Kinect technology for hand tracking control of surgical robots: technical and surgical skill comparison to current robotic masters

Background

Current surgical robots are controlled by a mechanical master located away from the patient, tracking surgeon’s hands by wire and pulleys or mechanical linkage. Contactless hand tracking for surgical robot control is an attractive alternative, because it can be executed with minimal footprint at the patient’s bedside without impairing sterility, while eliminating current disassociation between surgeon and patient. We compared technical and technologic feasibility of contactless hand tracking to the current clinical standard master controllers.

Methods

A hand-tracking system (Kinect?-based 3Gear), a wire-based mechanical master (Mantis Duo), and a clinical mechanical linkage master (da Vinci) were evaluated for technical parameters with strong clinical relevance: system latency, static noise, robot slave tremor, and controller range. Five experienced surgeons performed a skill comparison study, evaluating the three different master controllers for efficiency and accuracy in peg transfer and pointing tasks.

Results

da Vinci had the lowest latency of 89 ms, followed by Mantis with 374 ms and 3Gear with 576 ms. Mantis and da Vinci produced zero static error. 3Gear produced average static error of 0.49 mm. The tremor of the robot used by the 3Gear and Mantis system had a radius of 1.7 mm compared with 0.5 mm for da Vinci. The three master controllers all had similar range. The surgeons took 1.98 times longer to complete the peg transfer task with the 3Gear system compared with Mantis, and 2.72 times longer with Mantis compared with da Vinci (p value 2.1e?9). For the pointer task, surgeons were most accurate with da Vinci with average error of 0.72 mm compared with Mantis’s 1.61 mm and 3Gear’s 2.41 mm (p value 0.00078).

Conclusions

Contactless hand-tracking technology as a surgical master can execute simple surgical tasks. Whereas traditional master controllers outperformed, given that contactless hand-tracking is a first-generation technology, clinical potential is promising and could become a reality with some technical improvements.     

The role of mental rotation and memory scanning on the performance of laparoscopic skills

OBJECTIVE: The rotational angle of the laparoscopic image relative to the true horizon has an unknown influence on performance in laparoscopic procedures. This study evaluates the effect of increasing rotational angle on surgical performance. METHODS: Surgical residents (group 1) (n = 6) and attending surgeons (group 2) (n = 4) were tested on two laparoscopic skills. The tasks consisted of passing a suture through an aperture, and laparoscopic knot tying. These tasks were assessed at 15 degrees intervals between 0 degrees and 90 degrees , on three consecutive repetitions. The participant's performance was evaluated based on the time required to complete the tasks and number of errors incurred. RESULTS: There was an increasing deterioration in suturing performance as the degree of image rotation was increased. Participants showed a statistically significant 20-120% progressive increase in time to completion of the tasks (p = 0.004), with error rates increasing from 10% to 30% (p = 0.04) as the angle increased from 0 degrees to 90 degrees. Knot-tying performance similarly showed a decrease in performance that was evident in the less experienced surgeons (p = 0.02) but with no obvious effect on the advanced laparoscopic surgeons. CONCLUSIONS: When evaluated independently and as a group, both novice and experienced laparoscopic surgeons showed significant prolongation to completion of suturing tasks with increased errors as the rotational angle increased. The knot-tying task shows that experienced surgeons may be able to overcome rotational effects to some extent. This is consistent with results from cognitive neuroscience research evaluating the processing of directional information in spatial motor tasks. It appears that these tasks utilize the time-consuming processes of mental rotation and memory scanning. Optimal performance during laparoscopic procedures requires that the rotation of the camera, and thus the image, be kept to a minimum to maintain a stable horizon. New technology that corrects the rotational angle may benefit the surgeon, decrease operating time, and help to prevent adverse outcomes.     

The performance of master surgeons on the Advanced Dundee Endoscopic Psychomotor Tester: contrast validity study

HYPOTHESIS: The contrast validity of the Advanced Dundee Endoscopic Psychomotor Tester (ADEPT) was determined by comparing the performance of "master surgeons" with that of surgical trainees (also called junior surgeons) on the system. DESIGN: Twenty master surgeons and 20 junior surgeons were tested on the ADEPT system. The master surgeons, all of consultant grade, were recruited as established experts of national or international standing in laparoscopic surgery. The junior surgeons were participants of essential laparoscopic courses at the start of their higher surgical training. The ADEPT end points used in the study were instrument error, execution time, and task completion. An analysis of variance was used for the data analysis, with statistical significance set at.05. RESULTS: Master surgeons incurred a significantly lower instrument error rate than surgical trainees (P =.007), with no significant difference in execution time and the task completion score (P =.42 and P =.40, respectively). CONCLUSION: The ADEPT system has contrast validity because master surgeons completed the tasks more accurately without sacrificing execution time.     

The effect of delayed visual feedback on telerobotic surgery

Background Telerobotic surgery is ideally suited for remote applications in which the instrument control console is stationed separately from the end-effectors at the patient’s bedside. However, if the distance between the console and the patient is great enough, a lag effect or latency between end-effector manipulation and the depicted image leads to alterations in movement patterns. The purpose of this study was to determine the effect of visual delay on surgical task performance.Methods At an endoscopic skill station, an analogue delay device was interposed between the surgical field and monitor to delay the transmission of visual information, thus mimicking the distance effect of data transmission. Three surgeons with similar laparoscopic experience participated in the laparoscopic knot tying portion of the study, and seven residents participated in the accuracy and dexterity tasks. The time to complete a single throw was recorded in seconds after adding consecutively increasingly time delay in 50 ms increments. Similar time delay increments were added for the accuracy and dexterity tasks, which involved passing a needle through two adjacent circles and passing a small cylinder through a larger one to reproduce two-handed coordination and spatial resolution. Data were presented as the median time to complete each task.Results For all three tasks, an incremental increase in time delay was associated with a significant (p < 0.001) increase in the time to complete the task. For dexterity, a statistically significant (p ≤ 0.05) delay was identified at 0.25 s of delay from control values without delay. A move-and-wait strategy was gradually adopted up to 0.4 s of visual delay.Conclusions Compensation for visually delayed image perception occurs on several levels. Initial adaptations include slower end-effector manipulation; late adaptive changes include a move-and-wait strategy. Increased time to perform surgical maneuvers as well as diminished accuracy, diminished dexterity, and increasing fatigue represent additional performance encumbrances evoked by visual time delay. The nuances of both human and digital compensatory mechanisms for visual time delay must be defined and enhanced to maximize the potential for telerobotic surgical applications.     

Protective gloves for use in high-risk patients: how much do they affect the dexterity of the surgeon?

Twenty-five orthopaedic surgeons underwent eight motor and sensory tests while using four different glove combinations and without gloves. As well as single and double latex, surgeons wore a simple Kevlar glove with latex inside and outside and then wore a Kevlar and Medak glove with latex inside and outside, as recommended by the manufacturers. The effect of learning with each sequence was neutralised by randomising the glove order. The time taken to complete each test was recorded and, where appropriate, error rates were noted. Simple sensory tests took progressively longer to perform so that using the thickest glove combination led to the completion times being doubled. Error rates increased significantly. Tests of stereognosis also took longer and use of the thickest glove combination caused these tests to take three times as long on average. Error rates again increased significantly. However, prolongation of motor tasks was less marked. We conclude that, armed with this quantitative analysis of sensitivity and dexterity impairment, surgeons can judge the relative difficulties that may be incurred as a result of wearing the gloves against the benefits that they offer in protection.     

Comparison of robotic and laparoendoscopic single-site surgery systems in a suturing and knot tying task

Background

Laparoendoscopic single-site (LESS) surgery has been established for various procedures. Shortcomings of LESS surgery include loss of triangulation, instrument collisions, and poor ergonomics, making advanced laparoscopic tasks especially challenging. We compared a LESS system with a robotic single-site surgery platform in performance of a suturing and knot-tying task under clinically simulated conditions.

Methods

Each of five volunteer minimally invasive surgeons was tasked with suturing a 5 cm longitudinal enterotomy in porcine small intestine with square knots at either end, using a laparoendoscopic or da Vinci robotic single-site surgery platform, within a 20 min time limit. A saline leak test was then performed. Each surgeon performed the task twice using each system. The time to completion of the task and presence of a leak were noted. Fisher’s exact test was used to compare the overall completion rate within the defined time limit, and a Wilcoxon rank test was used to compare the specific times to complete the task. A p value of <0.05 was considered significant.

Results

All surgeons were able to complete the task on the first try within 20 min using the robot system; 60 % of surgeons were able to complete it after two attempts using the LESS surgery system. Time to completion using the robot system was significantly shorter than the time using the standard LESS system (p < 0.0001). There were no leaks after closure with the robot system; the leak rate following the standard LESS system was 90 %.

Conclusions

Surgeons demonstrated significantly better suturing and knot-tying capabilities using the robot single-site system compared to a standard LESS system. The robotic system has the potential to expand single-site surgery to more complex tasks.     

Effects of cognitive distraction on performance of laparoscopic surgical tasks

HYPOTHESIS: To quantify the effects of cognitive distraction on surgical task performance in residents and medical students using a laparoscopic surgical simulator. DESIGN: Within-subjects design. SETTING: A surgical skills laboratory. PARTICIPANTS: Thirteen surgical residents and medical students who volunteered for the study. METHODS AND MATERIALS: Subjects performed six tasks on the Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR), under two different conditions (distracted and undistracted). Task order remained the same for all subjects, but the order of distraction was counterbalanced. In the distracted condition, distractions consisted of mental arithmetic problems posed sequentially so that subjects were continually distracted. MAIN OUTCOME MEASURES: Time to task completion, surgical errors committed, economy of motion, and overall performance scores were generated by the MIST-VR program software. Arithmetic error was not a factor in the overall performance score. RESULTS: Time to task completion was significantly greater when subjects were distracted for all six tasks performed. Overall score and economy of motion were negatively affected by distraction but the effect did not reach th level of statistical significance. There was no effect of distract on surgical errors. CONCLUSION: Cognitive distraction appears to negatively influence the performance of laparoscopic surgical tasks by increasing task completion time. Further study is required to determine what the effects would be on experienced surgeons and actual surgical outcomes.     

Effects of low-dose isoflurane on saccadic eye movement generation

The effects of 0.15% quasi-steady-state end-tidal isoflurane on two saccadic eye-movement tests were examined in five volunteers using a newly devised computer-based recording system. The tests were saccadic latency and a countermanding task, the latter being an indicator of the highest levels of conscious performance. A moving light-emitting diode target was displayed on a screen and in the saccadic-latency task the latency of eye movement to the target was measured. In all five subjects the latency increased with anaesthetic by an amount which varied from 8 to 45 ms. This result was significantly different (p < 0.05) from subjects without anaesthetic. In the countermanding task, the subject had to voluntarily inhibit movement to the target. Again anaesthetic increased the latency of response, which varied from 6 to 33 ms. This result was significantly different (p < 0.05) from subjects without anaesthetic. In these studies it appeared that two tasks, one a simple latency test and the other, the countermanding task, requiring higher cortical processing were equally impaired at subanaesthetic concentrations of isoflurane.     

Measuring laparoscopic operative skill in a video trainer

Background Laparoscopic surgery requires a unique set of technical skills. More experienced laparoscopic surgeons perform certain tasks more efficiently in a video trainer than less experienced laparoscopic surgeons. The presumption is that the experienced surgeon possesses more of the skill required to complete the task. This study sought to determine the degree to which previous laparoscopic operative experience influenced the performance of selected video trainer tasks of varying complexity. Methods In this study, 19 general surgery residents with varying levels of laparoscopic operative case experience (as defined by operative case logs) were timed performing five tasks in a video trainer. The tasks were rope pass, peg drop, peg exchange, needle pass, and knot tie. All the residents watched a video demonstration of each skill before testing. None of the residents had previous exposure to video trainers, and no practice was allowed before testing. A composite score for all tasks was calculated for each resident as a measure of overall performance. Results There was a strong correlation between operative experience and time required for successful completion of each task, with the exception of the rope pass. The magnitude of correlation increased with tasks of increasing complexity. Composite scores were correlated with operative experience. Significant interval improvements in performance were observed for increasing experience up to a level of approximately 100 previous laparoscopic cases. Conclusions Overall composite scores and time required for the completion of each individual video trainer task (with the exception of the rope pass) may be an accurate reflection of laparoscopic surgical skill acquired in the operating room. A resident may need as many as 100 laparoscopic cases for full development of a basic skill set in the operating room. A more efficient and safe method of training, such as a validated skills curriculum conducted in a dry lab, is a desirable alternative to developing skill exclusively in the operating room.     

The influence of an auditory distraction on rapid naming after a mild traumatic brain injury: a longitudinal study

OBJECTIVE: The purpose of this investigation was to examine speeded performance over time and the impact of a common auditory distraction on performance after a mild traumatic brain injury (MTBI). METHODS: Fourteen adults (ages 18-53) treated for a MTBI and 14 age and education-matched controls were asked to perform two speeded naming tasks. Both tasks were presented with or without the presence a common auditory distraction. The MTBI group was tested within 5 days, 30 days, 60 days, and 6 months postinjury. Latency (ms) and accuracy of response were recorded. RESULTS: Initially, the MTBI group demonstrated significantly longer response latencies and lower accuracy levels for both tasks. Similar results were found at 30 days postinjury. At 60 days postinjury, no significant difference was found for task 1 accuracy. Significant differences remained for task 1 latency, task 2 latency, and task 2 accuracy. At 6 months postinjury, no significant differences were found. The presence of an auditory distraction differentially affected the MTBI group for task 2 accuracy upon initial testing and at 30 days postinjury only. CONCLUSIONS: The MTBI group performed both tasks significantly slower and less accurately than the control group upon initial testing and at 30 days postinjury. The presence of pop music further influenced accuracy of complex processing. At 60 days postinjury, accuracy of simple processing returned to preinjury levels and the auditory distraction no longer differentially influenced the MTBI group. All performance differences were resolved at 6 months postinjury.     

Measuring and developing suturing technique with a virtual reality surgical simulator.

BACKGROUND: We have developed an interactive virtual reality (VR) surgical simulator for the training and assessment of suturing technique. The surgical simulator is comprised of surgical tools with force feedback, a 3-dimensional graphics visual display of the simulated surgical field, physics-based computer simulations of the tissues and tools, and software to measure and evaluate the trainee's performance. STUDY DESIGN: This study uses the simulator to measure and compare the skills of 8 experienced vascular surgeons versus 12 medical students when performing a virtual reality suturing task. Eight parameters of the suturing task were measured: total tissue damage, accuracy of needle puncture, peak tissue tearing force, time to complete the task, damage to the surface of the tissue, angular error in needle technique, total distance traveled by the tool tip, and a measure of overall error. Three test conditions (dominant hand, nondominant hand, and 3-dimensional needle guide) were tested. Statistical significance was defined as a univariate two-sided p value < or = 0.05. RESULTS: The surgeons' average performance was significantly better than the students' average performance for three of the measured parameters (total tissue damage, time to complete the task, and total distance traveled by the tool tip) for each of the test conditions. For the test condition most similar to surgery (using the dominant hand to suture) one additional parameter was also significantly different (the measure of overall error). The medical students showed improvements for 6 of the 7 parameters for which the users received feedback during the training process. The surgeons also had significant improvement for 4 of the 7 parameters. The students had a larger improvement than the surgeons for 6 of the parameters, but these differences were not statistically significant. CONCLUSIONS: Data indicate differences between surgeon and nonsurgeon performance and in improvement in performance with training. One possible explanation for the superior performance of the surgeons is that their suturing skills applied well to the simulated suturing task. Additional research is required to confirm or deny the similarity between actual and simulated surgical tasks and the relevance of virtual reality surgical simulation to surgical skill assessment and training.     

Performance of basic manipulation and intracorporeal suturing tasks in a robotic surgical system: single- versus dual-monitor views

Background  Technical advances in the application of laparoscopic and robotic surgical systems have improved platform usability. The authors hypothesized that using two monitors instead of one would lead to faster performance with fewer errors. Methods  All tasks were performed using a surgical robot in a training box. One of the monitors was a standard camera with two preset zoom levels (zoomed in and zoomed out, single-monitor condition). The second monitor provided a static panoramic view of the whole surgical field. The standard camera was static at the zoomed-in level for the dual-monitor condition of the study. The study had two groups of participants: 4 surgeons proficient in both robotic and advanced laparoscopic skills and 10 lay persons (nonsurgeons) who were given adequate time to train and familiarize themselves with the equipment. Running a 50-cm rope was the basic task. Advanced tasks included running a suture through predetermined points and intracorporeal knot tying with 3–0 silk. Trial completion times and errors, categorized into three groups (orientation, precision, and task), were recorded. Results  The trial completion times for all the tasks, basic and advanced, in the two groups were not significantly different. Fewer orientation errors occurred in the nonsurgeon group during knot tying (p = 0.03) and in both groups during suturing (p = 0.0002) in the dual-monitor arm of the study. Differences in precision and task error were not significant. Conclusions  Using two camera views helps both surgeons and lay persons perform complex tasks with fewer errors. These results may be due to better awareness of the surgical field with regard to the location of the instruments, leading to better field orientation. This display setup has potential for use in complex minimally invasive surgeries such as esophagectomy and gastric bypass. This technique also would be applicable to open microsurgery. Presented at the 2008 SAGES meeting.     

Surgical fidelity: comparing the microscope and the endoscope

Background

Both the microscope and the endoscope are widely used as visualization tools in neurosurgery; however, surgical dexterity when operating with each may differ. The aim of this study was to compare the surgical fidelity when using each of these visualization tools.

Methods

Junior residents and expert surgeons performed standardized motor tasks under microscopic and endoscopic visualization. Demerits for inaccuracy and time needed to complete the tasks were used to compare the surgeons’ performance with the microscope and the endoscope. The participants also performed a motor task under direct vision using different instruments to evaluate whether the shape of the instrument had any impact on the surgical fidelity.

Results

For the junior residents, the number of demerits accrued was lower with the microscope than with the endoscope, and the time needed to complete the tasks was also lower with the microscope. There was no difference in the number of demerits between the microscopic and the endoscopic experts, but the microscopic expert completed the task in a shorter time. There was no difference in demerits or performance time when comparing a short, straight instrument and a longer, bayoneted one.

Conclusions

For junior residents, surgical fidelity is higher with the microscope than with the endoscope. This difference vanishes with experience, but a slower speed of execution is observed with endoscopic visualization, both in junior and expert surgeons.     

Determination of the latency effects on surgical performance and the acceptable latency levels in telesurgery using the dV-Trainer® simulator

Background

The primary limitation of telesurgery is the communication latency. Accurate and detailed data are lacking to reveal the latency effects on surgical performance; furthermore, the maximum acceptable latency in telesurgery remains unclear.

Methods

Sixteen medical students performed an energy dissection exercise and a needle-driving exercise on the robotic simulator dV-Trainer^®, and latencies varying between 0 and 1,000 ms with a 100-ms interval were randomly and blindly presented. Task completion time, instrument motion, and errors were automatically recorded. The difficulty, security, precision, and fluidity of manipulation were self-scored by subjects between 0 and 4 (0 the best, 2 moderate, and 4 the worst).

Results

Task completion time, motion, and errors increased gradually as latency increased. An exponential regression was fit to the mean times and motions (R ² > 0.98). Subjective scorings of the four items were similar. The mean scores were less than 1 at delays ≤200 ms, then increased from 1 to 2 at 300–700 ms, and finally approached 3 at delays above. In both exercises, latencies ≤300 ms were judged to be safe by all and 400–500 ms were accepted by 66–75 % of subjects. Less than 20 % of subjects accepted delays ≥800 ms.

Conclusions

The surgical performance deteriorates in an exponential way as the latency increases. The delay impact on instrument manipulation is mild at 0–200 ms, then increases from small to large at 300–700 ms, and finally becomes very large at 800–1,000 ms. Latencies ≤200 ms are ideal for telesurgery; 300 ms is also suitable; 400–500 ms may be acceptable but are already tiring; and 600–700 ms are difficult to deal with and only acceptable for low risk and simple procedures. Surgery is quite difficult at 800–1,000 ms, telementoring would be a better choice in this case.     

Effect of visual feedback on surgical performance using the da Vinci surgical system

Background: Robotic surgical systems quantify human movements in terms of position, velocity, and time span. This information can be used to objectively assess surgical skill. The aim of this study was to test the effects of three-dimensional vs. two-dimensional visualization on performance using the da Vinci(R) Surgical System (Intuitive Surgical, Sunnyvale, CA). Materials and Methods: The movements of novice and expert surgeons were recorded using the da Vinci((R)) Surgical System for a two-handed task in two visual environments (two-dimensional and three-dimensional). Data were analyzed to investigate the effect of visual feedback on performance. Results: Velocities and task completion times were significantly different for novices and experts (P < 0.05) for all velocity parameters in both visual conditions. Additionally, there was a significant difference between two-dimensional and three-dimensional times for novices (P < 0.05). Novices were idle significantly longer in two-dimensional than in three-dimensional visual input (P = 0.037), and overall, novices were idle longer than experts for both visual conditions (P = 0.001). Conclusion: Three-dimensional visual input allows novice surgeons to perform tasks with higher velocities, less idle time, and greater economy of motion. However, three-dimensional visual input provides no significant enhancement of performance for expert surgeons.     

A prospective randomized study to test the transfer of basic psychomotor skills from virtual reality to physical reality in a comparable training setting

OBJECTIVE: To test whether basic skills acquired on a virtual endoscopic surgery simulator are transferable from virtual reality to physical reality in a comparable training setting. SUMMARY BACKGROUND DATA: For surgical training in laparoscopic surgery, new training methods have to be developed that allow surgeons to first practice in a simulated setting before operating on real patients. A virtual endoscopic surgery trainer (VEST) has been developed within the framework of a joint project. Because of principal limitations of simulation techniques, it is essential to know whether training with this simulator is comparable to conventional training. METHODS: Devices used were the VEST system and a conventional video trainer (CVT). Two basic training tasks were constructed identically (a) as virtual tasks and (b) as mechanical models for the CVT. Test persons were divided into 2 groups each consisting of 12 novices and 4 experts. Each group carried out a defined training program over the course of 4 consecutive days on the VEST or the CVT, respectively. To test the transfer of skills, the groups switched devices on the 5th day. The main parameter was task completion time. RESULTS: The novices in both groups showed similar learning curves. The mean task completion times decreased significantly over the 4 training days of the study. The task completion times for the control task on Day 5 were significantly lower than on Days 1 and 2. The experts' task completion times were much lower than those of the novices. CONCLUSIONS: This study showed that training with a computer simulator, just as with the CVT, resulted in a reproducible training effect. The control task showed that skills learned in virtual reality are transferable to the physical reality of a CVT. The fact that the experts showed little improvement demonstrates that the simulation trains surgeons in basic laparoscopic skills learned in years of practice.     

Effect of alcohol on surgical dexterity after a night of moderate alcohol intake

Background

Alcohol misuse is commonplace among health professionals. The effects of alcohol on cognition and dexterity have been shown up to 14 hours after alcohol intake. The aerospace industry has restrictions on alcohol intake, and there is pressure for the health care industry to do the same. Few studies have addressed the lingering impact alcohol has on surgical performance, and none have measured surgical dexterity using well-established Fundamentals of Laparoscopic Surgery benchmarks.

Methods

Twenty-seven surgeons participated in this study: 11 attending surgeons, 2 fellows, and 14 resident surgeons. Three Fundamentals of Laparoscopic Surgery tasks measured surgical dexterity: peg transfer, pattern cutting, and intracorporeal suturing. Performance on these tasks was measured before alcohol intake and the morning after a night of social drinking. Alcohol levels were measured via breathalyzer 20 minutes after completion of drinking and the following morning before testing. Time and accuracy were compared.

Results

The mean blood alcohol level was .076 mg/100 mL blood. Times for peg transfer, pattern cutting, and intracorporeal suturing showed no differences. Accuracy in pattern cutting was not different, but accuracy for intracorporeal suturing was significantly worse the morning after alcohol intake.

Conclusions

The morning after moderate alcohol intake, the time to complete Fundamentals of Laparoscopic Surgery tasks was unchanged, but accuracy was worse.     

In-line versus pistol-grip handles in a laparoscopic simulators. A randomized controlled crossover trial

Background: Needleholders with in-line handles (ILH) and those with pistol-grip handles (PGH) were compared in terms of operative end-product quality (OEPQ), procedure effectiveness (PE), and surgeon forearm workload (SFWL) during suturing in a laparoscopic simulator. Methods: A 90% power crossover design at alpha 0.05 required 46 surgeons. Block randomization generated ILH–PGH or PGH–ILH sequence allocation. The task involved suturing a perforated ulcer on a foam stomach in a simulator. In this study, OEPQ was measured by tissue damage, accuracy error, water leak; PE by operating time and motion analysis including goal-directed actions (GDA) and non–goal-directed actions (NGDA); and SFWL by electromyogram (EMG) of six forearm and thumb muscles. Results: The 46 surgeons performed the tasks as allocated. All the variables but two were significantly different between the first and second tasks, ignoring the handle type. There was no evidence of an unequal carryover effect when the comparison was stratified by ILH–PGH or PGH–ILH sequence. As compared with ILH, PGH tissue damage (0.1 vs 0.2 mm; p = 0.06) and NGDA (1 vs 1 p = 0.09) were different, whereas accuracy error, leak rates, operating time, GDA, and EMG were not. Conclusions: As compared with ILH needleholders, the use of PGH needleholders led to increased tissue damage and non–goal-directed actions during a suturing task in a simulator.     

Design of a proficiency-based skills training curriculum for the fundamentals of laparoscopic surgery

Currently, no optimal curriculum exists for the Fundamentals of Laparoscopic Surgery (FLS) manual skills training program. The objective was to create a proficiency-based training curriculum that would allow both successful completion of the FLS manual skills exam and improved performance in the operating room. Two experienced laparoscopic surgeons performed 5 consecutive repetitions of all 5 FLS tasks. The mean performance times for both subjects were determined. Error parameters for each task were also recorded and used to establish a maximum allowable error parameter for each task. These data were used to create both error- and time-based proficiency levels for each task based on the importance of the task and the amount of resources consumed when practicing the task. This type of objective proficiency level was determined for each of the 5 FLS tasks. We have developed a proficiency-based training curriculum for the psychomotor skills portion of FLS. Work is under way to evaluate and validate this curricular design.     

Advanced stereoscopic projection technology significantly improves novice performance of minimally invasive surgical skills

Background

Three-dimensional (3D) surgical imaging systems provide stereoscopic depth cues that are lost in conventional two-dimensional (2D) display systems. Recent improvements in stereoscopic projection technology using passive polarising displays may improve performance of minimally invasive surgical skills. This study aims to identify the effect of passive polarising stereoscopic displays on novice surgeon performance of minimally invasive surgical skills.

Methods

20 novice surgeons performed 10 repetitions of 4 surgical skills tasks using a new passive polarising stereoscopic display under 3D and 2D conditions. The previously validated tasks used were rope pass, paper cut, needle capping and knot tying. Outcome measures included total error rate and time for task completion.

Results

Novice surgeons demonstrated a significant reduction in error rates for sequential repetitions of each task using the passive polarising stereoscopic display compared with the 2D display. Mean errors for the 3D versus the 2D mode were 2.0 versus 4.3 for rope pass (P?≤?0.001), 0.8 versus 1.6 for paper cut (P?=?0.001), 1.3 versus 4.2 for needle capping (P?≤?0.001) and 2.8 versus 8.0 for knot tying (P?≤?0.001). Novice surgeons demonstrated a significant improvement in mean time for completion for all four tasks when using the 3D system. Mean time (in seconds) for 3D versus 2D were 106.5 versus 134.4 for rope pass (P?≤?0.001), 116.1 versus 176.3 for paper cut (P?≤?0.001), 76.3 versus 141.6 for needle capping (P?≤?0.001) and 153.4 versus 252.6 for knot tying (P?≤?0.001).

Conclusion

Passive polarising stereoscopic displays significantly improve novice surgeon performance during acquisition of minimally invasive surgical skills.