Treatment process differences with and without an ambulance offload zone

In this paper we compare the emergency department (ED) treatment processes which occur when an Ambulance Offload Zone (OZ) is functioning and when it is not. An OZ is a monitored waiting space for ambulance patients which is designed to allow ambulance crews to return to service more quickly. The implementation of OZ style concepts has been trialled around the world with mixed results. In this paper we use concurrent comparison data and show how treatment processes and the behaviour of ED actors change when the OZ is functioning. We discuss how these changes in behaviour impact the effectiveness of the OZ.