Simulation for MESA is health care education with non-real patients for health care providers.
Medical emergencies are low-frequency, high-acuity events. They are situations in which it is really important for providers to get it right, but have very little time to do it right. Simulation allows providers to manage those events, but their patient is a manikin, a plastic stand-in for an actual patient. The manikin and the scenario are real enough that the providers learn from the simulation, even though no actual patient was involved.
When those providers are caring for an actual patient experiencing a similar event, they provide better care because they have provided that care before, in a simulation.