[Murphy, Kathleen M.]

Murphy, Kathleen M.  asked the Naked Scientists:
   
Hi Chris,

I have a weird question regarding a patient.

He had a stainless steel bar inserted into his chest to correct a cartilage deformity called Pectus Excavatum. It will remain in place for 3 years.

Mum called to ask if he has a higher chance than others to be electrocuted, not hit by lightning, but electrocuted. He is in auto tech classes at his high school. Mum is also afraid the bar, which is near to the heart, would cause increased damage to the heart if he was electrocuted. One of my physicians said he wasn't sure stainless steel in the body would conduct electricity

My thoughts are:

1.       Steel outweighs stainless in this case – no matter where it is at. It would conduct as it is a metal.

2.       He doesn't have a higher chance than anyone else of random electrocution unless  he is a total idiot.

3.       Stainless steel doesn't have a super high affinity for electricity traveling to a light or appliance, from a car battery, or from a socket that would cause the electricity to divert to his body.  Right? He'd have to do something to bring it to him like stick his finger in the socket, stand in water while working on an electrical circuit that is live, etc.

4.       If he were unfortunate enough to be electrocuted, the bar would have an increased concentration of electrical current traveling through it causing  a higher amount of local damage in the area where the bar is located.

Am I close to correct in your expert opinion?


Thanks for your time,

Kathleen M. Murphy BSN RN CWON
Houston, TX

What do you think?

[RD]

similar question ... http://www.thenakedscientists.com/forum/index.php?topic=35380.0

[CliffordK]

It is unlikely the bar in the chest will adversely affect him.

What type of cars is he dealing with.  Classic gasoline/diesel vehicles?  Hybrids and Electric Vehicles?

It turns out that a typical 12V car battery can produce about 1000 Amps current, more than enough to kill a person.  However, shocks are rare because the skin's resistance is so high that 12V power can not penetrate the skin unless one does something like sticking electrodes into one's hand.  And, even so, the risk is only high if one was to stick an electrode into each hand (right and left) so that the pathway for the power would lead through the heart.

Stainless steel is conductive, in the body or outside of the body, and probably has slightly less resistance than the saline solution that your body is bathed in.  Is the bar oriented vertically, or horizontally?  If it is horizontal (or some mix), it is possible that it would afford some protection to the heart by providing a lower resistance pathway for the power around the heart, but of course, one would have to do a study to know for sure.

Any power surge great enough to cause the bar to heat up would be great enough to cause massive internal damage if the bar was not in the body.  But, I wouldn't expect that unless he is doing electrical work on main-line power (1000V+)

Presumably your shop teachers are safety-conscious professionals.  If one is dealing with things like starters or other high power electrical devices, it is easy enough to disconnect the battery.  Always first disconnect the GROUND wire because you won't produce a short if you touch it and the car.  Once the ground is disconnected, you can disconnect the HOT wire.

Anyway, I would not worry about a routine High School / College automotive shop class if they are dealing with typical 12V power systems.  And, I would not be any more concerned for him if he was dealing with Hybrids and Electric Vehicles than I would be without the prosthetic device.