When I am writing I never label it as poetry. I just write my feelings of life and of what is in my heart so deep , my cries , my fears and life as it is or was . I have done this all my life .When I am done I read it and decide what to do with it.
So being derailed when writing poetry. I would call it more like getting lost in your world of writing/words that it becomes .... you .... on paper .
That is why there are so many ways and definitions of poetry that it all becomes our own style of writing that makes it unique.
And yes I do lose my thoughts at times when trying to find a word.Sometimes I just leave a space or stars in it place and keep writing and come back to it so I don't loss the thoughts that race so fast in my mind . I decided to get a tape recorder to do this for me. I try to carry it where ever I go. Like on hikes and driving places where a pen and paper are not easily used , and my IPOD is used always more so than paper . Then, they are saved and emailed to myself. I hope this a ok answer that helps ...