
  
• Australian Standards are now introducing performance parameters.
  Documentation is worth following up.
  Endoscopic procedures are minimally invasive
  1. Many advantages
  2 One of the disadvantages is that there is a risk of burns when using an ESU.
• ESU
  • Can cut
  • Can coagulate
  • Must be in top condition
  • Return electrode to be appropriate
  • Lead integrity is essential in terms of both insulation and conduction
• ESU instruments consist of conductive parts and non conductive parts
  The surgeon holds the instrument part that is insulated
  The instrument is mostly insulated except for the exposed conductive part that delivers the ESU current to the patient tissue
• ESU burn is a risk to the patient
  Can be due to poor surgical technique (field of view is also very limited)
  Or insulation breakdown
• NSW background
  Due to an ESU burn incident involving endoscope
  Preliminary discussion of BME’s led to the publishing of an Information Bulletin "97/20"
  This led to a Guidance Document "DOH 98/17"
  However, it is hard to tag and track surgical instruments
  Therefore they recommend checking instruments either each use, each week or each month.
  Use a suitable High Voltage insulation tester
  Either BME or CSSD staff can test
  A revised and updated guideline is imminent
  visual checking only is inadequate
  A visual check and electrical insulation testing is required
• The Surgeon’s perspective
  Stray currents can lead to injuries
  The Bile Duct is very sensitive, may not show up for 1 month
  The Bowel is also at risk of damage, may not show up for 1 week
  If ESU appears ineffective, selected power levels are then often increased,
  if there is an intermittent Cable connection it may suddenly work with a surge of high energy.
  Surgeons call this "surging".
  There is capacitive coupling through the trocars as well
  "Direct Coupling" is where the exposed tip of the instrument comes into unexpected contact with another conductive instrument at the time of ESU activation, leading to tissue damage somewhere away from the target area.
  "Electrical Injuries" are generally not considered by surgeons, they are predominantly aware of mechanical injuries, therefore their statistics are interesting.
  Laparoscopic incidents only 1/1000, and ESU related may only be around 1/6000
• Insulation Materials
  Heatshrink is common, often two layers, will eventually breakdown due to time, heat cycling, scratches, cuts abrasions, burnt, etc and is also easily damaged immediately after testing
  Powder coating, similar to heatshrink
  Ceramic, may be longer lasting and not as susceptible to heat deterioration to plastic insulation, however it is brittle.
• ESU produces up to 4Kv peak at approx. 750KHz
  sharp points have more concentrated electrical fields, therefore greatest electrical stresses
• Electrical Testing
  Who is doing this?
  BME’s
  Outside contractors
  CSSD staff
  How often?
  Every use, Weekly, Monthly, Quarterly, Annually, Never
  What equipment are they using to do the electrical testing?
  Mostly the "HiPot 140" due to a high O/P Z, Audible and Vis indication
• Approx 10% to 30% of failures on initial testing of all instruments.
  

CONCLUSIONS

There is a risk of insulation breakdown with ESU instruments.

AS 4187 on Sterilising requires that BME’s do routine electrical testing of instruments. This standard and recommendation may be under revision.

May be appropriate to have BME consult with CSSD on this.

Only the handles and shaft are to be tested on the laparoscopic instruments
as the hinge area is usually not well insulated and is not near the Surgeon or the Patient.

4Kv DC is recommended for testing. Higher Voltage is likely to damage the insulation.

The "HiPot 140" and the "PCWI Compact" dedicated test devices both cost approx. $1500

No need to test leads, except for continuity and a visual check.

Some method of tracking instruments will need to be developed in the future.

The NSW guideline is our best source of advice

Updated July 18, 2008

All Contents Copyright SMBE SA ©2004 Email: SMBE Enquiry