First off, I'm no MD. I was a lowly RRT for 28 year, and I worked ER's, Trauma Units, and various ICU's almost exclusively during that time, so I've been through more codes than most people will ever see. My experience with trauma induced arrests would overwhelmingly support surgeonstone's assertion.
However, what concerns me is the fact that 99 time out of 100, the first person on the scene is not going to have the medical skill or experience to distinguish a trauma induced arrest from an SCA that resulted in trauma when the victim went down. I fully understand that in many cases, it will be obvious. Missing limbs, compound fractures, obvious skull deformations, voluminous blood, these sorts of things combined with asystole pretty much tell the whole story. But what about the guy who has an SCA event while riding, falls and in the process of going down, lacerates his scalp. Let's further assume, for the sake of argument, that his guy is on Plavix because he has known CAD. So here you've got someone down without a pulse and a fair amount of blood on the pavement. If I'm that guy, I sure as hell hope the first person to come to my aid has
NOT read this thread.
And just so you fully understand my misgivings about a blanket approach that says "if there's trauma and no pulse, move on", on February 12th of this year, I was that guy who had the SCA. I was successfully resuscitated for 3 minutes before EMS showed up. I was down for another 2 minute before they hit me with the AED, and yeah, after the first 120 joule jolt, I did wake up just "like in the movies".
BTW, I'm back on the bike, and damned near back to the form I was in before the event.
In any case, I think the real point is having the training and equipment on hand to render intelligent basic first aid (and I do mean basic) is a good thing. I'd hate to see the value of that idea get lost in a discussion of "corner cases" vs coroner's cases.