Clinical simulation (CS) has gained ground as a fundamental pedagogical and assessment methodology in different health disciplines, including prehospital critical care [1]. Growing adoption is a response to the need to provide students and professionals with a safe and controlled environment to acquire and improve clinical skills, integrate theoretical knowledge, practice technical and nontechnical competencies, and develop critical and reflective thinking [2]. By recreating clinical scenarios as authentically as possible, CS affords the opportunity to experience complex and critical “real-life” situations without needlessly exposing patients or students to undue risk [3].

CS participation, particularly when formative or end-of-course assessments are involved, and CSs that replicate high-demand and potentially life-threatening events could trigger negative feelings related to fear, uncertainty and stress associated with a lack of preparation and an anxiety response in participants [1]. As a result, students experience emotions such as frustration, anger, feelings of being disadvantaged and even depression, which negatively affect learning, development and academic performance [4].

Early clinical encounters mark a crucial transitional step in the training of future healthcare providers and generate strong feelings and emotions [5]. The students must now integrate theory with practice, face the complexity of disease and assume responsibility for patient healthcare. Clinical simulation offers a valuable opportunity to experience this anxiety in a protected context prior to exposure to real situations, allowing the development of coping strategies and increasing self-confidence [6]. However, the simulation experience per se may generate negative feelings related to group interaction, social dynamics, perceived evaluation and self-image [7].

Simulated prehospital critical care scenarios may escalate the anxiety response of undergraduates [8]. The decision-making process under pressure of real-time monitoring, the fear of making unforced errors with potentially fatal consequences (even in a simulated and supervised scenario) and the inherent uncertainty of dealing with challenging clinical scenarios may contribute to increased anxiety levels [9]. Various studies suggest that excessive anxiety levels (“distress”) can exceed the psychological strength of the student, interfering with working memory, the capacity to recover information and the application of knowledge, with a two-way impact on the learning process and clinical performance [10,11].

To design pedagogical strategies aimed at optimizing learning and minimizing the negative impact of emotional response, a fundamental step is to understand the magnitude and manifestations of anxiety in students confronted with simulated medical emergencies. Accordingly, the primary aim of this study was to determine the delta anxiety index (before and after the simulation) in medical students performing prehospital critical care high-fidelity clinical simulations (sepsis, myocardial infarction, polytrauma and anaphylactic shock) case-by-case. The secondary outcome was to identify clinical scenarios resulting in extreme anxiety levels (> 25 % post-simulation vs. pre-simulation delta anxiety).