Well, yes and no. 'Clamp time' must be monitored quite closely, and in the event that a major vesel is not totally severed the tournquiet must be loosened periodically to restore some blood flow to oxigenate the tissues. Different tissues are tolerant to different degrees of ischemia, and there is a degree of temperature dependency. If you can get tissue temp down with ice, it can tolerate ischemia longer.

I spent a very long, very cold trip in the back of a horse trailer once loosening the torniquet on a horse's leg for five minutes out of every 30. Three hour trip in. He did OK.