Interconnected des models of emergency, outpatient, and inpatient departments of a hospital

National Health Service (NHS) performance targets in England have put pressure on hospital management to reduce waiting times. The stochastic nature of emergency patient arrivals creates problems for capacity planning for elective patients. We present a whole hospital model which can be used at policy level to investigate cause and effect relations, such as effects of increased emergency arrival volumes on elective waiting times. A typical general hospital can be abstracted in three main units; Accident and Emergency (A&E) department, outpatient clinics, and inpatient units. In real life these units are coupled and share hospital resources. We developed three discrete event simulation (DES) models for each unit to form a whole hospital DES model. We present our models conceptually and our main discussion is on the level of detail in these three models.