This study looks at the best way to remotely teach and guide doctors-in-training to perform a bedside ultrasound exam called eFAST (extended Focused Assessment with Sonography for Trauma), which is used to quickly check injured patients for internal bleeding or air around the lungs. The study takes place in a simulation setting, with no real patients. Resident physicians who have completed the basic ultrasound courses each watch the same short instructional video and then perform three eFAST examinations on the same healthy volunteer. Participants are randomly assigned to one of three groups: (1) the instructional video only, with no live help; (2) the video plus real-time audio guidance from a remote expert who can see the live ultrasound image; or (3) the video plus guidance through a head-mounted device that also lets the expert see the participant's own point of view. Afterwards, experts who were not involved in a given exam review the recorded ultrasound images, without knowing which group the participant was in, and rate the image quality and skill. The study also measures how long the exams take, the participants' workload, and the comfort and usability of the system. The goal is to learn whether real-time remote guidance, and in particular guidance through a head-mounted device, helps trainees produce better and faster eFAST examinations than an instructional video alone.
Background and rationale: eFAST is a highly operator-dependent skill, and remote (tele-ultrasound) guidance is increasingly used to extend expert support to less-experienced operators. Hands-free head-mounted devices may improve remote mentoring by giving the expert the operator's point of view, but there are no data on their use for eFAST training. This single-center, simulation-based, three-arm randomized controlled study compares three remote-guidance modalities. Setting and allocation: The study runs in a standardized simulation environment with no patients. Allocation to the three arms is 1:1:1 using permuted blocks with concealed allocation via the REDCap randomization module, with the assigned arm revealed only at the session. After a standardized instructional video and a brief ultrasound-system introduction, each participant performs three consecutive complete eFAST examinations on the same standardized healthy volunteer, under standardized environmental conditions to minimize anatomical and contextual variability. Technical setup: Examinations use a GE LOGIQ E10s (R4) with an M5Sc-D matrix sector probe. The native ultrasound image is sent over a secure connection to a dedicated study laptop that joins a Microsoft Teams call, so the remote expert sees the live image in real time; in the head-mounted-device arm the participant's point-of-view video is additionally transmitted. Probe motion (optical tracking) and a depth (RGBD) camera are recorded for exploratory workflow analyses, with shared time-stamps used to synchronize the data streams. Live audio is not recorded. Assessment workflow: The entire scan is recorded continuously; the participant verbally marks each window, and window-specific clips are extracted retrospectively from these time-stamps and pseudonymized. Experts who did not supervise a given examination review the clips while blinded to group allocation, and each scan is reviewed by two independent experts to support an inter-rater reliability estimate. The participating experts also perform on-site benchmark eFAST examinations as a reference. The study is designed in line with SPIRIT and reported in line with CONSORT 2025.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
HEALTH_SERVICES_RESEARCH
Masking
SINGLE
Enrollment
75
All participants watch the same brief standardized instructional eFAST video and receive a short standardized introduction to the ultrasound system, then perform three consecutive complete eFAST examinations on a standardized healthy volunteer. In the video-only arm this is the only instruction; no live expert guidance is provided during the examinations.
A remote emergency-ultrasound expert joins the session via Microsoft Teams, views the participant's live ultrasound image in real time (streamed from the GE system to a study laptop that shares it in the call), and provides verbal, audio-only guidance during the eFAST examinations. The expert does not see the participant's point of view. Guidance is real-time only.
In addition to the live ultrasound image shared via Microsoft Teams, the participant wears the Arc 3 head-mounted device (RealWear), which transmits their point-of-view video to the remote expert in the same Teams call. The expert sees both the point-of-view stream and the live ultrasound image and gives real-time guidance; the participant can see the expert's video on the head-mounted display.
Balgrist Campus, University Hospital Balgrist
Zurich, Canton of Zurich, Switzerland
eFAST image-quality score (QUICk Global Rating Scale, GRS)
Participant-level mean QUICk Global Rating Scale across the three eFAST examinations. The GRS has four domains (image adjustment, image sweeping, flow of procedure, overall performance), each rated 1 (Poor) to 5 (Excellent); total 4 to 20. Each examination is scored by two blinded experts who did not supervise it. Minimum 4, maximum 20; higher scores indicate better image quality. Unit of Measure: score on a 4 to 20 scale
Time frame: Three examinations during the study session (Day 1); blinded scoring during the rating period (up to ~3 months after)
eFAST image quality, QUICk Task-Specific Checklist (TSC)
Participant-level mean QUICk Task-Specific Checklist score across the three eFAST examinations. The TSC has 28 image-based items, each scored 1 (performed adequately) or 0, covering the four abdominal and cardiac windows and the right and left lung separately; total 0 to 28. Each examination is scored by two blinded experts who did not supervise it. Minimum 0, maximum 28; higher scores indicate better image quality. Unit of Measure: score on a 0 to 28 scale
Time frame: Day 1 examinations; blinded scoring during the rating period (up to ~3 months after the session)
eFAST operator competence, Adapted OSAUS
Participant-level mean Adapted OSAUS (Objective Structured Assessment of Ultrasound Skills) across the three examinations. Three domains (image optimization, systematic examination, interpretation/diagnostic value) are each rated 1 (Poor) to 5 (Excellent); total 3 to 15. Each examination is scored by two blinded experts who did not supervise it. Minimum 3, maximum 15; higher scores indicate better operator competence. Unit of Measure: score on a 3 to 15 scale
Time frame: Day 1 examinations; blinded scoring during the rating period (up to ~3 months after the session)
Global diagnostic adequacy rating
Participant-level mean global diagnostic-adequacy rating across the three examinations, scored by blinded experts on a 0 to 10 scale (a separate Yes/No "diagnostically adequate" judgement is also recorded). Minimum 0, maximum 10; higher scores indicate greater diagnostic adequacy. Unit of Measure: score on a 0 to 10 scale
Time frame: Day 1 examinations; blinded scoring during the rating period (up to ~3 months after the session)
Mean eFAST examination duration
Participant-level mean examination duration, averaged across the three eFAST examinations, measured from first probe-skin contact to final eFAST interpretation. Unit of Measure: minutes
Time frame: Day 1 (study session)
Perceived workload (NASA-TLX, raw)
Participant-reported task workload measured with the raw (unweighted) NASA Task Load Index. Six dimensions (mental demand, physical demand, temporal demand, performance, effort, frustration) are each rated from 1 (Very Low) to 20 (Very High) and reported as the mean (Performance reverse-scored). Minimum 1, maximum 20; higher scores indicate greater workload. Unit of Measure: score on a 1 to 20 scale
Time frame: Day 1, immediately after the session
System usability (System Usability Scale, SUS)
Participant-reported usability of the guidance method, measured with the System Usability Scale (ten items each rated 1 to 5, standard SUS scoring to a 0 to 100 total). Minimum 0, maximum 100; higher scores indicate better usability. Unit of Measure: score on a 0 to 100 scale
Time frame: Day 1, immediately after the session
Headset comfort and tolerability
Participant-reported comfort and tolerability of the guidance method, assessed with standardized items on a 7-point Likert scale (1 = Not at all, 7 = Extremely), with additional items for the head-mounted-device arm (device comfort, eye strain, interference with probe handling). Minimum 1, maximum 7; the favorable direction is item-specific (e.g., higher comfort is better, higher distraction or fatigue is worse). Unit of Measure: score on a 1 to 7 scale
Time frame: Day 1, immediately after the session
Perceived guidance quality (participant-rated)
Participant-reported quality of the guidance, including clarity of the expert's instructions and visual/gestural cues and helpfulness in locating eFAST windows and completing the examination efficiently, on a 7-point Likert scale. Minimum 1, maximum 7; higher scores indicate better perceived guidance. Unit of Measure: score on a 1 to 7 scale
Time frame: Day 1, immediately after the session
Expert-rated feasibility and communication quality
Mentoring-expert rating, after each guided session, of how easy it was to guide the participant, how effectively the expert could assess the participant's actions from the provided image(s), and the clarity of the ultrasound image stream (for HMD sessions, the usefulness of the operator-view video stream), on a 7-point Likert scale. Minimum 1, maximum 7; higher scores indicate more favorable feasibility and communication. Unit of Measure: score on a 1 to 7 scale
Time frame: Day 1, after each guided session
Expert-rated technical reliability
Mentoring-expert rating, after each guided session, of session technical reliability (connection stability, audio quality, ultrasound image-stream quality, and latency) on a 7-point Likert scale (minimum 1, maximum 7; higher = better). The frequency of needing to repeat instructions due to technical issues is recorded on a separate 0 to 5 item and summarized descriptively. Unit of Measure: score on a 1 to 7 scale
Time frame: Day 1, after each guided session
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