For How Long Can a Monitor Hold a Charge?

[Flying]

Does anyone know for how long a monitor's capacitor can hold a charge for defibrillation before it is programmed to "dump it"?

Usually it's sufficient to know only how quickly a monitor charges prior to being ready when working a cardiac arrest, but I this question came up a couple of times when reviewing CPR with others and I figure it would be worth asking for curiosity's sake.

I've seen a training monitor hold a "pre-charge" for about 90 seconds before everyone said "that's good enough", but I would like some real input from those who use a variety of equipment.

 

[chaz90]

Hmm. Interesting question. I never hold the shock too long. I pre charge my monitor ~15 or 20 seconds before a rhythm check to minimize the perishock pause, but I never hold it for longer than that. If it's not a shockable rhythm, I dump that charge and move back on to CPR before charging it again minutes later.

I can test it on my LP15 tomorrow for you. I'll attach the defib tester and try to let it hold for 5 minutes or so.

 

[NomadicMedic]

I would assume the circuitry in the monitor would top up the capacitor if there was any bleed off during the "standby to shock" mode.

As long as there was battery power to keep the capacitor fully charged, it should be able to retain the charge indefinitely.

I'm curious if the monitor is programmed with an "auto dump" feature. If the defib charge wasn't delivered within X number of minutes, the monitor would dump the charge to prevent an accidental discharge

 

[Flying]

I'm curious if the monitor is programmed with an "auto dump" feature. If the defib charge wasn't delivered within X number of minutes, the monitor would dump the charge to prevent an accidental discharge

I had assumed that this was a feature in monitors, or that's what I inferred from discussions with others.

 

[Carlos Danger]

I'm curious if the monitor is programmed with an "auto dump" feature. If the defib charge wasn't delivered within X number of minutes, the monitor would dump the charge to prevent an accidental discharge

I remember a long time ago asking that same question of someone smarter than me, and I was told that the system isn't meant to hold the charge for more than a few seconds, so the energy just bleeds away quickly on its own if not discharged.

Don't know for sure if it's true but I've always gone with it.

 

[TomB]

Even when you "dump" a charge, all you've done is disarm the shock button. The charge has to trickle off the capacitor over time.

 

[NomadicMedic]

Even when you "dump" a charge, all you've done is disarm the shock button. The charge has to trickle off the capacitor over time.

Interesting. I was under the impression that the cap discharged into a resistive load when it was dumped.

 

[TomB]

You may be right. I'm no physicist. Just repeating what the folks from Physio-Control said when I asked, "Where does it go?" during a discussion about dumping the charge during High Performance CPR (rhythm not shockable).

 

[NomadicMedic]

I jut sent an email to a friend at Physio in Redmond. Now I'm stupidly, obsessively curious.