Over the past two decades, bedside point-of-care ultrasound (PoCUS) has evolved into an important adjunct to clinical examination in acute care specialties such as emergency medicine, intensive care medicine, and internal medicine. The versatility of PoCUS makes it an ideal imaging modality in the evaluation of the critically ill patient. Multiple etiologies can be considered and investigated, all with the same machine, in a matter of minutes. Incorporation of goal-directed PoCUS in early patient management improves diagnostic accuracy, shortens the list of viable diagnostic etiologies, and changes treatment plans for certain emergency pathologies [1–3].
Goal-directed PoCUS protocols have been developed to provide a structured approach to improving the diagnostic accuracy of the initial clinical assessment of the critically ill patient and to monitor fluid resuscitation. Two common examples of these protocols are the 'abdominal and cardiac evaluation with sonography in shock’ (ACES) protocol, proposed by one of the authors (Atkinson et al.) in 2009 , and the 'rapid ultrasound for shock and hypotension’ (RUSH) protocol . These goal-directed scans aim to provide a structured approach to PoCUS in hypotension and require only an introductory level of training.
The ACES protocol describes a structured six-view scan involving a (1) cardiac view, (2) inferior vena cava (IVC) view, (3) abdominal aorta view, (4) right and (5) left flank views for intra-abdominal and pleural fluids, and (6) a pelvic view for free fluid as a helpful adjunct to clinical examination. The addition of appropriate windows for pneumothorax and DVT are advised where considered appropriate.
The limitation with PoCUS, as with many aspects of the physical exam and other bedside tests, is that ultrasound is operator dependent. Confidence and competence in both image acquisition and image interpretation is essential, as is the knowledge of how to incorporate findings into clinical decision-making. Given the increased usage and significance of PoCUS in clinical medicine  and the importance of ensuring that residents and students are familiar and competent with ultrasound, the purpose of this study is to evaluate the use of high-fidelity simulation to train medical learners in PoCUS.
Medical training using simulation is a well-established and respected practice [6, 7] and has many advantages when compared to traditional training techniques. Traditional medical teaching can be reliant on patient and pathology availability, and safety issues. With simulation, learners can be exposed to almost any clinical scenario as many times as needed without any consequence towards patient health. In this respect, simulator-based learning can provide a much more efficient and safer way of training inexperienced medical students, as well as seasoned physicians.
The breadth of simulator research is noteworthy . However, to the best of our knowledge, there is little research done in this field that focuses on the evaluation of PoCUS and using simulators in training medical students and resident physicians to diagnose emergency cardiac and pulmonary pathologies. As such, this study includes certain methodologies that are considered exploratory: the training and testing protocol itself, along with the employment of PoCUS with patient simulators.
Our primary objective is to assess whether the focused training process described in this study is effective in training medical students and resident physicians to competently perform a goal-directed PoCUS scan in a simulated setting. In this study, competency is defined as the participants' ability to acquire and interpret PoCUS images, as judged by an experienced emergency physician. We hypothesized that the ACES protocol could be learned on a high-fidelity simulator, and integrated into standardized emergency medical scenarios, by medical trainees with minimal or no prior ultrasound experience. As a secondary objective, information was collected that focused on participant confidence levels, as well as face and content validity of the PoCUS simulator.