Maybe this is where my EM background comes in handy.
If a patient presents with new onset rest pain, pain on movement, paresis/paralysis, and pain on passive flexion/extension on exam, I'm done, I've made the diagnosis, +/- history (there are folk with CS who just aren't very clear about what's been going on in their lives lately so this component has to be optional), +/- edema, +/- erythema, I call a surgeon, I get a Stryker (R), in that order, and make measurements, usually when the surgeon arrives to do the pokes once, takes just a couple of minutes. I might now muck around with other w/u, investigations, history, and pre-op orders.
I don't believe I have missed or misdiagnosed any compartment syndromes I've seen here in Detroit.
Fasciotomies work, but only if you get it done sonner rather than later, with few complications, , and if done soon enough, at least limitation of progression, and if done even earlier in the course, with restoration of function.
So, the goal is to rule out the need for a fasciotomy, NOT try to avoid a fasciotomy.
As suppose it may become a more complicated diagnostic process in the picture of spinal cord or other nerve injury with coincident anesthesia. There I would think it's history of mechanism, +/- exam, intracompartmental pressure measurement on clinical suspiscion.
If the goal is to prevent ischemic contracture then as with acute myocardial infarction, time is muscle.
http://emedicine.medscape.com/article/828456-overview