Optimum Management of Multiple Hospital Operating Room is a complex problem. Today Methods are limited by the static nature of the data used to take decision. Scheduling is done several days in advance, and uncertainties dominate the process of time allocation for any surgery procedure. We propose a non invasive method to track systematicaly OR functions in real time that will allow rigorous a posteriori analysis of OR management limitation and eventualy improved decision to update the schedule thanks to early detection of problem.