The conclusion has been moved here:
I mentioned this on another venue, but that connection doesn’t look appropriately keyed in order to prevent those sorts of Human-Machine Interface failures!
Something as simple as a red triangle on each side of the connection, which should point together. Or one side of the plug having a shared post for the two prongs, hence it could only be plugged in one way. These little things could have fixed the reversal problem.
Although, the last code I worked for a second there it looked like we were going to need a second monitor as the limb leads would not come up on the LP12. Route cause analysis: somebody managed to plug in the cables 90 degrees from normal. Due to wear on the connector, the keying mechanism had become worn down enough to allow a rotated connection. Took us a minute to realize the mistake.
This is a stunning case and a fantastic presentation; I am very grateful to see this– I have never seen so serious a diagnosis masked by such a mechanism. It is an important exemplar of systems error. Like Christopher I am surprised to see something like this post “Pt Safety Movement.”
Truly outstanding case study. Thank you Tom.
Seems like it would be a valuable feature if the monitor could recognize this sort of thing — really, how many legitimate circumstances would produce such global negativity of the limb leads (negative P, negative QRS, negative T) and the reverse in aVR? At least a “Check electrode placement!” warning would be nice; it would be at least as useful as some of the other non-diagnostic flags.
I know our LP12’s will output that message and I believe Zoll/Philips will too. Not sure why this machine wasn’t setup to do that. Maybe there was too much of a negative component in aVR?
Here’s a nice talk by Dr. Rich Harrigan I stumbled across yesterday on this very topic. He covers the most common ways to screw up electrode placement along with the hints on the tracing that can help diagnose the problem. Although only audio from the lecture is available, as people who look at ECG’s in our free time (and have probably made these mistakes a few times), it shouldn’t be too hard to picture what he’s talking about. LA-RA and RA-RL aren’t too tricky to pick up, but I’d never really noticed how easily a LA-LL switch could go by unrecognized.
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