Theory of constraints applied to scheduled and unscheduled patient flows: does it improve process performance?

Theory of constraints (TOC) is particularly effective for improving processes and maximising efficiency in systems that are resource-constrained. One of the most common applications of TOC in the service sector is healthcare, particularly patient flows which can be considered analogous to 'production lines'. However, one of the main TOC techniques, 'drum-buffer-rope' (DBR), is still poorly implemented in healthcare services. The study provides a new approach where traditional DBR or 'DBR for goods' (DBRG) is customised to improve admissions scheduling in a scheduled patient flow. However, when arrivals of patients are necessarily unscheduled the DBRG is not applicable. For these circumstances, a new procedure is also provided. This procedure uses a variant of DBR ('DBR for services', DBRS) that is adapted here for an unscheduled patient flow. The purpose of both the adapted DBRG and DBRS is to provide rules to control the throughput of patients. As ever in flow systems, there is a trade-off between minimising patient flow times and maximising the patient throughput volumes. The decision on where to be on this trade-off is the decision of service managers, perhaps subject to service-level agreements. To demonstrate this trade-off under the TOC DBR rules, several simulation experiments are conducted.