Track: Operations Management and Operations Research

Abstract

Sequencing and scheduling the surgeries in operating rooms (ORs) can be a very important problem since (i) the duration of each surgery can be uncertain, (ii) surgeries are a great source of revenue and a huge source of cost for the hospitals because doctors, OR staff, and surgery equipment are very expensive resources, and (iii) the satisfaction of patients and minimizing their waiting time is also a very important criterion. Solving this problem can reduce the costs and increase the satisfaction of patients significantly, but at the same time it is very hard to drive the solution mathematically. Even the sequencing sub-problem can be challenging if the number of surgeries are large. There is no known tractable optimal solution to this problem and in practice, mostly a heuristic policy which orders surgeries based on increasing duration variances, i.e. the surgery with the smaller variance is scheduled earlier, is applied. We propose a simple heuristic policy for the sequencing of the surgeries based on the Newsvendor cost, and analyze it using a hospital data set as a case study. We show that this heuristic policy outperforms the ordering based on variance since it takes the asymmetry of waiting and idle costs into account. For the cases where the difference between the idle and waiting cost is large, which is the case in surgery sequencing, this approach achieves a better improvement in the total expected cost.