Background

In comparison to open surgical techniques minimally invasive surgery (MIS) procedures require additional psychomotoric skills often referred to as MIS basic skills. [1]. MIS basic skills include the coping with different haptic competencies, the fact that opposite movements have to be applied to the instruments fixed at the level of the body wall (fulcrum effect) and the cognitive transfer of a two-dimensional monitor image to the three-dimensional surgical field. Completion of the learning process of these basic MIS skills takes a lot of time and practice [1]. Surgical training is currently mainly performed in the conventional teacher-learner mode. However, personal resources and time are often limited due to the increasing economic pressure in hospitals [1], [2].

Against this background, various virtual reality (VR)- and/or video-/box-trainers and MIS training curricula have been developed in recent years for residents to learn basic MIS skills outside the operation room (OR) in a safe and standardized environment [3], [4], [5]. Recently, we devised a comprehensive, strictly defined and goal-directed curriculum for the acquisition of minimally invasive basic skills (http://www.luebeck-toolbox.com) [6], [7]. The Lübeck Toolbox (LTB) curriculum encompasses a box-trainer, six iteratively developed tasks, pre-defined expert-levels for each task as well as online video-tutorials and documentation material for the training progress. The goals for each task were based on a benchmark-study with experts in MIS followed by a prospective validation study with MIS novices [6], [7]. In that study all MIS novices successfully completed the curriculum [7]. Consequently, the approach provides an adaptation of MIS basic skills regardless to the talent of the individual trainee. In addition we previously demonstrated the transferability of the LTB-based skills to an organic surgical model [6]. The LTB curriculum, however, so far has not been validated with regard to real OR performance in a prospective randomized study.

Several studies have demonstrated beneficial effect of MIS training outside the OR on MIS performance [8], [9], [10], [11], [12], [13], [6]. Mostly studies assessed MIS performance in the surgical laboratory as, i.e., a cholecystectomy (CHE) on a porcine model. However, transferability to the OR is essential to justify the implementation of MIS ex vivo training into surgical education. Indeed, there are some data from prospective randomized studies available focussing on the transferability of MIS ex vivo training to surgical performance in the OR on the patient:

The prospective randomized trials by Orzech et al. and Van Sickle et al. showed that ex vivo MIS training significantly improved surgical performance in intracorporal laparoscopic stitches during Nissen fundoplication on patients in the OR [14], [15]. Malik et al. demonstrated an improvement of surgical performance on surgical residents during dissection of gallbladder from the liver bed in the OR after the use of box simulators [16]. In addition, Palter et al. showed that a structured training and assessment curriculum significantly improved learning curves in five subsequent laparoscopic cholecystectomies on surgical residents compared to conventional trained residents [17]. In a further randomized controlled trial Palter et al. demonstrated same effect on residents performing MIS right hemicolectomy [18]. Sroka et al. randomized 19 training surgeons to undergo simulator training or not and analyzed OR performance in cholecystectomy before and after the curriculum [19]. In this study, the MIS performance increased significantly in both groups but the difference in the simulator group exceeded the other one. Furthermore, the effect of ex vivo MIS training also plays a relevant role for other surgical disciplines such as gynaecology and urology. Here, too, a positive effect of MIS training on OR performance has been shown in prospective randomized studies [20]. Despite this evidence the integration of ex vivo MIS training into formal residency training curricula is still lagging [21], [22].

A limitation of the prospective randomized studies investigating on the transferability of MIS training to the OR was that study populations were not homogenous as the participants were at very different levels of surgical education from the first to fourth year of surgical education [14], [15], [16], [17], [18], [19], [20]. In particular, most study participants had MIS experience in the operating room before. Indeed, there is a lack of prospective randomized controlled studies investigating the impact of MIS-skills training on residents without any previous MIS experience in performing their first MIS procedure on patients. The demonstration of evidence in this defined scenario could further strengthen the need to implement MIS simulation training in formal residency training curricula, in particular prior to first MIS experience in the OR.

In consequence, we conduct a prospective randomized trial to validate the efficacy of goal-directed minimally invasive surgery simulation training with the Lübeck Toolbox-curriculum to the first surgical procedures of surgical residents in the OR.

Materials and design

2.1 

Objectives

Primary objective of the study is to examine whether study participants with no prior experience in MIS perform better in laparoscopic MIS on a patient when they attended the LTB-MIS training beforehand (group A). The control group does not perform any MIS training (group B). The highly standardized LTB curriculum takes about six weeks to complete [6]. The operative performance in both groups will be evaluated for the procedure of a laparoscopic cholecystectomy (CHE) on a patient in the OR. As baseline of MIS performance, all participants perform a laparoscopic CHE on a patient at the beginning of the study with an experienced consultant surgeon assisting (pre-test). Following the pre-test, the participants undergo either MIS training (group A/intervention group) or no MIS training. Six weeks after, all participants perform a second laparoscopic CHE (post-test) (Fig. 1). The video material of the CHE procedures will be saved. Then, the MIS performance of both groups will be evaluated and compared using the validated Global Assessment Tool for Evaluation of Intraoperative Laparoscopic Skills (GOALS)-Score [23] (Table 2). In addition to the analysis of the video-documented surgery, operational performance will also be determined by the following two parameters: 1) the number and duration of takeovers by the experienced surgeon who assists the operation 2) (potential) termination of the operation by the participants.

Fig. 1 

Flowchart of the study design and the course of the study.

Study design

This is a registered prospective, multi-centre, two-arm, parallel-group randomized controlled trial (NCT03040544). The study was approved by the Ethics Committee of the Universität zu Lübeck (ethics committee protocol #16–316). In addition, the according respective local ethics committees must approve participation of centres before we begin recruitment at those centres. The study protocol is designed in accordance with the SPIRIT Guidelines (see populated SPIRIT checklist additional file 1).

3.7 

Lübeck Toolbox (LTB) curriculum

Group A will perform the MIS training according to the LTB Curriculum. The LTB Curriculum is a video training platform with an integrated camera and light source. The position of the camera and the monitor are standardized and identical for the entire curriculum. The curriculum comprises six subsequent exercises (Fig. 2).

Fig. 2 

The Lübeck Toolbox (LTB) curriculum. The curriculum consists of six subsequent exercises, including a) ‘pack your luggage’, b) ‘weaving’, c) ‘Chinese jump rope’, d) ‘Triangle Cut’, e) ‘Hammer Cut’ and e) ‘Suturing’, in which defined target times must be achieved in order to continue with the next exercise. The target times for each exercise were based on a benchmark-study with experts in MIS and are shown in the figure

In the current study, the curriculum will be carried out as previously described [6], [7].

Based on a preceding pilot study (unpublished data) to determine the optimal time schedule for MIS simulator training, the following practice intervals are defined for the current study: A maximum of three exercise units per day may be performed, there must be a break of at least 60 minutes between each exercise unit, the interval between individual exercise units may not exceed 3 days. The LTB curriculum includes video tutorials for each exercise, which explain the rules of each exercise and provide instructions on how to efficiently practice and complete each exercise. The latter factors are watched redundantly throughout the curriculum at pre-defined task repetitions. Based on data from our preceding prospective study, the inclusion of comprehensive video tutorials into a simulation curriculum lead to more efficient and more precise performance in MIS training than watching no tutorials (accepted manuscript) [34].

Discussion

This study aims to examine whether the standardized LTB MIS training curriculum improves performance of MIS inexperienced surgical residents prior to their first MIS procedure in the operating room in comparison to not undertaking LTB-based simulation training.

Generally, for MIS procedures, the surgeon requires additional psychomotoric skills in comparison to open surgery to perform the operation safely and efficiently [1]. These MIS basic skills can be efficiently well learned outside the operation room by MIS virtual reality (VR)- and/or video-/box-trainers [3], [4], [5]. This aspect resulted in the development of various simulation devices and curricula in order to train and further improve MIS skills.

Simulation of laparoscopic demands is a good option for the education of surgeons in a safe environment [8]. Still, according to van Dongen et al., the implementation of simulator practice into the surgical curriculum seems to be difficult [22]. Several studies demonstrated that surgeons profit from MIS training outside the operation room [8], [9], [10], [11], [12], [13], [6]. Even more, prospective randomized studies showed beneficial effect of MIS training with regard to its direct transferability to real surgical environments [14], [15], [16], [17], [18], [19], [20], [3]. However, as a limitation, these studies included residents with very different MIS experiences prior to training on a simulator. In particular, most study participants had MIS experience in the operating room before study inclusion. Based on our very own experience with the MIS LTB simulation system we believe that surgical residents benefit from a standardized simulation training outside the OR before starting to perform their first MIS procedures on patients. The presented study addresses this concept of MIS simulation training and its direct transferability to the OR.

However, in our study protocol we included a first laparoscopic CHE as a baseline evaluation. This is in contradiction to the desired sequence of MIS training before the first MIS experience in the OR. The reasons for implementing of the CHE I are as follows: The inclusion of a baseline evaluation is analogous to previously published studies on the effect of MIS training on surgical performance [16], [19]. By a baseline evaluation we aimed to exclude individual participant depending factors that may influence MIS performance at the beginning of the study. These factors include the number of assisted MIS procedures, playing a musical instrument or video games, which positively influence MIS performance [26], [27]. Additionally, it is also well known that surgical residents are differently talented in performing MIS [28]. By determining the differences in GOALS score between CHE I and II, we aim to compare the improvement in MIS performance and thereby to exclude different talents of the participants in MIS.

Proving a positive effect of MIS training on real MIS procedures could underline and fortify the need of an implementation of MIS simulation training into surgical education. As an positive example, the Fundamentals of Laparoscopic Surgery (FLS) program has been integrated into the surgical residency program by the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) and the American College of Surgeons (ACS) [29], [25], [30]. In contrast, in Germany MIS simulation training is still not incorporated into surgical residency curriculum. This fact does further underline the need to conduct this study.

Beside beneficial effects on resident́s surgical performance in the OR, MIS simulation training has the potential to translate into improved patient safety, decreased OR resources, and better patient outcomes [3]. In this context, the following ethical aspect of our study should be considered: Patients in the control group could have a disadvantage compared to the intervention group performing the LTB curriculum. However, in Germany there is still no need of ex vivo MIS training in formal residency training curricula [21]. Consequently, the control group reflects the standard surgical education situation of MIS in Germany. In the current study in both groups the CHE will be assisted by a surgeon who holds the formal authorization for surgical education in visceral and/or general surgery in the participating clinic. In Germany, this authorization requires a high degree of surgical experience and aptitude. Finally, the attending surgeon has both a high level of surgical expertise and a high experience in surgical education. Beside patient safety aspects, this should further ensure that all participants have the same standard of assisting in the CHE.

Most of the diverse VR- and video/box simulators do not offer defined curricula and those that do, are based on limited data with limited validity [21]. In order to examine the effect of MIS training on surgical performance in clinical trials, it is important to use validated, standardized and thus comparable training programs [31]. Furthermore, goal-directed proficiency-based training has been demonstrated to increase trainee motivation, including attendance to the curriculum’s schedule, entailing better performance in comparison to training without defined objectives [31], [32]. In the current study we used the LTB curriculum for the acquisition of MIS skills. In order to find widely accepted implementation face, content, construct, concurrent and predictive validity should have been demonstrated for the given device and curriculum [26]. So far, face, content and construct validity could be shown for the LTB curriculum. The goals for each of the six tasks of the LTB curriculum are based on a benchmark-study with n = 15 MIS experts followed by a prospective validation study with n = 30 novices [6]. The current prospective randomized trial could further verify the gain in MIS performance due to the LTB curriculum in a real surgical environment and cover the important aspect of predictive validity of the LTB curriculum.

At this point, we see the following possible limitations of the study: The participants will be not blinded, but will be informed in which group of the study they will be assigned to and know the course of the study. This could have an influence on the MIS performance of the participants (performance bias). Furthermore, the 5th domain of the GOALS-score (autonomy) will be determined by the attending surgeon assisting the laparoscopic CHE of the participant as first assistant. Since it is logistically almost impossible to blind the attending surgeon to whether the study participant had been randomized to undergo the curriculum or not, especially in smaller hospital units, the attending surgeon knows which intervention a participant received and which MIS procedure (CHE I or CHE II) has been performed, when determing the 5th domain of the GOALS-score (detection bias). This could have an influence on the evaluation of the GOALS score overall. However, a potential digital recording of the verbal interactions between the participant and the attending surgeon, which would also allow a blinded analysis of the 5th domain of the GOALS score, is technically and logistically demanding and almost not feasible in a multicentric setting. There are data that direct assessment of MIS skills predicts the qualification of a surgeon more accurately than a video-based assessment [33]. However, it should be considered that direct raters may use different evaluation methods, thus introducing variations in ratings [33]. In the current study, the fact that the study is being conducted in a multi-centre setting could additionally lead to relevant differences in MIS assessments. And, direct observers onsite would know in which arm of the study the participants were randomised and which surgery was performed (CHE I versus II), which could have an influence on evaluation of MIS performance. For these reasons, we decided against a direct evaluation on site and favoured a blinded video analysis.

It has been described, that prospective studies which had been conducted under the involvement of an industrial co-operating partner more often report positive results than non-industry funded trials [6]. The funding source remained significantly associated with reporting of positive outcome in a multivariate analysis. Although the sole sponsor of the present study is the University Medical Centre Schleswig-Holstein, two of the co-authors (TL, HE) are co-founders of the LTB Ltd. company which may possibly imply the above mentioned bias with regard to the interpretation and presentation of the results. Further limitations are shortcomings of the protocol. It lacked provisions for dissemination, for amendments, and participant retention. Lastly, the trial is powered to detect a considerable effect that may be larger than the minimum clinically interesting difference.

In summary, this prospective multi-centre randomized controlled trial will help to determine the effect of MIS training outside the OR prior to the first operations on patients. Proof of effectiveness of MIS training as the LTB curriculum, with regard to its transferability to real surgical practice could be of considerable relevance for the implementation of MIS simulation training programs into the surgical residency curriculum.

Trial status

Recruitment started in May 2017 and is planned to be finished in May 2020.

Funding

This research received no specific funding agency in the public, commercial, or not-for-profit sectors.