Bias
During the scenarios T-CPR was instructed by an emergency physician, who had been trained in T-CPR by a dispatcher before the first session of the study. To avoid bias the simulated dispatcher was not aware of the study hypothesis and was located in a different room. He did not see the rescuers and communication was possible only via telephone. Also, to avoid bias, the T-CPR protocol was instructed live, following real-life standards (Fig. 