Scheduling problem and optimization in operating rooms

Operating rooms are one of the most important departments of hospitals. Operating rooms, in addition to being the main source of income of hospitals, are also their most costly units. Along with the cost elements, the ability to provide timely and rapid intervention to patients who need urgent surgery increases this importance to a vital level. The most basic and critical problem for hospital and operating room supervisor is the planning of surgeries and the scheduling of operating rooms. The shortage of materials, medical equipment and devices used for surgery, as well as the fact that there are a limited number of surgeons, nurses and other operating room employees serving should be taken into account for the scheduling of operating rooms. At the same time, operating rooms with a certain working capacity should provide optimal service during working hours. In addition, being able to provide services to patients as soon as possible, without delay in operation processes and without creating queues in operating room units ensures both patient satisfaction and efficient operation of the staff. In this thesis, it is aimed to create the next day operation schedules for elective patients, and to ensure that there is no overlap as much as possible in the completion of the surgery and the setup processes between the cases. It is aimed to ensure optimal utilization of operating theatres and to realize operation flows quickly by minimizing simultaneous operation ends. In addition, the pre-op waiting times of the patients will be reduced by determining the operation order of the operations planned for the next day. A mixed integer programming model has been proposed for solving small and medium-sized problems in order to achieve the determined objectives. In the solution of medium and large sized problems, a two-stage application consisting of the shifting bottleneck heuristic and the sequence switching approach has been made. As a result of the applications, optimal schedules were obtained with mixed integer programming in pediatric surgery and general surgery services. In urology, obstetrics and neurosurgery services, operation schedules that were completed in a shorter time and had fewer overlaps than existing surgery plans were obtained with the proposed two-step method.