Scheduling elective and emergency surgeries at shared operating rooms with emergency uncertainty and waiting time limit

While timely emergency OR access is strictly required in many specialties, this paper provides a highly responsive preventive-reactive scheduling procedure to address emergency arrivals with waiting time limits before and on surgery day with no assumption on the emergency arrival patterns. To improve responsiveness in situations where existing break-in-moments-based scheduling does not perform well, a MIP model is first developed to generate initial schedules by making ex-ante preparations for future possible arrivals with the objective of minimizing the sacrifice in the throughput of elective surgeries. For applicability, two additional heuristics, which are derived from the MIP model but include other scheduling ideas, are also designed for preventive scheduling. Furthermore, as a supplement to preventive scheduling, a corresponding reactive scheduling method is designed to be applied on surgery day. Facing different emergency realizations, it provides effective and satisfactory adjustments on surgery day by scheduling arrived emergencies timely, properly updating the remaining schedule to prepare for subsequent arrivals with consideration of minimizing the adjusting impact on scheduled elective cases. The effectiveness and performances of the proposed procedures and heuristics are evaluated in comparison with traditional preventive and reactive scheduling strategies through simulations and statistical tests. The numerical results show that the methods developed in this study can significantly improve the responsiveness with an acceptable sacrifice in OR utilization and can provide satisfactory schedules for both types of patients. Some scheduling guidelines based on simulation results and the applicability of the proposed scheduless are also discussed at the end of this study.