A pilot study on a new anchoring mechanism for surgical applications based on mucoadhesives

Liver retraction system by C3-muco-adhesive polymer films for laparoscopic surgery

BACKGROUND

Conventional laparoscopic instruments used for retraction may cause trauma at the retraction site. Alternative retraction/lifting especially of heavy solid organs such as the liver may be obtained by other means. The present study was designed to explore the use of C3-muco-adhesive polymers (C3-MAPs), which exhibit strong binding to the liver shortly after application to the organ and which retain strong adhesion for sufficient time, to enable sustained retraction during laparoscopic operations.

METHODS AND MATERIALS

C3-muco-adhesive polymers were produced specifically for the study. In an ex vivo experimental set-up, discs of C3-MAPs were placed on the surface of porcine livers for adhesion and retraction studies involving objective measurements by tensiometry.

RESULTS

Experiments were carried out on 14 porcine livers. The force required to detach the C3-MAPs from the liver exceeded 2.0 N 30 s after application. The adhesion force by C3-MAPs files was sufficient to enable sustained retraction force necessary for exposure of the gall bladder, which was achieved by a mean retraction force of 4.85 N (SD = 0.63). This was sustained for a mean of 130 min (range 17.0-240.0). In the adhesion studies, the forces at 30 s required to detach the polymer discs from the liver exceeded 20 N (upper limit of the load cells of the Instron). The duration of the adhesion enabled sustained optimal gall bladder exposure for periods ranging from 17 to 240 min, with a mean of 130 ± 91 min.

CONCLUSIONS

The results of the present study demonstrate that the adhesion and retraction properties of the engineered C3-MAP films are sufficient to enable complete exposure of the gall bladder for a period exceeding 1 h, confirming their potential for atraumatic retraction in laparoscopic and other minimal-access surgical approaches.

Capsule endoscopy of the future: What's on the horizon?

Capsule endoscopes have evolved from passively moving diagnostic devices to actively moving systems with potential therapeutic capability. In this review, we will discuss the state of the art, define the current shortcomings of capsule endoscopy, and address research areas that aim to overcome said shortcomings. Developments in capsule mobility schemes are emphasized in this text, with magnetic actuation being the most promising endeavor. Research groups are working to integrate sensor data and fuse it with robotic control to outperform today's standard invasive procedures, but in a less intrusive manner. With recent advances in areas such as mobility, drug delivery, and therapeutics, we foresee a translation of interventional capsule technology from the bench-top to the clinical setting within the next 10 years.

A mucoadhesive endoluminal wearable sensory system

Bio- or muco-adhesive anchoring is a challenge for the development of advanced gastrointestinal (GI) surgical instruments, endoluminal monitoring devices and drug delivery systems. In this paper, we present a polymeric bio-adhesive film embedded with an optical sensor that can potentially be used to detect gastrointestinal bleeding. Four different formulas of mucoadhesive polymers were synthesized based on various chemical components and concentration combinations, and they were further layered with miniature photoplethymographic (PPG) sensors. The adhesive ability of the proposed mucoadhesive-sensor module was tested by attaching it to the lumen of a porcine stomach and compared amongst the four formulas. pH testing was also implemented to simulate the performance of the film in gastric cavity. To demonstrate the signal quality of this module, we also tested on the skin of five healthy subjects for hours. The observed shear detachment force between mucoadhesive film and porcine stomach tissue of all four formulations ranged from 0.09 to 1.38 N, and the performance of mucoadhesive film in pH 7 and pH 2 were similar. The module can attach firmly onto the skin for 3-10 hours with comparable PPG signal quality to traditional clip-based setup. With the advent of mucosal tissue anchoring by means of bioadhensive film, a wider extent of endoluminal procedures may become feasible. This emerging technology can also help shape the future of in-body wearable devices in the GI tract or other endoluminal cavities.

Wireless Robotic Capsule for Releasing Bioadhesive Patches in the Gastrointestinal Tract

A novel, miniature wireless robotic capsule for releasing bioadhesive patches in the gastrointestinal (GI) tract was designed, fabricated, and preliminarily tested. In particular, the assembled prototype was successfully navigated in a GI phantom, up to a target site where the release mechanism was verified. Then, deployment of a bioadhesive patch onto ex vivo porcine tissue was accomplished, and patch adhesion strength was verified. The main application of the present system is the deployment of anchoring patches for miniature robotic modules to be operated in the targeted anatomical domain. Such an innovative application stems from the wise blend of robotics and bioadhesion. Obtained results, which are consistent with previous investigations by the group, confirm the viability of the adopted bioadhesives for the envisaged anchoring tasks. The present feasibility study complies with the spirit of minimally invasive, wireless diagnosis, and therapy, and provides a preliminary contribution for their advancement.

Is single-incision laparoscopic cholecystectomy safe? Results of a systematic review and meta-analysis

BACKGROUND

Single-incision laparoscopic cholecystectomy (SILC) is gaining popularity. It is not evident whether the benefits of this procedure overcome the potential increased risk. We performed a systematic review and meta-analysis to compare SILC with conventional multi-incision laparoscopic cholecystectomy (MILC).

METHODS

Data from randomized, controlled trials published up to December 2011 and comparing SILC versus MILC were extracted. The primary end point was overall morbidity. A fixed-effect model was applied to summarize the study outcomes in the meta-analysis, and a random-effect model was used in the sensitivity analysis. The outcome measures were relative risk (RR) and mean difference (MD); a RR of <1.0 or a negative MD indicated a more favorable outcome after SILC. Publication bias was assessed by a funnel plot, and heterogeneity was tested by the I (2) measure and subgroup analyses.

RESULTS

A total of 12 trials (996 patients) were included. Mortality was nil in both treatment groups; the overall RR for morbidity was 1.36 (p = 0.098). The mean operating time was 47.2 min for MILC and 58.1 min for SILC (MD 9.47 min; p < 0.001). The visual analog scale pain score at 24 h after surgery was 2.96 in MILC and 2.34 in SILC (MD -0.64; p = 0.058), but sensitivity analysis of the four studies deemed at low risk of bias for pain assessment, according to blinding and postoperative analgesic protocols, showed significance at -0.43 points (95 % confidence interval -0.87 to 0.00; p = 0.049). Cosmetic outcome scored better in the SILC group, with its standardized MD being equal to 1.16 (95 % confidence interval 0.57 to 1.75; p < 0.001).

CONCLUSIONS

In selected patients, SILC has similar overall morbidity compared with MILC; further, it results in better cosmetic satisfaction and reduced postoperative pain despite longer operative time.

A prototype of an anchoring and extending intestinal micro-robot and an in vitro experiment

In order to minimize the invasiveness of intestinal disease diagnosis and surgery, we propose an anchoring and extending micro-robot. The gait of the micro-robot was designed according to the biomechanical features of the intestinal tract. The locomotion condition showed that the anchoring capability and extending ability should be balanced to enhance locomotion efficiency. The mechanical and control system was designed and fabricated under the requirements of the locomotive model. The assembled micro-robot was 90 mm in length and 13 mm in diameter. The micro-robot prototype was tested in in vitro experiments; its locomotion efficiency was approximately 100% in an ideal environment, but around 50% in a pig's small bowel (20 mm in diameter). The in vitro experiment results demonstrated that the gait is feasible for locomotion in the small bowel although the diameter of the small bowel is a limiting factor.