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INFECTION PREVENTION AND CONTROL
which rises up through the fluid until it hits an object, upon which the bubble implodes under high pressure, thus drawing away any contamination that may be on the surface of the object. However, it has been shown that machines used in sterile services departments in the past have an erratic distribution of sound that does not consistently render instruments clear of residual protein. It was felt by many that a new way of applying ultrasound into a fluid was required. To achieve the safe cleaning of these items, sound needs to be applied in a way that is both even as well as intense, with no gaps in activity where cleaning would not be effective.
In order to develop a new cleaning technology, a reliable method for measuring residual protein was needed and agreement reached on acceptable levels. The UK HTM 01-01 Guidance on the Management and Decontamination of Surgical Instruments,7 released in 2016, specifies that: “there should be <5µg of protein in situ, on a side of any instrument tested.” In situ testing is specified since: “detection of proteins on the surface of an instrument gives a more appropriate indication of cleaning efficacy related to prion risk,” than the swabbing techniques used in the past.8,9,10 Currently the ProReveal system, from Synoptics Health, Cambridge UK, is the only in situ system on the market worldwide. As well as high levels of accuracy, the system also identifies the precise location of any
remaining proteins on the instrument. To comply with UK HTM 01-01 guidance, therefore, any new cleaning system, ultrasonic or otherwise, needs to be validated against the levels of detection offered by ProReveal. A second issue to be addressed by any ultrasonic cleaning technology is how to measure the ultrasonic activity. HTM 01-01
states that machines should be periodically tested for ultrasonic activity. Historically, the only method available to manufacturers for validating the activity in an ultrasonic tank has been to insert a piece of aluminium foil into the fluid for a set time and then visually analyse the indentations in the foil to determine the ultrasonic activity. This is a somewhat inaccurate way of validating what is a critical phase in the decontamination process. Troughs of sound can be either macroscopic or microscopic and, as such, the reliance on sight alone is unacceptable when high levels of consistent cleanliness are expected. With both these issues in mind, Alphasonics (a Liverpool/UK company with more than 25 years’ experience in the field of ultrasonic cleaning systems) launched the ‘Medstar’ project with a view to developing ‘Advanced Ultrasonic Technology’ for cleaning surgical equipment. The project started in 2013 but it was not until 2015 when a ProReveal was purchased that substantive advances were made. Progress then accelerated quickly and over a three year period, a point was reached whereby instruments could be rendered “completely” free of residual protein, as assessed by ProReveal technology.
Cavitation Validation Device
To overcome the problems around accurately measuring ultrasonic activity, the world’s first Cavitation Validation Device (CVD) was
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