Bench Model Research Articles

Quantitative assessment of pulmonary aspiration: A novel porcine model

ObjectivesPulmonary aspiration is a common cause of ventilator-associated pneumonia in the intensive care setting. Current bench and animal models of aspiration are based on the qualitative assessments. The purpose of the present study was to develop a porcine model for the real-time quantitative assessment of aspiration. MethodsFive sus scrofa piglets were anaesthetized and underwent placement of a pH probe through the endotracheal tube so that the distal tip of the probe resided at the carina. The pH probe was sutured to the posterior tracheal wall via an open approach and the position of the probe tip was verified by flexible endoscopy. 10mL of acidic solution (pH=2.7) was delivered through a catheter attached to the outside of the endotracheal tube so that the solution remained between the endotracheal tube and trachea proximal to the inflated endotracheal tube cuff. The pH probe was connected to a pH metre, a multifunctional data acquisition device with an analogue output signal measuring the voltage generated, and a computer for analysis. Leakage of fluid past the endotracheal tube cuff (aspiration) was therefore continuously assessed quantitatively by detecting voltage changes over a period of time. ResultsThe mean voltage of the tracheal mucosa at the beginning of the experiment (maximum voltage) was 916.6mV±24.5mV (range 891.0–945.7mV). There was a slight drop in voltage at the end of the 2h period to 840.8±22.6mV (range=812.3–867.3mV). After deflation of the endotracheal tube cuff, the mean voltage dropped to 497.3mV±24.8mV (range 435.7–567.1mV) with a mean drop in voltage of 419.3mV±32.6mV (range 368.9–455.3mV). ConclusionsThis porcine model allows for the continuous quantitative assessment of aspiration over time. Such a model may be of value for the evaluation of techniques for reducing aspiration.

Non-invasive high-frequency oscillatory ventilation (n-HFOV). Thoughts about a bench model

Non-invasive high-frequency oscillatory ventilation (n-HFOV). Thoughts about a bench model

Beyond the Young-Laplace model for cluster growth during dewetting of thin films: Effective coarsening exponents and the role of long range dewetting interactions

Long range dewetting forces acting across thin films, such as the fundamental van der Waals interactions, may drive the formation of large clusters (tall multilayer islands) and pits, observed in thin films of diverse materials such as polymers, liquid crystals, and metals. In this study we further develop the methodology of the nonequilibrium statistical mechanics of thin films coarsening within continuum interface dynamics model incorporating long range dewetting interactions. The theoretical test bench model considered here is a generalization of the classical Mullins model for the dynamics of solid film surfaces. By analytic arguments and simulations of the model, we study the coarsening growth laws of clusters formed in thin films due to the dewetting interactions. The ultimate cluster growth scaling laws at long times are strongly universal: Short and long range dewetting interactions yield the same coarsening exponents. However, long range dewetting interactions, such as the van der Waals forces, introduce a distinct long lasting early time scaling behavior characterized by a slow growth of the cluster height/lateral size aspect ratio (i.e., a time-dependent Young angle) and by effective coarsening exponents that depend on cluster size. In this study, we develop a theory capable of analytically calculating these effective size-dependent coarsening exponents characterizing the cluster growth in the early time regime. Such a pronounced early time scaling behavior has been indeed seen in experiments; however, its physical origin has remained elusive to this date. Our theory attributes these observed phenomena to ubiquitous long range dewetting interactions acting across thin solid and liquid films. Our results are also applicable to cluster growth in initially very thin fluid films, formed by depositing a few monolayers or by a submonolayer deposition. Under this condition, the dominant coarsening mechanism is diffusive intercluster mass transport while the cluster coalescence plays a minor role, both in solid and in fluid films.

Bench surgical training with lyophilized esophageal segments

To present lyophilized esophageal segments that can be used to learn surgical skills. Four esophagus were harvested from four non-esophagus related research dogs at the moment of euthanasia. Each esophagus was trimmed in 3 cm long segments. They were lyophilized and stored during 30 days. The day programmed for surgical skills practice, they were rehydrated. Sixteen segments have been used. After rehydrating, all the segments kept their normal anatomic shape and structural integrity. One incision was made on every esophageal segment and sutured with running stitches of 3-0 polyglactin 910. There were no complications, such as tissue tears, nor esophageal hardening. The lyophilized esophagus is a high fidelity, practical, reproducible, portable, low-cost bench model. It allows general surgery apprentices to learn how to handle an esophagus, as well as to perfect their surgical and suture abilities before applying them on real patient's esophagus.

Computer-assisted teaching of skin flap surgery: validation of a mobile platform software for medical students.

The purpose of this study was to develop and validate a multimedia software application for mobile platforms to assist in the teaching and learning process of design and construction of a skin flap. Traditional training in surgery is based on learning by doing. Initially, the use of cadavers and animal models appeared to be a valid alternative for training. However, many conflicts with these training models prompted progression to synthetic and virtual reality models. Fifty volunteer fifth- and sixth-year medical students completed a pretest and were randomly allocated into two groups of 25 students each. The control group was exposed for 5 minutes to a standard text-based print article, while the test group used multimedia software describing how to fashion a rhomboid flap. Each group then performed a cutaneous flap on a training bench model while being evaluated by three blinded BSPS (Brazilian Society of Plastic Surgery) board-certified surgeons using the OSATS (Objective Structured Assessment of Technical Skill) protocol and answered a post-test. The text-based group was then tested again using the software. The computer-assisted learning (CAL) group had superior performance as confirmed by checklist scores (p<0.002), overall global assessment (p = 0.017) and post-test results (p<0.001). All participants ranked the multimedia method as the best study tool. CAL learners exhibited better subjective and objective performance when fashioning rhomboid flaps as compared to those taught with standard print material. These findings indicate that students preferred to learn using the multimedia method.

Quantification of Surgical Technique Using an Inertial Measurement Unit

Quantifying the algorithmic information content of hand motion patterns during a surgical task enables the comparison of different groups, novice and expert. Previously, we have shown that the information content/complexity of hand motion patterns during the surgical skill/subtask of knot tying reduces with increased expertise (J Surg Educ 2012;69:306-310). We therefore hypothesized that the information content/complexity of motion patterns would also reduce with expertise during a more complex surgical task of a bench model venous anastomosis. A custom inertial measurement unit was used to record 6-degrees of freedom hand motion from the right hand during a low-fidelity bench model venous anastomosis. Data were obtained from 2 groups as follows: novice (surgical residents, postgraduate year 1 and 2) and expert (attending surgeons). Each data set from the surgical task was processed into a symbolic time series from which the algorithmic entropy measure Lempel-Ziv complexity was calculated. A Student t test was used to test whether the 2 groups were sampled from the same population when using this metric, applying a P value of 0.05 to reject the null hypothesis. The expert surgeons had more complex patterns of motion compared with novice surgeons during this surgical task. This was statistically significant using the Lempel-Ziv complexity metric (P = 0.01). The hypothesis that increased surgical experience would reduce the complexity of hand motion patterns was not found to be true during this surgical task, and the opposite was found to be true. An alternative hypothesis that would combine the previous finding of a reduction in complexity of a subtask with this study's finding of increasing complexity of the whole task with increasing surgical expertise could be due to a hierarchy of pattern structure: experts use simpler subtask motifs in more complex and denser patterns.

Open Surgical Simulation—A Review

BackgroundSurgical simulation has benefited from a surge in interest over the last decade as a result of the increasing need for a change in the traditional apprentice model of teaching surgery. However, despite the recent interest in surgical simulation as an adjunct to surgical training, most of the literature focuses on laparoscopic, endovascular, and endoscopic surgical simulation with very few studies scrutinizing open surgical simulation and its benefit to surgical trainees. The aim of this review is to summarize the current standard of available open surgical simulators and to review the literature on the benefits of open surgical simulation. Current State of Open Surgical SimulationOpen surgical simulators currently used include live animals, cadavers, bench models, virtual reality, and software-based computer simulators. In the current literature, there are 18 different studies (including 6 randomized controlled trials and 12 cohort studies) investigating the efficacy of open surgical simulation using live animal, bench, and cadaveric models in many surgical specialties including general, cardiac, trauma, vascular, urologic, and gynecologic surgery. The current open surgical simulation studies show, in general, a significant benefit of open surgical simulation in developing the surgical skills of surgical trainees. However, these studies have their limitations including a low number of participants, variable assessment standards, and a focus on short-term results often with no follow-up assessment. Future of Open Surgical SimulationThe skills needed for open surgical procedures are the essential basis that a surgical trainee needs to grasp before attempting more technical procedures such as laparoscopic procedures. In this current climate of medical practice with reduced hours of surgical exposure for trainees and where the patient’s safety and outcome is key, open surgical simulation is a promising adjunct to modern surgical training, filling the void between surgeons being trained in a technique and a surgeon achieving fluency in that open surgical procedure. Better quality research is needed into the benefits of open surgical simulation, and this would hopefully stimulate further development of simulators with more accurate and objective assessment tools.

Biodegradability Assessment and Treatability of High Strength Complex Industrial Park Wastewater

AbstractIndustrial park wastewater (IPWW) includes complex non‐biodegradable organic compounds. A wastewater treatability study using biodegradability assessment approach was carried out for an industrial park housing mainly textile and machinery sectors. Biodegradable and inert chemical oxygen demand (COD) fractions with soluble and particulate counterparts were experimentally estimated by implementing respirometric methods. Aerobic batch test methods and oxygen uptake rate profiles were used to map kinetic parameters and COD fractions. Denitrification potential was also determined by application of anoxic batch tests. Relevant kinetic constants, stoichiometric, and design parameters were determined for biological processes. Tests were carried out for raw and physico‐chemically pre‐treated IPWW. Hence, it was aimed to assess the effects and necessity of pre‐treatment on biological processes. Biological mineralization, nitrification, and denitrification processes were also designed and tested using a bench scale continuous treatment model for pre‐treated IPWW. The sum of initial inert soluble COD fraction and production of soluble microbial products decreased about 25% for the case of pre‐treated IPWW as compared to raw IPWW. Eighty‐three percent total COD and 89% total Kjeldahl nitrogen removal efficiencies were attained for the modeling experiments of pre‐treated IPWW. Results showed the significance of pre‐treatment if complex strength industrial wastewaters are to be biologically treated.

Pressure changes during tracheal suctioning – a laboratory study

Suctioning is essential in managing tracheal tubes, but also has drawbacks. Using a bench model, we demonstrated the extent and time course of pressure changes during suctioning, examined their relationship with tracheal tube and catheter diameters and assessed the effects of artificial 'sputum' and of compensatory gas flow in the system. We suctioned at -20kPa (-150mmHg) and -80kPa (-600mmHg) using three different sized catheters and a 5.9-mm diameter bronchoscope through tracheal tubes ranging from 6.5mm to 9.0mm in diameter. Pressure changes ranged from -0.1kPa (-0.8mmHg) to -20.4kPa (-153.0mmHg). We demonstrated more negative pressures with decreasing tracheal tube diameter (p=0.024) and increasing catheter diameter (p=0.038). Addition of artificial 'sputum' led to more negative, but unpredictable, pressures than those seen with clean tubes (p=0.012). Bronchoscopic suctioning produced pressure changes even greater than the largest suction catheter (p=0.0039). Using a closed system with continuous positive airway pressure and 155l.min(-1) compensatory gas flow attenuated the pressure changes generated both with a 4.0-mm catheter (p=0.0005) and on bronchoscopic suctioning (p=0.0078). The time taken to reach 50% of minimum pressure was always less than 1s. The use of high compensatory flows during suctioning merits clinical evaluation.

Modelling the left ventricle using rapid prototyping techniques

Biomechanical research of left ventricular function involves the assessment and understanding of both ventricular wall mechanics and deformation and intraventricular flow patterns, as well as how they interact. Experimental research using hydraulic bench models should therefore aim for an as realistic as possible simulation of both. In previous experimental investigations, wall deformation was studied by means of thin-walled passive experimental models, consisting of a silicone membrane in a closed box, which is squeezed passively by an externally connected piston pump. Although the pump function of these models has already been well established, the membrane deformation remains unpredictable and the effect of muscle contraction – and hence natural wall deformation – cannot be simulated. In this study, we propose a new design of an experimental hydraulic left ventricular model in which left ventricular wall deformation can be controlled. We built this model by a combination of rapid prototyping techniques and tested it to demonstrate its wall deformation and pump function. Our experiments show that circumferential and longitudinal contraction can be attained and that this model can generate fairly normal values of pressure and flow.

Improving laparoscopic suturing skills

Acquiring surgical skills is an important and very challenging step during residency. We remember the classic paradigm, “See one, do one, teach one,” that applied to open surgery. The rapid and massive development of minimally invasive surgery (MIS) emphasized the urgent need to change this paradigm. Therefore, MIS skill laboratories have been created to transfer the surgical learning curve from the operating room (OR) to a more friendly, stress-free environment where residents can train without the limitations of OR time and can be assessed objectively through different physical and virtual reality simulators. Most of the urology residency programs in North America now include an MIS curriculum where residents are assessed on a regular basis in dry laboratories before gaining access to animal laboratories and then to patients. Laparoscopic suturing remains a very advanced technical step that is the key to reconstructive urological procedures such as laparoscopic radical prostatectomy, laparoscopic pyeloplasty and laparoscopic partial nephrectomy. Laparoscopic radical prostatectomy is a complex procedure requiring a difficult dissection directly related to familiarity with the male pelvic anatomy. Then a complex vesico-urethral anastomosis in a deep and narrow pelvis should be performed with interrupted or running suture. Obviously this step could be mastered in a more expeditious way if we were able to train residents on a good task-specific model mimicking the surgical procedure. The prospective randomized study by Sabbagh and colleagues1 comparing training on a task-specific low-fidelity bench suturing model versus basic laparoscopic suturing clearly demonstrates the superiority of the bench model. It therefore nicely proves that as difficult a laparoscopic task as vesico-urethral anastomosis could be learned and mastered outside of the OR with objective scoring assessment. The authors should therefore be commended for this achievement.

Task-specific bench model training versus basic laparoscopic skills training for laparoscopic radical prostatectomy: a randomized controlled study

Performing a laparoscopic urethrovesical anastomosis (LUA) after a radical prostatectomy is technically challenging for the novice laparoscopic surgeon. We developed a low-fidelity urethrovesical model (UVM) to allow a urologist to practise this critical step. The aim of our study was to compare the effect of task-specific bench model training (anastomotic suturing on the UVM) with that of basic laparoscopic suturing on intracorporeal urethrovesical anastomosis performance. We recruited 28 senior surgical residents, fellows or staff surgeons for this prospective, single-blinded, randomized controlled study. We randomly assigned participants to an intervention group practising LUA on the UVM or to a control group practising basic laparoscopic suturing and knot-tying on a foam pad. After practising, we videotaped participants performing 5 intra-corporeal interrupted sutures on a foam pad and a LUA on the UVM. A blinded expert scored the videotaped performance using a laparoscopic suturing checklist (CL) and a global rating scale (GRS), and timed the performance. On the foam pad suturing task, the group that trained on the UVM had significantly higher CL scores (10.9 v. 8.1, p = 0.017). On the LUA task, the group that trained on the UVM had significantly higher CL scores (10.9 v. 8.1, p = 0.017), GRS (29.6 v. 22.8, p = 0.005) and shorter times (27.6 v. 38.3 min, p = 0.004) than the control group. Our task-specific bench model was shown to be superior to basic laparoscopic suturing drills on a foam pad.

Pressure fluctuations in a hydrogen supply system during hydrogen injection

A test bench and simulation model are established to investigate the pressure fluctuations in the port fuel-injected hydrogen system of an internal combustion engine. Analyses are conducted, with injection pressure varied from 0.2 to 0.45 MPa and injection pulse width varied from 2 to 10 ms. The test and simulation results show that more severe fluctuations occur, fluctuation ranges are greater, and decay times are longer under higher injection pressures. Pressure decreases at the curve of pressure at the time during which the injector is opened. This time can be calculated by simulation. t0 decreases from 1.33 to 0.45 ms at an increase in injection pressure of 0.2–0.45 MPa. Therefore, the hydrogen injection time of the internal combustion engine is accurately controlled by considering t0 under different conditions. The results serve as guidance in the design of hydrogen rails in hydrogen internal combustion engine.

When Does a Left Anterior Descending Stenosis Alter Flow Across a Left Main Segment?

Attributed to Albert Einstein, the saying, “Everything should be made as simple as possible, but not simpler,” embodies a concept that certainly applies to our understanding and interpretation of fractional flow reserve (FFR) across the most clinically important stenosis interventionalists encounter, the left main (LM) stenosis. Remarkable technical advances supported by multicenter, long-term outcome studies have validated FFR for daily use in the cardiac catheterization laboratory. FFR, the ratio of coronary pressure beyond a stenosis to the aortic pressure (representing the normal coronary pressure in the absence of a stenosis), measured during maximal hyperemia (ie, minimal myocardial bed resistance) identifies the ischemic potential of the lesion. In practice, FFR guidance for multivessel percutaneous coronary intervention compared with angiographic guidance alone produces better clinical and economic outcomes.1,2 Article see p 161 Such as occurs with all diagnostic testing in medicine, the correct interpretation of results depends not only on the quality of the testing method, but also on the clinical circumstances under which the test is conducted. The same principle applies to FFR. Measuring FFR across an LM stenosis without disease in its branches is relatively simple. The pressure wire is advanced beyond the narrowing into the unobstructed branches, either the left anterior descending (LAD) or the circumflex (CFX) artery, and hyperemic coronary and aortic pressure ratios are computed as FFR. A few caveats for obtaining an accurate FFR include correct zeroing and equilibration of pressures, ensuring the guide catheter is not obstructing LM flow, and administering an adequate dose of adenosine (Table). For the slightly more complicated scenario of a distal LM bifurcation lesion, one should measure FFR in both branches. In either case, LM lesions treated medically for FFR >0.80 are associated with excellent 5-year major adverse cardiac event rates.3 Now for the not-so simple …

Synchronized oxygen delivery and its optimization method: A bench study

Long-term oxygen therapy (LTOT) has been widely used to treat patients with chronic obstructive pulmonary disease. The traditional oxygen delivery methods used for LTOT are continuous flow oxygen (CFO) and demand oxygen delivery (DOD). CFO wastes a considerable amount of oxygen, whereas DOD often makes patients feel uncomfortable because it abruptly supplies a large amount of oxygen at the onset of inhalation. Hence, we developed an algorithm for predicting the onset of inhalation, which allowed oxygen to be supplied smoothly before inhalation. Moreover, we minimized the discomfort index (DI) to offer more comfortable oxygen delivery. By integrating the prediction algorithm and the minimization of DI, the previous synchronized demand oxygen delivery (SDOD) method was modified. We constructed a bench model to validate the modified SDOD. The results showed that the proposed algorithm accurately predicted the onset of inhalation. The difference in the real-time measured and predicted values for the beginning of inhalation was less than 0.10 s. Using the proposed minimization technique, the DI was decreased by 50% under 20 breaths per minute when compared with the DI calculated from a previous study. In conclusion, the modified SDOD could supply oxygen more comfortably while synchronizing with patient breathing patterns.

The role of simulation in the development of technical competence during surgical training: a literature review

ObjectivesTo establish the current state of knowledge on the effect of surgical simulation on the development of technical competence during surgical training.MethodsUsing a defined search strategy, the medical and educational literature was searched to identify empirical research that uses simulation as an educational intervention with surgical trainees. Included studies were analysed according to guidelines adapted from a Best Evidence in Medical Education review.ResultsA total of 32 studies were analysed, across 5 main categories of surgical simulation technique - use of bench models and box trainers (9 studies); Virtual Reality (14 studies); human cadavers (4 studies); animal models (2 studies) and robotics (3 studies). An improvement in technical skill was seen within the simulated environment across all five categories. This improvement was seen to transfer to the real patient in the operating room in all categories except the use of animals.ConclusionsBased on current evidence, surgical trainees should be confident in the effects of using simulation, and should have access to formal, structured simulation as part of their training. Surgical simulation should incorporate the use of bench models and box trainers, with the use of Virtual Reality where resources allow. Alternatives to cadaveric and animal models should be considered due to the ethical and moral issues surrounding their use, and due to their equivalency with other simulation techniques. However, any use of surgical simulation must be tailored to the individual needs of trainees, and should be accompanied by feedback from expert tutors.

Teaching Basic Plastic Surgical Skills on an Alternative Synthetic Bench Model

Currently, plastic surgery occupies a negligible component of many undergraduate curricula, and its recognition as a specialty is poorly understood by both medical students and primary care physicians.1,2 One important reason for this is that medical students are seldom exposed to plastic surgery.1,2 Because it is difficult to change the undergraduate curriculum, alternative solutions are required for increased exposure to plastic surgery at the undergraduate level.1,2 To meet that need, we propose training in basic surgical skills pertinent to plastic surgery on an alternative low-fidelity synthetic bench model, prepared with 2.5-mm-thick laminated plates composed of rubber (flattened pure polyvinyl chloride) reinforced with mesh (polyester and cotton) (Emborrachado or Rubberised Line; Kelson's Industria e Comercio S.A., Rio de Janeiro, Brazil). Generally, these plates are used in the manufacture of decorative objects such as handpainted rugs and are readily purchased at craft stores (eg, Sonalk Representacoes Ltda, Sa Paulo, Brazil, and ANMAG Representacoes Ltda, Rio de Janeiro, Brazil). This synthetic material can also be purchased and shipped anywhere in the world through …

Development, Validation, and Implementation of a Cost-Effective Intermediate-Level Proficiency-Based Knot-Tying and Suturing Curriculum for Surgery Residents

The purpose of this study was to develop an intermediate-level proficiency-based knot-tying and suturing curriculum, evaluate construct validity, determine feasibility, document educational benefit, and quantify cost-effectiveness of implementation within a surgery residency program. Six tasks with standardized metrics were developed using commercially available bench models; 39 PGY-1 surgery residents were enrolled in a 2-month curriculum (orientation/pre-test, self-practice, and a proctored post-test). Baseline trainee and expert performance were compared to assess construct validity. Baseline trainee and expert performance were significantly different (451 ± 83 vs 644 ± 10, p < 0.001), supporting construct validity. All trainees achieved proficiency during self-practice, completing 30 ± 17 repetitions over 3.4 ± 3.8 hours. Significant differences were detected between baseline and final trainee composite scores (451 ± 83 vs 607 ± 34, p < 0.001). Implementation of this curriculum was feasible and cost-effective. Construct validity and educational benefit in terms of skill acquisition were demonstrated. The purpose of this study was to develop an intermediate-level proficiency-based knot-tying and suturing curriculum, evaluate construct validity, determine feasibility, document educational benefit, and quantify cost-effectiveness of implementation within a robust surgery residency training program.

A Cadaveric Porcine Model for Assessment in Laparoscopic Bariatric Surgery—a Validation Study

Laparoscopic Roux-en-Y gastric bypass (LRYGBP) is the most effective surgical therapy for morbid obesity. It is an advanced laparoscopic surgical procedure and has a protracted learning curve. Therefore, it is important to develop innovative ways of training and assessing surgeons. The aim of this study is to determine if a cadaveric porcine jejuno-jejunostomy model is an accurate way of assessing a surgeon's technical skills by determining if a correlation exists with how he performs in the operating room. Eight surgeons of varying experience performed a side-to-side stapled jejuno-jejunostomy on a cadaveric bench model before proceeding to perform the procedure on a real patient scheduled for LRYGBP. Performance was assessed using a motion tracking device, the Imperial College Surgical Assessment Device. Each procedure was recorded in video and scored by two blinded expert surgeons using procedure-specific rating scales. The cadaveric bench model demonstrated concurrent validity with significant correlations between performance on the cadaveric model and patient for dexterity measures. Left-hand path length, r = 0.857 (median, 27, 41.3; P = 0.007), right-hand path length, r = 0.810 (median, 31.5, 60; P = 0.015) and total number of movements, r = 0.743 (median, 422, 637; P = 0.035). This correlation in performance was also demonstrated in the video rating scales, r = 0.727 (median, 13.2, 14.8; P = 0.041). No correlation was found in operative time (median, 541, 742; P = 0.071). This study demonstrates the concurrent validity of the cadaveric porcine model, showing similar performances in surgeons completing a jejuno-jejunostomy on the cadaveric model and the patient.

Acquisition of suture skills during medical graduation by instructor-directed training: a randomized controlled study comparing senior medical students and faculty surgeons

Due to shortage of time and limited availability of faculty surgeons to teach basic surgical skills during medical graduation, the search for alternative ways of simulated training with feedback is needed. The purpose of this study was to compare the simulated teaching of suture skills to novice medical students by senior medical students and by experienced faculty surgeons. Forty-eight novice medical students were randomly assigned to three practice conditions on bench model (n=16): self-directed suture training (control), senior medical student-directed suture skills' training, or experienced faculty surgeon-directed suture skills' training. Pre- and post-tests were applied. Global Rating Scale with blinded evaluation and self-perceived confidence based on Likert scale were used to assess all suture performances in pre- and post-training. Effect size was also calculated. The analysis made after training showed that the students who received feedback from the instructors had better performance based on the Global Rating Scale (all p<0.0000) and felt more confident to carry out sutures (all p<0.0000) when compared to the control. There was no significant difference (all p>0.05) between the student-directed teaching and faculty-directed teaching groups. The magnitude of the effect (instructor-directed training suture) was considered large (>0.80) in all measurements. The acquisition of suture skills after student-directed training was similar to the training supervised by faculty surgeon, and the increase in suture performances of trainees that received instructor administered training was superior to self-directed learning.