INFECTION PREVENTION AND CONTROL
Changing the way instruments are cleaned
In a bid to address the issues surrounding ultrasonic cleaning technology, David Jones, MD Alphasonics, discusses a project to develop Advanced Ultrasonic Protein Removal Technology for cleaning surgical equipment.
In the UK, concerns about Creutzfeldt-Jacob Disease (CJD) date back to the mid-1980s when an outbreak of Bovine Spongiform Encephalopathy (BSE, a similar transmissible neuro-degenerative brain disease) in cattle raised concerns that the disease might be transmissible to humans. Confirmation came in 19961
that BSE
can indeed lead to a form of human CJD (variant (v)CJD) that particularly affected younger adults. This resulted in widespread public health concern, heightened again a few years ago when a study in the British Medical Journal2
bacteria hidden in or under any residual protein e.g. biofilms could also be passed on. A recent study in the journal Acta Neuropathologica4
also highlighted the potential
dangers associated with cross-contamination of neurosurgical instruments with the peptide amyloid beta (Aß), a substance implicated in brain haemorrhages and Alzheimer’s disease. Standard methods such as chaotropes (eg: hot alkaline solutions and surfactants) are known to be inconsistently effective in removing protein from surgical instruments5,6
and other suggested that as many as
In both model experiments and in actual human studies it has been shown that the prion protein is readily transmitted on stainless steel instruments from one animal to another.
one in 2000 Britons may be infected with the abnormal prion protein that causes vCJD. To date there have been 178 deaths due to vCJD in the UK with a few more elsewhere.3
vCJD highlighted to clinicians and decontamination/sterile services professionals alike, the critical requirement to remove protein, as well as other infectious agents, from neuro-surgical and other reusable surgical instruments. In addition to the risk of patient-to-patient transferal of vCJD prions, there is a danger that
difficulties in ensuring consistent cleanliness has led to a move towards single use instruments. However, questions remain as to how manufacturers of single use instruments can achieve consistent cleanliness and sterility when modern, well equipped Sterile Service and Decontamination (SSD) units apparently cannot. Unfortunately, single use instruments are not always clean and sterile as recent unpublished investigations have shown. In the UK, concerns about contamination mean that GPs and dentists, who have historically performed minor interventions such as lancing of boils, removal of small cysts, etc are now being discouraged from doing so. This, in turn, is funnelling more patients to A&E departments, which are already under tremendous strain. Post- operative infections also add to strain the
David Jones, MD Alphasonics
health service, leading to extended hospital stays and bed-blocking.
There is a clear need for a new approach to improve the cleaning of surgical devices. ‘Commercial grade’ ultrasonic cleaning systems have been available for a number of years and have been used as a first stage in the cleaning process.
Ultrasonics: The basics
Ultrasonics works via the process of cavitation. Transducers bonded to the base or side of a tank are excited by high frequency electricity causing them to expand and contract at very high speed. This mechanical action causes high speed downward flexure of the radiating tank face. The speed of this movement is too fast for the water in the tank to follow, resulting in the production of vacuum chambers.
On the upward flexure the vacuum is released in the form of a vacuum bubble
Graph 1 72 I
WWW.CLINICALSERVICESJOURNAL.COM
Graph 2 SEPTEMBER 2018
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