how many children have cardiac arrests each year?
Very few, probably none without an underlying condition and they usually go into respiratory arrest. Those with an underlying condition are likely to have had a defib fitted inside them.
I've never had to defib a child and I only remember one being defibed when I worked in cath labs. I remeber another child going into respiratory arrest and unfortunately passed away. In a respiratory arrest a defib is useless. This child had a heart condition, hence being in a cath lab, but even with a paediatric cardiologist and a room full of other medically qualified people the outcome was death.
This was discussed at length a while ago when a PTA wanted to buy a defib. I am aware some special schools have them.
First aid isn't something you just learn, it has a 'sell by' date, usually 3 years, so you have to retrain everyone every three years.
Look up the old thread, it was very interesting. I think (don't quote me) that there ended up being an AED available for public use at or near the school.