EBME Forums Forums Management Medical Equipment Management Electrical Safety of physiotherapy couches

I recently rejected an electrically operated physio couch from the hospital. The mains supply is via a L&N flexible cable. There is no earth, the framework is not earth bonded. The framework of the couch is exposed metalwork with metal adjustment handles. The cable has several trapment points and I proved the frame could go live if the cable was trapped with a shearing action as a foot-peddle was operated. Reported to MHRA and returning unit to vendor. I have now come across a second manufactures couch with exactly the same problem. Am I missing something? This seems a lethal hazard to me. Photos and videoclips available on request.

If a cable is cut that is a double fault condition, two layers of insulation, each one broken is a single fault. This is true of any mains cable. Just because the equipment has a means of breaking the cable more easily than another does not make it at fault. If all the electrical parts of the couch are double insulated from the live parts why earth the couch?
I have often wondered why beds/couches have all their matal work bonded to earth. If a leakage current occurs in another piece of equipment it provides a low resistance exit path, increasing the shock. Theatre tables etc have high resistance earth bonds to discharge static but not provide an earth path.
Robert

Hufty,
Just wondering if:
a/The couch was CE marked as a medical device?
b/What checks were made prior to purchase i.e. PPQ
and
c/Did you discuss the perceived problem with the manufacturer/distributor before reporting the "issue" to the MHRA and sending it back?
We have had many similar "issues" when techs have attempted to carry out earth bonding/leakage checks on our 12v and isolated chassis'despite the fact that they are CE marked and TUV approved!!!
Chris

Hello Chris,
The first couch was CE marked on the power supply unit. Whether that applies to the entire couch assembly I am not sure, I would think not. I was not party to a PPQ. I did discuss the issue with the manufacturer and they suggested routing the flexible cable away from the trapment areas with cable ties. But a flexible cable can run anywhere, by definition. They also suggested fitting a RCB.

Hufty,
Seems you may have made the right decision but perhaps for the wrong reasons!!!!;-)
Chris

Regardless of the legality of double insulated cables and unearthed metalwork, a safety hazard is still present in the form of a cable trap with potential to shear the cable, making the framework live. On this basis I am rejecting the couch and will continue to do so on any other similar designs. I will also check what other physio couches of a similar design we already have in the hospital.

Hufty,
This is only a problem if the equipment is incorrectly used. If the cable is placed in a safe "normal position it will not get damaged.
It is possible to cut a cable of a plaster saw with the equipment it powers and so render it unsafe. This also applies to many other pieces of equipment.
I would agree that there is good and bad design but even bad design can comply with the requirements for safety if it is used exactly as intended.
I have been thinking about CE marking and the definition of medical equipment. I personally believe that as a couch is neither used to treat or diagnose a patient, provide contraception or assist with a disability it is not medical equipment. It is a piece of electrical equipment used in a medical environment but so is the doctors PC and the ceiling light. It is used by the patient but so is a chair in a consulting room or the door. I do wonder if it needs to be CE marked to medical standards.
This does not obviate the need for safety and good design though.
Other opinions waited with interest.
Robert

PS I have asked the MHRA in the past about PCs in a patient environment of an outpatients consulting room as when the patient was seated it was inside the magical "patient environment". The official answer was that even if the letter of the regulation was correct, common sense had to prevail. Does a coke machine dispemsing to a patient in the out patients department have to comply with medical regulations? When does a patient stop having their "environment" around them?

in my view, physiotherapy couches are move a lot.

The nature of the design has the cables routed between the rear legs by the foot pedals.

I my experience it is normally the absence of judgement that causes the cables to get damaged...

for example:

A car can be safe with good judgement, but can also be lethal with bad.

I think you maybe be making mountains out of molehills, As we have only had 1 report of a damaged mainslead in the last 18 months.

perhaps the plastic foot is missing from the mase of the leg, I know the couches we have have plastic feet, which if the cable is caught underneath just crushes it flat...

I would check the couch in its working enviroment and to a risk assumption based on movement and useage....

MY opinion hope it helps.

I would love to post some pictures and video clips of the problem here to assist with this debate, but I don't know how to do this. In my opinion, if something can happen eventually it will happen. The design of the couch in question presents a real hazard. The user of the couch is probably not even aware of electrical safety issues, so we have to make judgements on their behalf. I am considering putting similar couches' mains cables in flexible conduit or spiral wrap to prevent them fitting into the trapment area. Other couches I have looked at have a different design of caster operation peddle that pushes the cable away rather than trap it.

Rojo,
"I personally believe that as a couch is neither used to treat or diagnose a patient---"
As we are specifically discussing a "Physio couch" surely it is being used to "treat" a patient therefore it must be classed as a medical device and CE marked as such.
Chris