A randomized cross-over single-blinded trial is designed. It compares the surgical performance in a laparoscopic/MIS training parkour using a passive polarizing 3D- and 4K-display system. It should be tested, whether the tasks of the training parkour could be performed faster and/or with less mistakes using one of the display systems. Also the influence of the display technique on the learning curve will be evaluated. The trial is performed at single institution (Department of General, Visceral and Cancer Surgery, University Hospital of Cologne). Subjects of the study will be surgeons from the University Hospital of Cologne as well as from primary and secondary hospitals/community clinics in Cologne. After written informed consent subjects will be randomized to start the training parkour with the 3D system or the 4K system. After completion of the parkour with the first display system the task load is evaluated by the NASA task load index (NASA-TLX). After that the parkour is performed with the other display system (vice-versa-setting) followed again by NASA-TLX. Three different groups of subjects participate in the trial: unexperienced novices to MIS (medial students), non-board certified abdominal surgeons in-training with some experience in MIS and board-certified abdominal surgeons with a high level of experience in MIS. The parkour consists of 7 tasks (novices 5 tasks), which will be repeated 3 times. After completion of the parkour all participant are examined by an ophthalmologist for stereoscopic vision and exclusion of manifest strabismus with five qualitative and semi-quantitative tests), Lang (I and II)-, Titmus-, Bagolini striated glasses test (near and far distance test) TNO-stereo tests (near distance) and cover-/uncover-test (near and far distance). Further, monocular visual acuity is tested (far distance) and anterior segment and central fundus are screened for relevant anomalies. Figure 1 shows the study flowchart. According to the SPIRIT 2013 guidelines a trial schedule (table 1) and a trial checklist (supplemental material) are part of the protocol9,10.
Outcome measures and data collection
Primary outcome measure is the surgical performance measured by the items
“time in seconds” and “ number of mistakes”. Both items are measured for each task separately and for all tasks together. The mistakes are defined for every task as any deviation from perfect performance (general and special mistakes). Secondary outcome parameters are the scores of the NASA-TLX and the learning curves.
Baseline characteristics are acquired by a questionnaire. The MIS tasks are recorded as standard 2D videos. NASA-TLX is performed as pen-and-paper version. Ophthalmological examination is performed and documented on a separate CRF. If data of one subject is completed, it will be transferred to the data trustee, who pseudonominized data and videos. The videos will be sent back to the investigators for evaluation of primary outcome measure, which will be documented on a CRF. This will be retransferred to the data trustee, who will reunite it all. Then the pseudonominized data are send to the principal investigator (R.W.) and statistician for final evaluation. Table 1 shows type and time of data collection. At the time of publishing the study protocol the trial is still recruiting.
Inclusion Criteria
Subjects fulfilling the following inclusion criteria may be enrolled in the study:
Medical student, surgeons in training, board-certified surgeons
Written informed consent given
Age>18 years
Exclusion criteria
Medical students with any experience in laparoscopic surgery
Experience in the laparoscopic training parkour (all subjects)
Non-correctable vision disorders
Known impaired stereoscopic vision
Manual skill disorders
Randomization and blinding
Randomization of subjects to sequences is based on permuted blocks and stratified by level of experience. It will be performed by the data trustee. After that subjects will perform the laparoscopic parkour, the NASA TLX and be examined by the ophthalmologist. The performance of the laparoscopic parkour will be video documented as standard 2D-videos. After completion of the study examination all data including the videos will be collected by the data trustee and pseudonominized and stored on a secured data base with routine backup. To guarantee blinding only pseudonominized data is sent back to the investigators for evaluation of the final study data. So the evaluating investigators could not find out if the 3D or 4K display system was used during the laparoscopic training parkour.
Data management
Data evaluation and entry to study data base is double checked and performed by two investigators. Final access to the data base is given to the sponsor, responsible party and authors of the protocol. It will not be provided to any third party.
Interim analysis and stopping guidelines
There is no interim analysis is planned. There are no stopping guidelines due to the fact, that the trial does not evaluate U.S.-FDA-regulated drug product nor U.S. FDA-regulated device product.
Sample Size
A sample size of 34 per stratum is required to detect a standardized effect of 0.5 with a power of 80% at two-sided type I error 5%. This effect size is based on preliminary experiments of the study group and published data. Thus, altogether 102 subjects need to be enrolled (power paired means, corr(0.5) altdiff(0.5); StataCorp LLC, College Station, TX, USA)7. Subjects who drop-out of the study may be replaced
Statistical analyses
Quantitative variables are summarized by mean ± standard deviation and percentiles (0, 25, 50, 75, 100), qualitative variables by count and percentage. Outcome measures are evaluated by modelling; specifically (generalized) linear mixed models for repeated measures (MMRM) with main effects modality, stratum and period (type III SS, REML, unstructured covariance matrix). Estimated marginal means and contrasts are derived. Interaction effects, particularly stratum*modality, are explored. Two-sided p-values <0.05 are interpreted to indicate statistical significance. Missing data will substituted by multiple imputations. Subgroup analysis will be performed according to the above mentioned strategies.
Trial organization
The IDOSP trial is an investigator initiated trial without external funding. The trail is sponsored by the university hospital of cologne. The department of general visceral and cancer surgery is responsible for coordination of the trial.
Ethics
Ethics Committee approval was obtained before the study (Ethikkommission der Medizinischen Fakultät der Universität zu Köln, Number 17-388, date 26th October 2017). Written informed consent will be given by all subjects before study inclusion and randomization. The pseudonominized data management is guaranteed by the data trustee. The study is performed in accordance with German national laws and guidelines, Good Clinical Practice and the Declaration of Helsinki. The study is registered at clinicaltrials.gov (trial number: NCT03445429).
Dissemination policy
Trial results will be published by the authors of this protocol in scientific journals and on clinicaltrials.gov.
3D- and 4K-Display system
As commercially available passive polarizing 3D-laparoscopic system the Einstein Vision® 2.0, 30° camera, 10 mm, 3D full high-definition monitor 32“, Aesculap AG, Tuttlingen, Germany is used. As commercially available 4K-system the Visera 4K UltraHighDefinition, 30° camera, 10 mm, 4K big screen monitor 55”, Olympus Medical system, Olympus Europa SE & Co. KG, Hamburg, Germany is used. The position of the complete laparoscopic training parkour, the camera position in the laparoscopic training system, and the distance from study subject to the screens are standardized. All positions are marked with signs on the training system or on the floor in the operating theater.
Laparoscopic training parkour
The laparoscopic training parkour consists of the training simulator (eoSim, eoSurgical Ltd,
Edinburgh, UK) were the task are performed in. Integrated in the training simulator is a video camera system connected to a standard tablet computer. It documents the tasks for evaluation in the 2D video standard. The training simulator is connected to the 3D- or 4K-display system via the main camera and monitor. The complete setup of the parkour is shown in picture 1 and 2. 7 different tasks (novices 5) with increasing difficulty are performed by the subjects. Each task is performed 3 times in row. Then the next task follows. The tasks are called “rope pass”, “paper cut”, “pegboard transfer”, “needle threading” “needle recapping”, “circle cutting” and “knot tying” (Figure 4). Table 2 describes the tasks in brief.
Before starting a video is shown to the participants, how the tasks of the laparoscopic training parkour should be performed. Also a handout describing all tasks is passed to them. After that no further explanations by the investigators will be made. Color coded standard laparoscopic instruments are used (grasper, Overholt clamp, scissors, needle holders). Each task starts with the first touch of the used tool and ends with drop-down to the bottom of the laparoscopic trainer box. Performance time is measured between these positions. Mistakes are documented as any deviance from perfect performance. There are general and special mistakes for the each task. General mistakes are dropping of the main objects of the tasks (e.g. the rope, paper, needle or thread on the floor of the box trainer), regrasping of the used objects and touching parts of the box trainer. A special mistake e.g. in rope passing is grasping the non-marked area, for paper cut a too long cut through the paper and for knot tying a slipping of the prepared loop.
3D- and 4K-Display system
The commercially available 3D imaging system Einstein Vision® 2.0, 30° camera, 10 mm, 3D Full HD monitor 32“ (82cm), Aesculap AG, Tuttlingen, Germany and the commercially available 4K system the Visera 4K UHD, 30° camera, 10 mm, 4K big screen monitor 55” (140cm), Olympus Medical system, Olympus Europa SE & Co. KG, Hamburg, Germany are used. The position of the complete laparoscopic training parkour, the camera position in the laparoscopic training system, and the distance from study subject to the screens are standardized