No need to worry about semantic arguments. Others all around us are debasing our "professional" language. Words matter.
Although I too have been in situations where I may have literally saved a kid's life by dispensing a bit of kindness, I am weary of the phrases "changing lives" and "transforming lives."
Both statements connote a treatment model where you do something to someone else and produce a desired result. I do not believe this is the nature of education. Also, "saving" lives sounds like an emergency action that remediates a situation instantly. Education is not CPR.
I really appreciate this blog entry. Our roles as teachers require, at our best, a deep appreciation for possibility, for us as well as our students. They require hope, caring, love, hard work... but I like how you point out that if we are "saving lives" there is no end to that task. It burdens us awfully much. That's not to say that for some individuals we may have that impact one day, but when we accept that as a mission, it undervalues our lives outside of school, and maybe even our relationships with the students whose lives don't need saving, but who simply need a good education in a caring, safe environment. Please read my blog entry at http://www.storiesfromschoolaz.org/2012/08/who-are-we-protecting.html, which is somewhat related. Your post gave me a little tidbit of insight to layer onto the story told there.
Perhaps a more apt term would be "altering trajectories". Think physics - two objects in motion strike each other, the path of each object is affected. One may be more profoundly affected than the other, but neither is a passive participant and both are capable of experiencing positive change.