Using an AED
Switch the AED on and do what it says: it checks the heart itself and only shocks if a shock is needed, so anyone can use one.
WHY A SHOCK
Resetting a chaotic rhythm
Many cardiac arrests start with the heart's electrical signals going chaotic: instead of squeezing together, the muscle only quivers. This is called ventricular fibrillation, and a quivering heart pumps almost no blood. A shock can stop the chaos so the heart's own normal rhythm has a chance to take over again. Time matters: every minute without CPR and a shock lowers the chance of survival, by roughly 7 to 10% a minute in figures that are often quoted (approximate, and CPR slows the drop).
This is why the plan is CPR and the AED together: CPR keeps the brain going, the shock tries to restart the pump.
AED (automated external defibrillator)
A portable device that checks the heart's rhythm itself through two sticky pads and, only if it finds a rhythm a shock can fix, delivers one. It speaks step-by-step instructions, and many show pictures too. It's designed for people with no training. Public AEDs are found in places like airports, metro stations, malls and sports centres, often in a wall box marked with a heart and a lightning bolt.
Send someone to fetch one while you start CPR. The dispatcher may know where the nearest one is.
Check yourself
Sara's friend brings an AED from the metro ticket hall while Sara is giving CPR. What's the first thing to do with it?
- Read the manual inside the case
- Switch it on (or open the lid) and follow the voice prompts
- Press the shock button to test it
- Wait for paramedics, since only they should use it
Show the answer
Switch it on (or open the lid) and follow the voice prompts
Yes. Turning it on is the whole first step: from then on it tells you what to do, one instruction at a time. Sara keeps pushing while her friend follows the prompts.
Using an AED
- Switch it on
Press the power button or open the lid. From here, do what it says.
- Bare and prepare the chest
Remove or cut away clothing. If the chest is wet, dry it. Peel off any medication patches.
- Stick the pads on
Follow the pictures on the pads: one below the right collarbone, the other on the left side of the chest, below the armpit. If there are two of you, one keeps doing CPR while the other attaches the pads.
- Hands off while it analyses
When it says "Analysing, don't touch the patient", nobody touches them: movement can confuse the reading.
- If a shock is advised: stand clear
Check that no one is touching them, say loudly "Stand clear", and press the flashing shock button. Fully automatic models deliver the shock by themselves after a warning.
- Straight back to CPR
After the shock, or after "no shock advised", restart compressions immediately. The AED re-analyses about every 2 minutes and will tell you when to stop again.
Check yourself
Where do the two AED pads go on an adult?
- Both side by side in the centre of the chest
- One below the right collarbone, one on the left side of the chest below the armpit
- One on each shoulder
- One on the chest and one on the stomach
Show the answer
One below the right collarbone, one on the left side of the chest below the armpit
Right. Below the right collarbone and low on the left side, below the armpit, so the current passes through the heart. The pictures on the pads show the same thing.
Check yourself
If you press the wrong button, an AED can shock someone who doesn't need it.
Show the answer
False
False. The AED decides, not you: it only allows a shock after it has detected a rhythm a shock can treat. Attaching one can't make things worse, so don't let fear of the machine slow you down.
Check yourself
The AED says "Shock delivered." What do you do next?
- Wait a minute to see whether the heart has restarted
- Check for a pulse
- Restart chest compressions immediately
- Remove the pads so you can do CPR properly
Show the answer
Restart chest compressions immediately
Yes. Straight back to CPR. Even a successful shock leaves a heart that is often too weak to pump well at first, and the AED will re-analyse in about 2 minutes.
Special cases, and after the shock
- Leave the pads on and the AED switched on until professionals take over, even if the person wakes up.
- A lump under the skin from a pacemaker or implant: put the pad a little away from it, not on top.
- Lots of chest hair: press the pads down firmly. Some kits include a razor for this.
- Water: move them out of puddles and dry the chest before sticking the pads on.
- Children: use child pads or a child mode if the AED has one. If not, adult pads are acceptable; follow the pad pictures, and place them front and back if they would touch.
Check yourself
- Kian is alone on a quiet street with a man who has collapsed and isn't breathing normally. The nearest AED is in a gym several minutes' walk away. Kian calls 115 on speaker and starts CPR without leaving.
- Kian is with Leila in a metro station when a man collapses and isn't breathing normally. There's an AED on the wall of the ticket hall. Kian starts CPR and sends Leila to bring the AED.
Why does Kian stay put in the first case but get the AED fetched in the second?
- AEDs in gyms don't work as well as ones in stations
- Leaving a person without CPR for minutes costs more than the AED gains, so the AED is fetched only when someone else can go
- CPR is only needed on quiet streets
- The man in the station was less ill
Show the answer
Leaving a person without CPR for minutes costs more than the AED gains, so the AED is fetched only when someone else can go
Exactly. When you're alone and the AED is far away, call first and keep doing CPR. When there's someone else, send them for it while you push.
Lesson recap
- CPR keeps blood moving; a shock can reset a chaotic rhythm. Every minute without both lowers the chance of survival.
- Switch the AED on and follow its voice. Bare and dry the chest, remove patches, pads below the right collarbone and on the left side below the armpit.
- Nobody touches the person while it analyses. Shock advised: "Stand clear", then press the button.
- After a shock or "no shock advised": straight back to CPR. Leave the pads and the AED on until professionals take over.
- It won't shock a heart that doesn't need it. Alone with a distant AED: call and do CPR; with others, send someone for it.