Discussion Main / MagicalDefibrillator

Advanced Cardiac Life Support protocols. Casualty is intubated or having O2 supplied through bag and mask... Normal practice when defibbing an adult will have the operator supply a 200-joule shock, then adrenalin would go in. If that fails, then they try a 300 joule shock. After that, it's 360, epi, 360, epi...

These are when they are shocking an adult externally. With a child (remembering from Casualty, I believe it's half that). *internally*, as in directly across the heart, it'll be down around the 20-50 joule mark.

Most automatic ones, though, have two settings - 200 and 360. In this case, it's 200, 200, 360...

Electrical dosages actually depend on a few things. For manual defibrillators, it's important to note if your device is monophasic or biphasic. Monophasic defibrillators max out at 360 joules, where biphasic devices max out at 200 joules. The difference being that biphasic devices deliver electricity more efficiently to the heart, so you need less voltage to achieve the same result.

For something like a cardiac arrest, where the heart is not beating in a perfusing rhythm (i.e. not beating in a way that is sending blood circulating throughout the body), most, if not all, protocols tell you to go straight to the maximum joules setting. The exception to this is for pediatric patients, where up to a certain age, the amount of electricity to be delivered is based on weight (usually about 2-10 joules/kg).

Now, to answer your question, one of the reasons people yell "charging" is so that people who are physically touching the patient (for CPR or whatever else needs to be done at the moment) know that a shock is incoming. Keep in mind, there's usually a lot going on in a cardiac arrest, and you don't want someone to get electrocuted because they didn't know the patient was about to receive a shock.

As for electrical dosages, the amount varies on the situation/condition. As stated before, for a cardiac arrest, the dosages are usually maxed. However, for something like Supra-ventricular Tachycardia (a condition where the heart is beating so quickly the chambers of the heart don't have enough time to fill with blood), the dosages will be different. On a monophasic monitor, you'd start at 200 joules, change to 300 joules if that doesn't work, and then finally max out at 360 joules if 300 joules didn't do the trick.