Crisis occurrence in the healthcare context is, for different reasons, a phenomenon that happens
abundantly. The priority of the healthcare system during a crisis is to provide quality care and superior
services to the injured people. However, given the usually extreme severity of the crisis that results
in a significant number of injured people, proper and timely responsiveness of healthcare systems is
a challenging issue This study proposes a novel framework using a hybrid simulation–optimization
approach to measure the healthcare responsiveness in crisis to address this real-world problem. This
paper closely connects operations research techniques to critical systems thinking notions to evaluate
the behavior of a system in the face of crisis. Since all arriving casualties to the hospital are first
taken to the emergency department (ED), the ED in a case study is used to illustrate the performance
of the presented approach. We designed seven crisis scenarios and one scenario of the ED system
in a normal situation and modeled them using discrete-event simulation (DES). Patients’ interarrival
times act as the driver of workload experienced in ED during crisis scenarios of varying severity. For
crisis simulation scenarios that are unable to cope with the severity of the crisis, we developed an
optimization model in an optimization tool to determine the optimal configuration of resources. The
optimal configuration can improve healthcare resilience. The results show that an interarrival time of
13.8 min is the maximum threshold, below which feasible solutions could not be found, and the ED
system is likely to collapse.