Anybody used a bark collar on their dog? Do they work?

I have a 12 year old retriever that barks all the time just outside my back door. I love him but it is extremely disruptive. No matter how much I scold him, he will not stop. He is getting old (12 yrs) and senile and can't hear very well. He is more stubborn now than ever. All he wants to do is be next to the kids, ages 1 & 3, from morning to night. As long as he is outside and the kids are inside, he is going to bark, and it seems impossible to stop. Is it cruel to use a bark collar on a 12 year old retriever that can't hear or see well? Do they work? And what is a good brand if so? Thank you for your help.