Abstract
Operating room scheduling is often done in steps. First, an operating room’s time blocks are assigned to surgical specialty groups and each specialty receives a number of blocks. Elective patients are then assigned to these time blocks. Assigned patient cases are sequenced, and idle time is often reserved at the end of the time block in order to buffer against possible overtime. This research focuses on the next step of determining the amount of time reserved for each of the pre-sequenced surgeries so that surgical teams know their exact start times. In this way, the buffer time is redistributed to each of the surgeries in order to minimise total overtime and idling costs. The problem is modelled as a special periodic review inventory model and a simulation-based response surface method is used to optimise surgery start times for a single operating room with stochastic operation durations represented by an infinite set of stochastic scenarios. This proposed method does not require extensive computational effort and is easy for practitioners to implement.