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1.  Expert and construct validity of the Simbionix GI Mentor II endoscopy simulator for colonoscopy 
Surgical Endoscopy  2007;22(1):158-162.
The main objectives of this study were to establish expert validity (a convincing realistic representation of colonoscopy according to experts) and construct validity (the ability to discriminate between different levels of expertise) of the Simbionix GI Mentor II virtual reality (VR) simulator for colonoscopy tasks, and to assess the didactic value of the simulator, as judged by experts.
Four groups were selected to perform one hand–eye coordination task (EndoBubble level 1) and two virtual colonoscopy simulations on the simulator; the levels were: novices (no endoscopy experience), intermediate experienced (<200 colonoscopies performed before), experienced (200–1,000 colonoscopies performed before), and experts (>1,000 colonoscopies performed before). All participants filled out a questionnaire about previous experience in flexible endoscopy and appreciation of the realism of the colonoscopy simulations. The average time to reach the cecum was defined as one of the main test parameters as well as the number of times view of the lumen was lost.
Novices (N = 35) reached the cecum in an average time of 29:57 (min:sec), intermediate experienced (N = 15) in 5:45, experienced (N = 20) in 4:19 and experts (N = 35) in 4:56. Novices lost view of the lumen significantly more often compared to the other groups, and the EndoBubble task was also completed significantly faster with increasing experience (Kruskal Wallis Test, p < 0.001). The group of expert endoscopists rated the colonoscopy simulation as 2.95 on a four-point scale for overall realism. Expert opinion was that the GI Mentor II simulator should be included in the training of novice endoscopists (3.51).
In this study we have demonstrated that the GI Mentor II simulator offers a convincing realistic representation of colonoscopy according to experts (expert validity) and that the simulator can discriminate between different levels of expertise (construct validity) in colonoscopy. According to experts the simulator should be implemented in the training programme of novice endoscopists.
PMCID: PMC2169271  PMID: 17516114
Endoscopy; Simulator; Training; Colonoscopy; Validation
2.  Colonic stenting as bridge to surgery versus emergency surgery for management of acute left-sided malignant colonic obstruction: a multicenter randomized trial (Stent-in 2 study) 
BMC Surgery  2007;7:12.
Acute left-sided colonic obstruction is most often caused by malignancy and the surgical treatment is associated with a high mortality and morbidity rate. Moreover, these operated patients end up with a temporary or permanent stoma. Initial insertion of an enteral stent to decompress the obstructed colon, allowing for surgery to be performed electively, is gaining popularity. In uncontrolled studies stent placement before elective surgery has been suggested to decrease mortality, morbidity and number of colostomies. However stent perforation can lead to peritoneal tumor spill, changing a potentially curable disease in an incurable one. Therefore it is of paramount importance to compare the outcomes of colonic stenting followed by elective surgery with emergency surgery for the management of acute left-sided malignant colonic obstruction in a randomized multicenter fashion.
Patients with acute left-sided malignant colonic obstruction eligible for this study will be randomized to either emergency surgery (current standard treatment) or colonic stenting as bridge to elective surgery. Outcome measurements are effectiveness and costs of both strategies. Effectiveness will be evaluated in terms of quality of life, morbidity and mortality. Quality of life will be measured with standardized questionnaires (EORTC QLQ-C30, EORTC QLQ-CR38, EQ-5D and EQ-VAS). Morbidity is defined as every event leading to hospital admission or prolonging hospital stay. Mortality will be analyzed as total mortality as well as procedure-related mortality. The total costs of treatment will be evaluated by counting volumes and calculating unit prices. Including 120 patients on a 1:1 basis will have 80% power to detect an effect size of 0.5 on the EORTC QLQ-C30 global health scale, using a two group t-test with a 0.05 two-sided significance level. Differences in quality of life and morbidity will be analyzed using mixed-models repeated measures analysis of variance. Mortality will be compared using Kaplan-Meier curves and log-rank statistics.
The Stent-in 2 study is a randomized controlled multicenter trial that will provide evidence whether or not colonic stenting as bridge to surgery is to be performed in patients with acute left-sided colonic obstruction.
Trial registration
Current Controlled Trials ISRCTN46462267.
PMCID: PMC1925059  PMID: 17608947

Results 1-2 (2)