Effect of coupling between emergency department and inpatient unit on the overcrowding in emergency departmetn

Emergency department (ED) overcrowding has become a common problem in the United States as well as other developed nations, threatening the safety of patients who rely on timely emergency treatment. Volume of high-acuity patients and the volume of patients that are later admitted to the inpatient unit (IU) are factors reported as major causes of ED overcrowding. These two factors can be interpreted to represent the strength of the interaction between an ED and its associated IU. In addition to confirming the observations reported in previous studies, we were able to use discrete event simulation to characterize the relationship between IU utilization and ED crowding: it was found that the sensitivity of ED overcrowding with respect to IU utilization depends on the degree of coupling between the two units. Our findings have potential implications in guiding a hospital's effort to optimize their system.