Aim
The present study aimed to compare the simulator-based TEE training with the video-based TEE training, both following a theoretical lecture, and to determine which of the two would better improve the interpretation of 20 cross-sectional views.
Study design
The present study was designed as a single-center, randomized, double-blinded, prospective clinical trial. It was conducted from April 2020 to May 2020 in the North Sichuan Medical College, Nanchong City, Sichuan Province, China, and was registered in the Chinese registry of clinical trials at http://www.chictr.org.cn (ChiCTR2000033519; 3/June/2020). The study adhered to the applicable CONSORT guidelines and was approved by the Research Ethics Committee of the Affiliated Hospital of North Sichuan Medical College (approval No. 2020/111–1)
Population
Informed written consent was obtained from all participants all subjects or, if subjects are under 18, from a parent and/or legal guardian. All 4th-year medical students with an anesthesia major and without any previous experience in cardiac anesthesia or echocardiography were eligible for participation in the present study. Participation was allowed only after signing the consent form and agreement to adhere to the study requirements.
Sample Size
Since no similar previous studies were reported in the literature, the sample size was calculated based on the initial pilot studies, according to which that the mean ±SD of retention-test 1 was 59.4% ±21.3% in the video-based training group comprising ten subjects. With a statistical power of 0.8 and a type 1 error rate of 0.05 in detecting 20% improvement as conservative, the sample size calculation determined that a minimum of 50 patients were required per group to distinctly present this difference using a two-tailed Student’s t-test. Considering a possible dropout rate of 20%, 120 patients were finally included in the present study.
Theoretical lecture
All the participants together attended a 90-min theoretical lecture, which was taught by a tutor with experience in over 200 cases of TEE image examinations for cardiac surgeries. The lecture entailed the basic concepts of echocardiography, normal cardiac anatomy, a simple explanation of 20 cross-sectional views, and the corresponding anatomical structures.
Randomization
After the post-test (refer to the assessment section), the participants were randomly divided (sealed envelope by SPSS with random seed 20200611) into the video-based group (Group V) and simulation-based group (Group S) by J.-Y.L. who was not involved in other parts of this study.
Intervention
The participants belonging to Group V received a 60-min video-based training (30-min of high-definition video-watching under supervision, twice). The video was recorded by Professor Robert L. Lobato, M.D. from Stanford University (refer to the manuscript attachment). The content of the 30-min video comprised: Professor Robert L. interpreting the probe location in each of the 20 cross-sectional views in the PowerPoint, verbally explaining how each of the 20 cross-sectional views formed by depicting the heart model and the corresponding two-dimensional echocardiographic cross-sectional image in the PowerPoint without a visual probe at hand. When the video was playing, each participant had a heart model at hand to understand what was being taught. The tutor also used native language with the participants when appropriate for a better understanding. The students were not allowed to have a discussion with each other and were encouraged to ask the tutor for help if they had any confusion regarding TEE.
Group S was demonstrated the 20 cross-sectional views through the simulator training system for 30 min by the tutor. The training included information regarding how to move the probe to obtain each view, an explanation of the relative position of the heart, and a demonstration of how each sectional image was formed, all of which assisted the trainees in understanding every anatomical structure in the 20 cross-sectional views. The participants were allowed to undertake this training only once. Subsequently, each trainee was allowed to manipulate the VirSim TEE simulator training system alone for 30 min under the tutor’s instructions. The participants were not allowed to watch how their peers manipulated the probe or to have a discussion with each other. Therefore, in total, each participant had 60 min of training.
The words delivered by the tutors in the 60-min training sessions were almost the same in both the groups, such as ‘this image is referred to as middle-esophagus four chambers image’, ‘when you placed the probe at the middle of the esophagus’, ‘regulate the scope into zero angle’, ‘the anatomic structure of the heart marked with the marker are the structures listed on the right part of the screen’, ’think, which image have you got’, ’so, the images on the screen are: left atrium, left ventricle, right atrium, right ventricle, and so on’.
The participants were requested not to review the related knowledge during the whole period of the trial. After the training sessions, the participants were required to individually complete a checklist, which included the names and the anatomic structures of each of the 20 cross-sectional views. Only those participants who answered all the questions correctly were allowed to undergo the next trial. The participants who could not provide correct answers to all the questions were assisted by the tutor in clarifying their concepts by demonstrating and explaining the heart model for Group V or by manipulating the simulator for Group S.
Measurements
Pre-test conducted prior to the training aimed at assessing the pre-existing knowledge of TEE in the participants. After the 90-min lecture, the post-test was conducted to assess the effect of the lecture. Subsequently, the participants were randomly divided into Group V and Group S (with equal participants). After the completion of all the training sessions, the participants were required to undertake the retention-test 1 conducted one week later and the retention-test 2 conducted one month later.
In all the tests, the participants were shown five slides in PowerPoint, each with an echocardiographic image that was depicted for a maximum of 5 min. The participants were required to select the correct name of the image and the corresponding anatomic structure from a list of options. 20 cross-sectional views included : (1) Middle esophagus ascend aortic short axis, ME Asc Aortic SAX; (2) Middle esophagus ascend aortic long axis,ME Asc Aortic LAX; (3) Middle esophagus descend aortic short axis, ME Desc Aortic SAX; (4) Middle esophagus descend aortic long axis,ME Desc Aortic LAX; (5)Upper esophagus aortic arch long axis, UE Aortic Arch LAX; (6)Upper esophagus aortic arch short axis, UE Aortic Arch SAX; (7)Middle esophagus four chamber, ME 4C; (8) Middle esophagus mitral commissural, ME MC; (9) Middle esophagus two chamber,ME 2C; (10)Middle esophagus long axis, ME LAX; (11)Middle esophagus aortic valve short axis,ME AV SAX; (12)Middle esophagus right ventricle inflow-outflow, ME RVOT;(13) Middle esophagus Bicaval,ME Bicaval; (14)Middle esophagus aortic valve long axis, ME AV LAX; (15) Transgastric basal short axis , TG Basal SAX; (16) Transgastric middle papillary short axis view, TG Mid Papillary SAX; (17) Transgastric two-chamber, TG 2C; (18) Transgastric long axis, TG LAX; (19) Transgastric right ventricle inflow, TG RV inflow; (20) Deep transgastric long axis, Deep TG LAX. Ten anatomic-structure lists included: (1) left atrium, LA (2)left ventricle, LV; (3)mitral valve, MV; (4)aortic valve, AV; (5) aorta, AO; (6) right atrium, RA; (7) right ventricle, RV; (8) tricuspid valve, TV; (9) pulmonary valve, PV; (10) pulmonary artery, PA. The overall accuracy, which was defined as the number of correct answers divided by the total number of questions in each test, was used to assess the performance of the participants.
The pre-test included five images, which were generated using SPSS (random seed = 20200610): UE Aortic Arch LAX; ME MC; ME RVOT; TG RV inflow; Deep TG LAX.
The post-test included 5 images, which were again generated using SPSS (random seed = 20200611): ME Desc Aortic LAX; ME 4C; ME LAX; TG LAX; TG RV inflow.
The retention-test 1 included five images generated using SPSS (random seed = 20200618): ME Asc Aortic SAX; ME Desc Aortic SAX; ME 2C; ME RVOT; TG Basal SAX.
The retention-test 2 included five images generated using SPSS (random seed = 20200711): ME Desc Aortic SAX; ME Desc Aortic LAX; ME RVOT; ME AV LAX; TG LAX.
Statistical analysis
All data were presented as Mean ±SD. A 2-sample t-test was used to evaluate the differences between the group in the pre-test, post-test, retention-test 1, and retention-test 2. The paired-sample t-test was used to compare the individual improvement prior to and after the theoretical lecture. The primary outcome was the mean overall accuracy of the retention-test 1 and the secondary outcome was the mean overall accuracy of the pre-test, post-test, and retention-test 2. Statistical significance was determined using the two-tailed test at the P-value threshold of 0.05. All data were analyzed using the SPSS Statistics 25.0 software (Statistical Program for Social Sciences, SPSS Inc, Chicago, Illinois, USA),