EBME Forums Forums Maintenance Technical Assistance ESD (Electrostatic Discharge)

Hi Gent's
I have always been aware of ESD but never gave it any deep thought, until other day whilst half listening in on a conversation about a patient receiving a static burn whilst been transferred from the theatre table back onto a trolley using transfer boards and sheets.
I'm puzzled and please correct me if I'm wrong.
The patient is earthed via the anaesthetic unit, the trolley should have antistatic wheels, the medical team should have antistatic footwear. The static must be generated from moving the patient using the nylon or polyester slide sheets. So how does the patient receive the ESD burn and who is completing the circuit for the discharge.

This is not a quiz of "Who's done it" but it would be good to get some ideas and feedback from you guy's.
Many thanks

I wonder whereabouts (on the patient) the burn occurred?

A couple of thoughts come to mind:-

1) A charge must have built up on the patient, which discharged as soon as the opportunity (a path to earth) arose.

2) Was any "kit" attached (to the patient) at the time? ECG or SpO2 monitor, for example?

3) Are we sure that the burn wasn't in fact caused earlier (at the site of the ESU return plate, or where the patient had been in accidental contact with the table ... etc.)?

4) At what stage in the transfer did this occur? Was the trolley still on the "anti-static" (conductive) flooring in the theatre at the time ... or was it outside the theatre proper?

5) And lastly ... (just for Mike-X), does the theatre have an isolated power system (and therefore a "floating" earth)?

"Earthed via the anaesthetic unit"? Hopefully not. In electrical terms, the patient would normally be "floating".

Post-op (and during transfer), what the patient needs is "gently bringing back down to earth" (in more senses than one). Equalising potentials via a resistance, in other words.

It is highly unlikely the energy transferred by static discharge would cause any visible mark. Any visible burn will be more likely from friction or by some other surgical device, such as the return plate of the ESU.

If static could so easily cause such burns then we would all have loads of burn marks from all our synthetic cloths!