Bill - Brian is right - the hospital shouldn't permit use of equipment in the patient environment if it is failing to meet the leakage current limit requirements for medical equipment. Your hospital administrators may well not see the point - does the hospital not have a clinical engineering dept? - if so they don't seem to be doing their job. I'm not familiar with US law, but on this side of the pond the relevant Standard is EN-60601-1; collateral Standard 60601-1-1 provides acceptable methods for achieving leakage current compliance in non-compliant equipment. Interestingly, whilst most of these Standards are written for the equipment manufacturer, this collateral Standard specifically states that it is intended to be applied by hospital personnel also. Whilst the Standard isn't UK law it is a harmonised Standard under law, so the hospital would have a lot of explaining to do if it chose to ignore its requirements. I'd suggest that your average hospital administrator has no expertise in this field and would therefore be unqualified to justify a decision to disregard the accepted safety limits. I beleive that a couple of decades or so ago there was something of a scare in the USA, with claims that 100s of patients were being killed by leakage currents in hospitals each year - this claim was subsequently shown to be greatly exaggerated, which may have been the source of the article you remember. Which isn't to say that the leakages current hazard doesn't exist. Also medical equipment is by and large much safer now than it was then - principally because of adherence to Standards such as those above. With regard you search for an article - I seem to remember there was quite a good chapter in a book called Medical Instrumentation (edited by J.Webster). When all else fails to persuade, a leakage current demonstration such as that described by John ought to do the trick; it is bxxxxx uncomfortable! Ged Dean, Nottingham City Hospital
From: Brian O'Connell [mailto:[email protected]] Sent: 16 November 2004 18:47 To: '[email protected]' Subject: RE: Hospital Leakage Current Research Good People Why is the hospital staff allowing IT equipment to contact the patient ? Not a Type Testing, agency, or even a manufacturer issue; but would seem to be that the end user (i.e., the medical community) is using improperly specified equipment. A hospital admin that puts his patients at danger by ignoring FDA/OSHA/UL/IEC standards is, at least in California, committing a criminal act. Perhaps the local D.A. could "convince" the admin to use the properly rated equipment. Of course, if the mfr or system "integrator" installs IT equipment that is inside of the radius delineated by IEC60601-1, than they are the guilty party. luck, Brian -----Original Message----- From: John Allen [ mailto:[email protected]] Sent: Tuesday, November 16, 2004 9:47 AM To: 'FastWave'; '[email protected]' Subject: RE: Hospital Leakage Current Research Bill The obvious first step is to look at the various parts of IEC 60479 on the effects of current on the human body - especially the graphical curves and explanations in 60479-1 Tables 4 (AC) and 6 (DC) - but you should then take a look at Helmut Hintz's "Protection against electric shock" PSES presentation, which should be somewhere on the forum website and outlines some of the proposed changes. It might also be worthwhile putting together a little "demonstration" of the effects of leakage currents on the hospital administrators! [I will always remember a demo from Al Kanode of HP to various regulatory engineers within the company of the differences between the effect of 0.75mA and 3.5mA - that was enough to convince me that the former was as much as I ever want to take on a continuous basis, and the latter is almost unbearable! In addition, we recently did a project for a customer who wanted to demonstrate the effects of electricity to large numbers of people from all sorts of backgrounds without hurting them - that provides a pulsed PEAK current of around a 1mA for about 2.5mS on a 1-shot per second basis. Anything higher that that induced a "that's unacceptable" (or more "explicit") reaction >from a lot of people! As it is, the demonstration has now been running for nearly 4 months without any complaints. It also proved that 60479 recommendations are pretty close to the mark - although bear in mind that they are now under review and the new proposals will effectively tighten up on the design controls required.] Finally, does'nt the AMA have something to say about all this? Regards John Allen, Technical Consultant EMC and Safety Engineering ERA Technology Ltd. Cleeve Road Leatherhead Surrey KT22 7SA UK Tel: +44-1372-367025 (Direct) +44-1372-367000 (Switchboard) Fax: +44-1372-367102 Please take a minute to visit my recently updated (Sept 04) web pages at http://www.era.co.uk/services/rcm.asp and the main ERA Website at http://www.era.co.uk -----Original Message----- From: FastWave [ mailto:[email protected]] Sent: 16 November 2004 17:23 To: '[email protected]' Subject: Hospital Leakage Current Research I am trying to assist some hospitals in our area who are working to assess the Leakage Current Hazards in their medical facilities. I believe a lot of this relates to the growing abundance of ITE products in medical facilities = in their words "flat screen monitors are showing up everywhere in patient areas" = the ITE certified products fail medical leakage current requirements. There are some people in the hospital (administrators) who do not believe they should be concerned at all with leakage current. The problem is proving that people are getting hurt/killed by leakage current = you can't see the problem and the cause is not obvious in an autopsy. I know I have seen at one time an article written in a medical journal questioning whether some patients are really being killed in surgery due to leakage current (rather than "complications of surgery" or "heart failure"). Can anybody direct me to any articles/research in this area? Thanks, Bill Bisenius, N.C.E. E.D.& D. [email protected] www.productsafeT.com 919-469-9434 ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
