The Problem
The Operational Services Department (OSD) at the UCLA Ronald Reagan
Medical Centre in California, USA, serves around 27,000 patients
annually by conducting around 2,700 types of elective and emergency
surgery across 12 specialities.
This department assigns to each surgery an operating room, an
anaesthesiologist, a nursing team and the requisite surgical materials.
The department also determines the sequence of surgeries and the
scheduled times. The department aims to minimise the resource usage and
overtime costs, requiring a significant amount of time devoted to making
these resource management decisions. Complexity arises because of four
primary reasons:
-
Operating rooms are expensive and in short supply.
- Surgical procedures are often very specialised.
- The duration of surgical procedures are very difficult to predict.
- The scale of large hospitals makes simultaneous scheduling of multiple resources a computationally challenging task.
Some specialities, such as plastics, ENT, urology, can use any of the
operating rooms, but for others, such as vascular, neuro, and liver,
only three or fewer operating rooms are available. Rooms have fixed
costs for staffing, equipment and cleaning, and overtime costs which are
incurred for nurses and technicians if the rooms are required to be
open beyond 3pm. There are three shifts or equal duration, with regular
working hours of eight hours. Staff who are required to be on call are
informed on the previous day. Consequently, the planning horizon is a
single day, and overtime costs are about 33% of revenues.