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Razor,
It's the build up of acids and potassium due to the cellular injury/death that comes from 2 sources. First, the tissue destruction from the trauma, second, from the hypoxic/ischemic tissues from lack of blood flow.. The release is like giving a bolus of "bad humors" that the heart doesn't like. Most of the bodies enzyme driven functions loose ~30-40% efficiency when the pH is < 7.28-7.30, and > 60-70% reduction when the pH is < 7.2...this is a problem with tourniquets. This is where the idea of an occasional release was born. Fact is we have kept some tourniquets on for 6-8 hrs, relizing the limb is non-salvagable and just keep it on, ice the extremity and amputate and the high potassium and/or acid "washout" never occurs. The answer to your question is different for injured (traumatic) vs non-injured (operated on) torniquet time. Any limb without adequate blood flow for >/= 6 hours can still survive but we have to do compartment fasciotomies because of the ischemia/reperfusion injury to the muscle. The nerve may be shot but the limb can survive. I'll put pics on tomorrow of this.
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'Revel in action, translate perceptions into instant judgements, and these into actions that are irrevocable, monumentous and dreadful - all this with lightning speed, in conditions of great stress and in an environment of high tension:what is expected of "us" is the impossible, yet we deliver just that.
(adapted from: Sherwin B. Nuland, MD, surgeon and author: The Wisdom of the Body, 1997 )
Education is the anti-ignorance we all need to better treat our patients. ss, 2008.
The blade is so sharp that the incision is perfect. They don't realize they've been cut until they're out of the fight: A Surgeon Warrior. I use a knife to defend life and to save it. ss (aka traumadoc)
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