Uncertainty Of Surgery Scheduling

Reasonable arrangement of surgeries is essential to ensure regular work of the hospital,especially the operating room (OR). Surgery scheduling involves the arrangement and restriction ofORs, doctors, nurses, anesthetists, PHU (Pre-operative holding unit) and PACU (Post anesthesiacare unit). Surgery scheduling aims to maximize ORs’ utilization and minimize ORs’ cost. Thosepublished researches were concentrated on surgery scheduling under certain circumstances. Alloperating resource and operation information can be predicted in advance, and the surgeryscheduling is to allocate operating time and resources to the scheduled surgeries from all divisionsin the future time. However, there exist many dynamic uncertainty factors which limit the practicaloptimization results. Uncertainties of surgery scheduling are mainly embodied in three aspects:resource uncertainties, surgery process uncertainties and surgery demand uncertainties. Resourceuncertainties describe the unavailability in medical resources (such as nurses, anesthetists, doctors),medical equipment and facilities; Surgery process uncertainties mainly refer to the changes ofsurgery duration and surgery flow process due to special reasons; Demand uncertainties mainlyrefer to uncertainties caused by emergency patients arrival or surgery cancel. This paper mainlyconsiders surgery scheduling problem under those three kinds of uncertainties.Resource uncertainties refer to absence or temporary unavailability of one or more resources;our research uses the absence of nurses as example, and considers the characteristics of surgeryscheduling and rescheduling problem under nurses’ absence. A multi-objective optimization modelwith four objectives (the earliest finish time, the balanced resource utilization, the least resourcesovertime and the minimum deviation of surgeries’ start time) is proposed and a two-layer antcolony algorithm is developed in this paper.Surgery process uncertainties mainly mean that the duration of different surgery flow processis varied in a certain range. An absolute robust optimization theory is adopted, considering all kindsof scenarios situation of the specific surgery duration, to minimize operating room cost. Amathematical model of proposed robust surgery scheduling considering duration uncertainties isproposed and a three-layer of ant colony algorithm is developed to solve such surgery schedulingrobust optimization problem.Demand uncertainties emphasize on the changing number of scheduled surgeries due to thepatient absence and emergency surgery. In this study, the emergency surgery demand is taken intoaccount. We establishes the online scheduling model with a goal of minimizing the OR cost andbalancing resource utilization. The online scheduling heuristic rules and the ant colony algorithm iscombined together to solve the surgery scheduling problem with demand uncertainties. Finally wedesign the simulation procedure to simulate and verify the online scheduling approach.According to the above three uncertainties in surgery scheduling problem, we built severalcases by actual data from hospital to verify these proposed algorithms. Results showed that theproposed approaches can not only optimize the performance of the operation rooms in severalindicators, but also can increase the practical application in hospital.