ED cognition: any decision by anyone at any time.

The ability of an emergency department (ED) to meet the needs of its patients depends largely on the resources available. Relevant resources include nurses, physicians, paramedics, specialty backup, care spaces, inpatient bed base, space, equipment, and supplies. All are important to ED function; however, one resource that is seldom considered is cognition, the cognitive capacity of ED staff. Although invisible, it is arguably our most critical resource. Everything that is done for patients—their diagnosis, management, treatment, and disposition—requires decision making that depends on both individual and collective cognition. In the past, we have taken cognition for granted, assuming that if we bring physicians, nurses, paramedics, and patients together, the necessary decision making will occur. However, things may not be quite so simple. In recent years, we have realized that ED cognition is finite, that overtaxing it may compromise patient care, and that we must protect it and use it judiciously. The purpose of this article is to explore how cognition is used (and abused) and the impact this may have on patient safety.