The "Iceberg Phenomenon": As Soon as One Technological Problem in NOTES Is Solved, the Next One Appears!

PURPOSE: Though already proclaimed about 7 years ago, natural orifice transluminal endoscopic surgery (NOTES) is still in its early stages. A multidisciplinary working team tried to analyze the technical obstacles and identify potential solutions. METHODS: After a comprehensive review of the literature, a group of 3 surgeons, 1 gastroenterologist, 10 engineers, and 1 representative of biomedical industry defined the most important deficiencies within the system and then compiled as well as evaluated innovative technologies that could be used to help overcome these problems. These technologies were classified with regard to the time needed for their implementation and associated hindrances, where priority is based on the level of impact and significance that it would make. RESULTS: Both visualization and actuation require significant improvement. Advanced illumination, mist elimination, image stabilization, view extension, 3-dimensional stereoscopy, and augmented reality are feasible options and could optimize visual information. Advanced mechatronic platforms with miniaturized, powerful actuators, and intuitive human-machine interfaces could optimize dexterity, as long as enabling technologies are used. The latter include depth maps in real time, precise navigation, fast pattern recognition, partial autonomy, and cognition systems. CONCLUSION: The majority of functional deficiencies that still exist in NOTES platforms could be overcome by a broad range of already existing or emerging enabling technologies. To combine them in an optimal manner, a permanent dialogue between researchers and clinicians is mandatory.

What Do We Really Need? Visions of an Ideal Human-Machine Interface for NOTES Mechatronic Support Systems From the View of Surgeons, Gastroenterologists, and Medical Engineers.

PURPOSE: To investigate why natural orifice translumenal endoscopic surgery (NOTES) has not yet become widely accepted and to prove whether the main reason is still the lack of appropriate platforms due to the deficiency of applicable interfaces. METHODS: To assess expectations of a suitable interface design, we performed a survey on human-machine interfaces for NOTES mechatronic support systems among surgeons, gastroenterologists, and medical engineers. Of 120 distributed questionnaires, each consisting of 14 distinct questions, 100 (83%) were eligible for analysis. RESULTS: A mechatronic platform for NOTES was considered "important" by 71% of surgeons, 83% of gastroenterologist,s and 56% of medical engineers. "Intuitivity" and "simple to use" were the most favored aspects (33% to 51%). Haptic feedback was considered "important" by 70% of participants. In all, 53% of surgeons, 50% of gastroenterologists, and 33% of medical engineers already had experience with NOTES platforms or other surgical robots; however, current interfaces only met expectations in just more than 50%. Whereas surgeons did not favor a certain working posture, gastroenterologists and medical engineers preferred a sitting position. Three-dimensional visualization was generally considered "nice to have" (67% to 72%); however, for 26% of surgeons, 17% of gastroenterologists, and 7% of medical engineers it did not matter (P = 0.018). CONCLUSION: Requests and expectations of human-machine interfaces for NOTES seem to be generally similar for surgeons, gastroenterologist, and medical engineers. Consensus exists on the importance of developing interfaces that should be both intuitive and simple to use, are similar to preexisting familiar instruments, and exceed current available systems.

Reliability of sensor-based real-time workflow recognition in laparoscopic cholecystectomy.

PURPOSE: Laparoscopic cholecystectomy is a very common minimally invasive surgical procedure that may be improved by autonomous or cooperative assistance support systems. Model-based surgery with a precise definition of distinct procedural tasks (PT) of the operation was implemented and tested to depict and analyze the process of this procedure. METHODS: Reliability of real-time workflow recognition in laparoscopic cholecystectomy ([Formula: see text] cases) was evaluated by continuous sensor-based data acquisition. Ten PTs were defined including begin/end preparation calots' triangle, clipping/cutting cystic artery and duct, begin/end gallbladder dissection, begin/end hemostasis, gallbladder removal, and end of operation. Data acquisition was achieved with continuous instrument detection, room/table light status, intra-abdominal pressure, table tilt, irrigation/aspiration volume and coagulation/cutting current application. Two independent observers recorded start and endpoint of each step by analysis of the sensor data. The data were cross-checked with laparoscopic video recordings serving as gold standard for PT identification. RESULTS: Bland-Altman analysis revealed for 95% of cases a difference of annotation results within the limits of agreement ranging from [Formula: see text]309 s (PT 7) to +368 s (PT 5). Laparoscopic video and sensor data matched to a greater or lesser extent within the different procedural tasks. In the majority of cases, the observer results exceeded those obtained from the laparoscopic video. Empirical knowledge was required to detect phase transit. CONCLUSIONS: A set of sensors used to monitor laparoscopic cholecystectomy procedures was sufficient to enable expert observers to reliably identify each PT. In the future, computer systems may automate the task identification process provided a more robust data inflow is available.

Real-time instrument detection in minimally invasive surgery using radiofrequency identification technology.

BACKGROUND: A key part of surgical workflow recording is recognition of the instrument in use. We present a radiofrequency identification (RFID)-based approach for real-time tracking of laparoscopic instruments. METHODS: The system consists of RFID-tagged instruments and an antenna unit positioned on the Mayo stand. For reliability analysis, RFID tracking data were compared with the assessment of the perioperative video data of instrument changes (the reference standard for instrument application detection) in 10 laparoscopic cholecystectomies. When the tagged instrument was on the Mayo stand, it was referred to as "not in use." Once it was handed to the surgeon, it was considered to be "in use." Temporal miscounts (incorrect number of instruments "in use") were analyzed. The surgeons and scrub nurses completed a questionnaire after each operation for individual system evaluation. RESULTS: A total of 110 distinct instrument applications ("in use" versus "not in use") were eligible for analysis. No RFID tag failure occurred. The RFID detection rates were consistent with the period of effective instrument application. The delay in instrument detection was 4.2 ± 1.7 s. The highest percentage of temporal miscounts occurred during phases with continuous application of coagulation current. Surgeons generally rated the system better than the scrub nurses (P = 0.54). CONCLUSIONS: The feasibility of RFID-based real-time instrument detection was successfully proved in our study, with reliable detection results during laparoscopic cholecystectomy. Thus, RFID technology has the potential to be a valuable additional tool for surgical workflow recognition that could enable a situation dependent assistance of the surgeon in the future.

Toward increased autonomy in the surgical OR: needs, requests, and expectations.

BACKGROUND: The current trend in surgery toward further trauma reduction inevitably leads to increased technological complexity. It must be assumed that this situation will not stay under the sole control of surgeons; mechanical systems will assist them. Certain segments of the work flow will likely have to be taken over by a machine in an automatized or autonomous mode. METHODS: In addition to the analysis of our own surgical practice, a literature search of the Medline database was performed to identify important aspects, methods, and technologies for increased operating room (OR) autonomy. RESULTS: Robotic surgical systems can help to increase OR autonomy by camera control, application of intelligent instruments, and even accomplishment of automated surgical procedures. However, the important step from simple task execution to autonomous decision making is difficult to realize. Another important aspect is the adaption of the general technical OR environment. This includes adaptive OR setting and context-adaptive interfaces, automated tool arrangement, and optimal visualization. Finally, integration of peri- and intraoperative data consisting of electronic patient record, OR documentation and logistics, medical imaging, and patient surveillance data could increase autonomy. CONCLUSIONS: To gain autonomy in the OR, a variety of assistance systems and methodologies need to be incorporated that endorse the surgeon autonomously as a first step toward the vision of cognitive surgery. Thus, we require establishment of model-based surgery and integration of procedural tasks. Structured knowledge is therefore indispensable.

Transgastric or trans-sigmoidal? The impact of the choice of access on task performance in target natural orifice translumenal endoscopic surgery procedures.

INTRODUCTION: The effect of the choice of access upon endoscope control during a navigational task is explored within a simulator model. MATERIALS AND METHODS: The study was conducted within the endoscopic-laparoscopic interdisciplinary training entity (ELITE) model (Minimally Invasive Therapy and Intervention Research Group [MITI], Technische Universität, Germany)--a validated natural orifice translumenal endoscopic surgery (NOTES) simulator. Seventeen subjects, 15 with no endoscopic experience, navigated the endoscope from predefined trans-sigmoidal and transgastric access points to the appendix and the gallbladder. A previously defined and validated quantitative analysis of endoscope control, in addition to time taken to complete the task, was used to evaluate overall performance. The quantitative analysis extrapolated the movements of the subject's wrist in control of the endoscope and rated the movements using a scoring system of 0-3 based upon the smoothness of the movements recorded. RESULTS: Although no significant difference in terms of performance time was demonstrated between the two approaches to the appendix (36.6 ± 14.7 seconds TG and 29.8 ± 16 seconds TS) (P = .214), when the endoscope control score was compared, a significant difference was confirmed (3 TG and 7 TS) (P < .001). With regard to the approach to the gallbladder, a significant difference in terms of both the performance time (19.8 seconds TG and 35.6 seconds TS) (P < .001) and the quality of endoscope control (7 TG and 5 TS) (P = .001) was demonstrated. CONCLUSION: The choice of access route impacts directly on the ease with which the endoscopist navigates to the target. Within this study, the trans-sigmoidal appears the most appropriate to access the appendix and the transgastric for the gallbladder.

ELITE--the ex vivo training unit for NOTES: development and validation.

Skill training is an essential part of surgical education. Every physician has to get familiar with the various operation techniques and needs to handle the different instruments. However, mechanical and computer-based VR-simulators offer only one specific procedure, either laparoscopic or endoscopic. We designed the universal training system ELITE (endoscopic-laparoscopic interdisciplinary training entity) which is a new full synthetic ex vivo surgical training model for laparoscopic surgery, combined endoluminal/endocavitary procedures ("hybrid surgery") and NOTES. The aim of the current investigation was to integrate respiration and electro dissection into the model, and the evaluation of both innovations. The ELITE is a full-size replica of a human female torso including a gas-tight abdominal wall and offering various accesses to the abdomen. A complete organ package including liver, gallbladder, spleen, gastrointestinal tract, including the mesentery and omentum is available for this system. Cholecystectomy and appendectomy can be simulated realistically with this new training system. For more realistic conditions during operations breathing-induced organ motion could be integrated into this system. Two latex balloons were inserted into the system to imitate the function of the diaphragm. They are inflated and deflated according to the respiration cycle and move the artificial organs in a natural way. Physicians, including endoscopic/laparoscopic novices and experts, were asked to train different NOTES procedures on the model. Performance of their training and subjective appraisal of the model itself were evaluated. The opportunity of electrodissection of the gallbladder and appendix and simulation of breath excursion of the diaphragm could successfully be implemented into the training system. One recently published study showed that ELITE is a suitable tool to train different surgical procedures. All subjects (novices and endoscopic/laparoscopic experts) showed a significant learning curve during the assessment. Experts could be reliably differentiated from novices. The actual evaluation of the model showed that 97% of the subjects considered the ELITE as a useful simulator for NOTES. ELITE was validated to be a suitable tool to train different NOTES procedures. As a step by step training of NOTES is highly recommended, this training system offers the opportunity by degrees that animal experiments can be replaced, especially, for learning of basic techniques and thus costs can be significantly reduced.

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.

The mechatronic support system "HVSPS" and the way to NOTES.

Since the publication of the first paper on NOTES, a dramatic increase of activities in this new surgical field is to be observed. However, a "pure" NOTES operation does not yet exist. Only NOTES-like operations have been proposed so far. One of the essential barriers is the limited intraoperative performance due to the lack of suitable mechatronic platforms. Some solutions have already been suggested but they are still far from having any practical impact upon the development of more advanced NOTES procedures. The "Highly Versatile Single Port System", a two-armed device with two manipulators and a semi-flexible telescope, was developed to overcome these drawbacks. A transsigmoid cholecystectomy on a NOTES simulator (the ELITE) could be accomplished successfully in 75 minutes. We could therefore show that the HVSPS is in principle applicable for such a NOTES procedure. However, before these mechatronic support systems can be used under clinical conditions, required human machine interface and extended intelligence have to be solved.

Set of instruments for innovative, safe and sterile sigmoid access for natural-orifice transluminal endoscopic surgery.

One of the current main challenges in transluminal surgery is in obtaining sterile and secure access to the peritoneal cavity. Since the transgastric approach has not fulfilled these requirements up to now, a new transcolonic surgical approach was developed to achieve these objectives and enhance the potential of transluminal surgery. A new set of instruments comprising an endoscopic trocar, a flexible obturator and a modified transanal endoscopic microsurgery device was designed to permit sterile sigmoid access for transcolonic surgery. The set of instruments has already been successfully tested in an experimental in vivo survival study that confirmed safety and sterility as objectives during surgical intervention. The suitability of the instruments for use in the human anatomy was confirmed by a cadaveric study.

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.