Dear Mehdi,
Take care of failures and everything.You alreday have been given good suggestion in this manner specially by Kai and the latest reply by Erik.I like Erik's suggestions about thermostats.

I don't know what Amenic means , but if this is going to be a sort of life saving application , I suppose that you have been read these part of the datasheets :

Personaly i don't even think about desiging something that could relate to life saving applications.Being in such situations, i just see the time that unfortunately my system had a failure.Due to the failure something have been happened to the patient. Relatives of the patient would never ever accept any excuse and they neither accept any 'technical' explanation of the problem(e.g. Reset generator failed...).You can imagine being in such a situation for your patient,althought you're an engineer would you accept such an excuse ?
I don't want to make you dissapointed or anything , i just wanted to take your attention to this side of the project.

Good Luck
Farshid