| BackgroundSince the first report in 1991 by Reich et al, laparoscopic liver resection (LLR) has exponentially grown for treating benign and malignant tumors of the liver due to its advantages of minimal invasiveness. The benefits of LLR are less surgical trauma associated with less postoperative pain, less touch of the humor, reduced analgesic requirements, and an early return to normal daily activities. Even some of LLR, such as laparoscopic left lateral sectionectomy (LLLS), were introduced as a standard procedure for patients suitable for minimally invasive surgery (Louisiville statement). However, the adoption of LLR were appeared extremely low compared to other abdominal procedures, the reason might be the technical difficulty of LLR with a steep learning curve and its perceived risk such as intraoperative bleeding. Surgeons undertaking laparoscopic liver resection should have specialist training and expertise both in laparoscopic techniques and in the specific issues relating to liver surgery.Suture hemostasis is still essential to LLR as skilled suture ligature technique can reduce the rate of laparotomy, even good laparoscopic suturing technique can achieve the same effect with the open. In addition, repeatedly coagulation or bleeding blood vessel rupture in liver surgery, it is the need for suture hemostasis. However, compared with laparoscopic suture under direct vision, laparoscopic abdominal puncture fixed, suture knot angle limited, and the long of surgical instruments, limiting the mobile of the laparoscopic devices. In addition, the learning curve is long as the different 2D and 3D perspectives eye. In real life, the young doctor rarely have the opportunity to practice suture hemostasis in the bleeding situation, and thus, young doctors need to go through specialized training outside the operating room to master the technology.Various laparoscopic training programs are available, but their efficiency is dubious. The surgeons in most contraries were conventionally apprenticeship trained inside operation room. It is unclear whether trainees have enough access to these programs and whether they are sufficient enough to develop the required skills. Furthermore, it has been recognized that the modern operating room is not the ideal learning environment because of increasing time constraints, cost, stress, and ethical considerations.Simulation could provide the opportunity for a safe learning environment that is both immersive and experiential. Multiple studies have assessed the efficacy of simulation training and have shown that surgeons who are trained using simulation show improved technical skills in the operating room. However, most of the available systems are expensive and do not have tactile feedback. And to our knowledge, there is no virtual reality simulation program for LLR.Live animal training models could offer a wide range of training applications in acquiring advanced laparoscopic skills. However the live animals were expensive, with integral expertise for anesthesia and ethical concerns, making it difficult for widespread use for advanced training curriculum. Even in some countries (eg, United Kingdom), training with live animals is currently unavailable.Currently training models for laparoscopic suture knot training is mainly rubber models, as its simple preparation, cheap for purchase, but there is an obvious difference between the rubber model and real human tissue in not only their anatomical structure but also their texture. Liver tissue with complex pipeline structure and brittle texture, the slightest mistake will lead to intraoperative bleeding, making rubber model cannot meet the demand of the liver hemostatic sutures training techniques.As an alternative, in vitro animal organ, which could shorten the preparation time and lower the costs, might be the optimal model with which to be integrated into the advanced curriculum. Strickland et al. selected ex vivo lamb liver to perform the laparoscopic stitches with intracorporeal knots. However, this model didn’t have the circulation environment, which could not simulate the intraoperative bleeding.1993 Szinicz,G and the co-workers first proposed POP (pulsating organ perfusion, pulsatile perfusion of organ) concept. The study pump the ex-vivo liver using red-dry water and found this model can simulate the capillary oozing and bleeding lacerations caused by major blood vessels. But the water is easy to penetrate the vessel wall and blood vessels, making the trainees cannot distinguish the bleeding site. And in real surgical environment, less than 3mm of vascular can be used closed by knife ultrasound, so the water does not simulate the real perfusion surgery section. In addition, this study did not prove whether the pop model can be used for advanced skills training courses.The anatomy of the lamb liver lobes and hepatic portal is similar to the human liver, so the purpose of this study is to construct a simple, cost-effective, training model that can simulate liver blood circulation by combining the ex-vivo lamb liver and perfusion techniques and exploring a perfusion liquid impermeable. Then give a test of the model by construct validity and explore the learning curve of laparoscopic liver resection hemostasis technology, to provide a theoretical foundation for future LLR advanced training courses.ObjectiveThe aims of the study was to construct a simple, cost-effective, training model with maximum simulation of the in vivo situation for acquiring suture ligature skills involved in LLR and to construct a three-dimensional (3D) liver model of lamb liver. Construct validity will be proven for the suture hemostasis component of the model. Exploration of the learning curve of laparoscopic suture hemostasis technology will be performed, and hope that will provide theoretical basis for future LLR advanced training courses.MethodsThe study recruited 23 volunteers, divided into three groups:novices (postgraduates who had assisted at or observed laparoscopic procedures), Intermediates (attending doctors who had performed laparoscopic procedures such as laparoscopic cholecystectomy, but who rarely performed LLR procedures), Experts (surgeons who had extensive LLR experience). Recruitment was though personal communication. Written informed consent was obtained from all volunteers.1. Construction of the ex-vivo simulated bleeding modelWith the purpose of development of a better model for participants to perform laparoscopic suturing and knot tying, a specialized training device was constructed and an ex vivo lamb liver was selected. The training device consists of a metallic box and open laparoscopic simulated box. The lamb liver was placed on the board of the simulated box with numerous small holes and the hepatic vein or portal vein were infused with red-dyed liquid gelatin (30g gelatin mixture 100ml water) to simulate the blood supply of the liver. The main body of the metallic box was used as a reservoir that will store the dyed gelatin liquid. A laparoscope with a video-recording device was inserted into the middle port and was fixed at a predetermined set angle and focal length allowing the trainees to work independently. The video-recording device was connected to the computer to record each knot-tying procedure for later objective assessment.2. Construct a three-dimensional (3D) liver model of lamb liverTo visualize the biliary tree by perfusing perchloroethylene and ethyl acetate together with lead oxide, but the hepatic vein and portal vein were used dental base acrylic resin together with lead oxide injection casting. The sectional images were acquired by a 64-slice spiral CT. The 3D models of portal vein, hepatic vein, biliary tree, and liver parenchyma were reconstructed in Mimics software. Cast was acquired by corrode the soft tissue.3. Volunteers recruitedThe study recruited 23 volunteers, divided into three groups:novices (postgraduates who had assisted at or observed laparoscopic procedures), Intermediates (attending doctors who had performed laparoscopic procedures such as laparoscopic cholecystectomy, but who rarely performed LLR procedures), Experts (surgeons who had extensive LLR experience). Recruitment was though personal communication. Written informed consent was obtained from all volunteers.4. Task performedA longitudinal incision was made on the surface of the lamb liver, and 2 targets for needle placement were drawn onto the liver 10 mm away from each side of the incision. A superficial stitches, according to the predetermined points and a deep stiches at predetermined bleeding region were performed for once by intermediate and expert surgeons, and for ten sessions by novices. A standardized teaching video was shown to all novices and intermediates before commencing the tasks, demonstrating how to carry out a laparoscopic suture hemostasis. Before the task was performed, novices had completed dry laboratory training program such as, picking up beans and anatomizing the orange and all were able to navigate laparoscopic instruments harmoniously. The volunteers worked in group of 2, one guide the vacuum extractor and other performed the suture hemostasis. Novice performed the task once a day.5. Performance evaluationTime of completion, knot performance, suture placement accuracy,defined the parameters for superficial stiches assessment in this study. Time of completion defined the parameters for deep stiches assessment. Time of completion (seconds) was measured from the moment the needle was loaded onto the needle holder to when the suture was placed and secured with 3 throws. Accuracy was determined by measuring the distance (mm) between the entrance and exit points of the thread and the marked targets on the surface of the liver. A modified 23-point checklist, initially published by Munz Y.et al.2007 was used for quality evaluation of each superficial stitches performance.Construct validity will be proven if a model can differentiate between different levels of surgeon experience, and then can be used to assess technical skills. Comparison of time of completion at the first time between the three groups of surgeons was used to assess whether the suture hemostasis task was construct valid and substantiated the use of the training model to assess laparoscopic technical skill.Statistical analysis of the learning curves for novices was used to clarify whether repeated practice improved laparoscopic performance toward that of the experienced group, this can provide theoretical basis for future LLR advanced training courses.6. The training model evaluationQuestionnaire was designed to assess the reality of the liver model compared to the clinic were completed by all volunteers after the task, Date were collected using a Likert scale (1=strongly disagree; 2=disagree; 3=neither agree nor disagree; 4= agree; and 5=strongly agree). Feedback on the ex vivo liver model was obtained relative to the realism of the simulated blood supply,anatomical condition of the model, operative tactile properties, quality of the tissue and organ color, and over satisfaction during suture hemostasis.7. Statistically analysisStatistical analysis was performed with Microsoft Excel 2013 and SPSS 20.0 software. Comparison of performance between novice, intermediate and expert groups was undertaken using the One-way analyses of variance (ANOVA). Improvement for the novice group from the first experience to the tenth was analyzed using repeated measures ANOVA. Multiple comparisons were then made to identify when skills had plateaued. P< 0.05 was considered statistically significant.Results23 volunteers, consist of 11 novices,6 intermediate, and 6 experts, were recruited. All the intermediates and experts completed only one superficial stitches and deep stitches. The novices performed the task once a day during the 10-day training period. One novices performed 7 exercises because of the body reason and was exclude in our study, and others performed 10 exercises.1. Time of completionThe time of the task demonstrated construct validity, there were significant differences in time taken for superficial stitches between novices, intermediates, experts (755,271,174 sec, respectively; P< 0.001) and deep stitches (796,423,277 sec, respectively; P<0.001). There were also significant differences in the time of superficial and deep stitches between novice and intermediate, and novice and expert groups, but not between intermediate and expert groups.Analysis of learning curves for the novice group revealed significant levels of improvement for skills, the time taken for superficial stitches declined significantly from an initial 755±275 sec (range,398-1233 sec) to 202±49 sec (range,146-305sec), and for deep stitches declined from 796±321 sec (range,445-1667 sec) to 305±85 sec (range,221-494 sec). This metric was shown to plateau at the fifth for superficial stitch and sixth for deep.2. The suture and knot qualityThe superficial stitches revealed group differences between novices, intermediates, experts for suture accuracy (4.5,1.8,0.2 mm respectively; P< 0.001) and suturing knot performance (12.7,21.5,22.0 respectively; P< 0.001). There were also significant differences for suture accuracy between novice and intermediate (P= 0.004), novice and expert (P<0.001), and intermediate and expert groups (P=0.004). Suturing knot performance revealed group differences between both novice and intermediate (P<0.001), novice and expert groups (P<0.001), but not between intermediate and expert groups (P=0.693).Learning curves for the eleven novices were statistically significant (P<0.001) for suture accuracy and suturing knot performance, and the suture accuracy plateaued at the third repetition, but the suturing knot performance plateaued at the fourth session.3. Quality evaluation of the training modelQuestionnaires were completed by all the experts and intermediates, and analysis was performed. All of the specific comments given by the subjects were positive.4. The 3D modelThe 3D model could clearly display the spatial relationship between vasculature and soft tissue by resection liver tissue virtually.ConclusionThe simulated bleeding model of liver offers trainees an opportunity to acquire the advanced suture skill for LLR. The 3D model can clearly display the distribution of vessels and biliary tree stereoscopically. And the suture hemostasis skill improved significantly at the sixth exercise. |
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