Repeated participation in the cadaver-based educational seminar for trauma surgery (C-BEST) could maintain training effects: skill retention at a 2-year follow-up

1. Introduction

Recently, cadaver surgical training has spread in each specialized area, and its educational effects have been clarified. This application extends to radiological training, infiltration techniques for general practitioners, and combined with virtual reality simulation training [1, 2, 3, 4]. A facility has set up a large-scale skills center to conduct core skills workshops for surgical training and has reported its usefulness [5].

However, the decline in training effects over time has become a problem. We previously reported that cadaver-based educational seminar for trauma surgery (C-BEST) and advanced C-BEST were useful for trauma surgery training. Furthermore, we highlighted the issue that the self-assessment of confidence levels (SACL) at half a year after the seminar decreased compared with SACL immediately after the seminar [6, 7]. Regarding this issue, we also speculated that repeated participation in seminars would prevent the decline because other simulation seminars reported that repeated participation could maintain the skills. To verify this assumption, we focused on the idea that basic and advanced C-BEST have pelvic package (PP) and fasciotomy of the lower extremity (FLE) as common training skills. For participants who took these skills twice each, we examined whether repeated participation in the seminar could suppress the decline in training effects.

2. Methods

2.1 Setting

2.1.1 Basic C-BEST

We held a 1-day C-BEST (a total of 38 times) from January 2013 to March 2018, with each session using 2–3 cadavers embalmed using a formalin solution.

A total of 375 participants were recruited on the basis of the following three criteria. First, they need to have board certifications. The councilors of the society recommended them from the websites of the Japanese Association for Acute Medicine, the Japanese Association for the Surgery of Trauma, and the Japanese Society for Acute Care Surgery. Second, participants with $<$10 postgraduate years (PGYs) who were recommended by the councilors of the society from the websites of the annual meetings of the Japanese Association for Acute Medicine were considered. Third, they were recruited on the recommendations of C-BEST instructors.

The participants were asked to conduct 21 surgical skills on the cadavers as shown in Fig. 1A. Briefly, in the morning, they first practiced two basic techniques. Thereafter, in terms of thoracic trauma, they practiced their skills related to the heart and lungs, and in the afternoon, they practiced femoral and neck vascular exposure and repairs, followed by skills related to abdominal and pelvic trauma. Finally, they practiced FLE, which is related to extremity trauma. Additionally, we conducted a mini-lecture using a slide presentation before each section to confirm what the participants were expected to do. The groups divided by a cadaver comprised 4–5 participants, and 1–2 dedicated instructors were assigned to each group. Subsequently, the participants proceeded to each session according to the directions and advice of the instructor, and all participants performed their skills for equal learning opportunities.

Fig. 1.C-BEST Time Schedule. (A) Time schedule for the 1-day basic cadaver-based educational seminar for trauma surgery, (B) Time schedule for the 1-day advanced cadaver-based educational seminar for trauma surgery. min, minutes.

Moreover, the participants answered the questionnaires, including the SACL for these 21 surgical skills. This was measured using a 10-point visual analog scale (0 points, cannot do at all; 5 points, can do with the help of an adviser; and 10 points, can do independently) and an evaluation of the contents before, immediately after, and at half a year after the seminar. The participants were also asked to answer the questionnaires via e-mail (Fig. 2).

Fig. 2.Example of a self-assessment of the confidence levels of the “pelvic package” and the “fasciotomy of the lower extremity” covered in basic and advanced cadaver-based educational seminar for trauma surgery explained through self-assessment examples.

2.1.2 Advanced C-BEST

Among the 375 participants in basic C-BEST, we sent an invitation of advanced C-BEST via e-mail to the senior surgeons (defined as a holder of surgical board certification) who responded to the questionnaire at half a year after basic C-BEST. Subsequently, 62 participants (as a result, selected from 28 times basic C-BEST) who wished to participate attended in 5 times advanced C-BEST held from September 2015 to January 2020. In advanced C-BEST, each session involved 2–3 cadavers embalmed using the saturated salt solution (SSS) method.

The participants were further asked to perform 11 surgical skills on the cadavers as shown in Fig. 1B. Briefly, in the morning, they practiced lung resection-related skills, and in the afternoon, they practiced hepatectomy-related skills, followed by skills related to the repair of abdominal aorta. Finally, they practiced external fixation for pelvic fracture, PP, and FLE, which is related to the extremity trauma. Additionally, we conducted a mini-lecture by specialists (a thoracic surgeon, a liver trauma surgeon, a cardiovascular surgeon, and an orthopedic trauma surgeon) using a slide presentation before each section to confirm what the participants were expected to do. The groups divided by a cadaver comprised 4–6 participants, and 1–2 dedicated instructors were assigned to each group. Thereafter, the participants proceeded to each session according to the directions and advice of the instructor, and all participants performed their skills to provide equal learning opportunities.

As with the basic seminar, the participants answered the questionnaires including the SACL for these 11 surgical skills. This was measured using a 10-point visual analog scale and an evaluation of the contents before, immediately after, and at half a year after the seminar. The participants were also asked to answer the questionnaires via e-mail (Fig. 2).

2.1.3 Changes in the SACL of PP and FLE between basic and advanced C-BEST

In basic C-BEST, the participants were asked about the 10-point SACL at three time points: before the seminar of basic C-BEST (BS-b), immediately after basic C-BEST (AS-b), and at half a year after basic C-BEST (HS-b). Similarly, in advanced C-BEST, the participants were asked about the 10-point SACL at three time points: before advanced C-BEST (BS-a), immediately after advanced C-BEST (AS-a), and at half a year after advanced C-BEST (HS-a). Thus, we examined the changes in the SACL of PP and FLE as common training skills at six time points: (1) BS-b, (2) AS-b, (3) HS-b, (4) BS-a, (5) AS-a, and (6) HS-a. Fig. 3 shows the training scene of PP and FLE. We conducted the survey in a format similar to the Delphi method, which repeats the questionnaire survey to the participants, although we did not present the obtained results.

Fig. 3.Procedure of the pelvic package and fasciotomy of the lower extremity. (A) Procedure of the pelvic package with gauze in advanced cadaver-based educational seminar for trauma surgery (C-BEST) using cadavers embalmed using the saturated salt solution (SSS) method, (B) procedure of the opening of an anterior compartment with a knife in the fasciotomy of the lower extremity (FLE) in advanced C-BEST using cadavers embalmed using the SSS method, (C) procedure of the opening of a deep posterior compartment with a knife in FLE in advanced C-BEST using cadavers embalmed using the SSS method. These pictures were taken during advanced C-BEST held in September 2015.

3. Results

Of the 62 participants, 2 did not respond to the questionnaire at three time points in advanced C-BEST (response rate, 97%). Consequently, 60 participants were enrolled (PGY, 16.5 $\pm$ 5.7). Participants were recruited from 34 hospitals and 18 universities. The interval between basic and advanced C-BEST was 27.1 $\pm$ 6.9 months. Table 1 displays participant information, including their board certification.

Data were not normally distributed according to the Shapiro–Wilk test; thus, we used the Friedman test as a nonparametric method for statistical analysis.

The changes in SACL in PP are shown in Table 2. In the statistical analyses of PP, BS-b versus AS-b was increased (P $<$ 0.001), AS-b versus HS-b was not changed (not decreased), HS-b versus BS-a was not changed, BS-a versus AS-a was not changed, and AS-a versus HS-a was not changed.

Table 3 shows the changes in SACL in FLE. In the statistical analyses of FLE, BS-b versus AS-b was increased (P $<$ 0.001), AS-b versus HS-b was not changed, HS-b versus BS-a was not changed, BS-a versus AS-a was increased (P $<$ 0.001), and AS-a versus HS-a was not changed.

We also included a free-response question via e-mail assessing whether the participants practiced skills in their clinical work at HS-b, BS-a, and HS-a. Table 4 presents the cumulative number of practiced skills. Throughout the three time points, FLE (cumulative number, 12) was more performed than PP (cumulative number, 8). Some participants responded: “If surgeons have experience in abdominal surgery, then PP can be performed without any resistance once they have experienced it by cadaver training” or “I used to consult with an orthopedic surgeon about procedures, such as FLE; however, after attending the seminar, I was able to do it on my own”.

4. Discussion

The present study comprised 60 senior surgeons. The interval between basic and advanced C-BEST was approximately 2 years. In PP, the SACL did not decrease at all six points. In FLE, SACL did not decrease at all six points, increased at BS-a versus AS-a, and did not decrease thereafter. Cumulatively, 12 FLEs and 8 PPs were performed during participants’ clinical work at HS-b, BS-a, and HS-a.

We previously reported that basic and advanced C-BEST were useful for trauma surgery training [6, 7]. Nonetheless, the issue was that SACL at half a year after the seminar was decreased compared with SACL immediately after the seminar. The issue of the decline in the cadaver training effect over time has been reported by several studies. Mackenzie et al. [8] evaluated extremity vascular exposure and FLE procedures in fresh cadavers for 38 surgical residents of average 14 months after taking the cadaver ASSET course and 10 experts practicing traumatologists of average 16 months after. They further evaluated the same procedures for 38 PGY 3–6 residents of average 14 months after taking the cadaver ASSET course, 35 practicing surgeons of average 30 months after, and 10 experts practicing traumatologists of average 46 months after [9]. They concluded that, in both studies, skill decreases were associated with interval procedure performance, and not time since taking the seminar [8, 9]. Conversely, there is also a report that the skills were maintained. Gunst et al. [10] held their original 1-day trauma surgery course using fresh cadavers. The five-point Likert scale of the 18 participants (6 trauma fellows and 12 surgical chief residents) significantly increased immediately after the course compared with that before the course and did not decrease several months after (average, 6 months). However, the number of participants in this report was small, and no follow-up report was issued. The evidence of skill retention has also been reviewed as lacking [11]. In our study, we did not study a control group in which no additional training was performed during the interval of approximately 2 years. However, if no training was done, we suppose that the SACL would decrease after 2 years, as reported by others.

Certainly, the best way to retain the skills acquired in the seminar training is to practice the procedures in the clinical work. Nevertheless, unlike the routine surgery procedure, the trauma surgery procedure cannot always be experienced. Hence, as a realistic countermeasure, the training will be repeatedly taken. Although many reports have suggested the usefulness of repeated attendance, few studies have actually verified it. Bruwaene et al. [12] performed a retention test after 5 months for 39 medical students divided into four groups of laparoscopic simulation training: (1) no additional training, (2) mass training with one instructor after 2.5 months, (3) five times training a month by a box trainer without an instructor, and (4) five times training a month by a virtual trainer without an instructor. The procedure was maintained in (3), followed by (2) more than in other groups. Moit et al. [13] conducted training using the “da Vinci” skill simulator from 2017 as robotic surgery training for the general surgery residency program. The program consisted of Phase 1 of training for PGY 1–2 and Phase 2 of PGY 3–5 refresh training every 6 months. Thereafter, the training evaluations of the six residents surveyed improved with each training.

To verify the assumption that “Repeated participation in the seminar can suppress the decline in cadaver training effects”, we focused on the idea that basic and advanced C-BEST have PP and FLE as common training procedures. We reintroduced the skills of PP and FLE in advanced C-BEST for the reason that the participants and instructors of orthopedic surgeons have commented the lack of practical procedures because these musculoskeletal procedures were performed on formalin-fixed cadavers in basic C-BEST. In that respect, we could use cadavers embalmed using the SSS method in advanced C-BEST. Cadavers embalmed using the SSS method were first developed by Coleman and Kogan [14], and we introduced it into cadaver surgical training to obtain a realistic feel [7, 15, 16]. It has also been reported that the cadavers embalmed using the SSS method are suitable for surgical training in the field of orthopedics dealing with the musculoskeletal system [17, 18].

The participants of this study were all senior surgeons who have surgical board certification, and the SACL was retained for PP and FLE, even at half a year after basic C-BEST. Furthermore, approximately 2 years (27.1 $\pm$ 6.9 months) after the first course, before taking advanced C-BEST, the SACL of PP and FLE were retained. However, although the SACL of PP was maintained at a high score, the SACL of FLE was not high. This may be because most of the participants were abdominal surgeons who would be familiar with PP because it involves incising the abdomen, but not with FLE, an orthopedic procedure. When the procedure was retaken, that is, refreshed participation [19], during this period of low self-confidence in FLE, the SACL of FLE significantly increased and was retained at half a year after. Meanwhile, PP maintained high self-evaluation values after retaking the seminar (Fig. 4). However, this result was from the senior surgeons and may be different if residents or physicians were the target. We would like to encourage the participants of various categories to retake C-BEST. We also believe that similar studies should be conducted on participants in other categories to verify these results.

Fig. 4.Changes in the 10-point self-assessment of confidence levels at six time points of the “pelvic package” and the “fasciotomy of the lower extremity”.
PP, pelvic package; FLE, fasciotomy of the lower extremity.
Six time points: before the seminar of basic cadaver-based educational seminar for trauma surgery (C-BEST) (BS-b), immediately after basic C-BEST (AS-b), half a year after basic C-BEST (HS-b), before advanced C-BEST (BS-a), immediately after advanced C-BEST (AS-a), and half a year after advanced C-BEST(HS-a).
Data are expressed as mean $\pm$ SD, with n = 60 participants. * P $<$ 0.001 versus BS-a in FLE.

This good result may have been influenced by the fact that the training was conducted with cadavers embalmed using the SSS method. Cadaver training involves the handling of cadavers. In the cadaver fixation method, in addition to our SSS method, there is a report using N-vinyl-2-pyrrolidone [20], and there is also a report of creating a perfusion model by cannulating the cadaver’s blood vessels [21, 22, 23, 24, 25]. In this way, cadaver training using a model closer to the living body may change the training effect of the participants and the result of their skills maintenance.

The confidence of these acquired skills was also confirmed in the practical example report in the free-response question obtained from them. This question was asked at HS-b, BS-a, and HS-a. Although the trauma surgery procedure cannot be experienced regularly, the most performed procedure was FLE (cumulative number, 7), which was answered half a year after the refresh participation (HS-a) (Table 4). The report from a gastroenterological surgeon at PGY 12 was impressive. While working at a regional hospital, he encountered a patient who showed lower leg compartment syndrome due to fractures of the lower leg by a motorcycle fall accident. The hospital had only an orthopedic resident who had no experience with FLE at that time. He took the lead in performing FLE with the orthopedic resident and then transferred the patient to a higher hospital. The patient was discharged without after-effects.

This study has a few limitations. First, the number of participants was small. Second, the evaluation items were only self-evaluation points with no objective index. Third, the participants evaluated were only senior surgeons. Lastly, there was no control group assessed for self-evaluation after approximately 2 years without refresh training. These limit the applicability of our results. Further studies with more participants, an objective evaluation index, various category participants, and a control group must address these limitations.

5. Conclusions

After participants retook the seminar, FLE-like procedures, which are unfamiliar to nonorthopedic surgeons, had increased and maintained self-evaluation values, whereas PP-like procedures, which are familiar to abdominal surgeons, had maintained high self-evaluation values. Therefore, repeated seminar participation could maintain the effects of cadaver training. This study is unprecedented as it investigated how reparticipation in cadaver training affects the retention of training effects over approximately 2 years.

Author contributions

HH designed the research study, and HH, JO, and HS performed the research. Additionally, JO, SK, and MI provided help and advice on the cadaver training, and HH analyzed the data and wrote the manuscript. All authors contributed to editorial changes in the manuscript and read and approved the final manuscript.

Ethics approval and consent to participate

The present study was approved by the Institutional Review Board (IRB) of the Faculty of Tokyo Medical University (IRB: SH3412). All study participants provided informed consent.

Acknowledgment

The authors wish to thank Mr. Zhong-Lian Li and Mr. Makoto Miyawaki for cadaver technical assistance, and Dr. Shiro Mishima for his advice on statistical analysis. The authors respect and appreciate the cadaver donors and their families.

Funding

This research received no external funding.

Conflict of interest

The authors declare no conflict of interest.