On another topic, in our institution our staff is vehemently against ED thoracotomy except in the most extreme circumstances, i.e. penetrating trauma to chest loss of pulse in ED or just before arrival, and I agree. The needle stick, exposure rate during these procedures is extremely high and the pt if they come back ~.5-15% depending on study is usually neurologically devastated. Plus at our place it takes just a couple minutes to get to the trauma OR. It's usually worth it as far as better lighting, suction, instruments, anesthesia resuscitation.
You could argue that not all institutions have a dedicated OR or a surgeon around, but if you don't, what's the point? If you manage to open the chest and cross clamp the aorta, not easy feats in the Er, and the patient comes back he needs an operation right then and there. If he has a pulmonary hilar injury or great vessel he's almost certainly done. The only survivable injury in this scenario would like be a single stab wound to the ventricle causing tamponade, that you could decompress than hold pressure, but if there's no surgeon readily available, the pt's probably done.