Performance evaluation of operating room schedules in orthopedic surgery

In orthopedic surgery department, multiple surgeries are carried out in the same operating room (OR) every day. Each surgery may have a random duration, which results in room idle time and patient waiting time. One of the major factors affecting the idle and waiting times is the schedule of surgeries in the OR. To better sequence multiple surgeries to reduce idle and waiting time, an effective performance evaluation method is needed. Although discrete event simulation can be used to evaluate the performance of surgery schedules, the long simulation time makes scheduling optimization more computationally intensive. In this paper, an analytical model to evaluate the performance of OR schedules in orthopedic surgery department is introduced. First, closed formulas to evaluate the case of two surgeries are developed and used as a building block in subsequent studies. Then, an iteration procedure is presented by aggregating every two surgeries into one using the two-surgery formula, and continuing to approach the next one, until all surgeries are aggregated into one. Using such a model, the expected idle time and waiting time for a given surgery schedule can be calculated quickly and accurately. Such a work provides an efficient performance evaluation tool that can be used for optimization of OR schedules and investigation of the impacts of different schedules.