Development of a novel 3D-printed multifunctional thorax model simulator for the simulation-based training of tube thoracostomy

Tube thoracostomy is a high-acuity, low-occurrence (HALO) procedure with significant morbidity when performed incorrectly; this is amendable through simulation. Commercially available trainers exist but often have limited realism or exorbitant cost. Three-dimensional (3D) printing produces realistic and cost-effective models suitable for simulation, but no simulator has been developed for tube thoracostomy. The aim of this paper is to describe the initial development of a multifunctional 3D-printed thorax trainer for the instruction of tube thoracostomy. The thorax model was developed in conjunction with a multi-disciplinary team using 3D-printing capable software. An existing ribcage model was modified and printed in separate elements, including bony portions (ribcage, sternum and clavicles), flexible joints, skin, heart and lungs and then assembled. The total printing cost was $180 CAD. Future research will focus on incorporating the model's ability to simulate other HALO procedures and evaluating it as a training adjunct.

Long-Term Exposure to Ambient Air Pollution in Childhood-Adolescence and Lung Function in Adulthood

The aim of the study was to evaluate the effect of air pollution in the dwelling place during childhood-adolescence on respiratory function in early adulthood. The study was conducted in 220 female and 160 male university undergraduates in the cities of Cracow and Wroclaw in Poland and consisted of spirometry to assess lung function. The subjects' exposure to pollution during childhood-adolescence was assessed from the data acquired by the Polish Chief Inspectorate for Environmental Protection. We found differences in all spirometry variables depending on benz[a]piren exposure, in FVC% and FEV₁/%FVC depending on PM_2.5 content, and in FVC% depending on NO₂ content_. Statistically significant differences in spirometry variables were also found in relation to the degree of urbanization of the place of living during the early life period in question. The higher the urbanization, the higher is FEV₁% and FCV%, and the lower FEV₁/%FVC. Additionally, undergraduates of Cracow University had worse lung function compared to those of Wroclaw University. In conclusion, air pollution in the dwelling place during childhood-adolescence has an impact on lung function in early adulthood, independently of the current exposure to pollutants.

A model of cardiopulmonary bypass staged training integrating technical and non-technical skills dedicated to cardiac trainees

OBJECTIVES

To develop a standardized simulation-based curriculum to teach medical knowledge and technical, communication and critical thinking skills necessary to initiate and wean from cardiopulmonary bypass (CPB) to junior cardiac trainees (CTs) in France. Performance on post-curricular tests was compared between CTs who participated in the new curriculum to those who did not.

METHODS

The simulation-based curriculum was developed by content and education experts. Simulations sequentially taught the skills necessary for initiating and weaning from CPB as well as managing crises by adding fidelity and complexity to scenarios. Nine CTs were randomly assigned to the new curriculum (n=5) or the traditional curriculum (n=4). Skills were assessed using tests of medical knowledge and technical, communication (GRS) and critical thinking (SCT) skills. A two-sample Wilcoxon rank-sum test compared average scores between the two groups. Alpha of 0.05 was set to indicate statistically significant differences.

RESULTS

The resutls revealed that CTs in the new curriculum significantly outperformed CTs in the traditional curriculum on technical (18.2 vs 14.8, p=0.05) and communication (3.5 vs 2.2, p=0.013) skills. There was no significant difference between CTs in the new curriculum in the Script Concordance Test (16.5 vs 14.8, p=0.141) and knowledge tests (26.9 vs 24.6, p=0.14) compared to CTs in the traditional curriculum.

CONCLUSION

Our new curriculum teaches communication and technical skills necessary for CPB. The results of this pilot study are encouraging and relevant. They give grounds for future research with a larger panel of trainees. Based on the current distribution of scores, a sample size of 12 CTs per group should yield significant results for all tests.

55. Simulation based training of technical surgical skills: A review of a five-year collaborative research program supported by the RCPSC Medical Education Funds

During the past five years, with support from the RCPSC, a collaborative group of researchers conducted projects investigating issues related to simulation based training of technical surgical skills. The aim of this presentation is to review the body of work generated, its significance, and outline future research plans. In all studies, participants were medical students and residents from 3 medical schools in Ontario. First, we successfully demonstrated that trainees benefit from simulation-based practice by improving their ability to multitask. This ability not only increases technical proficiency, but also results in an enhanced ability to learn other aspects of surgery. Second, we showed that the adaptation of learning theories helps in optimizing training curricula by matching the fidelity of a simulator to the trainees’ level of expertise. Third, we provided validation of both expert and computer based methods for assessment. We showed that computer based assessments are sufficient for the evaluation of trainees learning fundamental skills, while expert based measures are more effective in the evaluation of performance on complex technical skills. Finally we demonstrated that examination-induced stress has a facilitating effect on trainees’ skills performance. This body of research lends support for the inclusion of a simulation based approach to training technical skills. It also highlights the importance of the choice of assessment methods. Collectively this work highlights the need for further research in the optimization of training methods by the incorporation of learning theory into the existing training curricula. Related to this, further research in our laboratory will investigate the effects of practice schedule and expert feedback, as well as the role of self-regulated practice in the acquisition of technical surgical skills. Xeroulis GJ, Park J, Moulton CA, Reznick RK, Leblanc V, Dubrowski A. Teaching suturing and knot-tying skills to medical students: a randomized controlled study comparing computer-based video instruction and (concurrent and summary) expert feedback. Surgery 2007; 141(4):442-9. Brydges R, Sidhu R, Park J, Dubrowski A. Construct validity of computer-assisted assessment: quantification of movement processes during a vascular anastomosis on a live porcine model. Am J Surg. 2007; 193(4):523-9. Brydges R, Carnahan H, Backstein D, Dubrowski A. Application of motor learning principles to complex surgical tasks: searching for the optimal practice schedule. J Mot Behav. 2007; 39(1):40-8.

56. Proficiency at the end of practice predicts retention of a technical clinical skills

A debate is emerging regarding the efficacy of proficiency based versus duration based training of technical skills. It is not clear whether the performance level attained at the end of practice (i.e., proficiency criteria), or the overall amount of practice performed during learning will best predict the retention of a technical clinical skill. The skill learned was the single-handed double square-knot. Forty two trainees learned the skill through video-based instruction and were divided into three groups (14 participants per group) each with a specific criterion time to tie the knot (10, 15, and 20 seconds). Practice continued until participants completed the knot within their criterion time. The total number of trials, and the overall practice time required to obtain each respective criterion were recorded during practice. Participants returned one-week later for a timed retention test consisting of one trial of the knot tying skill with no video instruction. A multiple regression analysis tested whether the amount of practice, the total practice time, or the criterion reached at the end of practice was the best predictor of the time taken to perform the skill during retention. This analysis showed that the number of practice trials was highly correlated with total practice time (r = .82, p = .01), therefore total practice time was withdrawn as a predictor variable from the subsequent analysis. The regression showed that the only significant predictor of retention performance was the criterion reached at the end of practice (p = .03). The number of practice trials was not found to significantly predict the retention performance (p = .87). The results support the notion that proficiency based training results in better retention of a technical clinical skill in comparison to duration based approaches. This provides evidence for the introduction of proficiency based educational approaches in technical skills curricula. Jowett N, LeBlanc V, Xeroulis G, MacRae H, Dubrowski A. Surgical skill acquisition with self-directed practice using computer-based video training. Am J Surg. 2007; 193(2):237-42. Gallagher AG, Ritter EM, Champion H, Higgins G, Fried MP, Moses G, Smith CD, Satava RM. Virtual reality simulation for the operating room: proficiency-based training as a paradigm shift in surgical skills training. Ann Surg. 2005; 241(2):364-72. Van Sickle KR, Ritter EM, McClusky DA, Lederman A, Baghai M, Gallagher AG, Smith CD. Attempted establishment of proficiency levels for laparoscopic performance on a national scale using simulation: the results from the 2004 SAGES Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR) learning center study. Surg Endosc. 2007; 21(1):5-10.

Application of Motor Learning Principles to Complex Surgical Tasks: Searching for the Optimal Practice Schedule

Practice of complex tasks can be scheduled in several ways: as whole-task practice or as practice of the individual skills composing the task in either a blocked or a random order. The authors used those 3 schedules to study 18 participants' learning of an orthopedic surgical task. They assessed learning by obtaining expert evaluation of performance and objective kinematic measures before, immediately after, and 1 week after practice (transfer test). During acquisition, the blocked group showed superior performance for simple skills but not for more complex skills. For the expert-based measures of performance, all groups improved from pretest to posttest and remained constant from posttest to transfer. Measures of the final product showed that the whole-practice group's outcomes were significantly better than those of the random group on transfer. All groups showed better efficiency of motions in the posttest than in the pretest. Those measures were also poorer on the transfer test than on the posttest. The present evidence does not support the contextual interference effect--hypothetically, because of the inherent cognitive effort effect associated with some of the component skills. The authors recommend that surgical tasks composed of several discrete skills be practiced as a whole. The results of this study demonstrate the importance of critically appraising basic theories in applied environments.

Quantification of process measures in laparoscopic suturing

BACKGROUND

Process measures describing the generation of movement are useful for evaluation and performance feedback purposes. This study aimed to identify process measures that differ between novice and advanced laparoscopists while completing a suturing skill.

METHODS

A group of junior and a group of senior residents and fellows in surgery (n = 6) placed 10 laparoscopic sutures in a synthetic model. Process measures were quantified using an opto-electric motion/force sensor assembly that recorded: instrument rotation, applied forces, time, and time delays between force application and instrument rotation.

RESULTS

Advanced trainees showed increased instrument rotation, higher peak applied force, and faster performance compared to novices (alll p < .01). However, over trials, only novices showed adaptations for instrument rotation and total time (interactions at p < .01) with no adaptation for the force application. The difference between the moments of force application and instrument rotation was not sensitive to participant training.

CONCLUSIONS

Movement process measures can enhance our understanding of early adaptation processes and how such factors might be used as feedback to facilitate skill acquisition.

Structural flexibility of laparoscopic instruments: implication for the design of virtual reality simulators

Laparoscopic training, under simulated settings, benefits from high fidelity models of the actual environment. This study was aimed at reducing uncertainty in the displacement and loads experienced by a laparoscopic instrument during surgical training. Infrared tracking of laparoscopic instruments is ineffective when real tissues attenuate the infrared signals. Incorporating the use of strain gauges for tip deflection measurements allows for online motion and load tracking during a procedure. Strain gauge voltages and infrared markers indicating displacement were both linear with respect to loads up to 700 grams. The resultant strain gauge voltage was equated to deflection values with a calibration constant. The results serve two purposes. First, it may enable the tracking and analysis of the skill level of novice surgeons using bench models. Second, the mechanical model of each instrument can be quantified and incorporated into virtual simulations, thus increasing model fidelity, effectively leading to better learning.

Surface exploration using laparoscopic surgical instruments: the perception of surface roughness

During laparoscopic surgery video images are used to guide the movements of the hand and instruments, and objects in the operating field often obscure these images. Thus, surgeons often rely heavily on tactile information (sense of touch) to help guide their movements. It is important to understand how tactile perception is affected when using laparoscopic instruments, since many surgical judgements are based on how a tissue 'feels' to the surgeon, particularly in situations where visual inputs are degraded. Twelve naïve participants used either their index finger or a laparoscopic instrument to explore sandpaper surfaces of various grits (60, 100, 150 and 220). These movements were generated with either vision or no vision. Participants were asked to estimate the roughness of the surfaces they explored. The normal and tangential forces of either the finger or instrument on the sandpaper surfaces were measured. Results showed that participants were able to judge the roughness of the sandpaper surfaces when using both the finger and the instrument. However, post hoc comparisons showed that perceptual judgements of surface texture were altered in the no vision condition compared to the vision condition. This was also the case when using the instrument, compared to the judgements provided when exploring with the finger. This highlights the importance of the completeness of the video images during laparoscopic surgery. More normal and tangential force was used when exploring the surfaces with the finger as opposed to the instrument. This was probably an attempt to increase the contact area of the fingertip to maximize tactile input. With the instrument, texture was probably sensed through vibrations of the instrument in the hand. Applications of the findings lie in the field of laparoscopic surgery simulation techniques and tactile perception.

The coordination of hand transport and grasp formation during single- and double-perturbed human prehension movements

We investigated the mechanisms underlying human prehension movements, by perturbing the size and position of virtual targets. Subjects grasped virtual target discs with thumb and index finger. In 25% of trials, target size or position (single perturbation), or both (double perturbation) were changed 300 ms after target appearance. The experiments were designed such that the kinematic profiles of grasp formation and hand transport had a similar shape, and were analysed by the same algorithm. We found that grasp kinematics were influenced by changes of target position, and transport kinematics by changes of target size; we also found that the kinematics of double-perturbation trials could not be explained as a linear combination of single-perturbation effects. These findings confirm and expand previous evidence against the view that grasp and transport are controlled by fully independent channels. Most importantly, we found that the time of correction onset was not the same for grasp and transport, neither in single- nor in double-perturbation trials. This outcome argues against a holistic (single-channel) model of prehension; instead, our data are consistent with the notion of two mutually coupled channels.

Control strategies when intercepting slowly moving targets

In 3 experiments, the authors investigated and described how individuals control manual interceptive movements to slowly moving targets. Participants (N = 8 in each experiment) used a computer mouse and a graphics tablet assembly to manually intercept targets moving across a computer screen toward a marked target zone. They moved the cursor so that it would arrive in the target zone simultaneously with the target. In Experiment 1, there was a range of target velocities, including some very slow targets. In Experiment 2, there were 2 movement distance conditions. Participants moved the cursor either the same distance as the target or twice as far. For both experiments, hand speed was found to be related to target speed, even for the very slowly moving targets and when the target-to-cursor distance ratios were altered, suggesting that participants may have used a strategy similar to tracking. To test that notion, in Experiment 3, the authors added a tracking task in which the participants tracked the target cursor into the target zone. Longer time was spent planning the interception movements; however, there was a longer time in deceleration for the tracking movements, suggesting that more visually guided trajectory updates were made in that condition. Thus, although participants scaled their interception movements to the cursor speed, they were using a different strategy than they used in tracking. It is proposed that during target interception, anticipatory mechanisms are used rather than the visual feedback mechanism used when tracking and when pointing to stationary targets.

The effect of illusory size on force production when grasping objects

Milner and Goodale (1995) have proposed that visuomotor and perceptual processes are mediated by discrete visual systems that reflect the functional independence of action and perception. The visuomotor system is proposed to be insensitive to pictorial illusions of object size, whereas the perceptual system is reliably "tricked" by such figures. Brenner and Smeets (1996) and Jackson and Shaw (2000) demonstrated that grasp preshaping, but not grasping force, is immune to the Ponzo visual illusion, suggesting that not all visuomotor processes operate independently of the perceptual system. The present study investigated the effect of illusory object size on prehension kinematics and grasping dynamics (i.e., grip force and load force) as well as perceptual judgements of object size. Unlike previous investigations, object mass was held constant independent of changes in size. The Ponzo figure reliably affected perceptual estimates of object size, but this effect was restricted to one form of the illusion. Some aspects of the prehension movement were sensitive to veridical but not illusory object size (peak grip aperture, peak grip force, peak vertical wrist acceleration), whereas other movement parameters demonstrated illusory size effects (movement time, peak wrist velocity). Still other movement parameters were not sensitive to veridical or illusory object size (peak load force). Together the data suggest that certain prehension components are immune to pictorial illusions of object size, whereas others are not. Complex interactions between the perceptual and visuomotor systems appear to underlie the anticipatory scaling of grasping forces in prehension.

Task dependent processing of visual information about target acceleration

The objective of this study was to investigate the sensitivity of the perceptual and motor systems to target acceleration information using verbal magnitude estimations of target acceleration and manual interception of these targets. The results showed that in the perceptual task the participants were responding mainly to acceleration threshold values, which is acceleration as a function of initial, final, and average velocities, rather then to the absolute accelerations. When manually intercepting the targets the participants responded mainly to the absolute acceleration value and target initial velocity. Thus, these results suggest that target motion can be processed in the ventral (perception) and dorsal (action) visual streams however different motion characteristics are processed in these streams depending on the required output.

Target velocity effects on manual interception kinematics

Participants generated manual interception movements toward a target cursor that moved across a computer screen. The target reached its peak velocity either during the first third, at the midpoint, or during the last third of the movement. In Experiment 1 the view of the target was available for either the first 316, 633, 950, or 1267 ms, after which it disappeared. Results showed that for all viewing conditions, the timing of the interception velocity was related to the temporal properties of the target's trajectory. In Experiment 2, when the portion of the target trajectory that was viewed was reversed (such that participants did not see the first 316, 633, 950, or 1267 ms of the trajectory, but instead saw only the later portions of the trajectory), there was no clear relationship between the target trajectory and the timing of the aiming trajectory. These results suggest that participants use visual information early in the target's trajectory to form a representation of the target motion that is used to facilitate manual interception.