Bench Model Research Articles

Full‐Field Strain Characterizations and Fracture Process of Rock Blasting Using a Small‐Scale Double‐Hole Bench Model

A small‐scale double‐hole bench model is designed with granite to study the fracture mechanism of rock blasting. By combining high‐speed camera and digital image correlation, the full‐field strain characterization and fracture process of the specimen bevel surface are investigated. The preliminary test results show that the strain concentration zone corresponds to the crack propagation location, and digital image correlation can well detect the crack propagation. In addition, through observing the crack propagation pattern on the specimen bevel surface, it can be seen that the fracture of the specimen is caused by the dominant horizontal crack and the dominant vertical crack, and the generation of the dominant horizontal crack takes precedence over that of the dominant vertical. Finally, the measurements of two‐dimensional digital image correlation and three‐dimensional digital image correlation are discussed.

Temperature loss by ventilation in a calorimetric bench model.

In intensive care medicine heat moisture exchangers are standard tools to warm and humidify ventilation gases in order to prevent temperature loss of patients or airway epithelia damage. Despite being at risk of hypothermia especially after trauma, intubated emergency medicine patients are often ventilated with dry and in winter probably cold ventilation gases. We tried to assess the amount of temperature-loss due to ventilation with cold, dry medical oxygen in comparison to ventilation with warm and humidified oxygen. We ventilated a 50-kg water-dummy representing the calorimetric capacity of a 60-kg patient over a period of 2 hours (tidal volume 6.6 mL/kg = 400 mL; respiratory rate 13/min). Our formal null-hypothesis was that there would be no differences in temperature loss in a 50 kg water-dummy between ventilation with dry oxygen at 10°C vs. ventilation with humidified oxygen at 43°C. After 2 hours the temperature in the water-dummy using cold and dry oxygen was 29.7 ± 0.1°C compared to 30.4 ± 0.1°C using warm and humidified oxygen. This difference in cooling rates between both ventilation attempts of 0.7 ± 0.1°C after 2 hours represents an increased cooling rate of ~0.35°C per hour. Ventilation with cool, dry oxygen using an automated transport ventilator resulted in a 0.35°C faster cooling rate per hour than ventilation with warm humidified oxygen in a bench model simulating calorimetric features of a 60-kg human body.

Sound Measurement in Patient-Specific 3D Printed Bench Models of Venous Pulsatile Tinnitus.

We hypothesize patient-specific flow models to be an adequate in vitro surrogate to allow for characterization of pulsatile tinnitus (PT) that affects three to five million Americans. PT, rhythmic sounds without an extracorporeal source that patients appreciate, can be caused by aberrant blood flow in large cerebral veins near the cochlea. To investigate the sound production mechanism, we created 3D printed flow models based on patient-specific cerebral venous anatomies. Magnetic resonance angiography datasets from two patients with PT were used to generate patient-specific 3D printed flow models. A flow circuit connecting the patient-specific models to a pulsatile, continuous flow pump simulating cardiac cycle was created. Sound recordings were made along the surface of the models using an electronic stethoscope. Peak-to-rms amplitude, and area under the power spectral density (PSD) curve values were computed to evaluate the sound measurements. Wilcoxon rank sum test was used to statistically determine the differences in measurements between the patient-specific models. In patient-1, the recordings (peak-to-rms) from the internal jugular vein stenosis of baseline model (4.29 ± 1.26 for 146 samples) were significantly louder (p < 0.001) than that of the altered model (3.29 ± 0.96 for 143 samples). In patient-2, the sound measured at the transverse sinus stenosis in the pre-lumbar puncture model (4.84 ± 1.11 for 148 samples) was significantly louder (p < 0.0001) than that of the post-lumbar puncture model (3.14 ± 0.87 for 135 samples). The models are able to generate sounds very similar to those appreciated by patients and examiners in the cases of objective PT.

Effect of Endotracheal Tube Size, Respiratory System Mechanics, and Ventilator Settings on Driving Pressure.

We sought to investigate factors that affect the difference between the peak inspiratory pressure measured at the Y-piece under dynamic flow conditions and plateau pressure measured under zero-flow conditions (resistive pressure) during pressure controlled ventilation across a range of endotracheal tube sizes, respiratory mechanics, and ventilator settings. In vitro study. Research laboratory. None. An in vitro bench model of the intubated respiratory system during pressure controlled ventilation was used to obtain the difference between peak inspiratory pressure measured at the Y-piece under dynamic flow conditions and plateau pressure measured under zero-flow conditions across a range of endotracheal tubes sizes (3.0-8.0 mm). Measurements were taken at combinations of pressure above positive end-expiratory pressure (10, 15, and 20 cm H2O), airway resistance (no, low, high), respiratory system compliance (ranging from normal to extremely severe), and inspiratory time at constant positive end-expiratory pressure (5 cm H2O). Multiple regression analysis was used to construct models predicting resistive pressure stratified by endotracheal tube size. On univariate regression analysis, respiratory system compliance (β -1.5; 95% CI, -1.7 to -1.4; p < 0.001), respiratory system resistance (β 1.7; 95% CI, 1.5-2.0; p < 0.001), pressure above positive end-expiratory pressure (β 1.7; 95% CI, 1.4-2.0; p < 0.001), and inspiratory time (β -0.7; 95% CI, -1.0 to -0.4; p < 0.001) were associated with resistive pressure. Multiple linear regression analysis showed the independent association between increasing respiratory system compliance, increasing airway resistance, increasing pressure above positive end-expiratory pressure, and decreasing inspiratory time and resistive pressure across all endotracheal tube sizes. Inspiratory time was the strongest variable associated with a proportional increase in resistive pressure. The contribution of airway resistance became more prominent with increasing endotracheal tube size. Peak inspiratory pressures measured during pressure controlled ventilation overestimated plateau pressure irrespective of endotracheal tube size, especially with decreased inspiratory time or increased airway resistance.

Simulation-based surgical education in cardiothoracic training.

Simulation has emerged as a feasible adjunct to surgical education and training for most specialties. It provides trainees with an immersive, realistic way to learn a variety of skills in a safe environment with the end goal of improving patient safety. There are three broad types of simulators: full mannequin simulators, part-task trainers or bench models and virtual reality systems. This review aims to describe the current use of simulation in cardiothoracic surgical education and training. We identified multiple procedures that can be simulated in cardiothoracic surgery using a combination of the above simulators, three-dimensional printing and computer-based simulation. All studies that assessed the efficacy of simulators showed that simulation enhances learning and trainee performance allowing for repetitive training until the acquisition of competence but further research into how it translates into the operating theatre is required. In Australia, cardiac surgery simulation is not yet part of the training curricula, but simulators are available for certain tasks and procedures.

Novel single-use duodenoscope compared with 3 models of reusable duodenoscopes for ERCP: a randomized bench-model comparison

Multidrug-resistant infectious outbreaks associated with duodenoscope reuse have been documented internationally. A single-use endoscope could eliminate exogenous patient-to-patient infection associated with ERCP. We conducted a comparative bench simulation study of a new single-use and 3 models of reusable duodenoscopes on a synthetic anatomic bench model. Four ERCP tasks were performed: guidewire locking (single-use and 1 reusable duodenoscope only), plastic stent placement and removal, metal stent placement and removal, and basket sweeping. The study schedule included block randomization by 4 duodenoscopes, 4 tasks, and 2 anatomic model ERCP stations. Ability to complete tasks, task completion times, and subjective ratings of overall performance, navigation/pushability, tip control, and image quality on a scale of 1 (worst) to 10 (best) were compared among duodenoscopes. All 4 ERCP tasks (total 14 subtasks) were completed by 6 expert endoscopists using all 4 duodenoscopes, with similar task completion times (median, 1.5-8.0 minutes per task) and overall performance ratings by task (median, 8.0-10.0). Navigation/pushability ratings were lower for the single-use duodenoscope than for the 3 reusable duodenoscopes (median, 8.0, 10.0, 9.0, and 9.0, respectively; P< .01). Tip control ratings were similar among all the duodenoscopes (median, 9.0-10.0; P= .77). Image quality ratings were lower for 1 reusable duodenoscope compared with the single-use and other 2 reusable duodenoscopes (median, 8.0, 9.0, 9.0, and 9.0, respectively; P< .01). A new single-use duodenoscope was used to simulate 4 ERCP tasks in an anatomic model, with performance ratings and completion times comparable with 3 models of reusable duodenoscopes.

863 Single-Use Duodenoscope for Endoscopic Retrograde Cholangiopancreatography: Performance Ratings From a Case Series of 60 Patients

INTRODUCTION: Exogenous transmission of infection via duodenoscope cross-contamination after failed disinfection is a preventable risk. Inadequate reprocessing of reusable duodenoscopes can occur. Given this possibility, a new single-use duodenoscope was recently developed. It had comparable performance to reusable duodenoscopes when tested by expert endoscopists in a comparative bench model for endoscopic retrograde cholangiopancreatography (ERCP). We subsequently aimed to assess the performance of this disposable duodenoscope in a series of human cases. METHODS: Six academic medical centers enrolled consecutive adults 18 years or older without altered pancreaticobiliary anatomy scheduled for an ERCP. Seven ERCP experts rated the new EXALT single-use Model D duodenoscope (Boston Scientific, Marlborough, MA; ClinicalTrials.gov NCT03701958) in ERCP procedures for Overall Satisfaction on a scale of 1 (unsatisfied) to 10 (very satisfied), “Not preferred/Neutral/Preferred” compared to reusable duodenoscopes on 23 ERCP maneuvers, and Qualitative Comparison of 17 performance characteristics on a scale of 1 (not preferred) to 5 (comparable to reusable duodenoscopes). RESULTS: Sixty consecutive patients had an ERCP using the first-generation single-use duodenoscope in April and May 2019. Thirty-seven (61.7%) were male, mean age was 64.4 years, and 44 (73.3%) had a prior ERCP at baseline. All 60 ERCP procedures were successfully performed, 58 (96.7%) with the single-use duodenoscope alone and 2 (3.3%) with crossover to a reusable duodenoscope. Median overall satisfaction with the single-use duodenoscope was rated 9.0 (range 1-10). The overall satisfaction rating was ≥ 7 in 56 (93.3%) ERCPs. All three ratings were at or above midpoint (Overall satisfaction ≥ 5, Comparative ERCP maneuver “Neutral/Preferred,” Qualitative Comparative rating of performance characteristic 3-5) in 47 (78.3%) cases. Four ERCPs had low (≤4) overall satisfaction ratings attributed to inadequate pushability of instruments due to suboptimal positioning of the duodenoscope in front of the papilla; these ERCPs were a subset in which biliary or pancreatic duct strictures were dilated and/or stented. CONCLUSION: Expert endoscopists reported good overall performance of a new single-use duodenoscope in a broad array of cases. Low ratings occurred rarely and were associated with particular ERCP maneuvers. Detailed design improvements to the single-use duodenoscope are underway.

Current status of simulation and training models in microsurgery: A systematic review

With the prolific uptake of simulation-based training courses, this systematic review aims to identify the available microsurgical simulation and training models, their status of validation, associated studies, and levels of evidence (LoE) for each training model, thereby establishing a level of recommendation (LoR). MEDLINE, Embase, and the Cochrane Library databases were searched for English language articles, describing microsurgery simulators and/or validation studies. All studies were assessed for LoE, and each model was subsequently awarded a LoR using a modified Oxford Centre for Evidence-Based Medicine classification, adapted for education, with 1 being the highest and 4 the lowest score. A total of 86 studies were identified describing 64 models and simulators ranging from bench models, cadaveric animal tissue, cadaveric human tissue, live animal models, virtual reality simulators, and training curricula. Of these, 49 simulators had at least one validation study. Models were assessed for face (n = 42), content (n = 31), construct (n = 25), transfer (n = 10), and concurrent validity (n = 1) by these studies. The most commonly identified modality was bench models (n = 28) followed by cadaveric animal tissue (n = 24). The cryopreserved rat aorta model received the highest LoR followed by chicken wing, chicken thigh and practice cardboard models. Microsurgery simulation is a growing field and increasing numbers of models are being produced. However, there are still only a few validation studies with a high LoE. It is therefore imperative that training models and/or programs are evaluated for validity and efficacy in order to allow utilization in microsurgical skills acquisition.

Vaginal Hysterectomy Suturing Skills Training Model and Curriculum.

Declining vaginal hysterectomy numbers in obstetrics and gynecology training programs highlights the need for innovative methods to teach vaginal surgical skills. We describe our experience with a vaginal hysterectomy skills simulation curriculum. A low-fidelity bench model was constructed to simulate four vaginal hysterectomy suturing tasks. A polyvinyl chloride downspout adapter and low-cost materials simulate the Heaney pedicle stitch, simple pedicle stitch, double ligature, and continuous running stitch. Faculty expert vaginal surgeons established proficiency levels for each task. Resident (N=30) pass rates for tasks 1, 2, and 3 were 1 of 30 (3.3%), 7 of 30 (23.3%), and 4 of 30 (13.3%), respectively, for the left side, and 3 of 30 (10%), 9 of 30 (30%), and 10 of 30 (33.3%), respectively, for the right side. For task 4, the pass rate was 14 of 30 (46.7%). The majority of residents felt that the model simulates the technical skills required for vaginal hysterectomy and agreed that vaginal skills laboratory training would improve their ability to perform procedures in the operating room. Ninety-two percent of residents felt that a vaginal surgery skills curriculum would be a useful addition to their simulation education. A proficiency-based vaginal hysterectomy skills simulation curriculum using a low-fidelity model may be an important training and evaluation tool for vaginal surgical skills training.

Objective assessment of surgeon’s psychomotor skill using virtual reality module

&lt;span&gt;This study aims to identify measurable parameters that could be used as objective assessment parameters to evaluate surgical dexterity using computer-based assessment module. A virtual reality module was developed to measure dynamic and static hand movements in a bimanual experimental setting. The experiment was conducted with sixteen subjects divided into two groups: surgeons (N = 5) and non-surgeons (N = 11). Results showed that surgeons outperformed the non-surgeons in motion path accuracy, motion path precision, economy of movement, motion smoothness, end-point accuracy and end-point precision. The six objective parameters can complement existing assessment methods to better quantify a trainee’s performance. These parameters also could provide information of hand movements that cannot be measured with the human eye. An assessment strategy using appropriate parameters could help trainees learn on computer-based systems, identify their mistakes and improve their skill towards the competency, without relying too much on bench models and cadavers.&lt;/span&gt;

Ventilation During Cardiopulmonary Resuscitation: What Have We Learned From Models?

The optimization of ventilation during cardiopulmonary resuscitation (CPR) is a broad field of research. Recent physiological observations in this field challenge the current understanding of respiratory and circulatory interactions. Thanks to different models available (bench, animal, human), the understanding of physiological phenomena occurring during CPR has progressed. In this review, we describe the clinical observations that have led to the emerging concept of lung volume reduction and associated thoracic airway closure. We summarize the clinical and animal observations supporting these concepts. We then discuss the different contributions of bench, animal, and human models to the understanding of airway closure and their impact on intrathoracic pressure, airway closure, and hemodynamics generated by chest compression. The limitation of airway pressure and ventilation, resulting from airway closure reproducible in models, may play a major role in ventilation and gas exchange impairment observed during prolonged resuscitation.

Optimal balloon positioning for the proximal optimization technique? An experimental bench study

AimsThe proximal optimization technique (POT) in coronary bifurcation stenting improves apposition and side-branch obstruction. The POT balloon should be positioned with the distal radio-opaque marker at the carina cut plane. However, the real impact of positioning remains unknown. Methods and resultsSynergy™ stents (Boston Scientific, USA) were implanted on left-main fractal bench models. Initial POT was performed in 3 positions according to distal shoulder position (loss of balloon parallelism) relative to the carina cut plane (n = 5/group): i) “proximal”, 1 mm before carina; ii) “medium”, just at carina; iii) “distal”, 1 mm after carina. Results were quantified on 2D- and 3D-OCT.Compared to implantation, initial POT improved malapposition in all positions (“proximal”: 61.5 ± 1.4% vs. 5.1 ± 2.7%; “medium”: 60.2 ± 2.4% vs. 1.3 ± 0.6%; “distal”: 60.5 ± 2.9% vs. 1.1 ± 1.8%, p < 0.05). However, residual malapposition was greater in “proximal” position (p < 0.05). “Proximal”, unlike “medium” or “distal” POT, also failed to improve side-branch obstruction. Conversely, “distal” POT significantly overstretched the main-branch ostium, with stent/artery ratio 1.22 ± 0.04 vs. 1.11 ± 0.07 for “medium” POT (p < 0.05). ConclusionShoulder positioning is essential to optimize the mechanical benefit of POT without main-branch overstretch (too distal position). Experimentally, the best position is just at the carina cut plane (“medium”).

Mechanics of nasal mask-delivered HFOV in neonates: A physiologic study.

To clarify if nasal mask influences noninvasive high-frequency oscillatory ventilation (NHFOV) mechanics to optimize the clinical use of nasal mask-delivered NHFOV. Nasal mask may affect the mechanical efficacy of NHFOV. We designed a physiologic study composed of an in vitro phase aiming to investigate pressure transmission and volume delivery in a bench model of nasal mask-delivered NHFOV. In a second phase, we measured the leaks in vivo in a series of neonates receiving nasal mask-delivered NHFOV or other forms of noninvasive respiratory support with same nasal masks. In vitro pressure transmission is lower with nasal mask (pressure at the lung [Plung]: 2 [0.8]), than with the endotracheal tube (Plung 9.5 [1.5] cmH2 O; P = 0.007). Same applies for volume delivery (Vol: 0.6 [0.2] vs 1.8 [0.5] mL; P = 0.0001). Increasing ventilatory boundaries slowly affects pressure and volume delivery. Ventilating the model with maximal parameters (∆P = 55 cmH2 O; frequency = 8 Hz) we obtained a Vol 1.5 (0.2) mL. The nasal mask provides lower volume delivery and ventilation, compared with nasal prongs studied in previously published studies. Changing frequency allows a better performance than changing ∆P. In vivo leaks are approximately 30% and are similar during NHFOV or other forms of nasal mask-delivered noninvasive ventilation. Nasal mask-delivered NHFOV is feasible, but it may require more aggressive ventilatory parameters to increase volume delivery and ventilation. The use of the nasal mask is associated with some leaks, but this is independent from the type of noninvasive respiratory support applied.

MRI of the Colon in the Pharmaceutical Field: The Future before us.

Oral solid drug formulation is the most common route for administration and it is vital to increase knowledge of the gastrointestinal physiological environment to understand dissolution and absorption processes and to develop reliable biorelevant in vitro tools. In particular, colon targeted drug formulations have raised the attention of pharmaceutical scientists because of the great potential of colonic drug delivery. However, the distal bowel is still a relatively understudied part of the gastrointestinal tract. Recently, magnetic resonance imaging (MRI) has been gaining an emerging role in studying the colon. This article provides a comprehensive; contemporary review of the literature on luminal MRI of the colonic environment of the last 15 years with specific focus on colon physiological dimensions; motility; chyme and fluids; transit and luminal flow. The work reviewed provides novel physiological insight that will have a profound impact on our understanding of the colonic environment for drug delivery and absorption and will ultimately help to raise the in vitro/in vivo relevance of computer simulations and bench models.

In-vitro adsorption and sieving coefficient of ticarcillin-clavulanate during continuous haemofiltration

There are very limited data on ticarcillin-clavulanate elimination by haemofiltration. We measured in vitro ticarcillin-clavulanate adsorption to polyacrylonitrile (PAN) filters and the sieving coefficient using a well-described bench model of haemofiltration. The dose of ticarcillin-clavulanate was 60/2 mg or 180/3 mg, and 0 or 12 g albumin was added to the 1 L of circulating blood-crystalloid mixture to produce four different experimental conditions. The experiment was repeated four times under each condition. Median (interquartile range [IQR] ) ticarcillin adsorption varied from 28 (27-30) mg to 85 (78-90) mg. Adsorption was increased when the dose of ticarcillin was higher (P<0.001), but was not affected by the addition of albumin. Median (IQR) adsorption of clavulanate ranged from 0.67 (0.55-0.75) mg to 1.8 (0.33-3.5) mg and was neither dose dependent (P = 0.505) nor significantly affected by the addition of albumin. Median (IQR) ticarcillin sieving coefficient ranged from 0.73 (0.67-0.75) to 0.99 (0.97-1.03). It was significantly higher with a higher dose of ticarcillin (P = 0.021) and without addition of albumin (P = 0.015). Median (IQR) clavulanate sieving coefficient ranged from 1.03 (1.00-2.24) to 2.0 (1.98-2.47). Clavulanate sieving coefficient was not significantly affected by dose or the addition of albumin.These data indicate that significant adsorption of both ticarcillin and clavulanate occurs in vitro; however, this requires confirmation by clinical pharmacokinetic studies. The sieving coefficient data may help guide appropriate dosing of critically ill patients receiving haemofiltration until more extensive clinical pharmacokinetic data are available.

Intrathoracic Airway Closure Impacts CO2 Signal and Delivered Ventilation during Cardiopulmonary Resuscitation.

End-tidal CO2 (EtCO2) is used to monitor cardiopulmonary resuscitation (CPR), but it can be affected by intrathoracic airway closure. Chest compressions induce oscillations in expired CO2, and this could reflect variable degrees of airway patency. To understand the impact of airway closure during CPR, and the relationship between the capnogram shape, airway closure, and delivered ventilation. This study had three parts: 1) a clinical study analyzing capnograms after intubation in patients with out-of-hospital cardiac arrest receiving continuous chest compressions, 2) a bench model, and 3) experiments with human cadavers. For 2 and 3, a constant CO2 flow was added in the lung to simulate CO2 production. Capnograms similar to clinical recordings were obtained and different ventilator settings tested. EtCO2 was compared with alveolar CO2 (bench). An airway opening index was used to quantify chest compression-induced expired CO2 oscillations in all three clinical and experimental settings. A total of 89 patients were analyzed (mean age, 69 ± 15 yr; 23% female; 12% of hospital admission survival): capnograms exhibited various degrees of oscillations, quantified by the opening index. CO2 value varied considerably across oscillations related to consecutive chest compressions. In bench and cadavers, similar capnograms were reproduced with different degrees of airway closure. Differences in airway patency were associated with huge changes in delivered ventilation. The opening index and delivered ventilation increased with positive end-expiratory pressure, without affecting intrathoracic pressure. Maximal EtCO2 recorded between ventilator breaths reflected alveolar CO2 (bench). During chest compressions, intrathoracic airway patency greatly affects the delivered ventilation. The expired CO2 signal can reflect CPR effectiveness but is also dependent on airway patency. The maximal EtCO2 recorded between consecutive ventilator breaths best reflects alveolar CO2.

STENT EXPANSION AND ENDOTHELIAL SHEAR STRESS IN BIFURCATION LESION: COMPARISON OF KISSING BALLOON INFLATION AND PROXIMAL OPTIMIZING TECHNIQUE

Treatment of bifurcation lesions remains technically challenging for interventional cardiologists. Previous idealized in vitro bench models have shown that kissing balloon inflation (KBI) might result in a less circular stent shape, worse stent apposition and lower endothelial shear stress (ESS)

Simultaneous in situ temperature and relative humidity monitoring in mechanical ventilators using an array of functionalised optical fibre long period grating sensors

An array of optical fibre long period gratings (LPGs) has been demonstrated for biomedical application to monitor temperature and relative humidity (RH) changes in the air delivered by a mechanical ventilator operating in different modes. The LPG array consists of two gratings, where one was kept bare to monitor the temperature change and the second was modified with 10 layers of silica nanoparticles to measure relative humidity.A mesoporous film was deposited on the surface of an optical fibre LPG using the layer-by-layer method. The sensor was calibrated in a bench model against a commercially available temperature and relative humidity sensor and sensitivity of the sensor was 0.46 ± 0.01 nm/ oC and 0.53 nm/RH%, respectively.The tip of the sensor array was modified with reflection mirror and placed inside an endotracheal tube (ETT) and tested in typical clinical equipment to enable the in-situ real-time monitoring of humidity and temperature. Temperature and RH changes associated with the breathing frequency of 8 and 15 breaths per minute were successfully monitored using developed sensor array.

Technical Feasibility and Design of a Shape Memory Alloy Support Device to Increase Ejection Fraction in Patients with Heart Failure

PurposeHeart failure is increasingly prevalent in the elderly. Treatment of patients with heart failure aims at improving their clinical condition, quality of life, prevent hospital (re)admissions and reduce mortality. Unfortunately, only a select group of heart failure patients with reduced ejection fraction are eligible for Cardiac Resynchronization Therapy where 30–40% remain non-responders and need left ventricular support. The aim of this study is to investigate if a shape memory alloy (SMA) is able to increase the ejection fraction of a mono-chamber static heart model by 5%.MethodsA pediatric ventilation balloon was used as a heart model (mono-chamber). Flexinol®, a SMA, was placed around the heart model in multiple configurations and activated using pulse width modulation techniques to determine influence of diameter and configuration on volume displacement. Furthermore, pressure within the heart model was measured with a custom-made pressure sensor.ResultsSMA with a diameter of 0.38 mm, placed in a spiral shape and activated with a duty cycle of 80% and a frequency of 50/min gave the highest ejection fraction increase of 3.5%.ConclusionsThis study demonstrated the feasibility of volume displacement in a static heart model by activation of SMA-wires. Configuration, duty cycle, frequency, pulse intervals and diameter were identified as important factors affecting the activation of SMA-wires on volume displacement. Future research should include the use of parallel SMA-wires, prototype testing in dynamic or ex vivo bench models.

Role of simulation in AETCOM and skill development of surgery interns

Background: Simulation is a way of learning skills in life like situations that are not real. Simulation based training according to many studies turned out to be effective method in skill development. In this study we have used bench top models available in our institute with simulated patients, which are accessible, and cost effective. The use of simulation in Graduate Medical Education has evolved significantly over time, particularly during the past decade. The applications of simulation include training budding surgeons in technical and non-technical skills and better prepared to face clinical situations.Methods: After 5 days of focused group discussion, 60 interns were asked to perform the two basic tasks in bench models attached to simulated patents. Skills assessed by pre-test, post-test and feedback module created for the 2 tasks. Scores was compared and analyzed, at the end of the module by summative assessment. Tasks were graded to100 point system, using rubrics and difference calculated using pair t test.Results: Mean of the skill score in pre-test 78.26±5.58, range found to be 86-73. There was significant improvement in post test score in which 86.54±4.41, range 97-66. t was found to be 5.5256, a significant improvement, and p value found in post-test 0.0002.Conclusions: Skill development with Mannequins and Standardized patients is found effective in training the interns. In addition to developing technical and non-technical skills, interns also get to communicate with simulated patients, which will make them more competent.