I have just received a copy of an article submitted to the journal of clinical engineering (Jan-Mar 2003). Called "Equipment Inclusion Criteria Revisited", it basically introduces statistical sampling to the risk based PPM systems in use on both sides of the pond. It is a radical departure from current thinking and looks as though it would be difficult to implement on a small scale, but nontheless illustrates (as usual) how far the US is in terms of this particular aspect of equipment management :

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I would be happy to make a pdf available provided Huw is happy about copyright infringement

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Regards
Paul