It's hard to write a poem about the mind I know but I like the fact that you have given animation to it....I really would have liked to hear more....

Heavily breathing, their noses are producing steam
^^^

This just seemed a little tame to me....I want to hear teeth gnashing....the chains being strained to breaking point...etc...do you know what I'm saying? I loved that you had a formed character in this piece....I'd work on that some more if I were you....this is a poem that could be without limitation if you let your imagination loose I feel....