First agreement analysis and day-to-day comparison of pharyngeal pH monitoring with pH/impedance monitoring in patients with suspected laryngopharyngeal reflux

OBJECTIVE

Diagnosis of laryngopharyngeal reflux (LPR) is still challenging. Recently a diagnostic device for pH values in the aerosolized environment of the pharynx has been introduced (Dx-pH). We evaluated results of Dx-pH with objective criteria of pH/impedance monitoring (MII) and subjective reflux scoring systems and assessed day-to-day variability.

DESIGN

This study makes use of a prospective single-center trial. Thirty patients with suspected LPR were analyzed. Upper endoscopic examination, manometry, phoniatric examination, and reflux scores were assessed. Dx-pH was performed on two consecutive days, first in combination with MII and second as single measurement. Thereafter, proton pump inhibitor (PPI) trial was performed. Patients were interviewed about symptom relief after 3 months.

RESULTS

There were considerable differences between MII and results on Dx-pH: day 1 (agreement 11 out of 30, kappa 0.137) and day 2 (agreement 14 out of 30, kappa 0.036). Statistically significant differences were detected correlating all single reflux episodes (n = 453) of Dx-pH with MII and vice versa. Furthermore acidic reflux episodes did not result in pH drops of the pharynx. There was a fair agreement between Dx-pH measurements on subsequent days. After follow-up, 3 out of 18 patients with pathological Dx-pH results reported positive response to PPIs, in contrast to 5 out of 6 patients with pathological MII.

CONCLUSION

According to our data, acid pharyngeal pH levels detected with Dx-pH are not related to GERD and acid esophageal reflux episodes do not result in pharyngeal pH alterations. Hence, present etiology of LPR needs to be reconsidered since neither mixed nor gas reflux events result in pharyngeal pH alteration. Other acid-producing or retaining factors should be taken into account.

[Zenker's diverticulum: pro operation]

In case of Zenker's diverticulum, treatment is indicated as soon as the diagnosis is established. Therapy should aim at the elimination of dysphagia and the symptoms of food retention and should reliably prevent recurrence. Currently, three different therapeutic approaches are applied: the classical option is open transcervical myotomy and diverticulectomy/diverticulopexy and alternatively stapled diverticulostomy with a linear stapler or flexible endoscopic diverticulostomy is propagated. As compared to the surgical (open) approach, rigid or flexible endotherapy is less invasive. However, endotherapy is not always feasible for all types of Zenker's diverticulum and the recurrence rate is high. Accordingly, open diverticulectomy is recommended in patients with an adequate life expectancy and good general operability.

Safe sigmoid access for natural orifice transluminal endoscopic surgery (NOTES)

One of the main challenges in transluminal surgery is sterile and safe access. For many interventions, a transanal approach would be ideal but it is considered too risky because of contamination and the danger of secondary leakage. A new safe and sterile transanal access was developed, combining four basic principles: (i) the creation of a decontaminating hydroperitoneum, (ii) the use of an overtube, (iii) defining the entry point with ultrasound and (iv) dedicated closure technique. Applicability and reliability was first proven in extensive animal experiments. Feasibility of the concept in humans was subsequently demonstrated in cadavers.

Training of a standardized natural orifice transluminal endoscopic surgery cholecystectomy using an ex vivo training unit

BACKGROUND AND STUDY AIMS

The endoscopic-laparoscopic interdisciplinary training entity (ELITE) is one of the first training models for the training of natural orifice transluminal endoscopic surgery (NOTES) and conventional laparoscopic and endoscopic skills. The current study was designed to assess whether the effect of surgical simulation with an ex vivo training unit is relevant to surgical practice in the operating room and who, in particular, might benefit from this training.

PATIENTS AND METHODS

A group of 30 participants (gastroenterologists, laparoscopists, and novices) performed a standardized NOTES cholecystectomy via a trans-sigmoidal approach. Fifteen participants performed the cholecystectomy following training with ELITE and 15 participants performed the procedures without previous training. The parameters studied were task times, quality and safety of the surgical procedure, and subjective evaluation of the ELITE trainer as a teaching model.

RESULTS

During the training courses all participants showed a significant learning curve, with a total time needed on the first pass of 32 minutes vs. 18 minutes for the fourth pass ( P < 0.001). For the cholecystectomy in the pig model, participants with prior training needed less time to complete the procedure than participants without training. In the group without training, more complications/difficulties occurred than in the group with prior training (16 vs. 8). The video analyses by two independent NOTES experts showed an inter-rater validity of 1.0. Subjective evaluation showed that participants considered ELITE to be a suitable and recommendable simulator for NOTES.

CONCLUSIONS

The ELITE model is suitable for training in the NOTES cholecystectomy procedure. This type of simulator training leads to fewer intraoperative complications.

Natural-orifice transluminal endoscopic surgery: low-pressure pneumoperitoneum is sufficient and is associated with an improved cardiopulmonary response (PressurePig Study)

BACKGROUND AND AIMS

The aim of this randomized trial in the acute porcine model was to compare the quality of transgastric peritoneoscopy with the use of low-pressure versus standard-pressure pneumoperitoneum and to evaluate the respective associated cardiopulmonary changes.

METHODS

For transgastric peritoneoscopy, carbon dioxide was insufflated via the endoscope for a constant intraperitoneal pressure of 6 mmHg or 12 mmHg in 9 pigs each. The quality of transgastric peritoneoscopy was rated on a visual analog scale (0 mm, min.; 100 mm, max.) by the endoscopist, who was blinded to the intraperitoneal pressure. The cardiac index and global end-diastolic volume index (GEDVI, reflecting preload) were measured every 3 minutes by transpulmonary thermodilution. The following were also recorded: heart rate, mean arterial pressure (MAP), systemic vascular resistance index (SVRI, reflecting afterload), peak inspiratory pressure (PIP), pH, PCO (2), and PO (2).

RESULTS

The quality of transgastric peritoneoscopy with the use of low-pressure pneumoperitoneum was not inferior to that obtained using standard-pressure pneumoperitoneum (87.0 mm vs. 87.3 mm; P<0.05). In both groups we observed a statistically significant rise in MAP and SVRI. The increase in SVRI was less pronounced during low-pressure peritoneum ( P=0.042), indicating a reduced stress response in comparison to standard-pressure peritoneum. There were no relevant differences between the groups in relation to cardiac index, GEDVI, and heart rate. An intra-abdominal pressure of 6 mmHg also led to better oxygenation ( P=0.031 for difference in PO (2) between the two groups) due to lower peak inspiratory pressure ( P<0.001 for difference). There were only slight differences between the groups with regard to pH and PCO (2).

CONCLUSIONS

Pneumoperitoneum of 12-16 mmHg is used for standard laparoscopy. For NOTES, low-pressure pneumoperitoneum is sufficient and is associated with an improved cardiopulmonary response compared to standard-pressure pneumoperitoneum.

Prediction of intraoperative complexity from preoperative patient data for laparoscopic cholecystectomy

OBJECTIVE

Different reasons may cause difficult intraoperative surgical situations. This study aims to predict intraoperative complexity by classifying and evaluating preoperative patient data. The basic prediction problem addressed in this paper involves the classification of preoperative data into two classes: easy (Class 0) and complex (Class 1) surgeries.

METHODS AND MATERIAL

preoperative patient data were collected from 337 patients admitted to the Klinikum rechts der Isar hospital in Munich, Germany for laparoscopic cholecystectomy (LAPCHOL) in the period of 2005-2008. The data include the patient's body mass index (BMI), sex, inflammation, wall thickening, age and history of previous surgery, as well as the name and level of experience of the operating surgeon. The operating surgeon was asked to label the intraoperative complexity after the surgery: '0' if the surgery was easy and '1' if it was complex. For the classification task a set of classifiers was evaluated, including linear discriminant classifier (LDC), quadratic discriminant classifier (QDC), Parzen and support vector machine (SVM). Moreover, feature-selection was applied to derive the optimal preoperative patient parameters for predicting intraoperative complexity.

RESULTS

Classification results indicate a preference for the LDC in terms of classification error, although the SVM classifier is preferred in terms of results concerning the area under the curve. The trained LDC or SVM classifier can therefore be used in preoperative settings to predict complexity from preoperative patient data with classification error rates below 17%. Moreover, feature-selection results identify bias in the process of labelling surgical complexity, although this bias is irrelevant for patients with inflammation, wall thickening, male sex and high BMI. These patients tend to be at high risk for complex LAPCHOL surgeries, regardless of labelling bias.

CONCLUSIONS

Intraoperative complexity can be predicted before surgery according to preoperative data with accuracy up to 83% using an LDC or SVM classifier. The set of features that are relevant for predicting complexity includes inflammation, wall thickening, sex and BMI score.

Automation of a suturing device for minimally invasive surgery

BACKGROUND

In minimally invasive surgery, hand suturing is categorized as a challenge in technique as well as in its duration. This calls for an easily manageable tool, permitting an all-purpose, cost-efficient, and secure viscerosynthesis. Such a tool for this field already exists: the Autosuture EndoStitch(®). In a series of studies the potential for the EndoStitch to accelerate suturing has been proven. However, its ergonomics still limits its applicability. The goal of this study was twofold: propose an optimized and partially automated EndoStitch and compare the conventional EndoStitch to the optimized and partially automated EndoStitch with respect to the speed and precision of suturing.

METHODS

Based on the EndoStitch, a partially automated suturing tool has been developed. With the aid of a DC motor, triggered by a button, one can suture by one-fingered handling. Using the partially automated suturing manipulator, 20 surgeons with different levels of laparoscopic experience successfully completed a continuous suture with 10 stitches using the conventional and the partially automated suture manipulator. Before that, each participant was given 1 min of instruction and 1 min for training. Absolute suturing time and stitch accuracy were measured. The quality of the automated EndoStitch with respect to manipulation was tested with the aid of a standardized questionnaire.

RESULTS

To compare the two instruments, t tests were used for suturing accuracy and time. Of the 20 surgeons with laparoscopic experience (fewer than 5 laparoscopic interventions, n=9; fewer than 20 laparoscopic interventions, n=7; more than 20 laparoscopic interventions, n=4), there was no significant difference between the two tested systems with respect to stitching accuracy. However, the suturing time was significantly shorter with the Autostitch (P=0.01). The difference in accuracy and speed was not statistically significant considering the laparoscopic experience of the surgeons. The weight and size of the Autostitch have been criticized as well as its cable. However, the comfortable handhold, automatic needle change, and ergonomic manipulation have been rated positive.

CONCLUSION

Partially automated suturing in minimally invasive surgery offers advantages with respect to the speed of operation and ergonomics. Ongoing work in this field has to concentrate on minimization, implementation in robotic systems, and development of new operation methods (NOTES).

Natural-orifice transluminal endoscopic surgery (NOTES) in Europe: summary of the working group reports of the Euro-NOTES meeting 2010

The fourth Euro-NOTES workshop took place in September 2010 and focused on enabling intensive scientific dialogue and interaction between participants to discuss the state of the practice and development of natural-orifice transluminal endoscopic surgery (NOTES) in Europe. Five working groups were formed, consisting of participants with varying scientific and medical backgrounds. Each group was assigned to an important topic: the correct strategy for dealing with bacterial contamination and related complications, the question of the ideal entry point and secure closure, interdisciplinary collaboration and indications, robotics and platforms, and matters related to training and education. This review summarizes consensus statements of the working groups to give an overview of what has been achieved so far and what might be relevant for research related to NOTES in the near future.

Randomized controlled trial of ultrasonic dissection versus standard surgical technique in open left hemicolectomy or total gastrectomy

Background

Ultrasonic dissection devices have been designed for use in open surgery but it is not certain how they compare with standard surgical techniques.

Methods

This was a multicentre randomized controlled trial comparing ultrasonic dissection with the traditional surgical technique for haemostasis and dissection during left hemicolectomy and total gastrectomy. The primary endpoint was duration of operation; secondary endpoints were blood loss and other intraoperative parameters, and patient outcomes. Performance of the two techniques was rated by surgeons and assistants on a ten-point Likert scale.

Results

The analysis included 100 patients in the ultrasonic and 101 in the conventional dissection group. Patient demographics, and clinical and tumour-related parameters were similar in the two groups. There was no significant difference in duration of operation (mean 170 and 178 min in ultrasonic and conventional groups respectively; P = 0·405). Nor were there significant differences in intraoperative blood loss (median 350 and 400 ml respectively; P = 0·882), other intraoperative parameters, oncological or functional outcome. The ultrasonic dissector device was rated one point higher than conventional techniques by the surgeons.

Conclusion

Use of the ultrasonic dissector in open total gastrectomy and hemicolectomy had no impact on the overall operating time or other endpoints studied. Surgeons preferred the ultrasonic device for dissection. Registration number: ISRCTN97779420 (http://www.controlled-trials.com).

NOTES for the cardia: antireflux therapy via transluminal access

BACKGROUND AND STUDY AIMS

The current standard for surgical antireflux therapy is laparoscopic Nissen fundoplication, but natural orifice transluminal endoscopic surgery (NOTES) enables even less invasive access to the peritoneal cavity. We therefore aimed to evaluate a NOTES approach to antireflux therapy.

PATIENTS AND METHODS

An animal study including 24 pigs (16 nonsurvival and eight survival). After the peritoneal cavity had been accessed via the rectosigmoid, the gastroesophageal junction (GEJ) was laid open using conventional endoscopic instruments. Thereafter, a transcutaneously introduced hook was used for tunneling and lifting of the distal esophagus. Finally, an antireflux ring was placed around the cardia. Animals were observed over 10 days in the survival series. Correct application of the prosthesis, adverse events as a result of the procedure, and bacterial contamination were evaluated by autopsy.

RESULTS

The esophagogastric junction was strengthened by applying the ring prosthesis in 22 of 24 animals. Four bleeding episodes were observed, three of which were handled endoscopically. Correct placement of the prosthesis was accomplished in 21 of 22 animals. In the survival series, 1 pig died after transhiatal herniation of the stomach, and 1 pig suffered from peritonitis due to intraoperative contamination. In 7 of the 8 survival animals, no bacterial growth was noted by smear culture. The intervention had to be performed as a hybrid NOTES procedure in all cases.

CONCLUSION

Exposure of the GEJ and placement of an antireflux prosthesis via a hybrid NOTES procedure is feasible, despite some complications. This approach may be considered as a basis for optimization and further development of pure NOTES antireflux procedures.

Natural orifice transluminal endoscopic surgery in pancreatic diseases

Natural orifice transluminal endoscopic surgery (NOTES) is a surgical technique that has received considerable interest in recent years. Although minimal access surgery has increasingly replaced traditional open abdominal surgical approaches for a wide spectrum of indications, in pancreatic diseases its widespread use is limited to few indications because of the challenging and demanding nature of major pancreatic operations. Nonetheless, there have been attempts in animal models as well as in the clinical setting to perform diagnostic and resectional NOTES for pancreatic diseases. Here, we review and comment upon the available data regarding currently analyzed and performed pancreatic NOTES procedures. Potential indications for NOTES include peritoneoscopy, cyst drainage, and necrosectomy, palliative procedures such as gastroenterostomy, as well as resections such as distal pancreatectomy or enucleation. These procedures have already been shown to be technically feasible in several studies in animal models and a few clinical trials. In conclusion, NOTES is a rapidly developing concept/technique that could potentially become an integral part of the armamentarium dealing with surgical approaches to pancreatic diseases.

[Orientation of endoscopic images: rectification by gravity]

A known problem in endoscopic surgery (especially with flexible video endoscopes) is the absence of a stable horizon in endoscopic images displayed on a monitor. With our "ENDOrientation" approach, image rectification, even in non-rigid endoscopic surgery (particularly NOTES), can be realized with a tiny MEMS tri-axial inertial sensor placed on the tip of an endoscope. This sensor measures the impact of gravity on each of the three orthogonal accelerometer axes in real time. After an initial calibration and temporal filtering of these three data steams, the rotation angle of an endoscope can be estimated directly. The achievable sampling rate of the inertial sensor is above the usual endoscopic video frame rate of 25 Hz; the rotation accuracy is approximately one degree. The image rectification can be performed in real time by digitally rotating the endoscopic video signal. Improvements and benefits have been evaluated in animal studies: coordination and movement of different instruments was rated to be much more intuitive with a stable horizon on endoscopic images. The recorded time stamps and position tracks clearly support this observation.

Carbon dioxide versus room air for natural orifice transluminal endoscopic surgery (NOTES) and comparison with standard laparoscopic pneumoperitoneum

BACKGROUND

Most studies investigating natural orifice transluminal endoscopic surgery (NOTES) have used room air, whereas carbon dioxide (CO(2)) is traditionally preferred for laparoscopic insufflation.

OBJECTIVE

Evaluation of CO(2) versus room air for NOTES and comparison with standard laparoscopic pneumoperitoneum.

DESIGN

Prospective experiments in an acute porcine model.

INTERVENTIONS

For transgastric peritoneoscopy, either CO(2) or room air were insufflated via the endoscope for a constant intraperitoneal pressure of 12 mm Hg in 16 pigs. Another 8 pigs received laparoscopic insufflation with CO(2). Identification of intra-abdominal organs during NOTES was documented. Additionally, standardized video recordings of peritoneoscopy were evaluated by an independent blinded observer. Complete cardiopulmonary status was assessed every 3 minutes.

MAIN OUTCOME MEASUREMENTS

Quality of transgastric peritoneoscopy and cardiopulmonary response.

RESULTS

In the NOTES room air group, significantly more target organs (18/64, 28%) were missed than in the NOTES CO(2) group (8/64, 13%; P = .028). However, blinded video analysis showed no difference between the groups. An increase in systemic vascular resistance index during pneumoperitoneum in the NOTES room air group was less pronounced than in the NOTES CO(2) group, almost reaching the level of significance (P = .050). With respect to hemodynamics, there were no significant differences between the NOTES CO(2) group and the laparoscopy CO(2) group.

LIMITATIONS

Nonsurvival animal experiments.

CONCLUSIONS

Pressure-controlled endoscopic insufflation of CO(2) for NOTES showed minor advantages compared with insufflation of room air regarding intra-abdominal visualization, but resulted in an increase in cardiac afterload. However, the cardiorespiratory responses during endoscopic insufflation of CO(2) were similar to the widely accepted standard laparoscopic CO(2) insufflation.

Natural orifice transluminal endoscopic surgery: cardiopulmonary safety of transesophageal mediastinoscopy

BACKGROUND AND STUDY AIMS

Physiological reactions during natural orifice transluminal endoscopic surgery (NOTES) mediastinoscopy may lead to cardiorespiratory depression. The aim of the current study was to assess cardiopulmonary changes during transesophageal mediastinoscopy in an acute porcine model.

METHODS

Transesophageal mediastinoscopy was performed under general anesthesia in eight female pigs with a bodyweight of 39 +/- 6 kg. Mediastinal access was achieved via a submucosal tunnel. The cardiac index and global end-diastolic volume index (reflecting preload) were measured every 3 minutes by transpulmonary thermodilution. The following parameters were also recorded: mediastinal pressure, heart rate, mean arterial pressure, systemic vascular resistance index (SVRI; reflecting afterload), peak inspiratory pressure, pH, pCO (2), and pO (2).

RESULTS

In three animals, small tears in the parietal pleura resulted in tension pneumothoraces. The associated cardioplumonary deterioration was fatal in one pig. The other two pigs recovered after decompression with a chest tube. In the remaining five animals there were only mild hemodynamic and respiratory changes during mediastinoscopy. There was a significant ( P = 0.005) but minor transient fall in cardiac index, which correlated with a small rise in SVRI (r = - 0.857, P < 0.001). In the pigs with uncomplicated mediastinoscopy, on-demand insufflation via the endoscope resulted in median mediastinal pressures of 4.5 mm Hg (range 2.3 - 10.2 mm Hg). Overall, mediastinal and thoracic structures could be identified without difficulty via the transesophageal approach.

CONCLUSIONS

NOTES mediastinoscopy carries a substantial risk of inadvertent development of a pneumothorax. Otherwise, it leads to negligible hemodynamic and pulmonary changes. In conclusion, close monitoring for the presence of a pneumothorax during NOTES mediastinoscopy appears to be mandatory.

[Natural orifices transluminal endoscopic surgery (NOTES) in Germany: summary of the working group reports of the "D-NOTES meeting 2009"]

The D-NOTES-group met in June 2009 for an evaluation of ongoing preclinical and clinical activities in natural orifice endoscopic surgery and the further coordination of research in Germany. Different working groups with various topics were formed. Consensus statements among various participants with different scientific and medical background were initiated. In summary, important topics were handled such as the correct handling of bacterial contamination and related complications, the question of the ideal entry point and a secure closure, interdisciplinary cooperation, and matters related to training and education. Furthermore, participants agreed on terminological basics. A to-do-list for medical engineering was formulated.

A family of new instruments for laparoscopic radiofrequency ablation of malignant liver lesions

Primary and secondary liver tumors may be treated with radiofrequency ablation (RFA) to improve tumor control and to increase patient survival. Lesions are punctured percutaneously or during open surgery. However, not all of the lesions are accessible percutaneously due to their localization: Adjacent structures could be endangered and/or the treatment would cause severe pain. Open surgery is an option in these cases but significantly more invasive. Laparoscopic RFA (LRFA) is an additional possibility in those cases: It offers a better access to difficult lesions than via the percutaneous route and is also less invasive than open surgery. The precision of targeting, however, in LRFA still has to be improved. In an in-vivo feasibility study we used a tumor mimic model in pigs to examine the applicability of laparoscopic RFA in combination with laparoscopic ultrasound using a set of dedicated new instruments to handle the RFA probe. To increase the ablation volume, the liver blood flow was reduced performing a Pringle maneuver. It is demonstrated that this set of specially designed instruments is indeed applicable and facilitates the targeting of liver lesions of any localization. Accordingly, it could significantly enlarge the applicability of LRFA.

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.

Development, standardization, and evaluation of NOTES cholecystectomy using a transsigmoid approach in the porcine model: an acute feasibility study

BACKGROUND

Transluminal cholecystectomy is feasible. However, the procedure is time consuming, difficult, and poorly standardized so far. In the present study we therefore aimed to further evaluate and optimize a transsigmoid approach for cholecystectomy with minimal transabdominal assistance in the porcine model.

METHODS

After a pilot series of 6 pigs, NOTES (natural-orifice transluminal endoscopic surgery) cholecystectomy was performed in a standardized manner in another 12 pigs. A transsigmoid approach was applied via a specially designed trocar (ISSA) with a double-channel gastroscope advanced into the peritoneal cavity. After identification of the infundibulum, the cystic duct and artery were closed by application of hemostasis clips. After dissection of these structures, the gallbladder was separated from the liver by electrocautery following injection of isotonic saline solution. A grasper introduced through a modified Veress needle (initially used for establishing the hydroperitoneum) and an additional transcutaneous stay suture were used to ease preparation of the gallbladder.

RESULTS

Transluminal cholecystectomy was successfully performed in all animals. No serious acute complications occurred; minor bleeding in 4 out of 12 cases (1 cystic artery and 3 liver parenchyma) was successfully handled by electrocautery. Clip application to close the cystic duct and artery resulted in complete sealing. Standardization of the procedure was associated with a significant decrease in total operating time (113.3 +/- 31.8 minutes for the first 6 pigs and 73.6 +/- 17.2 minutes for the last 6 pigs).

CONCLUSIONS

In pigs with a healthy gallbladder, our standardized technique of transsigmoid cholecystectomy could be performed relatively fast with acceptable complication rates at this level of evolution, as shown in these acute experiments.