I've just been reading about that poor lad Sam Linton who died following an asthma attack in school. That was 2 years ago. A pointless, avoidable death.
One question I asked myself was whether he had a mobile phone and could have called/texted his parents for help.
Do any of your kids have a phone? Have you set up an emergency speed dial/text for them?
There is some debate on the safety of mobile phones and until this is resolved, I wouldn't be too keen to give one to the tot. Apart from safety, there are all the issues of cost and usability.
However, if she had some condition that could lead to death, I may change my mind. Mind you by the time she's in full time school, we will all be connected on the net all the time and I'll be able to track her movements using a gps, twitter-like and facebook-like. Won't that be fun when she's a teenager ;)
Other options could be an emergency button like the elderly used.
While this may be overly protective, I'd rather be that then a parent attending her child's funeral.
p.s. On your phone have you set up an ICE number? (in case of emergency...call "number").