Integrated operating room scheduling and surgical instrument inventory management: Models, algorithms, and cost-saving insights

Surgical operations account for a significant proportion of hospital costs. One factor often overlooked in Operating room (OR) scheduling is the management of reusable surgical instruments. Instruments are either owned by the hospital or rented from vendors. Rental instruments incur costs up to 12%–25% of the purchase price. We propose a deterministic mixed-integer programming model that integrates inventory management and OR scheduling to minimize total costs. This model determines the number of open ORs, the surgery schedule, instrument sourcing decisions (owned vs. rented), and instrument assignments for each surgery. We propose and evaluate easy-to-implement solution methods including a construction heuristic and a Lagrangean decomposition-based heuristic. As part of our heuristic solution approach, we also propose two upper-bounding procedures to solve this challenging problem. We compare our integrated approach against a sequential scheduling approach where schedules are created prior to determining the instrument assignment. An extensive sensitivity analysis is also performed to evaluate the effects of various parameters on the total cost of the system and the running time of the algorithms. Numerical experiments show that the integrated approach reduces total system costs by up to 6.65%, driven by an average 72% reduction in instrument rentals. Our decomposition heuristic finds solutions with an average optimality gap below 1% in significantly less time than solving the integrated model with commercial solvers.