The goal of this study is to evaluate whether remote asynchronous feedback is non-inferior to direct synchronous feedback during simulation-based training for ultrasound-guided popliteal sciatic nerve block performance. The main questions it aims to answer are:

Does asynchronous feedback achieve technical skill acquisition outcomes comparable to direct synchronous feedback? Can asynchronous feedback optimize teaching resources without compromising training quality?

Researchers will compare two feedback modalities within a simulation-based training program for deliberate practice of ultrasound-guided popliteal sciatic nerve block techniques.

Participants will:

Receive training with either direct synchronous feedback or remote asynchronous feedback Perform simulation-based deliberate practice sessions Be assessed using validated instruments for technical skill performance

For the use of the simulation program based on the implementation of a continuous sciatic popliteal nerve block. To achieve this, a simulation program developed by researchers from the School of Medicine of the Pontificia Universidad Católica de Chile will be used for residents from the Emergency Medicine and Critical Care specialty program.

Following approval by the institutional ethics committee, the scenario for 50 students will be prepared. The procedure room will include all the equipment required for performing the intervention, consisting of a video explaining the technique. The study will assess:

(i) Fundamentals and use of echography. (ii) Knowledge of anatomy, physiology, and pharmacology. (iii) Development of dexterity: ability to perform the procedure correctly.

The students will receive a one-hour lecture on the procedure. This assessment will consist of performing a sciatic popliteal nerve block on a simulated clinical scenario. An evaluator blinded to the study objectives will assess participants using a Global Rating Scale (GRS) and a checklist. Additionally, a third evaluator will use the GRS and the checklist remotely (asynchronous feedback).

After the evaluations, the simulation room will remain open throughout the week for students to perform up to five practice sessions. The number of movements and total procedure time will be recorded during each assessment. Students will also complete a satisfaction questionnaire and a final written test after the simulation activity and before the final assessment.

Once the previous evaluation is completed, residents may begin their training.

Subsequently, residents will attend simulation sessions specifically designed to practice the sciatic popliteal nerve block under the guidance of an instructor. Sessions will last 2 hours. Each resident will complete 2 sessions, each separated by 1 week. During the first session, the instructor will explain and supervise correct use of the ultrasound equipment. During the second session, the resident will perform the entire procedure independently. The resident's performance will be recorded and later evaluated through an assessment platform.

One week after training completion, residents will undergo a final assessment using the same tools. The duration of the simulation-based sciatic popliteal nerve block procedure will be recorded. Total procedure time and the number of movements performed during the procedure will also be documented. Additionally, the procedure will be video recorded.

Inclusion Criteria:

• Medicine students

Exclusion Criteria:

• No exclusion Criteria

The video assessment will be done by 2 blinded instructors (blinded to the group assignment of participants)