- Email: [email protected]
Training With Curved Laparoscopic Instruments in Single-Port Setting Improves Performance Using Straight Instruments: A Prospective Randomized Simulation Study
ORIGINAL REPORTS
Training With Curved Laparoscopic Instruments in Single-Port Setting Improves Performance Using Straight Instruments: A Prospective Randomized Simulation Study Peter Lukovich, MD, Valery Ben Sionov, MD, and Timea Kakucs, MD 1st Department of Surgery, Semmelweis University, Budapest, Hungary OBJECTIVE: Lately single-port surgery is becoming a widespread procedure, but it is more difficult than conventional laparoscopy owing to the lack of triangulation. Although, these operations are also possible with standard laparoscopic instruments, curved instruments are being developed. The aims of the study were to identify the effect of training on a box trainer in single-port setting on the quality of acquired skills, and transferred with the straight and curved instruments for the basic laparoscopic tasks, and highlight the importance of a special laparoscopic training curriculum. DESIGN: A prospective study on a box trainer in single-
port setting was conducted using 2 groups. Each group performed 2 tasks on the box trainer in single-port setting. Group-S used conventional straight laparoscopic instruments, and Group-C used curved laparoscopic instruments. Learning curves were obtained by daily measurements recorded in 7-day sessions. On the last day, the 2 groups changed instruments between each other. SETTING: 1st Department of Surgery, Semmelweis University of Medicine from Budapest, Hungary, a university teaching hospital. PARTICIPANTS: In all, 20 fifth-year medical students were
randomized into 2 groups. None of them had any laparoscopic or endoscopic experience. Participation was voluntary. RESULTS: Although Group-S performed all tasks significantly faster than Group-C on the first day, the difference proved to be nonsignificant on the last day. All participants achieved significantly shorter task completion time on the last day than on the first day, regardless of the instrument they used. Group-S showed improvement of 63.5%, and
Correspondence: Inquiries to Peter Lukovich, MD, 1st Department of Surgery, Semmelweis University of Medicine, , Üllői Street 78, Budapest H-1082, Hungary; fax: (36) 140-311-25; e-mail: [email protected]
348
Group-C 69.0% improvement by the end of the session. After swapping the instruments, Group-S reached significantly higher task completion time with curved instruments, whereas Group-C showed further progression of 8.9% with straight instruments. CONCLUSIONS: Training with curved instruments in a
single-port setting allows for a better acquisition of skills in a shorter period. For this reason, there is a need for proficiency-based conventional, but also for a single-port, laparoscopic training curriculum in general surgery resiC 2015 Associadency education. ( J Surg Ed 73:348-354. J tion of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.) KEY WORDS: straight instrument, curved instrument,
learning curve, single-port training curriculum COMPETENCIES: Practice-Based Learning and Improve-
ment, Interpersonal and Communication Skills, SystemsBased Practice
INTRODUCTION The “learning curve” concept was first introduced by Hermann Ebbinghaus in 1909, a German psychologist who pioneered the experimental study of memory, the “forgetting curve” and the “spacing effect.” In 1936, Theodore Paul Wright proposed a mathematical model for the learning curve in the aircraft industry. In medicine, the concept of learning curve was first assessed in coronary artery bypass grafting, mitral valvuloplasty, and the use of end-to-end anastomosis stapler for low rectal resection. The term was later introduced to laparoscopic surgery. The learning curve is characterized by a sudden drop in its first phase, followed by a second phase, in which the pace of the drop slows down. In the last stage, a straight line
Journal of Surgical Education & 2015 Association of Program Directors in Surgery. Published by 1931-7204/$30.00 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jsurg.2015.10.013
indicates no further significant changes, but the aspect depends on the interrelation of the trainee and the training method. The major examined parameter in the study of a surgical intervention’s learning curve is the operative time. However, the rate of complications, incidence of conversions, and the duration of hospital stay are also measured. As the initial phase of the learning curve is associated with a high incidence of complications, the common aim of the surgeons, patients, and health insurers is to shorten this initial phase. Published data show that multiple factors influence the learning process of laparoscopic surgery. It is obvious that virtual-reality simulators and training boxes have a positive effect on the learning process of laparoscopy, shortening the first phase of the curve.1 The findings of such investigations could enhance the efficiency of surgeons (in training) and improve patient safety. To acquire the basic knowledge, judgment, and technical skills required for laparoscopic operations, the Society of American Gastrointestinal and Endoscopic Surgeons developed an educational program titled “The Fundamentals of Laparoscopic Surgery” in 1997. The Fundamentals of Laparoscopic Surgery is composed of a cognitive component and a skill-based portion pertinent to laparoscopic surgery. The objectives of the manual skills module are (1) to require a surgeon to work using a monocular optical system, (2) to manipulate instruments placed through a trocar, and (3) to use both hands in a complementary fashion to manipulate objects within a box. A metric system was designed for each task to provide objective measurement of efficiency and precision and also penalize specific errors. In the United States, the Fundamentals of Laparoscopic Surgery examination is compulsory for the surgical board examination and has been adopted in several other countries. Natural Orifice Translumenal Endoscopic Surgery evolved in 2004 to reduce the invasive value of laparoscopic surgery, but numerous problems arose regarding this method. To find solutions of a certain extent, single-port surgery through the umbilicus has been developed. Although this could not eliminate difficulties completely, this does provide some solutions in many cases. The first interventions—such as in case of conventional laparoscopy —were simpler operation types (cholecystectomy2 and appendectomy). Lately, all surgical areas use this method. In 2014, the number of articles on single-site laparoscopic interventions published on Pubmed exceeded 100. An important limitation of single-port surgery is that the triangulation needed for a safe laparoscopic intervention cannot be achieved through a single incision. To eliminate this problem, several methods were introduced. The most appropriate method seems to be the one using special curved instruments. Nonetheless, a notable portion of surgeons still operate with conventional straight instruments through a single port. The number of surgical procedures performed using single-port access (SPA) is growing; however, the number
of publications on the training and efficiency of this technique and on its learning curve is still insignificant. Therefore, the aim of this study is to compare the acquired skills in using straight vs. curved instruments in a laparoscopic training box and underline their importance in the laparoscopic curriculum.
MATERIAL AND METHODS A total of 20 (n ¼ 20) fifth-year medical students without prior laparoscopic or surgical experience were recruited for this study at the 1st Department of Surgery of Semmelweis University, Budapest, Hungary. The study was approved by the Ethics Committee of the Department. Equipment The Single Incision Laparoscopic Surgery port by Covidien (Dublin, Ireland) was inserted into a standard training box. Both conventional straight (Olympus, Hamburg, Germany) and curved instruments (Covidien) were used in an SPA setting. Tasks Task 1 (Peg transfer): In this task, a series of 3 rings had to be transferred from the right site to the left of the box and vice versa. In all, 2 graspers had to be used while exchanging the rings between the 2 in air. Task 2 (Curved peg transfer): This task was similar to the first task, but the pegs were curved to create a further depth of perception. The participants had to perform the task in the same manner as the first one. Task 3 (Loops and string): This task required passing a string through 3 rings from the right to left. The string had to be passed successively through all rings, starting from the first. Timing for this task began when the participant grasped the string, and ended on its release (Fig. 1). Protocol The study participants were prospectively randomized into 2 groups of Group-S (straight and conventional instruments) and Group-C (curved instruments and in a crossed position). Group-S began the tasks in the SPA-straight setting that lasted for 7 consecutive days, and in the last session they switched to the SPA-curved setting. Group-C started the same tasks in the SPA-curved setting in the same manner, followed by the SPA-straight setting for the last session.
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A
B
C
FIGURE 1. The 3 tasks: (A) peg transfer, (B) curved peg transfer, and (C) loops and string.
All 20 participants completed all 3 tasks in their assigned setting, and changed the instruments in the last session. Daily measurements were recorded to obtain the learning curve for each group (Fig. 2). After completion of the study, a questionnaire was completed by the participants. Questionnaire The questionnaire completed at the end of the study consisted of 3 parts. The first part contained questions on the demographics and on previous experience (video games, music, and typing) of the trainees. In the second part, questions were asked regarding the handling and ergonomics of the instruments used in the different SPA settings (rated on a 5-point Likert scale: 5—strongly agree, 4— agree, 3—neutral, 2—disagree, and 1—strongly disagree). The final questions were concerning the opinion and preference of the participants of the straight instruments vs. the curved instruments.
proficiency in typing and playing a musical instrument (Table 1). On the first day, group-C reached higher task completion times in all 3 tasks than group-S. The completion time of the first and the third task demonstrated significant statistical difference (first task: 367 vs. 223 s, unpaired t-test with Welch correction, po 0.0001; third task: 606 vs. 456 s, unpaired t-test, Welch corrected, p ¼ 0.0054).
Participants (n=20)
Group-S Straight instruments
Group-C Curved instruments
(n=10)
(n=10)
Statistical Analysis The data were processed using the GraphPad Instat 3 (GraphPad Software, San Diego, CA) statistical program. We used the Kolmogorov-Smirnov test for normality analysis. Further evaluation of the data was performed using Mann-Whitney, paired and unpaired t-test, and Pearson and Spearman correlations. In all cases, p o 0.05 was considered to be statistically significant.
Task 1 Task 2 Task 3
seven sessions
Switched to Curved instruments
RESULTS
seven sessions
Switched to Straight instruments
final test
Group-C participants played more video games, but equivalent numbers of students in both groups reported 350
Task 1 Task 2 Task 3
final test
FIGURE 2. Study protocol.
Journal of Surgical Education Volume 73/Number 2 March/April 2016
TABLE 1. Demographics
Mean age (range) Female/male ratio Playing video games no. Playing on musical instrument no. Typing no.
Group-S (n ¼ 10) Conventional Instruments
Group-C (n ¼ 10) Curved Instruments
23.5 year (23-25) 4/6 5 (50%) 3 (30%) 8 (80%)
24 year (23-25) 5/5 4 (40%) 4 (40%) 9 (90%)
The second-task comparison showed no statistical difference (317 vs. 257 s, Mann-Whitney U test, p ¼ 0.19). The mean (3 tasks) completion was significantly shorter for Group-S than Group-C (938 vs. 1280 s, unpaired t-test, Welch corrected, p ¼ 0.0001). On the last day, the average task completion time of all 3 tasks was shorter for Group-S, but the difference was nonsignificant (338 vs. 430, unpaired t-test, Welch corrected, p ¼ 0.0724). The first task showed statistical significance in the 2 groups (94 s for Group-S vs. 119 s for Group-C, unpaired t-test, Welch corrected, p ¼ 0.025). Contrary to this, the second and third task demonstrated no statistical difference between the 2 groups (second task: 111 vs.126, unpaired t-test, Welch corrected, p ¼ 0.3313; third task: 131 vs. 185 s, Mann-Whitney U test, p ¼ 0.666). We found significant difference between the first and the last measurement in all cases (Table 2). Group-S showed a 61.9% improvement, whereas Group-C showed 65.8% improvement (steeper learning curve). On the last day, Group-S reached significantly higher task completion time with curved instruments, doubling its
TABLE 2. Statistical Analysis Between the First and Last Day of Measuring and Calculated Improvement During the Training Session First task First day Last day p Value Improvement Second task First day Last day p Value Improvement Third task First day Last day p Value Improvement Overall First day Last day p Value Improvement
Group-S
Group-C
223 s 94 s o0.0001 58%
367 s 119 s o0.0001 68%
257 s 111 s 0.0039 57 %
317 s 126 s o0.0001 60 %
456 s 131 s o0.0001 71%
606 s 185 s 0.0039 70 %
938 s 336 s o0.0001 62%
1280 s 430 s o0.0001 66%
time. Group-C showed 8.8% progression with straight instruments (Table 3 and Fig. 3). The participants considered that the curved instruments are more promising than the conventional (straight) instruments for SPA surgery. However, the straight instruments are easier to handle, whereas SPA-curved setting in a crossed manner is initially harder to learn. Participants complained of the need to cross the straight instruments, which decreases visibility during task completion (Table 4). Overall, most participants preferred curved instruments for future practice. The curved instruments’ usefulness was similar during the first 2 tasks (peg transfer ¼ 2.6 points and curved peg transfer ¼ 3.3) but for the third task, participants preferred the use of curved instruments in SPA (3.9 points).
DISCUSSION Laparoscopic surgery requires acquisition of special skills, such as video hand-eye coordination, “fulcrum” effect, and manipulation of long instruments. For this reason at the time of introduction of minimally invasive surgery, higher rates of complication were observed. In the last 3 decades, numerous articles were published supporting the role of training and education in minimally invasive surgery. However, not many centers have managed to implement a robust and competency-based educational system for laparoscopic training projects. Currently, the Fundamentals of Laparoscopic Surgery remains the most reputable training program. Although the principles of a functional laparoscopic educational system have not been completely identified yet, new efforts are being made to reduce the invasiveness of laparoscopic operations even more.3 Single-port surgery was developed with this purpose, although the advantages of the technique seem to be only cosmetic.4 The most encouraging evolution of laparoscopic surgery is the part of the Natural Orifice Transluminal Endoscopic Surgery that uses the instruments developed for single-port surgery. This technique can reduce the invasiveness, but concerns are raised by the aggravated postoperative pain and extended recovery time.5-7 To date, various types of operations are performed in SPA settings and the literature seems to complement this in theory.
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TABLE 3. Results After Changing the Instrument First task Last measurement Other instrument p Value Improvement Second task Last measurement Other instrument p Value Improvement Third task Last measurement Other instrument p Value Improvement Overall Last measurement Other instrument p Value Improvement
Group-S
Group-C
with the same instrument
94 s 202 s o0.0001 115%
119 s 113 s 0.7027 4%
with the same instrument
111 s 165 s 0.0178 49%
129 s 118 s 0.5052 8%
with the same instrument
133 s 272 s 0.0014 105%
185 s 158 s 0.8203 14%
with the same instrument
338 s 639 s 0.0012 90%
433 s 389 s 0.6318 9%
Despite the aforementioned outcomes, no educational platform has yet been established to address the technical requirements of SPA laparoscopic surgery. The major limitation of this type of access is related to a restrictive view because of intracorporeal and extracorporeal instrumental clash (crossing). To resolve this challenge, curved instruments were developed permitting a crossed or parallel positioning of the instruments intraabdominally.8 Comparative studies to date have not demonstrated any conclusive evidence with the 2 types of instruments (straight and curved ones).9 Performing the required tasks using a training box with SPA setting was found to be more difficult compared with traditional multiport laparoscopic settings, independent of the participant’s qualification and experience as well.10 The
most difficult part during the traditional multiport setting was the 2-dimensional vision and the depth perception, with poor maneuverability of the instruments in SPA.11 Curved instruments were developed more than 20 years ago, but they did not come into general use because of their difficult handling.12 Both the constant clash of the instruments and the unusual rotatory movements are troublesome,13 which was also confirmed by a SAGES learning center.11 Crossing the instruments can ease these problems, but it can cause the surgeons to use their nondominant hand,14 thus decreasing precision. Our results also proved the difficulty with the curved instruments, as the task completion time was nearly double for Group-C on the first day.
1400 1280 1200 1003 1000 838
938 800
716
638.34 Group-S with curved instruments
622
695 600
470
571 400
430
499 419 347
200
338
391.65 Group-C with straight instruments Improvement: 8.92%
0
Group-C
Group-S
FIGURE 3. Learning curve during the 7 days and result after changing to the other type of instrument. 352
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TABLE 4. Participants' Opinion About the Instruments on a 5-Point Likert Scale Mean (Standard Deviation) Opinion About the Instruments Visualization with the instruments Angle of movement Ergonomic properties General opinion
Straight Instruments 3.2 3 2.4 2.9
points points points points
(0.70) (0.90) (0.60) (0.75)
Practicing on a training box is recommended before the clinical use of these instruments, but there is no information about the necessary time or the expected improvement.15 No reliable conclusion was reached concerning the learning curve in single-port setting in previous studies, owing to the small number of participants and practice occasions. There is even less data on the effect of training with curved instruments on the performance with straight ones. Our results showed an unexpected pattern, as the task completion times for the 2 groups became similar by the last day, although there was a significant difference on the first day. Such improvement was recognized also by Kwasnicki et al. Medical students were divided into 2 groups and laparoscopic cholecystectomies were performed on porcine models. One of the groups began with 5 traditional laparoscopic cholecystectomies, whereas the other group started with 5 single-port cholecystectomies. The operation was switched to the other type at the 6th time. The duration documented for the 6th procedure performed by the members of the second group was similar to that of the traditional laparoscopic cholecystectomy group on its fifth day. The first group reached a significantly longer operation time when performing its first single-port cholecystectomy.14 In our study, Group-C showed further improvement with the straight instruments, whereas Group-S worsened its task completion time with the curved ones. Our hypothesis was that task completion time would decrease over the course of the evaluation for both groups, but unexpectedly at the end of the week, there was no significant difference between the task completion times of the 2 groups. We consider that Group-C achieved further improvement with the straight instruments, because working with the simpler type of instruments requires less complex spatial orientation and movement coordination than working with the curved ones. There is a consensus in the literature on the need for a structured training system for single-port surgery.16 Clinical practice proves that previous laparoscopic experience has a positive influence on acquiring the skills needed for singleport surgery, resulting in a steeper learning curve. This is because of the knowledge of the instruments, video handeye coordination, fulcrum effect, and 2-dimensional vision. However, traditional laparoscopic technical skills training curricula are insufficient for teaching single-port surgery skills.17 Moreover, for the SPA curriculum, specific exercises
Curved Instruments 3.4 3.7 2.7 3.6
points points points points
(0.83) (0.50) (0.82) (0.92)
p Value (Paired t-Test) 0.552 0.08 0.493 0.139
are necessary to be developed. This is especially true if we consider that surgeons not familiar with single-port surgery and crossed instruments tend to reverse the dominant and nondominant hand. In the first instance, curved instruments were used to stretch and to expose, whereas straight instruments were used for fine dissection.18 We also developed the curved peg transfer task to improve the skills for 3-dimensional orientation. The study by Kwasnicki should be considered for designing a laparoscopic educational curriculum. The initial results in their experiment were better for the SPA operations compared with traditional multiport procedures using Global Rate Score and procedure-specific rating scales. They explained these findings by the more difficult operative settings that may have caused participants to consider and concentrate on all movements, leading to a reduction in the risk of rushing and losing points through mistakes.14
CONCLUSION Based on our current study we can establish that similar results can be achieved with curved instruments and straight instruments after 1 week of training in single-port setting. In the long term, using curved instruments does not lead to prolongation of surgery time. As better triangulation can be performed while using curved instruments, supposedly better results could be achieved than with straight instruments, even if at the beginning of the learning curve a longer completion time can be observed. Considering that single-port operations are becoming more and more widespread, incorporating curved instrument training into a structured laparoscopic educational curriculum, or even into Fundamentals of Laparoscopic Surgerylike systems, should be considered. Even more, in view of Group-C’s improvement after changing to the straight instruments, we can declare that training with curved instruments leads to a steeper learning curve, resulting in a faster progress. Further investigations are needed to find out what effect it has on traditional laparoscopic skills. However, our study has some limitations (single institution study involving a relatively small number of participants); to the best of our knowledge this is the first study that examines an entire learning curve with crossed instruments in single-port setting and observes the acquired skills’ utility in working
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with straight instruments, this way initiating the basics of a structured single-port training curriculum.
uncrossed straight and curved instruments through a single port. Surg Endosc. 2012;26:3605-3611. 10. Santos BF, Enter D, Soper NJ, Hungness ES. Single
incision laparoscopic surgery (SILSTM) versus standard laparoscopic surgery: a comparison of performance using a surgical simulator. Surg Endosc. 2011;25:483-490.
REFERENCES 1. Debes AJ, Aggarwal R, Balasundaran I, Jacobsen MBJ.
Construction of an evidence-based, graduated training curriculum for D-box, a webcam-based laparoscopic basic skills trainer box. Am J Surg. 2012;203:768-775. 2. Cuesta MA, Berends F, Veenhof AA. The invisible
cholecystectomy. A transumbilical operation without a scar. Surg Endosc. 2008;22:1211-1213. 3. Navarra G, Pozza E, Occhionorelli S, Carcoforo P,
Donini I. One-wound laparoscopic cholecystectomy. Br J Surg. 1997;84:695. 4. Froghi F, Sodergren MH, Darzi A, Paraskeva P. Single
incision laparoscopic surgery (SILS) in general surgery: a review of current practice. Surg Laparosc Endosc Percutan Tech. 2010;20:191-204. 5. Bulian DR, Knuth J, Cerasani N, Sauerwald A,
11. Miernik A, Schoenthaler M, Lilienthal K, Frankensch-
midt A, Karcz WK, Kuesters S. Pre-bent instruments used in single-port laparoscopic surgery versus conventional laparoscopic surgery: comparative study of performance in a dry lab. Surg Endosc. 2012;26:1924-1930. 12. Islam A, Castellvi AO, Tesfay ST, Castellvi AD,
Wright AS, Scott DJ. Early surgeon impressions and technical difficulty associated with laparoendoscopic single-site surgery: a Society of American Gastrointestinal and Endoscopic Surgeons learning center study. Surg Endosc. 2011;25:2597-2603. 13. Cuschieri A, Shimi S, Banting S, Van Velpen G,
Dunkley P. Coaxial curved instrumentation for minimal access surgery. Endosc Surg Allied Technol. 1993; 1:30-35.
Lefering R, Heiss MM. Transvaginal/transumbilical hybrid-NOTES-versus 3-trocar needlescopic cholecystectomy: short-term results of a randomized clinical trial. Ann Surg. 2013.
14. Kwasnicki RM, Aggarwal R, Lewis TM, Purkayastha S,
6. Wood SG, Dabu-Bondoc S, Dai F, Mikhael H,
15. Botden S, Strijkers R, Fransen S, Stassen L, Bouvy N.
Vadivelu N, Roberts KE. Comparison of immediate postoperative pain after transvaginal versus traditional laparoscopic cholecystectomy. Surg Endosc. 2014;28 (4):1141-1145.
The use of curved vs. straight instruments in single port access surgery, on standardized box trainer tasks. Surg Endosc. 2011;25:2703-2710.
7. Borchert DH, Federlein M, Fritze-Büttner F, et al.
Postoperative pain after transvaginal cholecystectomy: single-center, double-blind, randomized controlled trial. Surg Endosc. 2014;28:1886-1894. 8. Philipp SR, Miedema BW, Thaler K. Single-incision
laparoscopic cholecystectomy using conventional instruments: early experience in comparison with the gold standard. J Am Coll Surg. 2009;209:632-637. 9. Rimonda R, Tang B, Brown SI, Cuschieri A. Compar-
ison of endoscopic task performance with crossed versus
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Darzi A, Paraskeva PA. A comparison of skill acquisition and transfer in single incision and multi-port laparoscopic surgery. J Surg Educ. 2013;70:172-179.
16. Müller EM, Cavazzola LT, Machado Grossi JV,
Mariano MB, Morales C, Brun M. Training for laparoendoscopic single-site surgery (LESS). Int J Surg. 2010;8:64-68. 17. Lewis T, Aggarwal R, Kwasnicki R, Darzi A, Paraskeva P.
Does previous laparoscopic experience improve ability to perform single-incision laparoscopic surgery? Surg Endosc. 2012;26:1214-1219. 18. Yang B, Xu B, Zeng O, et al. A specialized course of
basic skills training for single-port laparoscopic surgery. Surgery. 2011;149:766-775.
Journal of Surgical Education Volume 73/Number 2 March/April 2016
Training With Curved Laparoscopic Instruments in Single-Port Setting Improves Performance Using Straight Instruments: A Prospective Randomized Simulation Study Peter Lukovich, MD, Valery Ben Sionov, MD, and Timea Kakucs, MD 1st Department of Surgery, Semmelweis University, Budapest, Hungary OBJECTIVE: Lately single-port surgery is becoming a widespread procedure, but it is more difficult than conventional laparoscopy owing to the lack of triangulation. Although, these operations are also possible with standard laparoscopic instruments, curved instruments are being developed. The aims of the study were to identify the effect of training on a box trainer in single-port setting on the quality of acquired skills, and transferred with the straight and curved instruments for the basic laparoscopic tasks, and highlight the importance of a special laparoscopic training curriculum. DESIGN: A prospective study on a box trainer in single-
port setting was conducted using 2 groups. Each group performed 2 tasks on the box trainer in single-port setting. Group-S used conventional straight laparoscopic instruments, and Group-C used curved laparoscopic instruments. Learning curves were obtained by daily measurements recorded in 7-day sessions. On the last day, the 2 groups changed instruments between each other. SETTING: 1st Department of Surgery, Semmelweis University of Medicine from Budapest, Hungary, a university teaching hospital. PARTICIPANTS: In all, 20 fifth-year medical students were
randomized into 2 groups. None of them had any laparoscopic or endoscopic experience. Participation was voluntary. RESULTS: Although Group-S performed all tasks significantly faster than Group-C on the first day, the difference proved to be nonsignificant on the last day. All participants achieved significantly shorter task completion time on the last day than on the first day, regardless of the instrument they used. Group-S showed improvement of 63.5%, and
Correspondence: Inquiries to Peter Lukovich, MD, 1st Department of Surgery, Semmelweis University of Medicine, , Üllői Street 78, Budapest H-1082, Hungary; fax: (36) 140-311-25; e-mail: [email protected]
348
Group-C 69.0% improvement by the end of the session. After swapping the instruments, Group-S reached significantly higher task completion time with curved instruments, whereas Group-C showed further progression of 8.9% with straight instruments. CONCLUSIONS: Training with curved instruments in a
single-port setting allows for a better acquisition of skills in a shorter period. For this reason, there is a need for proficiency-based conventional, but also for a single-port, laparoscopic training curriculum in general surgery resiC 2015 Associadency education. ( J Surg Ed 73:348-354. J tion of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.) KEY WORDS: straight instrument, curved instrument,
learning curve, single-port training curriculum COMPETENCIES: Practice-Based Learning and Improve-
ment, Interpersonal and Communication Skills, SystemsBased Practice
INTRODUCTION The “learning curve” concept was first introduced by Hermann Ebbinghaus in 1909, a German psychologist who pioneered the experimental study of memory, the “forgetting curve” and the “spacing effect.” In 1936, Theodore Paul Wright proposed a mathematical model for the learning curve in the aircraft industry. In medicine, the concept of learning curve was first assessed in coronary artery bypass grafting, mitral valvuloplasty, and the use of end-to-end anastomosis stapler for low rectal resection. The term was later introduced to laparoscopic surgery. The learning curve is characterized by a sudden drop in its first phase, followed by a second phase, in which the pace of the drop slows down. In the last stage, a straight line
Journal of Surgical Education & 2015 Association of Program Directors in Surgery. Published by 1931-7204/$30.00 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jsurg.2015.10.013
indicates no further significant changes, but the aspect depends on the interrelation of the trainee and the training method. The major examined parameter in the study of a surgical intervention’s learning curve is the operative time. However, the rate of complications, incidence of conversions, and the duration of hospital stay are also measured. As the initial phase of the learning curve is associated with a high incidence of complications, the common aim of the surgeons, patients, and health insurers is to shorten this initial phase. Published data show that multiple factors influence the learning process of laparoscopic surgery. It is obvious that virtual-reality simulators and training boxes have a positive effect on the learning process of laparoscopy, shortening the first phase of the curve.1 The findings of such investigations could enhance the efficiency of surgeons (in training) and improve patient safety. To acquire the basic knowledge, judgment, and technical skills required for laparoscopic operations, the Society of American Gastrointestinal and Endoscopic Surgeons developed an educational program titled “The Fundamentals of Laparoscopic Surgery” in 1997. The Fundamentals of Laparoscopic Surgery is composed of a cognitive component and a skill-based portion pertinent to laparoscopic surgery. The objectives of the manual skills module are (1) to require a surgeon to work using a monocular optical system, (2) to manipulate instruments placed through a trocar, and (3) to use both hands in a complementary fashion to manipulate objects within a box. A metric system was designed for each task to provide objective measurement of efficiency and precision and also penalize specific errors. In the United States, the Fundamentals of Laparoscopic Surgery examination is compulsory for the surgical board examination and has been adopted in several other countries. Natural Orifice Translumenal Endoscopic Surgery evolved in 2004 to reduce the invasive value of laparoscopic surgery, but numerous problems arose regarding this method. To find solutions of a certain extent, single-port surgery through the umbilicus has been developed. Although this could not eliminate difficulties completely, this does provide some solutions in many cases. The first interventions—such as in case of conventional laparoscopy —were simpler operation types (cholecystectomy2 and appendectomy). Lately, all surgical areas use this method. In 2014, the number of articles on single-site laparoscopic interventions published on Pubmed exceeded 100. An important limitation of single-port surgery is that the triangulation needed for a safe laparoscopic intervention cannot be achieved through a single incision. To eliminate this problem, several methods were introduced. The most appropriate method seems to be the one using special curved instruments. Nonetheless, a notable portion of surgeons still operate with conventional straight instruments through a single port. The number of surgical procedures performed using single-port access (SPA) is growing; however, the number
of publications on the training and efficiency of this technique and on its learning curve is still insignificant. Therefore, the aim of this study is to compare the acquired skills in using straight vs. curved instruments in a laparoscopic training box and underline their importance in the laparoscopic curriculum.
MATERIAL AND METHODS A total of 20 (n ¼ 20) fifth-year medical students without prior laparoscopic or surgical experience were recruited for this study at the 1st Department of Surgery of Semmelweis University, Budapest, Hungary. The study was approved by the Ethics Committee of the Department. Equipment The Single Incision Laparoscopic Surgery port by Covidien (Dublin, Ireland) was inserted into a standard training box. Both conventional straight (Olympus, Hamburg, Germany) and curved instruments (Covidien) were used in an SPA setting. Tasks Task 1 (Peg transfer): In this task, a series of 3 rings had to be transferred from the right site to the left of the box and vice versa. In all, 2 graspers had to be used while exchanging the rings between the 2 in air. Task 2 (Curved peg transfer): This task was similar to the first task, but the pegs were curved to create a further depth of perception. The participants had to perform the task in the same manner as the first one. Task 3 (Loops and string): This task required passing a string through 3 rings from the right to left. The string had to be passed successively through all rings, starting from the first. Timing for this task began when the participant grasped the string, and ended on its release (Fig. 1). Protocol The study participants were prospectively randomized into 2 groups of Group-S (straight and conventional instruments) and Group-C (curved instruments and in a crossed position). Group-S began the tasks in the SPA-straight setting that lasted for 7 consecutive days, and in the last session they switched to the SPA-curved setting. Group-C started the same tasks in the SPA-curved setting in the same manner, followed by the SPA-straight setting for the last session.
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A
B
C
FIGURE 1. The 3 tasks: (A) peg transfer, (B) curved peg transfer, and (C) loops and string.
All 20 participants completed all 3 tasks in their assigned setting, and changed the instruments in the last session. Daily measurements were recorded to obtain the learning curve for each group (Fig. 2). After completion of the study, a questionnaire was completed by the participants. Questionnaire The questionnaire completed at the end of the study consisted of 3 parts. The first part contained questions on the demographics and on previous experience (video games, music, and typing) of the trainees. In the second part, questions were asked regarding the handling and ergonomics of the instruments used in the different SPA settings (rated on a 5-point Likert scale: 5—strongly agree, 4— agree, 3—neutral, 2—disagree, and 1—strongly disagree). The final questions were concerning the opinion and preference of the participants of the straight instruments vs. the curved instruments.
proficiency in typing and playing a musical instrument (Table 1). On the first day, group-C reached higher task completion times in all 3 tasks than group-S. The completion time of the first and the third task demonstrated significant statistical difference (first task: 367 vs. 223 s, unpaired t-test with Welch correction, po 0.0001; third task: 606 vs. 456 s, unpaired t-test, Welch corrected, p ¼ 0.0054).
Participants (n=20)
Group-S Straight instruments
Group-C Curved instruments
(n=10)
(n=10)
Statistical Analysis The data were processed using the GraphPad Instat 3 (GraphPad Software, San Diego, CA) statistical program. We used the Kolmogorov-Smirnov test for normality analysis. Further evaluation of the data was performed using Mann-Whitney, paired and unpaired t-test, and Pearson and Spearman correlations. In all cases, p o 0.05 was considered to be statistically significant.
Task 1 Task 2 Task 3
seven sessions
Switched to Curved instruments
RESULTS
seven sessions
Switched to Straight instruments
final test
Group-C participants played more video games, but equivalent numbers of students in both groups reported 350
Task 1 Task 2 Task 3
final test
FIGURE 2. Study protocol.
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TABLE 1. Demographics
Mean age (range) Female/male ratio Playing video games no. Playing on musical instrument no. Typing no.
Group-S (n ¼ 10) Conventional Instruments
Group-C (n ¼ 10) Curved Instruments
23.5 year (23-25) 4/6 5 (50%) 3 (30%) 8 (80%)
24 year (23-25) 5/5 4 (40%) 4 (40%) 9 (90%)
The second-task comparison showed no statistical difference (317 vs. 257 s, Mann-Whitney U test, p ¼ 0.19). The mean (3 tasks) completion was significantly shorter for Group-S than Group-C (938 vs. 1280 s, unpaired t-test, Welch corrected, p ¼ 0.0001). On the last day, the average task completion time of all 3 tasks was shorter for Group-S, but the difference was nonsignificant (338 vs. 430, unpaired t-test, Welch corrected, p ¼ 0.0724). The first task showed statistical significance in the 2 groups (94 s for Group-S vs. 119 s for Group-C, unpaired t-test, Welch corrected, p ¼ 0.025). Contrary to this, the second and third task demonstrated no statistical difference between the 2 groups (second task: 111 vs.126, unpaired t-test, Welch corrected, p ¼ 0.3313; third task: 131 vs. 185 s, Mann-Whitney U test, p ¼ 0.666). We found significant difference between the first and the last measurement in all cases (Table 2). Group-S showed a 61.9% improvement, whereas Group-C showed 65.8% improvement (steeper learning curve). On the last day, Group-S reached significantly higher task completion time with curved instruments, doubling its
TABLE 2. Statistical Analysis Between the First and Last Day of Measuring and Calculated Improvement During the Training Session First task First day Last day p Value Improvement Second task First day Last day p Value Improvement Third task First day Last day p Value Improvement Overall First day Last day p Value Improvement
Group-S
Group-C
223 s 94 s o0.0001 58%
367 s 119 s o0.0001 68%
257 s 111 s 0.0039 57 %
317 s 126 s o0.0001 60 %
456 s 131 s o0.0001 71%
606 s 185 s 0.0039 70 %
938 s 336 s o0.0001 62%
1280 s 430 s o0.0001 66%
time. Group-C showed 8.8% progression with straight instruments (Table 3 and Fig. 3). The participants considered that the curved instruments are more promising than the conventional (straight) instruments for SPA surgery. However, the straight instruments are easier to handle, whereas SPA-curved setting in a crossed manner is initially harder to learn. Participants complained of the need to cross the straight instruments, which decreases visibility during task completion (Table 4). Overall, most participants preferred curved instruments for future practice. The curved instruments’ usefulness was similar during the first 2 tasks (peg transfer ¼ 2.6 points and curved peg transfer ¼ 3.3) but for the third task, participants preferred the use of curved instruments in SPA (3.9 points).
DISCUSSION Laparoscopic surgery requires acquisition of special skills, such as video hand-eye coordination, “fulcrum” effect, and manipulation of long instruments. For this reason at the time of introduction of minimally invasive surgery, higher rates of complication were observed. In the last 3 decades, numerous articles were published supporting the role of training and education in minimally invasive surgery. However, not many centers have managed to implement a robust and competency-based educational system for laparoscopic training projects. Currently, the Fundamentals of Laparoscopic Surgery remains the most reputable training program. Although the principles of a functional laparoscopic educational system have not been completely identified yet, new efforts are being made to reduce the invasiveness of laparoscopic operations even more.3 Single-port surgery was developed with this purpose, although the advantages of the technique seem to be only cosmetic.4 The most encouraging evolution of laparoscopic surgery is the part of the Natural Orifice Transluminal Endoscopic Surgery that uses the instruments developed for single-port surgery. This technique can reduce the invasiveness, but concerns are raised by the aggravated postoperative pain and extended recovery time.5-7 To date, various types of operations are performed in SPA settings and the literature seems to complement this in theory.
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TABLE 3. Results After Changing the Instrument First task Last measurement Other instrument p Value Improvement Second task Last measurement Other instrument p Value Improvement Third task Last measurement Other instrument p Value Improvement Overall Last measurement Other instrument p Value Improvement
Group-S
Group-C
with the same instrument
94 s 202 s o0.0001 115%
119 s 113 s 0.7027 4%
with the same instrument
111 s 165 s 0.0178 49%
129 s 118 s 0.5052 8%
with the same instrument
133 s 272 s 0.0014 105%
185 s 158 s 0.8203 14%
with the same instrument
338 s 639 s 0.0012 90%
433 s 389 s 0.6318 9%
Despite the aforementioned outcomes, no educational platform has yet been established to address the technical requirements of SPA laparoscopic surgery. The major limitation of this type of access is related to a restrictive view because of intracorporeal and extracorporeal instrumental clash (crossing). To resolve this challenge, curved instruments were developed permitting a crossed or parallel positioning of the instruments intraabdominally.8 Comparative studies to date have not demonstrated any conclusive evidence with the 2 types of instruments (straight and curved ones).9 Performing the required tasks using a training box with SPA setting was found to be more difficult compared with traditional multiport laparoscopic settings, independent of the participant’s qualification and experience as well.10 The
most difficult part during the traditional multiport setting was the 2-dimensional vision and the depth perception, with poor maneuverability of the instruments in SPA.11 Curved instruments were developed more than 20 years ago, but they did not come into general use because of their difficult handling.12 Both the constant clash of the instruments and the unusual rotatory movements are troublesome,13 which was also confirmed by a SAGES learning center.11 Crossing the instruments can ease these problems, but it can cause the surgeons to use their nondominant hand,14 thus decreasing precision. Our results also proved the difficulty with the curved instruments, as the task completion time was nearly double for Group-C on the first day.
1400 1280 1200 1003 1000 838
938 800
716
638.34 Group-S with curved instruments
622
695 600
470
571 400
430
499 419 347
200
338
391.65 Group-C with straight instruments Improvement: 8.92%
0
Group-C
Group-S
FIGURE 3. Learning curve during the 7 days and result after changing to the other type of instrument. 352
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TABLE 4. Participants' Opinion About the Instruments on a 5-Point Likert Scale Mean (Standard Deviation) Opinion About the Instruments Visualization with the instruments Angle of movement Ergonomic properties General opinion
Straight Instruments 3.2 3 2.4 2.9
points points points points
(0.70) (0.90) (0.60) (0.75)
Practicing on a training box is recommended before the clinical use of these instruments, but there is no information about the necessary time or the expected improvement.15 No reliable conclusion was reached concerning the learning curve in single-port setting in previous studies, owing to the small number of participants and practice occasions. There is even less data on the effect of training with curved instruments on the performance with straight ones. Our results showed an unexpected pattern, as the task completion times for the 2 groups became similar by the last day, although there was a significant difference on the first day. Such improvement was recognized also by Kwasnicki et al. Medical students were divided into 2 groups and laparoscopic cholecystectomies were performed on porcine models. One of the groups began with 5 traditional laparoscopic cholecystectomies, whereas the other group started with 5 single-port cholecystectomies. The operation was switched to the other type at the 6th time. The duration documented for the 6th procedure performed by the members of the second group was similar to that of the traditional laparoscopic cholecystectomy group on its fifth day. The first group reached a significantly longer operation time when performing its first single-port cholecystectomy.14 In our study, Group-C showed further improvement with the straight instruments, whereas Group-S worsened its task completion time with the curved ones. Our hypothesis was that task completion time would decrease over the course of the evaluation for both groups, but unexpectedly at the end of the week, there was no significant difference between the task completion times of the 2 groups. We consider that Group-C achieved further improvement with the straight instruments, because working with the simpler type of instruments requires less complex spatial orientation and movement coordination than working with the curved ones. There is a consensus in the literature on the need for a structured training system for single-port surgery.16 Clinical practice proves that previous laparoscopic experience has a positive influence on acquiring the skills needed for singleport surgery, resulting in a steeper learning curve. This is because of the knowledge of the instruments, video handeye coordination, fulcrum effect, and 2-dimensional vision. However, traditional laparoscopic technical skills training curricula are insufficient for teaching single-port surgery skills.17 Moreover, for the SPA curriculum, specific exercises
Curved Instruments 3.4 3.7 2.7 3.6
points points points points
(0.83) (0.50) (0.82) (0.92)
p Value (Paired t-Test) 0.552 0.08 0.493 0.139
are necessary to be developed. This is especially true if we consider that surgeons not familiar with single-port surgery and crossed instruments tend to reverse the dominant and nondominant hand. In the first instance, curved instruments were used to stretch and to expose, whereas straight instruments were used for fine dissection.18 We also developed the curved peg transfer task to improve the skills for 3-dimensional orientation. The study by Kwasnicki should be considered for designing a laparoscopic educational curriculum. The initial results in their experiment were better for the SPA operations compared with traditional multiport procedures using Global Rate Score and procedure-specific rating scales. They explained these findings by the more difficult operative settings that may have caused participants to consider and concentrate on all movements, leading to a reduction in the risk of rushing and losing points through mistakes.14
CONCLUSION Based on our current study we can establish that similar results can be achieved with curved instruments and straight instruments after 1 week of training in single-port setting. In the long term, using curved instruments does not lead to prolongation of surgery time. As better triangulation can be performed while using curved instruments, supposedly better results could be achieved than with straight instruments, even if at the beginning of the learning curve a longer completion time can be observed. Considering that single-port operations are becoming more and more widespread, incorporating curved instrument training into a structured laparoscopic educational curriculum, or even into Fundamentals of Laparoscopic Surgerylike systems, should be considered. Even more, in view of Group-C’s improvement after changing to the straight instruments, we can declare that training with curved instruments leads to a steeper learning curve, resulting in a faster progress. Further investigations are needed to find out what effect it has on traditional laparoscopic skills. However, our study has some limitations (single institution study involving a relatively small number of participants); to the best of our knowledge this is the first study that examines an entire learning curve with crossed instruments in single-port setting and observes the acquired skills’ utility in working
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with straight instruments, this way initiating the basics of a structured single-port training curriculum.
uncrossed straight and curved instruments through a single port. Surg Endosc. 2012;26:3605-3611. 10. Santos BF, Enter D, Soper NJ, Hungness ES. Single
incision laparoscopic surgery (SILSTM) versus standard laparoscopic surgery: a comparison of performance using a surgical simulator. Surg Endosc. 2011;25:483-490.
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