Design and Evaluation of a Balanced Compliant Laparoscopic Grasper.

In laparoscopic surgery, quality of haptic feedback is reduced compared to conventional surgery, leading to unintentional tissue damage during grasping. From the perspective of haptics, poor mechanical design of laparoscopic instrument joints induces friction and a nonlinear actuation-tip force relation. In this study, a novel laparoscopic grasper using compliant joints and a magnetic balancer is presented, and the reduction in hysteresis and friction is evaluated. The hysteresis loop of the novel compliant grasper and two conventional laparoscopic graspers (high quality leading commercial brand and low quality unbranded grasper) were measured. In order to assess quality of haptic feedback, the lowest grasper tip load perceivable by instrument users was measured with the novel and the conventional laparoscopic graspers. The hysteresis loop measurement yielded a mechanical efficiency of 43% for the novel grasper, compared to- 25% and 23% for the Aesculap and the unbranded grasper, respectively. The forces perceivable by the user through the novel grasper were significantly lower (mean 1.37N, SD 0.44N) than those of conventional graspers (mean 2.15N, SD 0.71N and mean 2.65N, SD 1.20N, respectively). The balanced compliant grasper technology has the ability to improve the quality of haptic feedback compared to conventional laparoscopic graspers. Research is needed to relate these results to soft and delicate tissue grasping in a clinical setting, for which this instrument is intended.

Pre-clinical evaluation of the new veress needle+ mechanism on thiel-embalmed bodies: a controlled crossover study - Experimental research.

Veress needles (VN) are commonly used in establishing pneumoperitoneum in laparoscopic surgery. Previously, a VN with a new safety mechanism 'VeressPLUS' needle (VN+) was developed to reduce the amount of overshoot. Methods: Eighteen participants (novices, intermediates, and experts) performed in total of 248 insertions in a systematic way on Thiel-embalmed bodies with wide and small bore versions of the conventional VN (VNc) and the VN+. Insertion depth was measured by recording the graduations on the needle under direct laparoscopic vision. Results: Participants graded the bodies and the procedures as lifelike. Overall, a significant reduction (P<0.001) in average insertion depth was found for the VN+ compared to the VNc of 26.0 SD16 mm versus 46.2 SD15 mm. The insertion depth difference in the novice group was higher compared to the intermediates and experts (P<0.001). The average insertion depth for both needle types was less (P<0.001) for female participants compared to male. Conclusion: This study indicated that the VN+ significantly reduced the insertion depth in all tested conditions. Whether the difference between female and male performance can be linked to differences in muscle control or arm mass should be further investigated. Useful technical information was gathered from this study to further improve the VN+.

A novel Veress needle mechanism that reduces overshooting after puncturing the abdominal wall.

BACKGROUND: Complications that occur in laparoscopic surgery are often associated with the initial entry into the peritoneal cavity. The literature reported incidences of Veress needle (VN) injuries of e.g. 0.31% and 0.23%. In a 2010 national survey of laparoscopic entry techniques in the Canadian General Surgical practice, 57.3% of respondents had either experienced or witnessed a serious laparoscopic entry complication like bowel perforation and vascular injury. As those complications are potentially life threatening and should be avoided at all costs, improving safety of this initial action is paramount. METHODS: Based on a bare minimum design approach with focus on function expansion of existing components, a new Safety mechanism was developed for the VN that decreases the risks of VN overshooting. The mechanism works by preventing the puncturing acceleration of the tip of the VN by decoupling the surgeon's hand from the VN immediately after entering the abdomen. RESULTS: Based on a set of requirements, a first prototype of the VN+ with force decoupling safety mechanism is presented and evaluated on an ex vivo porcine abdominal wall tissue model in a custom setup. The experiments conducted by two novices and one experienced surgeon indicated a significant difference between the attempts with a standard, conventional working VN (41.4 mm [37.5-45 mm]) and VN+ with decoupling mechanism (20.8 mm [17.5-22.5 mm]) of p < 0.001. CONCLUSION: A new decoupling safety mechanism was integrated successfully in a standard VN resulting in a VN+ . The results from the pilot study indicate that this new VN+ reduces overshooting with a minimum of 50% in a standardised ex vivo setting on fresh porcine abdominal wall specimens.

Haptic exploration improves performance of a laparoscopic training task.

BACKGROUND: Laparoscopy has reduced tactile and visual feedback compared to open surgery. There is increasing evidence that visual and haptic information converge to form a more robust mental representation of an object. We investigated whether tactile exploration of an object prior to executing a laparoscopic action on it improves performance. METHODS: A prospective cohort study with 20 medical students randomized in two different groups was conducted. A silicone ileocecal model, on which a laparoscopic action had to be performed, was used inside an outside a ForceSense box trainer. During the pre-test, students either did a combined manual and visual exploration or only visual exploration of the caecum model. To track performance during the trials of the study we used force, motion and time parameters as representatives of technical skills development. The final trial data were used for statistical comparison between groups. RESULTS: All included time and motion parameters did not show any clear differences between groups. However, the force parameters Mean force non-zero (p = 004), Maximal force (p = 0.01) Maximal impulse (p = 0.02), Force volume (p = 0.02) and SD force (p = 0.01) showed significant lower values in favour of the tactile exploration group for the final trials. CONCLUSIONS: By adding haptic sensation to the existing visual information during training of laparoscopic tasks on life-like models, tissue manipulation skills improve during training.

[Ileus due to oranges in Meckel's diverticulum]. / Sinaasappelileus bij een Meckel-divertikel.

BACKGROUND: A Meckel's diverticulum is a remnant of the primitive bowel and the yolk sac which occurs in 1-5% of the population. It causes problems in only very few people. CASE DESCRIPTION: A 39-year-old man developed acute abdominal pain after eating two oranges. The cause of the pain was found during a lower abdominal laparotomy - the small bowel was obstructed by a Meckel's diverticulum and a phytobezoar composed of orange fibres. Both were removed surgically. CONCLUSION: A symptomatic Meckel's diverticulum should be removed; however, in an asymptomatic Meckel's diverticulum this approach is controversial. One of the problems that can arise is an obstructive ileus. Patients who in the past have had an obstructive ileus resulting from a phytobezoar are advised to avoid eating large quantities of fruit rich in fibre and to chew very well.