Objectives To investigate the association between the time taken to make a decision to go to surgery and gender, ethnicity, years in profession, experience of trauma team training, experience of structured trauma courses and trauma in the trauma team, as well as use of closed-loop communication and leadership styles during trauma team training.

Design In situ trauma team training. The patient simulator was preprogrammed to represent a severely injured patient (injury severity score: 25) suffering from hypovolemia due to external trauma.

Setting An emergency room in an urban Scandinavian level one trauma centre.

Participants A total of 96 participants were divided into 16 trauma teams. Each team consisted of six team members: one surgeon/emergency physician (designated team leader), one anaesthesiologist, one registered nurse anaesthetist, one registered nurse from the emergency department, one enrolled nurse from the emergency department and one enrolled nurse from the operating theatre.

Primary outcome HRs with CIs (95% CI) for the time taken to make a decision to go to surgery was computed from a Cox proportional hazards model.

Results Three variables remained significant in the final model. Closed-loop communication initiated by the team leader increased the chance of a decision to go to surgery (HR: 3.88; CI 1.02 to 14.69). Only 8 of the 16 teams made the decision to go to surgery within the timeframe of the trauma team training. Conversely, call-outs and closed-loop communication initiated by the team members significantly decreased the chance of a decision to go to surgery, (HR: 0.82; CI 0.71 to 0.96, and HR: 0.23; CI 0.08 to 0.71, respectively).

Conclusions Closed-loop communication initiated by the leader appears to be beneficial for teamwork. In contrast, a high number of call-outs and closed-loop communication initiated by team members might lead to a communication overload.