Abstract:
Due to the sheer number of patients and the high costs of running operating rooms (ORs), hospitals create incredibly tight surgery schedules to maximise their OR utilisation and patient throughput. While a utilisation rate of close to 100% creates a lean and efficient system, the lack of buffers leads to schedule fragility and a system that is incapable of handling unexpected disruptions. One major disruptive event experienced by Auckland City Hospital is the arrival of acute liver transplantation surgeries, which require an OR and a surgical team immediately. To create an OR vacancy, an existing elective surgery list is cancelled and then rescheduled for the near future. Since the following weeks are fully booked, the postponed surgery will need to displace another elective surgery list. In turn, this newly cancelled surgery list will need to undergo a similar rescheduling process, and so on. Such a cascade of cancellations and re-scheduling is a well-known domino effect. To solve this, we sought out some hidden sources of flexibility from within existing resources to provide a buffer without sacrificing utilisation. The first of two strategies we explored was to exploit the multiplicity of the scheduling solution. A penalty cost is used in the optimisation to minimize the changes to the schedule following disruptive events. Secondly, we identified surgeons who are less averse to schedule changes and are therefore able to act as "shock absorbers" to the system by absorbing the schedule changes so that other surgeons schedules would remain unaffected by disruptive events. To test the effectiveness of these strategies, a specialised simulation tool has been developed using widely available software - VBA and OpenSolver. Therefore, this tool can be easily adapted by any hospital to test different strategies under their specific circumstances.
