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Biomedical subjects

A Darzi

Publications and source records attributed to A Darzi.

At least 73 records · Page 4Linked to original sources
PubMed2003

Use of suturing as a measure of technical competence.

There is an ongoing demand for surgeons to demonstrate that they can operate well, maintain their performance, and deliver acceptable results. Currently, surgeons are assessed by a series of subjective and peer-reviewed interviews, but at no stage is the objective assessment of surgical competence measured. The authors have introduced an objective test of suturing skill as one of an array of tests used to assess technical ability. A range of surgeons with differing surgical skill was tested. The candidates were asked to suture a 4-cm wound on a latex skin pad. They were videotaped during the procedure and were scored by four independent observers using the Objective Structured Assessment of Technical Skill scoring system. Their movements were also monitored using an electromagnetic tracking system. Forty-three plastic surgeons and 46 general surgeons were divided into four groups, depending on grade, and were assessed. The difference in scores among the plastic surgeons gave a value of p < 0.001, whereas the general surgeons gave a value of p = 0.001. However, when similar grade but different specialties were compared, plastic surgeons scored significantly higher (down to senior house officer [resident year 1-2] level; mean p value = 0.019). Interrater reliability was also high (Cronbach alpha = 0.89). This task has shown that technical ability can be assessed objectively. The task has also been shown to exhibit face, construct, and concurrent validity. This has important implications for the future of surgical training in that it allows one to identify whether the fundamentals of surgical technique have been passed on to the trainee and to monitor their progress continually. It also may be used in revalidation of surgeons.

Clinical Competence↗
PubMed2003

Validation of a web-based training tool for lumbar puncture.

WebSET is an Internet based educational tool that can be used on any standard personal computer. It has been developed by a European collaboration and integrates high quality courseware, self-assessment exercises, video clips and VR simulation. This pilot study was carried out to validate the lumbar puncture (LP) module in training. Subjects who had never performed an LP participated in the study. The subjects were randomized into 2 groups: 1) underwent training and 2) control group. Both groups performed a pre-test and post-test LP on a synthetic mannequin. There was a significant improvement in the training group in terms of performance assessment as compared to the control group. This study showed that there was a significant improvement in the performance of the procedure and in procedural knowledge after training with WebSET.

Computer Simulation↗
PubMed2002

The PreOp flexible sigmoidoscopy trainer. Validation and early evaluation of a virtual reality based system.

AIM: To demonstrate face and construct validity of a computer based flexible sigmoidoscopy trainer. METHODS: The PreOp (Immersion Medical, USA) system is a virtual reality based flexible sigmoidoscopy simulator. The system records several performance parameters, such as percentage of colonic mucosa visualized, time taken, and pathlength of endoscope travel. Forty-five subjects were divided into three groups: novice (never performed a lower GI endoscopy), intermediate (5-50 examinations), and trained (greater than 200 examinations). After initial familiarization subjects were assessed three times on a case module. Results showed a nonparametric distribution. RESULTS: There was a significant difference between all three groups with respect to percentage of mucosa visualized (novice 71.0 +/- 3.7%, intermediate 77.3 +/- 5.6%, expert 84.8 +/- 4.6%, Kruskal-Wallis p <0.001) and efficiency ratio (%mucosa/time, novice 0.163 +/- 0.055, intermediate 0.259 +/- 0.07, expert 0.306 +/- 0.058, p <0.001). The novice group was also slower and had a lower pathlength of instrument travel compared to the others. CONCLUSION: PreOp virtual reality simulator is a valid discriminator of flexible sigmoidoscopic experience. Its effect on training needs to be explored.

Clinical Competence↗
PubMed2002

Practice distribution in procedural skills training: a randomized controlled trial.

BACKGROUND: "Massed" and "distributed" practice are important concepts in the acquisition of fine motor skills, and may be important in training in procedural skills. METHODS: A total of 41 novice subjects were recruited and randomized to three groups to receive training on the MIST VR surgical trainer. There were 14 subjects in each of groups A and B and 13 subjects in group C. Training comprised 20 min of massed practice for group A, 20 min of distributed practice in 5 min blocks for group B, and 15 min of distributed practice in 5-min blocks for group C. Following the training period, all groups had a 5-min rest period, followed by a 5-min retention test. Comparisons were made between groups A and B, and groups A and C. RESULTS: There was a statistically significant difference between groups A and B (p = 0.023) on the retention test, with group B performing better. The increment between the groups was 19% for the overall score on MIST VR. There were also significant differences in the time taken to complete the task during the training phase (p = 0.023, training blocks 3 and 4). Graphical representation suggests no effect between groups A and C, and statistical analysis confirms that the observed difference in median score is not significant. CONCLUSION: This study demonstrates a benefit for distributed practice over massed practice in learning laparoscopic surgical skills on the MIST VR surgical trainer. This finding has potential implications for skills training in all areas of medicine.

Adult↗
PubMed2002

Image-guided surgery for anal fistula in a 0.5T interventional MRI unit.

PURPOSE: To determine whether MR-guided anorectal surgery is feasible, and to develop techniques for MR-guided anal fistula surgery. MATERIALS AND METHODS: Six patients with pilonidal sinus (PNS), and 21 with suspected anal fistulae were operated on in the GE Signa SPIO 0.5T interventional MRI unit. Procedures were performed with magnet-safe Lockhart-Mummery fistula probes. Preprocedural and intra-operative MRI (IOMRI) techniques were used to identify the extent of the fistula tracts and septic foci, and to ensure the adequacy of the surgical procedure. RESULTS: IOMRI demonstrated the PNS lesions and the adequacy of excision. Imaging failed to demonstrate a fistula in two patients, as confirmed by surgical examination. No images were obtained in one patient due to his size (weight in excess of 100 kg). In 18 patients a fistula tract or abscess was demonstrated and IOMRI was used to assess the adequacy of the surgical procedure. In three patients this demonstrated incomplete drainage of septic foci, which was not obvious on inspection of the surgical field. We believe that in these patients IOMRI prevented an incomplete procedure and the potential requirement for a second operation. Further surgery was performed to rectify this situation. The fistula tract was laid open in 13 patients, and a Seton drain was inserted in five. CONCLUSION: MRI-guided surgery for anal fistula is feasible. IOMRI demonstrates the exact anatomy of the tracts and abscesses, and confirms that all have been adequately treated. We believe it may become particularly useful in surgery for recurrent and complex anal fistulae, and may lead to fewer recurrences.

Adult↗
PubMed2002

Validation of a flexible cystoscopy course.

OBJECTIVE: To examine the instructional effectiveness of a course for nurses wishing to learn flexible cystoscopy, using a virtual reality flexible cystoscopy simulator to measure the outcome. SUBJECTS AND METHODS: Fourteen urology nurse practitioners with no previous experience of cystoscopy were taught the basic techniques of flexible cystoscopy. They then had supervised group instruction during which they practised flexible cystoscopy on an inanimate latex model, and were taught how to handle the cystoscope, followed by unsupervised practice, including use of the virtual reality (VR) simulator (URO Mentor, Simbionix, Israel). They then undertook a cystoscopy task on the simulator; within the bladder there were 10 flags (numbered 1-10) at key positions. By visualizing and photographing each of the flags the subject would have visualized the entire bladder mucosa. The number of flags seen was thus used as a measure of how much of the bladder mucosa was examined. The VR simulator also measured the total procedure time. After a day of training the subjects were reassessed and the changes in performance evaluated. Subjects were also asked their opinion of the use of VR for flexible cystoscopy. RESULTS: The median (range) time to complete the procedure before the course was 3.33 (2-5.5) min and the number of flags seen 7 (6-9). After the course, the median time decreased to 2.85 (1.5-4.42) min and the number of flags seen increased to 8 (6-9). The change in time was significant (P = 0.03) but the difference in the number of flags was not (P = 0.12). All 14 subjects enjoyed the use of VR for learning flexible cystoscopy; they all reported that they were more confident in handling a flexible cystoscope and in undertaking flexible cystoscopy. CONCLUSION: The virtual reality simulator was an effecctive tool for teaching flexible cystoscopy.

Adult↗
PubMed2002

Virtual reality flexible cystoscopy: a validation study.

OBJECTIVES: To validate a flexible cystoscopy simulator by determining if it could differentiate between expert and novice cystoscopists. SUBJECTS AND METHODS: Seventeen subjects (10 novices with no previous endoscopic experience and seven urologists who had all carried out > 1000 flexible cystoscopies each) were asked to undertake a flexible cystoscopy task on the URO Mentor (Simbionix, Israel) virtual reality (VR) machine. In the task used the bladder mucosa has 10 flags (numbered 1-10) at key positions in the bladder; by visualizing each of the 10 flags and photographing them the subject will have indirectly visualized the entire mucosa. Subjects were asked to carry out the task 10 times, to allow their rate of acquisition of skill to be assessed. The total time taken for the task and the number of flags visualized were used as measures of performance. RESULTS: The experienced urologists were significantly better at flexible cystoscopy than the medical students on the first trial for the mean number of flags seen (9.57 vs 8.0, P = 0.01) and the mean time to complete the task (2.33 vs 4.89 min, P = 0.03). At the 10th trial there was still a significant difference for the time taken, between the medical students and the urologists (2.33 vs 0.81 min, P = 0.01) but not for the number of flags seen (9.2 vs 9.6, P = 0.46). The medical students improved between the first and the 10th attempt, being significantly quicker for trial 10 than trial 1 (P = 0.005). However, although the medical students appeared to see more flags (8.0 vs 9.2) this was not significant (P = 0.05). The urologists did not differ in the number of flags visualized between the first and 10th trial, although they were significantly quicker in completing the task (P = 0.02). The urologists were significantly faster in trial 2 than trial 1, but no faster thereafter (P = 0.04). CONCLUSIONS: Using the URO Mentor simulator, it was possible to assess the level of experience of flexible cystoscopy, and therefore the system has construct validity. As in the real situation there is a period of learning during which the subject becomes familiar with the computer/machine/human interface, the task and the handling of the instruments. These results support the view that there is a role for VR simulators in urological training.

Clinical Competence↗
PubMed2001

Motion analysis.

BACKGROUND: The ability to make an objective evaluation of a surgeon's operative ability remains an elusive goal. In this study, we used motion analysis as a measure of dexterity in the performance of a simulated operation. METHODS: Fifteen surgeons performed a total of 45 laboratory-based laparoscopic cholecystectomies on a cadaveric porcine liver model. Subjects were assigned to one of three groups according to their level of experience in human laparoscopic cholecystectomy. Electromagnetic tracking devices were used to analyze the surgeon's hand movements as they performed the procedure. Movement data (time, distance, number of movements, and speed of movement) were then compared. RESULTS: Analysis of variance (ANOVA) movement scores across the three groups showed significantly better performance among the experienced laparoscopic surgeons than the novices. Learning curves across repetitions of procedures were plotted. Novices made more improvement than experts. CONCLUSIONS: Motion analysis provides useful data for the assessment of laparoscopic dexterity, and the porcine liver model is a valid simulation of the real procedure.

Animals↗
PubMed2001

Intraperitoneal hypothermia during surgery enhances postoperative tumor growth.

BACKGROUND: Recent work has shown that intraoperative hypothermia is a significant source of surgical trauma, with wide-ranging physiological and immunological sequelae. The aim of this study was to examine the effects of intraperitoneal hypothermia during laparoscopy on tumor growth in an animal model. METHODS: Thirty WAG rats were randomized to undergo anesthesia alone (n = 10), insufflation with cold carbon dioxide (CO2) (n = 10), or insufflation with warm CO2 (n = 10). During insufflation, 1 x 105/ml CC531s colon cancer cells in suspension were injected into the peritoneal cavity. The control group was anesthetized and tumor cells were injected without insufflation. After 3 weeks, total tumor weight and the extent of tumor spread, as assessed by the modified Peritoneal Cancer Index (PCI), were compared at autopsy. RESULTS: Laparoscopy with cold CO2 resulted in a significant reduction in local and core body temperatures (p <0.05). Tumor growth in both groups that underwent CO2 pneumoperitoneum was significantly increased compared with the group that did not (p <0.0001, control vs warm CO2 and cold CO2). There was significantly more tumor growth in the rats insufflated with unwarmed CO2 than in the normothermic group (mean total tumor 0.01 g +/- 0.03 vs. 0.043 g +/- 0.07; p = 0.025 Mann-Whitney U test). Tumor spread as shown by the PCI scores was less in the warm gas group than it was in the animals insufflated with cold gas (151 vs 266). CONCLUSIONS: These data demonstrate that the peritoneal insufflation of CO2 enhances tumor growth and that the prevention of perioperative hypothermia during laparoscopy attenuates tumor growth. This effect may be partially mediated by the increased peritoneal trauma that results from insufflation with cold gas.

Animals↗
PubMed2001

Dynamic imaging of the pelvic floor using an open-configuration magnetic resonance scanner.

The aims of this study were to develop a noninvasive, erect, gravity-dependent method for assessing movements of the female pelvic floor, to describe the range of movements in pelvic floor ascent and descent in asymptomatic and symptomatic women, and to quantify any differences. A total of 102 women, 28-86 years of age, 35 symptomatic and 67 asymptomatic, were included in the study. They were scanned in a sitting position in an open scanner with good vertical access using fast-gradient echo sequences fast spoiled grass (FSPGR). Measurements of the bladder base, uterocervical junction, and anorectal junction were taken in the sagittal plane. The levator ani (LA) muscle insertion was assessed in the coronal plane with the patients at rest, during maximal strain, and during maximum contraction of the pelvic floor. Premenopausal multiparous women have a significantly lower bladder base (8/0 mm above the baseline; P value = 0.009) and uterocervical junction (15.5/3.5 mm; P value = 0.03) at rest than nulliparous women, and this becomes more apparent on straining. Parity confers a more significant effect on the position and function of the pelvic floor than menopausal status. All pelvic organs are lower at rest and on straining in women with defecation difficulties (0/-24 mm; P value = 0.001). These differences are also seen when comparing women with and without urinary incontinence. Dynamic seated magnetic resonance imaging (MRI) shows that all the pelvic organs are lower at rest and on straining in multiparous women and in those with urinary incontinence than in a group of asymptomatic nulliparous volunteers. This difference is also seen in the position of the bladder base and anorectal junction during pelvic floor contraction. These findings suggest general pelvic floor weakness in women who present with symptoms in one compartment and indicate the need for evaluation of the entire pelvic floor particularly prior to surgery. J. Magn. Reson. Imaging 2001;13:923-929.

Adult↗
PubMed2001

The role of the basic surgical skills course in the acquisition and retention of laparoscopic skill.

BACKGROUND: This study assesses the transfer of laparoscopic skills to a group of Basic Surgical Trainees (BST) attending the Basic Surgical Skills (BSS) course. METHODS: The virtual reality simulator MIST-VR was used to assess 13 trainees before and after the course and again 3 weeks and 3 months later. Analysis of kinematic data using the Imperial College Surgical Assessment Device gave measures of distance traveled, distance efficiency ratio, time taken, number of errors made, and number of movements made in completing a virtual laparoscopic task. The performance of the group was compared to a control group who underwent no training. RESULTS: All parameters improved significantly after the course, with the exception of distance traveled by the instruments. All outcome measures were significantly improved at 3 weeks. The control group showed a nonsignificant trend toward improvement in all parameters. CONCLUSIONS: The Basic Surgical Skills course produces quantifiable improvements in laparoscopic skill that are measurable by MIST-VR. There is a learning effect associated with using MIST-VR alone.

Case-Control Studies↗
PubMed2001

Skill transfer from virtual reality to a real laparoscopic task.

BACKGROUND: To validate the usefulness of virtual reality surgical simulators, we investigated the transfer of skills achieved by their use to real tasks. METHODS: Thirty medical students underwent a pretest using a real laparoscopic trainer. They were then randomized to the following three groups: group I received no training; group II received training using the Minimal Invasive Surgical Trainer in Virtual Reality (MIST-VR); and group III received training using conventional training exercises. Each group then underwent a posttest. Using the Imperial College Surgical Assessment Device (ICSAD), scores were generated for time taken, distance traveled, number of movements made, and speed of instrument movement. RESULTS: Significant changes between the MIST-VR group (group II) and the conventionally trained group (group III), were observed in the speed of movement of the left hand and the numbers of movements taken by each hand, when compared to the untrained group (group I). CONCLUSION: The training of novices using MIST-VR yields quantifiable changes in skill that are transferable to a simple real task and are similar to the results achieved with conventional training.

Clinical Competence↗
PubMed2001

Systematic review of laparoscopic surgery for colorectal malignancy.

BACKGROUND: We set out to evaluate the current literature on the use of laparoscopic surgery for malignant colorectal disease and identify its place in current practice. METHODS: We performed a systematic review of the literature that included papers published from January 1991 to March 1997. Inclusion criteria were used to select the most robust studies. The quality of each study was assessed against predefined criteria and weighted according to hierarchy of evidence and sample size. RESULTS: The published literature was found to be low in the hierarchy of evidence. Of the 157 studies located, only 42 papers were found to be of sufficiently high quality to be included in the review. Only 13 of these 42 papers concentrated specifically on malignant colorectal disease. We noted the following findings: The average age of patients was 63.2 years. The most frequently reported contraindication to laparoscopic surgery was obesity. Conversion rate to open procedure varied between 1.5% and 48%. The most common postoperative complication was wound infection. Thirty-day mortality varied between 0 and 5.1%. Disease stage and pathology were poorly reported. Patient recovery benefits varied. It was not possible to identify the effectiveness, safety, survival outcome, or cost of laparoscopic surgery for colorectal malignancy in comparison to open surgery. CONCLUSIONS: Six years after the first report of laparoscopic surgery, studies low in the hierarchy of evidence continue to be reported. This reflects a lack of control following the introduction of this new technology. The majority of reports continue to be feasibility studies. The variable nature and content of the literature demonstrate the lack of standardization and the absence of an agreed core minimum data set. The benefit of laparoscopic surgery for malignant colorectal disease remains unclear. Until the mechanisms of port site recurrences are elucidated and long-term data on survival outcomes become available, laparoscopic surgery for malignant disease should be carried out only in the context of a large, multicenter randomized controlled trial.

Carcinoma↗