Anticipating urgent surgery in operating room departments

Operating Room (OR) departments need to create robust surgical schedules that anticipate urgent surgery, while minimizing urgent surgery waiting time and overtime, and maximizing utilization. We consider two levels of planning and control to anticipate urgent surgery. At the tactical level, we study the allocation of slack for urgent surgery to one or more operating rooms, and at operational off-line level, we experiment with the sequencing of elective surgeries in the operating rooms to which slack for urgent surgery is allocated. We try to sequence the elective surgeries such that their completion times, which are break-in-moments (BIMs) for urgent surgery, are spread as equally as possible over the day. We refer to this problem as BIM optimization problem, which is NP-hard in the strong sense. In this paper, we develop and test various heuristics for this sequencing problem. By means of a simulation study, we compare five methods of anticipating urgent surgery: (1) concentrating slack for urgent surgery in a dedicated operating room, (2) allocating slack for urgent surgery to a subset of the operating rooms without BIM optimization and (3) with BIM optimization, and (4) allocating slack for urgent surgery to all operating rooms without BIM optimization, and (5) with BIM optimization. For the test instances, the computational experiments show that urgent surgery can be anticipated best by allocating slack for urgent surgery to all available operating rooms, and thus allowing urgent surgeries to interfere with the schedule of elective surgeries. Further savings in urgent surgery waiting time can be achieved by BIM optimization, especially for the first urgent surgical cases that arrive during a day.