Study design
Prior to the BLS training, students were informed about the study and were assured that their participation was voluntary and would not affect their course grade. To be eligible for study participation, students had to provide written informed consent. Subsequently, students received a short pre-questionnaire in which they were asked to report their previous medical education and prior BLS training experience. Participants were then randomly assigned to either a control group or an intervention group. Both study groups received a BLS training according to Peyton’s 4 step teaching approach, which is commonly used to teach procedural skills in medical education [The BLS training lasted 90 minutes in total including 30 minutes for Steps 1–3 and 60 minutes for Step 4. In the last step, 5 minutes of individual training time was available per participants. First, participants were asked to provide an initial assessment followed by approximately 45 seconds of chest compressions and ventilations with simultaneous feedback. In a second run, participants applied the initial assessment followed by 120 seconds of chest compressions and ventilations with final feedback. Based on this process, participants were given the chance to implement feedback from the first round. With 30 chest compressions according to the guidelines, one sequence of compressions would last from 15 (for 120 compressions/min) to 18 seconds (for 100 compressions/min). Including ventilations, we conservatively estimate that a compression-ventilation sequence lasts no longer than 30 seconds. Therefore, participants were able to complete at least 5 complete compression-ventilation sequences in the 165 seconds of practical training time. Moreover, every participant had the chance to actively watch the performance of the group members and listen to the feedback provided to them as well. The study groups only differed in the training method provided after the final step of the training: