Abstract for: Hospital Emergency Departments: Learning from a Simple Stock and Flow Model

Boarding in emergency departments (EDs) is worsening over time. Boarding occurs when patients admitted to the hospital must wait in the ED because no hospital beds are available, due to “bed block.” Boarding is getting worse over time despite significant efforts to address the problem. Misappreciation of fundamental stock and flow dynamics can powerfully hamper efforts to improving patient flow in EDs. We conducted a case study of an inner-city, tertiary care academic medical center. We built a simple system dynamics model of patient flow through the ED into the hospital. We parameterize the model using data from the hospital’s electronic medical records, including several time series for patient arrivals and outflow. We use the model for experiments to reveal important stock and flow insights, with a focus on ED boarding. A quite simple stock and flow structure forms the core of a model that faithfully recreates the notable dynamics in the ED. Boarding ebbs and flows but persists. Patients leaving of their own accord when the system is busy provide a stabilizing influence to the system, although perhaps not best for the patients. Experiments reveal other insights into possible improvements. Basic concepts of stock and flows and their dynamics are foundational for understanding patient flow in the ED. Even a simple model can help to improve understanding amongst those, such as hospital administrators and others with no first-hand ED experience, who lack an intuitive grasp of patient flow dynamics.