Evaluation of mist production and tissue dissection efficiency using different types of ultrasound shears

BACKGROUND

Ultrasound shears often are applied in minimally invasive surgery because they facilitate fast and secure tissue dissection, thereby reducing operative time. Although the technical principle underlying all the shears is almost identical, considerable differences exist between specific instruments. However, production of disturbing mist should be avoided.

METHODS

To obtain quantitative measurements regarding mist production, a novel hermetically sealed test system was developed. Tissue dissection efficiency was evaluated by means of a standardized cutting test. The dissection time and the numbers of cuttings were recorded. In this study, four different ultrasound dissectors from three manufacturers were assessed. One manufacturer provided two instruments: a conventional instrument and an improved version, which was designed particularly to reduce mist emission.

RESULTS

The fastest ultrasound dissector emitted the highest quantity of disturbing mist. However, improved dissection efficiency does not linearly correlate with mist production. This clearly could be shown for the improved "less mist production instrument," which turned out to work faster than the comparable standard dissector but produced significantly less mist.

CONCLUSION

Ultrasonic shears are effective for bloodless tissue dissection but may impede surgical proceeding by mist production. The findings of this study demonstrate that emission of mist can be reduced not only by lowering the dissection power, resulting in a prolonged dissection time, but also by modifying the technical design of an instrument. Further development of ultrasonic cutting devices therefore should account for the desired results.

Long-term outcome of endoscopic therapy in patients with bile duct injury after cholecystectomy

BACKGROUND AND AIM

Bile duct lesions, including leaks and strictures, are immanent complications of open or laparoscopic cholecystectomy. Endoscopic procedures have gained increasing potential as the treatment of choice in the management of postoperative bile duct injuries.

METHODS

Between January 1996 and December 2006, 44 patients with biliary leakages and 12 patients with biliary strictures after cholecystectomy were identified by analyzing the endoscopic retrograde cholangiopancreatography database, clinical records, and cholangiograms. The long-term follow up of endoscopic treatment in biliary lesions after cholecystectomy was evaluated by this retrospective study.

RESULTS

In 34 of 35 patients (97%) with peripheral bile duct leakages, endoscopic therapy was successful. Transpapillary endoprothesis and/or nasobiliary drainage were removed after 31 (5-399) days. After stent removal, the median follow-up period was 81 (11-137) months. In patients with central bile duct leakages, the success rate after median 90 (4-145) days of endoscopic therapy was 66.7% (6/9 patients). The median follow up after stent removal in six successfully treated patients was 70 (48-92) months. Eleven of 12 patients (91.6%) with bile duct strictures had successfully completed stent therapy. The follow-up period of this patient group was 99 (53-140) months.

CONCLUSIONS

Endoscopic treatment of bile duct lesions after cholecystectomy is effective, particularly in patients with peripheral bile duct leakages and bile duct strictures. Therefore, it should be the first-line therapy used in these patients. Although endoscopic management is less successful in patients with central bile duct leakages, an attempt is warranted.

The "ELITE" model: construct validation of a new training system for natural orifice transluminal endoscopic surgery (NOTES)

BACKGROUND AND STUDY AIMS

The ELITE (endoscopic-laparoscopic interdisciplinary training entity) trainer is a new ex vivo model designed to train conventional laparoscopic and endoscopic skills and to perform hybrid interventions. The aim of the present study was to assess its usefulness for natural orifice transluminal endoscopic surgery (NOTES) procedures.

MATERIALS AND METHODS

A group of 30 participants (eight gastroenterologists, 22 surgeons) ranging from novices to experts completed the following tasks. Via a trans-sigmoidal approach, anchor points in each quadrant in the abdominal cavity had to be reached. Each participant performed five consecutive courses. The time needed to perform the experiment was evaluated. In a second step to assess advanced skill for NOTES in an external face validation, 20 randomly selected individuals performed a cholecystectomy via the same trans-sigmoidal access.

RESULTS

All participants passed a significant learning curve during the assessment (total time needed: 473.1 +/- 178.5 seconds for first pass vs. 321.9 +/- 182.0 seconds for fifth pass; P = 0.02, Wilcoxon test). There were 15 novices and 15 endoscopy experts. Significant differences were observed for the total time required to perform the respective procedures between these two groups (first pass: 394.3 +/- 176.6 seconds for experts vs. 531.9 +/- 166.7 seconds for novices; P = 0.040, Mann-Whitney test). Furthermore, NOTES cholecystectomies could successfully be simulated. Participants considered the ELITE to represent a useful simulator for NOTES.

CONCLUSION

The newly developed ELITE trainer is a suitable tool to train NOTES techniques. Experts could reliably be distinguished from novices and a significant progress by training could be demonstrated.

Notes: technical aspects - hype or hope?

Natural orifice transluminal endoscopic surgery (NOTES) is currently an intensely discussed topic. The debate is extremely controversial, ranging from euphoric visions to complete refusal, and the future clinical role of natural orifice surgery is difficult to describe. This chapter analyzes the current technological status, and addresses the question of whether to enrich the surgical procedures will become an option. A literature research was undertaken using Medline and Pubmed. Personal experiences and communications were also included in this state-of-the-art report. The individual barriers currently impeding the clinical use, as defined by the NOSCAR group, are addressed in detail. With the exception of the vaginal access, no natural orifice-entering technique is already clinically mature. The selective use-potentially in combination-in a more refined technique than currently, is likely to provide a breakthrough. Most of the remaining obstacles are just a matter of further progress in advanced medical engineering. However, it should not be forgotten that the problems to be solved are less than trivial, and close cooperation between engineers and surgeons is essential. NOTES is still in the early stages of development. Currently available tools and techniques remain in the pioneer stage. However, worldwide activities in research and development will lead to promising solutions, which certainly will help to overcome the existing barriers. Whether "pure NOTES" or hybrid procedures only, surgery will take another step forward toward a less-invasive discipline.

Combined laparoscopic-endoscopic resections of colorectal polyps: 10-year experience and follow-up

BACKGROUND

Large, colorectal polyps or those that are difficult to access may be unamenable to conventional snare polypectomy and may require surgical resection. This study was designed to evaluate the resection of such lesions by the use of combined laparoscopic-endoscopic resections (CLER).

METHODS

Patients who had received CLER for colorectal polyps between January 1997 and December 2006 were identified from a prospectively maintained database. Patients with biopsies consistent with invasive cancer were excluded from the combined approach. Baseline characteristics, surgical, pathological, postoperative, and follow-up data of patients and lesions were reviewed.

RESULTS

A total of 146 consecutive patients underwent CLER for 154 lesions, and 120 (82%) patients underwent local excision (i.e., laparoscopy-assisted endoscopic resection, endoscopy-assisted wedge resection, and endoscopy-assisted transluminal resection). Twenty-six (18%) patients received endoscopy-assisted segmental colon resection. Conversion rate was 5% and intraoperative complications occurred in two patients (1%). Major postoperative complications occurred in five patients (3%), necessitating surgical reintervention in four of them. Follow-up colonoscopy revealed metachronous adenomas in 33 patients, of which 8 patients showed macroscopic or microscopic characteristics of advanced lesions. One patient, who had been converted to open resection because of incomplete laparoscopic resection of an adenoma, developed relapse of the initial adenoma and was successfully treated with repeat CLER accounting for a local recurrence rate of 0.9%.

CONCLUSIONS

Combined laparoscopic-endoscopic resection is an efficient, safe, and minimally invasive alternative to open resection for selected patients with difficult polyps, but it should be restricted to benign disease.

Time-of-Flight 3-D endoscopy

This paper describes the first accomplishment of the Time-of-Flight (ToF) measurement principle via endoscope optics. The applicability of the approach is verified by in-vitro experiments. Off-the-shelf ToF camera sensors enable the per-pixel, on-chip, real-time, marker-less acquisition of distance information. The transfer of the emerging ToF measurement technique to endoscope optics is the basis for a new generation of ToF rigid or flexible 3-D endoscopes. No modification of the endoscope optic itself is necessary as only an enhancement of illumination unit and image sensors is necessary. The major contribution of this paper is threefold: First, the accomplishment of the ToF measurement principle via endoscope optics; second, the development and validation of a complete calibration and post-processing routine; third, accomplishment of extensive in-vitro experiments. Currently, a depth measurement precision of 0.89 mm at 20 fps with 3072 3-D points is achieved.

Evaluation of dual-phase multi-detector-row CT for detection of intestinal bleeding using an experimental bowel model

To evaluate dual-phase multi-detector-row computed tomography (MDCT) in the detection of intestinal bleeding using an experimental bowel model and varying bleeding velocities. The model consisted of a high pressure injector tube with a single perforation (1 mm) placed in 10-m-long small bowel of a pig. The bowel was filled with water/contrast solution of 30-40 HU and was incorporated in a phantom model containing vegetable oil to simulate mesenteric fat. Intestinal bleeding in different locations and bleeding velocities varying from zero to 1 ml/min (0.05 ml/min increments, constant bleeding duration of 20 s) was simulated. Nineteen complete datasets in arterial and portal-venous phase using increasing bleeding velocities, and seven negative controls were measured using a 64 MDCT (3-mm slice thickness, 1.5-mm reconstruction increment). Three radiologists blinded to the experimental settings evaluated the datasets in a random order. The likelihood for intestinal bleeding was assessed using a 5-point scale with subsequent ROC analysis. The sensitivity to detect bleeding was 0.44 for a bleeding velocity of 0.10-0.50 ml/min and 0.97 for 0.55-1.00 ml/min. The specificity was 1.00. The area under the curve was calculated to be 0.73, 0.88 and 0.89 for reader 1, 2 and 3, respectively. Dual-phase MDCT provides high sensitivity and specificity in the detection of intestinal bleeding with bleeding velocities of 0.5-1.0 ml/min. Therefore, MDCT should be considered as a primary diagnostic technique in the management of patients with suspected intestinal bleeding.

Comparison of transgastric access techniques for natural orifice transluminal endoscopic surgery

BACKGROUND

Different transgastric access techniques for natural orifice transluminal endoscopic surgery (NOTES) have been described.

OBJECTIVE

To evaluate different methods of transluminal access with regard to leak pressures after the procedure.

DESIGN AND SETTING

Experimental endoscopic study in an ex vivo porcine stomach model.

METHODS

The following endoscopic techniques for transgastric access were evaluated in 34 stomachs: (1) 1.5-cm to 2-cm linear incision, (2) balloon dilation after needle-knife puncture, (3) via a short submucosal tunnel, and (4) via an extended submucosal tunnel. For techniques 3 and 4, a submucosal tract was endoscopically created by physically separating the mucosa from the muscularis. Mucosal incisions were closed by the standardized application of clips. Handsewn gastric closure after a linear needle-knife incision served as a positive control, whereas, open 1.5-cm to 2-cm gastrotomies were negative controls. After the procedure, pressures to liquid leakage were recorded.

RESULTS

The unclosed controls demonstrated leakage at mean (SD) 2 +/- 2 mm Hg, which represents a baseline system resistance. The handsewn gastric closure after linear incision leaked at 50 +/- 7 mm Hg. The needle-knife gastrotomy, the balloon dilation, the short submucosal tunnel, and the extended submucosal tunnel leaked at 37 +/- 15 mm Hg, 41 +/- 24 mm Hg, 44 +/- 13 mm Hg, and 87 +/- 19 mm Hg, respectively. There were significant differences in leakage pressures between the group with the extended submucosal tunnel and all other transgastric access techniques (all P < or = .002).

CONCLUSIONS

The extended submucosal tunnel yielded the best leak resistance, which is superior to standard transgastric access methods and rival handsewn interrupted stitches.

[Breast volume assessment based on 3D surface geometry: verification of the method using MR imaging]

Differences in breast volume and contour are subjectively estimated by surgeons. 3D surface imaging using 3D scanners provides objective breast volume quantification, but precision and accuracy of the method requires verification. Breast volumes of five test individuals were assessed using a 3D surface scanner. Magnetic resonance imaging (MRI) reference volumes were obtained to verify and compare the 3D scan measurements. The anatomical thorax wall curvature was segmented using MRI data and compared to the interpolated curvature of the posterior breast volume delimitation of 3D scan data. MRI showed higher measurement precision, mean deviation (expressed as percentage of volume) of 1.10+/-0.34% compared to 1.63+/-0.53% for the 3D scanner. Mean MRI [right (left) breasts: 638 (629)+/-143 (138) cc] and 3D scan [right (left) breasts: 493 (497)+/-112 (116) cc] breast volumes significantly correlated [right (left) breasts: r=0.982 (0.977), p=0.003 (0.004)]. The posterior thorax wall of the 3D scan model showed high agreement with the MRI thorax wall curvature [mean positive (negative) deviation: 0.33 (-0.17)+/-0.37 cm]. High correspondence and correlation of 3D scan data with MRI-based verifications support 3D surface imaging as sufficiently precise and accurate for breast volume measurements.

Percutaneously assisted endoscopic surgery using a new PEG-minitrocar for advanced endoscopic submucosal dissection (with videos)

BACKGROUND

For endoscopic submucosal dissection (ESD), adequate exposure and visualization of the submucosa for controlled dissection is of eminent importance.

OBJECTIVE

To determine the feasibility and safety of percutaneously assisted endoscopic surgery (PA-ES) with a new prototype PEG-minitrocar (PMT) for advanced ESD in a porcine model.

INTERVENTIONS

Placement of the PMT was done in all pigs by the use of a modified pull-through technique. After endoscopic incision of the mucosa, traction was provided for ESD by grasping the incisional margins of the mucosa with a rigid forceps introduced through the PMT, enabling stepwise dissection of the exposed submucosa under direct vision.

MAIN OUTCOME MEASUREMENTS

Feasibility and safety of the new PMT for PA-ES and en bloc resection of prespecified mucosal areas.

RESULTS

The study started with acute experiments in 8 animals, followed by a 10-day survival study in another 8 pigs. A total of 20 mucosal pieces were resected. The sizes of the resected pieces varied up to 7.5 x 4.0 cm ex vivo. All but one could be resected en bloc. Percutaneous assistance resulted in an excellent exposure of the submucosal space and enabled stepwise dissection of the submucosal connective tissue. Neither the PMT nor advanced ESD led to relevant complications.

CONCLUSIONS

We demonstrated the feasibility and safety of a new PMT for advanced ESD. With the use of PA-ES, mucosal pieces of various sizes can be resected en bloc in gastric locations that are difficult to access by flexible endoscopy alone.

[Short version of the updated S3 (level 3) guidelines for diagnosis and treatment of gallstones of the German Society for Digestive and Metabolic Diseases and the German Society for the Surgery of the Alimentary Tract]

This short version of the guidelines summarizes the evidence-based key recommendations for the diagnosis and treatment of gallstones. The guidelines were developed by an interdisciplinary team of gastroenterologists, surgeons, radiologists, geneticists, and patient support groups, under the auspice of the German Society for Gastroenterology and Metabolic Diseases and the German Society for General Surgery and Surgery of the Alimentary Tract. It used structural level 3 consensus-based methodology and includes statements on clinical practice, prevention, quality assurance, outcome analysis, and integration of outpatient and inpatient care for patients with gallstone disease.

Informatics and medicine--from molecules to populations

OBJECTIVES

To clarify challenges and research topics for informatics in health and to describe new approaches for interdisciplinary collaboration and education.

METHODS

Research challenges and possible solutions were elaborated by scientists of two universities using an interdisciplinary approach, in a series of meetings over several months.

RESULTS AND CONCLUSION

In order to translate scientific results from bench to bedside and further into an evidence-based and efficient health system, intensive collaboration is needed between experts from medicine, biology, informatics, engineering, public health, as well as social and economic sciences. Research challenges can be attributed to four areas: bioinformatics and systems biology, biomedical engineering and informatics, health informatics and individual healthcare, and public health informatics. In order to bridge existing gaps between different disciplines and cultures, we suggest focusing on interdisciplinary education, taking an integrative approach and starting interdisciplinary practice at early stages of education.

[S3-guidelines for diagnosis and treatment of gallstones. German Society for Digestive and Metabolic Diseases and German Society for Surgery of the Alimentary Tract]

This guideline provides evidence-based key recommendations for diagnosis and therapy of gallstones and upgrades version 2000. It was developed by an interdisciplinary team of gastroenterologists, surgeons, radiologists, geneticists, external comparative quality assurance and patient support groups under the auspices of the German Society for Digestive and Metabolic Diseases and the German Society for Surgery of the Alimentary Tract. The guideline used structural S3 consensus-based methodology and includes statements on clinical practice, prevention, outcome analysis, and integration of outpatient and inpatient care for patients with gallstone diseases.

[Are there technological advances in minimally invasive surgery and who will pay them?]

The successful development of minimally invasive surgery would have been inconceivable without continuous advances in medical technology. The users, i.e. the surgeons, however, only accepted innovations with a clear-cut positive impact on clinical care. Accordingly, the expected exponential rise in costs could be avoided. The imbalance in cost/benefit aspects between the deliverers of medical care on one hand, and the patients, the insurance companies and the employers on the other is critical. In addition, further innovations are to be expected. This will not be possible without increasing costs, but there are good reasons to assume that expenses will rise only moderately. Each modern society is able (and obliged) to afford a certain amount of medical progress in order to maintain a high level of medical care and economic strength.

Submucosal endoscopy: a novel approach to en bloc endoscopic mucosal resection (with videos)

BACKGROUND

The submucosal layer is of eminent importance for endoscopic mucosal resection (EMR) in the GI tract.

OBJECTIVE

Development of submucosal endoscopy, which allows diagnostic and therapeutic endoscopy of the submucosal space (SS) in the esophagus.

DESIGN

Acute experiments in a live porcine model.

INTERVENTIONS

An area in the esophagus was marked with a diathermic probe to define a mucosal piece for resection. After local infiltration, a 1- to 2-cm transverse incision was performed 1 to 2 cm proximal and distal of these margins. We entered the SS with a flexible small-caliber videoendoscope through the proximal incision and dissected the fibrous submucosal connective tissue in a longitudinal direction with a blunt forceps. For EMR, the lifted mucosa was subsequently separated by use of an insulated-tip hook needle-knife.

MAIN OUTCOME MEASUREMENTS

En bloc resection of prespecified mucosal areas.

RESULTS

A total of 15 mucosal pieces were resected in 4 pigs. The size of the resected pieces varied from 1.6 cm x 0.9 cm to 7.4 cm x 1.7 cm ex vivo. In a fifth pig, 2 circular mucosectomies (lengths 3.0 cm and 1.6 cm) were done. All mucosal pieces could be completely resected en bloc. The endoscopic view in the SS was excellent. There were no procedure-related complications.

LIMITATIONS

The method has not yet been evaluated in humans.

CONCLUSIONS

Entering the SS for submucosal endoscopy is a novel, innovative, and practicable method for the dissection of mucosal neoplastic lesions. We demonstrated that mucosal areas of various sizes could be resected en bloc without complications.

Effect of pneumoperitoneum on hemodynamics and inspiratory pressures during natural orifice transluminal endoscopic surgery (NOTES): an experimental, controlled study in an acute porcine model

BACKGROUND AND STUDY AIM

Physiologic reactions during natural orifice transluminal endoscopic surgery (NOTES) may differ from those at laparoscopy. This experimental study assessed the effect of pneumoperitoneum induced by endoscope air pump on hemodynamics and inspiratory pressures during transgastric peritoneoscopy.

METHODS

Transgastric peritoneoscopy was performed in 11 female pigs (35 - 50 kg) under general anesthesia. Five pigs with controlled insufflation and no endoscopic intervention served as controls. Cardiac index and global end-diastolic volume index (GEDVI; reflecting preload) were measured every 3 minutes by transpulmonary thermodilution. We also recorded: intra-abdominal pressure (IAP), heart rate, mean arterial pressure (MAP), systemic vascular resistance index (SVRI; reflecting afterload), peak inspiratory pressure (PIP), and oxygenation.

RESULTS

One study group pig was excluded from analysis because of a major complication related to the gastric incision. In the remaining 15 animals we performed 264 paired measurements. On-demand insufflation in the study group produced wide variation in intra-abdominal pressures; the control group demonstrated minimal fluctuation around a predetermined value. In the study group, IAP and PIP correlated well ( R = 0.667, P = 0.000), with maximum PIP values of 40 mbar contrasting with the control group maximum of 26.5 mbar. Hemodynamically, there was a minor decrease of cardiac index in the study group (in contrast to the control group). Relative changes in cardiac index and IAP during transgastric peritoneoscopy correlated highly significantly ( R = - 0.416, P = 0.000). Neither group showed hemodynamic instability or decline in oxygen saturation.

CONCLUSIONS

On-demand insufflation with a standard endoscopic light source/insufflator resulted in a marked median increase and wide variation in IAP throughout transgastric peritoneoscopy. Hemodynamic changes were moderate. However, major increases in PIP suggest a need for stricter control of intra-abdominal hypertension during NOTES.