This single-center randomized controlled study aims to evaluate the effectiveness of Case-Based Learning (CBL) compared with traditional teaching in clinical training of bedside lung ultrasound (BLUE) for emergency medicine residents and medical students. The hypothesis is that CBL improves theoretical understanding, practical ultrasound skills, and clinical reasoning in emergency settings.

This single-center randomized controlled educational trial will be conducted in the Intensive Care Unit (ICU) of the First Affiliated Hospital of Wannan Medical College, China. The study aims to compare the effectiveness of Case-Based Learning (CBL) and traditional lecture-based teaching in bedside lung ultrasound (BLUE) education for residents and medical students participating in critical care rotations.

Participants will be randomized in a 1:1 ratio by computer-generated sequence into either the CBL group or the traditional teaching group. Both groups will receive a total of 8 hours of instruction delivered in two 4-hour sessions during their ICU rotation period.

In the CBL group, teaching will be guided by authentic clinical cases that include varied respiratory pathologies (e.g., pneumonia, pneumothorax, pulmonary edema). Each case will involve small-group discussion of diagnostic reasoning, interpretation of ultrasound findings, and supervised scanning practice at the bedside. Instructors will facilitate feedback and reflective learning, integrating theoretical concepts with clinical application.

In the traditional teaching group, participants will attend classroom lectures on ultrasound principles and watch instructor-led demonstrations of standardized BLUE examination techniques. Short hands-on practice sessions will follow under supervision but without case-based discussion or peer-feedback components.

All teaching sessions will be delivered by faculty certified in critical ultrasonography, using standardized instruction materials and the same ultrasound equipment and scanning protocols across groups. Data collection will occur within one week after completion of the teaching intervention. Primary outcomes include Objective Structured Clinical Examination (OSCE) score reflecting image acquisition, interpretation, and clinical reasoning. Secondary outcomes comprise written knowledge test scores and learner-reported measures of learning motivation and satisfaction.

All analyses will follow the intention-to-treat principle. Group differences will be tested using appropriate statistical methods (e.g., independent t-test or Mann-Whitney U test for continuous variables and chi-square test for categorical variables). The results will provide empirical evidence to guide optimization of bedside lung ultrasound education and the implementation of interactive, case-based teaching strategies in the context of intensive and emergency care training programs.

Inclusion Criteria:

• Standardized residency trainees currently rotating in the Intensive Care Unit (ICU), specializing in Internal Medicine, Surgery, Emergency Medicine, Anesthesiology, or General Practice.
• Have completed institutional basic ultrasound theory training or possess preliminary ultrasound knowledge.
• Voluntarily participate and provide written informed consent.
• Able to complete the entire teaching and evaluation schedule (including written test and OSCE).

Exclusion Criteria:

• Prior formal training or certification in lung/critical care ultrasound.
• Unable to complete the study period due to rotation scheduling or absence.
• Decline or withdraw informed consent.