In cardiac arrest, pad placement matters.

But not because one position is clearly superior.

It matters because good placement helps the shock reach the heart.

That is the goal.

You need enough current to pass through the myocardium and stop VF or pulseless VT.

First principle: do not overcomplicate pad placement

What does the evidence actually show?

The data do not show a clear winner between pad positions.

For adult cardiac arrest, anterolateral (AL) and anteroposterior (AP) placement are both reasonable.

Other pad positions may also work.

But in practice, AL and AP are the main options most teams use.

One study showed no difference in shock success between AL and AP.

Another study found more ROSC with AP placement.

But it did not show better survival to discharge or better neurological outcome.

So the bottom line is simple:

We still do not have strong enough evidence to say one position is clearly superior.

What actually matters in real life

Place pads on the bare chest.

Use adult pads larger than 8 cm.

Press for full skin contact.

Do not let pads touch each other.

If you use anterolateral placement, the lateral pad must be truly mid-axillary.

Not too anterior.

That small mistake can change the shock vector.

And that can reduce effectiveness.

The physiology is simple

A shock works by depolarizing a critical mass of heart muscle.

Poor pad position increases transthoracic impedance.

Poor skin contact does the same.

So does bad pad location.

The result is simple:

Less current reaches the heart.

CPR still comes first

Do not pause and stare at the monitor.

Do not stop compressions early.

For adults in cardiac arrest, perform CPR until the defibrillator or AED is applied.

If the arrest is unmonitored, a brief period of CPR while the defibrillator is being prepared is reasonable.

If VF/pVT is witnessed or monitored, and the defibrillator is already there, shock immediately.

That is the practical rule.

A useful 2025 update

A bra does not always need to be removed.

If you can adjust it and place the pads directly on exposed skin, that is reasonable.

This is practical.

It may also reduce hesitation in public defibrillation.

What should the team remember?

Do not chase perfection.

Chase effective defibrillation.

That means:

• bare chest
• good pad contact
• correct position
• minimal pause in CPR
• fast shock delivery when appropriate

The bedside takeaway

In adult cardiac arrest, the winning strategy is not fancy.

It is disciplined basics.

Place the pads well.

Keep the lateral AL pad in the mid-axilla.

Continue CPR until the device is ready.

Shock early when VF/pVT is witnessed and the defibrillator is immediately available.

Then get right back on the chest.

Because in cardiac arrest, fast, clean, practical defibrillation saves more lives than beautiful theory.