I taught a first-aid course to a group of Boy Scout leaders last weekend and did my usual spiel of "never, ever tie a tourniquet unless you are prepared to have everything below it amputated". One of the students, a retired EMR, said that only once in his entire career had he ever been forced to use a tourniquet - that was for someone who got his arm caught in a piece of machinery and basically shredded everything below the elbow. <img src="images/graemlins/crazy.gif" alt="" />

As he had been a paramedical professional when he did it, I wasn't in a position to second-guess him. That's the only time I've ever heard of a practising EMR resorting to a tourniquet, though.

I would probably consider it for a broken thigh-bone with internal bleeding from a severed femoral artery, although other instructors more experienced than me insist that even then, direct pressure would probably work better.