Acute medical unit design – The impact of rearranged patient flows

Acute Medical Units (AMUs) are instigated in many hospitals across the world. An AMU admits acute patients, mainly arriving via the emergency department, for further assessment, care and treatment for a maximum designated period. Thereafter, patients who require additional care are transferred to regular wards that also admit elective patients. The literature reports several benefits (including reductions in in-patient mortality and in the length of stay), with these conclusions mostly based on empirical findings from studies focused on acute patient performance only. This paper sheds light on the potential hospital-wide impact of implementing a range of AMU designs in terms of length of the designated period, size and transfer policy. A simulation study is performed based on data from a large Dutch hospital. When establishing an AMU, hospitals usually transfer resources from existing wards to the new AMU. This seems logical since these wards receive fewer acute admissions once an AMU is in place. However, our research shows that this transfer of resources decreases the overall performance (of the AMU and the wards) for all the AMU designs investigated. We report on the scale of these negative effects and the required reduction in the length of acute patients' stays required to compensate for these effects.