The aim of this study was to investigate critical incidents in a large medical exercise (mass casualty incident) including the Swedish Armed Forces (SwAF) and a regional hospital using activity theory. A total of 96 individuals played injured patients with a variety of injuries from simple cuts and bruises to severe head injuries. Patients were evacuated by different means of transportation i.e. minivan, ambulance, military as well as civilian ambulance helicopter.We participated in the final planning of the exercise in order to obtain access for the research team. Data was collected through observations, shadowing technique and 20 semi structured interviews. Professionals from the regional hospital and SwAF as well as evaluating personnel were interviewed. The interviewees were asked to describe significant events experienced during the exercise.

Two researchers observed the triage and registration process in the ambulance intake and the emergency room of the hospital. One researcher observed the command and control (C2) function within the mass casualty management (MCM).Two students from the Swedish Defense University and three from University West collected data by playing injured patients according to the determined injure play card provided by SwAF. The students were instructed to observe what they themselves would classify as critical incidents based on their own subject i.e. education, economics and command and control studies. Five questions guided the observations: What happened? Who were involved? What consequences did the incident have? How were these consequences handled by the organization? Did the incident affect other areas?Data was analyzed, thematized and coded using the third generation of activity theory and its areas: tools, rules, community, division of labor, subject and object as a guide for identifying contradictions within the regional hospital and the emergency medical plan developed for handling large casualty events.Preliminary results indicated that participating personnel were not faced with conditions mimicking real life but learned to deal with a corrected version of reality i.e. preparations before the start of the exercise created shortcuts affecting the veracity of the exercise. This was manifested through contradictions within and between the activity systems and the conflicting motives carried by the objects.The results might impact the future designs of large exercises, influencing the conditions that the participants will face in exercises and thereby increasing preparedness for authentic situations.