SMTL Newsletter, Volume 1, Issue 3, Jan 1999

SMTL have moved ....

... to a new laboratory in the Princess of Wales Hospital.

The Surgical Materials Testing Laboratory has completed its move to new premises at the Princess of Wales Hospital in Bridgend. We would like to take this opportunity of formally thanking everyone in the Bridgend and District NHS Trust who helped make the move possible, especially Paul Stauber and Sian Morgan.

We now have a range of excellent laboratory facilities, including

  • A chemical laboratory, where we are currently working on test methods to measure the rate of chemical permeation (such as cytotoxic drugs) through gloves.
  • A controlled environment laboratory (CEL), where the temperature and humidity are maintained at constant levels. In this lab we carry out testing of elastic products (e.g., gloves, bandages, stockings) and any tests requiring the use of the Instron tensiometer.
  • A cell culture laboratory, where toxicity testing of medical devices is performed, including the tests used to ensure that catheters purchased on the new All Wales urology contract were free of toxic residues, and therefore would not cause urethral stricture.
  • A physical testing laboratory, for tests which do not require the special conditions of the CEL. The equipment in this laboratory was used recently to produce evidence for an inquest into the death of a patient due to defective renal catheter equipment.
  • A microbiological laboratory, where sterility testing and endotoxin testing is performed. This same lab also houses the equipment used to determine the levels of protein in gloves, which is vital to ensure that NHS staff in Wales do not develop latex allergies.
  • A "Wets" laboratory -- so called because it is used to test gloves and sharps bins for leakage, and failure of these products can result in copious amounts of water flooding over the floor!
  • The Biosurgery Research Unit - a suite of 4 laboratories where flies and their larvae are cultured for use in wound debridement. (See later in the newsletter for more on the success of our larvae).
  • As well as offices and store-rooms for samples, the upstairs includes a small seminar room, which can seat up to 12 people, and is frequently used for pre-adjudication meetings with Welsh Health Supplies.

If you are in Bridgend and would like to see the laboratory, please contact us to arrange a visit.


Maggots - The New Millennium Bug

In November, Peter Mandelson announced that The Biosurgical Research Unit (part of SMTL and the only centre to produce sterile maggots in the United Kingdom) had been granted Millennium Product status by the Design Council. The maggots, sold under the brand name of LarvE, have been distributed to over 350 centres in the United Kingdom and elsewhere in Europe.

Used to clean wounds that have leg ulcer pressure sores and necrotic areas on the feet of diabetic patients, they have been found to be remarkably effective. Wounds that may require weeks or months of treatment with conventional dressings can sometimes be cleaned with a single application of LarvE over a three day period.

Since the announcement, the laboratory has received a lot of interest from the media, including articles in the Independent, The Mirror, The Evening Standard, Marketing and The Times, as well as coverage on the BBC.

The Biosurgical Research Unit now has the right to apply the highly prestigious ``Millennium Product Marque'' to the larval containers. It is hoped that the larvae will be selected to be included in the Millennium Dome when it's opened in Year 2000.

Dr Stephen Thomas


Pre-use inspection of disposables.

SMTL is the defect reporting centre for disposables for Wales. We receive between 130 - 200 defect reports a year ranging from labelling defects through to potentially life threatening defects. Procedures for carrying out defect reporting are documented in WHC(97)28 and subsequent amendments. Recently ECRI (an American based organisation), recommended that pre-use inspection of every medical disposable medical device was carried out to reduce the impact of defective disposables on patient care. The general procedures are included below.

Pre-use Inspection Procedure.

Consistently perform brief pre-use inspections, focusing both on the packaging and the device. Typical steps include the following:-

  • Before opening the package conduct a visual through the package inspection device for obvious defects where possible.
  • Check the packaging integrity. Are the package and seals intact? If not, the sterility of the devise may be compromised and it should not be used.
  • Verify the package label.
    • Is this the correct device for the patient and procedure ?
    • Does the label accurately identify the type and size of the device contained in the package ?
    • If the device has an expiration date has the date passed ?
  • Determine if there is any debris or unidentified material within the package. This may be an indication that the integrity of the packaging has been compromised and the device should not be used.
  • Check the label instructions to ensure proper usage. Manufacturers sometimes change the instructions, and the label may not necessarily indicate that a change has occurred.
  • Determine whether the device is complete and properly assembled.
  • Verify all lumens are patent and balloons are intact.
  • Look for any external defects (eg. broken insulation of electrodes, cracks or splits in catheters), check that all connections and junctions are intact and secure, verify that all valves and ports are properly oriented and functional.

What to do if a device is found to be defective.

Record the device name, model, batch number, expiry date of any defective product. Save the device in its packaging if possible. If possible obtain a number of unused sample from the same batch for submission to SMTL for examination and testing.

Complete details of this procedure should be found in WHC(97)28 appendix C, monographs 7 - 9. A form is also included in this circular from Welsh Office to enable full reporting of the incident. Please send the device and completed forms to SMTL. Peter Phillips


Purchasing non-CE marked devices.

Since the 14th June, all medical devices placed on the market must be bear the CE mark. The only exceptions are allowed by the Commission Decision 98/C 242/05, for those products already in the supply chain (i.e., manufactured before this date and shipped to distributors etc). However, certain products are still not CE marked, either because the manufacturer has taken a decision not to CE mark them (if, for example their European market is too small), or because they are ignorant of the legislation (very few manufacturers are now unaware of the Directive).

As it is now illegal to place on the market a medical device which isn't CE marked, any manufacturer doing so is committing an offence. It is not against the directive for someone to purchase a non-CE marked device, but the medical device itself would be in breach of the law. If an incident occurred, and subsequent investigation found that the device involved did not comply with current legislation (i.e., was not CE marked), the purchaser could be found to be liable.

Therefore, if an NHS Trust wishes to purchase a non-CE marked device, they should take legal advice before purchasing the device as to the potential implications for the Trust.

The Medical Devices Agency. should be informed of any medical devices which are not CE marked.

Peter Phillips


SMTL success in the Journal of Wound Care awards.

Each year, the Journal of Wound Care in conjunction with Johnson & Johnson, invite submissions for awards in three categories. These are Research, a Literature Review, and Clinical Innovation. This year SMTL was successful in winning first prize in the clinical innovation section with a paper that describes a new technique of the management of meningococcal skin lesions, the characteristic areas of reddish blue discolouration most frequently found at the front or lower limbs patients with this disease.

In severe cases these areas darken in colour and become necrotic leading to extensive tissue loss that may involve muscle and bone. The winning study described a case history in which a patient with such lesions was treated with hydrogel and other modern dressings. As a result of the treatment supplied, the patients wounds healed with minimal scarring and no loss of movement. It is hoped that this approach maybe considered in other situations in patients with this condition. This submission also won a special award for the paper which made the greatest contribution to patient care.

In addition the lab won a second prize in the literature review category for a review of the role of Compression Hosiery in the Prevention of Deep Vein Thrombosis. This condition can develop resulting in formation of a fatal pulmonary embolism or cause damage to the veins of the lower leg which result in leg ulceration in later life. This history causes and diagnosis of DVT were discussed as was the literature relating to the clinical evidence for the use of various types of compression therapy.

Dr Stephen Thomas


Chlorinated gloves and Shelf Life.

Many users are confused over the effect chlorination has on medical latex gloves, and whether it affects the shelf life.

Chlorination is an alternative to powdering medical gloves, so that they can be donned. Without powder, chlorination or some other coating, the gloves are very difficult to put on as they are very "grippy". As powder becomes less popular as a lubricant, many NHS staff are turning to powder-free gloves, which are usually chlorinated.

The chlorination process is carried out by dipping the gloves in a solution of chlorine for approximately 15 minutes. A chemical reaction takes place, where the rubber polyisoprene molecules cross-link with the chlorine to produce polychloroprene (the material that Neopreneis made of). Thus a chlorinated latex glove can be thought of as being ``polychloroprene plated''.

Although the chlorine has an affect on the tensile strength (a chlorinated gloves is usually less than 5% weaker than a non-chlorinated glove), the shelf life is not reduced. In fact, as the chlorinated surface is less receptive to oxygen, it may well be that the gloves have a slightly better shelf life than their non-chlorinated counterparts.

Peter Phillips


Personal Sharps Containers

Personal sharps containers, used in the community by drug misusers participating in needle exchange schemes, have caused confusion in recent years.

Problems have been experienced in arranging All Wales contracts for these devices as it has not been clear whether the containers complied with current standards or legislation. This article attempts to clarify some of these issues. Personal sharps containers, used in the community by drug misusers participating in needle exchange schemes, have caused confusion in recent years.

Problems have been experienced in arranging All Wales contracts for these devices as it has not been clear whether the containers complied with current standards or legislation. This article attempts to clarify some of these issues.

Health and Safety Legislation.

In 1996, a piece of Health and Safety legislation was introduced into the UK, the "Carriage of Dangerous Goods" regulations, 1996. These regulations stipulate the technical specifications for containers containing clinical waste, being transported by road or rail in a vehicle.

Containers which comply with the Act must carry the correct designation (in the case of sharps containers and other infected clinical waste containers is "Clinical waste, unspecified, not otherwise stated" or "(Bio) Medical waste, not otherwise stated" or "Regulated medical waste not otherwise stated"), a UN number, a UN mark, and the correct danger sign (for sharps containers this should be the "Infectious substances" sign).

The ``UN number'' is a 4 digit number prefixed by ``UN'' and used as a means of identification for dangerous goods. For example, UN 3291 correlates with "Clinical waste, unspecified, not otherwise specified" etc.

The ``UN mark'' is a 14 character code, which shows that the containers have been tested in accordance with the requirements for packaging performance in the United Nations ``Recommendations on the Transport of Dangerous Goods (9th revised edition)''.

Whilst sharps containers and other clinical waste containers used in hospitals must comply with these regulations, the Health and Safety Executive state that the act applies to the workplace, not to private use. Their opinion is that sharps containers used by drug misusers at home do not have to comply with the act.

As long as the containers in question are disposed of by the drug misuser in larger sharps containers which are in compliance with the regulations, the question of compliance of the personal container is irrelevant. If, however, the containers are being transported as individual units by a waste disposal firm, health professional or a drug worker (perhaps disposing of the unit on behalf of their client) in their line of duty then they should comply with the regulations.

British Standards.

British Standard BS 7320:1990 is a standard specifically for sharps containers.

It includes specifications for the labelling and performance of sharps containers. Conforming containers must meet minimum performance criteria for the penetration force of needles through the container, and leakage after toppling or dropping from 1 metre.

It also requires that the containers be mainly yellow in colour and possess a handle. As most of these ``personal containers'' are black and without handles, they cannot comply with this standard. The handles are intended to reduce the risk of touching needles which have been forced through the container wall.

The standard is not mandatory, but SMTL and the Medical Devices Agency always recommend that where possible, products be purchased which comply with the relevant British Standards.

Welsh Health Legal Services (WHLS), advising Welsh Health Supplies, state that Trusts are unlikely to have a legal liability in relation to the containers unless it can be shown that they collected the particular container and failed to dispose of it appropriately.

Some manufacturers participate in the BSI kite-marking scheme for sharps containers. To carry a BSI kitemark, the company has to be inspected by BSI, and have products tested independently on a regular basis.

Good Practice Guidelines

  • Black containers are acceptable for home use only.
  • Containers used to dispose of black sharps containers must be UN marked to comply with H&S legislation.
  • These containers should also, preferably, comply with BS 7320.
  • If a manufacturer makes claims for compliance with BS 7320, purchasers should obtain independent data to ensure they comply.
  • A BSI kitemark means they have been independently tested and audited.

Peter Phillips


The Medical
Disposables and
Dressings Newsletter
Vol.~1 No.~3
January 1999

Published by:
The Surgical Materials
Testing Laboratory
Edited by:
Dr Stephen Thomas
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Peter Phillips
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Contact Information
Tel: 01656-752820
Fax: 01656-752830
Princess of Wales Hospital
Coity Road
CF31 1RQ

©1999 by SMTL.
All rights reserved. No permission necessary to copy, reprint and distribute unaltered within the NHS as required.
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