The impact of prior endoscopic or surgical therapy on open Zenker's diverticulum surgery: analysis on a large single center cohort : Comparison of primary and revisional open surgery for Zenker's diverticulum.

BACKGROUND: Endoscopic treatment of Zenker's diverticulum is an attractive minimally invasive alternative compared to the classic open approach. However, increased recurrence rate were reported. In case of relapse, endoscopic therapy might be repeated, or alternatively open surgery is performed. This study aimed to identify potential differences in the outcomes between primary or secondary surgical treatment in Zenker's diverticulum. METHODS: From January 2003 to April 2019, 227 subsequent patients underwent surgical diverticulectomy and cervical myotomy at the surgical department of TUM. 41 of 227 patients had received previous therapy, either open or endoscopic. Perioperative parameters in priorly untreated patients were retrospectively compared to those after previous therapy (mostly endoscopic) with special regard to perioperative data and postoperative complications. Univariate and multivariate regression analyses were performed to identify predictors for postoperative complications. RESULTS: We could show that the number of complications (p = 0.047) in pretreated patients is significant higher as well as the severity after Clavien-Dindo (p = 0.025). Stapler line leakage, wound infections, and operative revision rate was higher also pretreated group. Pretreatment and surgery time showed a significant association with postoperative complications in univariate analysis. In multivariate analysis, pretreatment remained a significant independent predictor of complications. CONCLUSION: The present data indicate that endoscopic therapy might represent a risk factor for postoperative complications in case of relapse surgery. Therefore primary open surgery should be debated in patients with an increased high risk of relapse.

Machine Learning in the OR: A Collaborative Environment for Surgical Interventions in Visceral Medicine.

Modern surgical methods are becoming increasingly sophisticated and the number of technical devices that are used during these interventions is increasing. However, the surgical operating room (OR) remains a mere conglomerate of unconnected medical devices. The increase in the complexity of device functionality, in addition to the demands of surgery, pushes human mental capacity to its limit. Hence, an "intelligent" collaborative support system would be more than welcome. We envision a "human-like" intelligent system, which could support the surgical team as a situation-aware consultant. This so-called "active collaborative support system" (ACSS) is based on four main pillars: real-time data inflow, a comprehensive knowledge-base, access to the Internet of Things (surgical devices), and an understanding of human language through natural language processing. Recent advances in the area of AI are bringing this ambitious goal within reach, but there is still a considerable amount of work to be done, including the establishment of a new way of thinking in the collaboration between surgeons and computer scientists/engineers, and possibly one day with intelligent machines-provided that AI systems can be sufficiently trusted.

5th-Generation Mobile Communication: Data Highway for Surgery 4.0.

INTRODUCTION: 5th generation cellular mobile communications (5G) is one of the main requirements for the digital future. The new standard will offer high bandwidths (10GB/s), low latency (<1ms), and a high quality of service. It is not yet known whether 5G performance is sufficient for demanding eHealth applications (e.g., telemedicine). MATERIAL AND METHODS: We evaluated 5G performance in two different medical applications (person/asset track & tracing and video data transmission for telesurgery) to appraise the impact of this new technology. In addition, a Delphi study was conducted evaluating the expectations and acceptance of 5G in the medical field in general. RESULTS: Delphi study revealed that 5G has great potential for the future information transfer in the healthcare domain, and an increase of research activities for 5G applications in hospitals is needed. Clinical evaluation proved technical feasibility and accuracy of the 5G track & trace prototype solution. For the telepresence use case, the video stream data rate varied between 900KB-1MB/s (7.2-8 Mb/s). The data rate of the robotic control command varied between 2.4-7.2KB/s (19.2-57.6Kb/s). Delay time (latency) ranged between 2-60ms depending on the transmitted data packet length. Seventy-five percent of data packets were processed after 30ms. CONCLUSION: 5G data transmission volume, rate, and latency met the requirements for real-time track & trace and telemedicine applications. Especially for the latter, 5G data transmission offers a high potential and further research should be carried out.

Endoluminal perforation of a magnetic antireflux device.

BACKGROUND: The history of surgical antireflux treatment is coined by the search for better alternatives to Nissen fundoplication. Implantable devices are one option, beginning with the "Angelchik" prosthesis 30 years ago. However, this procedure was left soon because of the high rate of foreign body connected problems (migration, perforation). A modern approach is a magnetic sphincter augmentation device (LINX Reflux Management System, Torax Medical, Shoreview, MN, USA), a magnetic chain which is implanted laparoscopically. Advantages reported are simplicity to apply and good results in reflux control, with up to now only rare complication rates as reported in the literature (Lipham et al. in Dis Esophagus, 2014). METHODS: We report one case of erosion of the esophagus by a LINX system resulting in severe dysphagia. RESULTS: A complete endoluminal removal could be achieved by a prototype OTSC-clip remover. Complete remission could be achieved. The technique is presented in detail (video). CONCLUSIONS: In principle, total endoscopic removal of the LINX device is feasible in case of major erosion.

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.

Design of a test system for the development of advanced video chips and software algorithms.

BACKGROUND: Visual deterioration is a crucial point in minimally invasive surgery impeding surgical performance. Modern image processing technologies appear to be promising approaches for further image optimization by digital elimination of disturbing particles. To make them mature for clinical application, an experimental test environment for evaluation of possible image interferences would be most helpful. METHODS: After a comprehensive review of the literature (MEDLINE, IEEE, Google Scholar), a test bed for generation of artificial surgical smoke and mist was evolved. Smoke was generated by a fog machine and mist produced by a nebulizer. The size of resulting droplets was measured microscopically and compared with biological smoke (electrocautery) and mist (ultrasound dissection) emerging during minimally invasive surgical procedures. RESULTS: The particles resulting from artificial generation are in the range of the size of biological droplets. For surgical smoke, the droplet dimension produced by the fog machine was 4.19 µm compared with 4.65 µm generated by electrocautery during a surgical procedure. The size of artificial mist produced by the nebulizer ranged between 45.38 and 48.04 µm compared with the range between 30.80 and 56.27 µm that was generated during minimally invasive ultrasonic dissection. CONCLUSION: A suitable test bed for artificial smoke and mist generation was developed revealing almost identical droplet characteristics as produced during minimally invasive surgical procedures. The possibility to generate image interferences comparable to those occurring during laparoscopy (electrocautery and ultrasound dissection) provides a basis for the future development of image processing technologies for clinical applications.

A probe-based electromagnetic navigation system to integrate computed tomography during upper gastrointestinal endoscopy.

BACKGROUND AND STUDY AIMS: For preoperative work-up, an examination tool that visualizes separately compiled diagnostics in augmented reality would be desirable. We developed a probe-based electromagnetic navigation system, which can be passed through the working channel of an endoscope, to integrate computed tomography (CT) information during upper gastrointestinal endoscopy. PATIENTS AND METHODS: The target registration error (TRE) of the system was evaluated experimentally and clinically. A total of 24 study patients with upper gastrointestinal cancer were included in the study. The cancerous lesion was endoscopically located (mean duration 8.4 minutes, range 7.1 - 23.2) and the TRE (coronal, transverse, sagittal layer) was measured by comparing the distance between the navigation probe (at the tip of the endoscope) and the target lesion shown on the corresponding CT cross section. RESULTS: Experimental evaluations showed an accuracy in line with the system's inherent failure rate, with a median TRE of 2.8 mm (IQR 1.8 - 4.3), 2.2 mm (0.4 - 3.7), and 2.8 mm (1.1 - 5.9) in the coronal, transverse, and sagittal planes, respectively. Clinical evaluation revealed a median TRE of 4.8 mm (1.9 - 10.1), 3.9 mm (0.7 - 7.1), and 4.2 mm (0.9 - 8.9), respectively. No complications occurred during navigated endoscopy. CONCLUSIONS: The probe-based electromagnetic navigation system revealed high accuracy (TRE < 5 mm), facilitating improved interpretation of endoluminal imaging.

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.

Chylothorax after esophagectomy for cancer: impact of the surgical approach and neoadjuvant treatment: systematic review and institutional analysis.

BACKGROUND: Esophagectomy is a challenging operation with considerable potential for postoperative complications, including chylothorax. METHODS: Because no randomized controlled trial or metaanalysis is available to clarify the incidence of chylothorax in esophageal cancer surgery, the authors analyzed their own institutional data for 1,856 patients and performed a systematic review using the MEDLINE database (9,794 patients) to identify risk factors, compare success rates of therapeutic approaches, and investigate long-term outcomes. RESULTS: The overall institutional chylothorax rate was 2 % (n = 39). Reoperation was performed for 69 % of the patients. No significant difference was noted between the transthoracic and transhiatal approaches. Regression analysis showed neoadjuvant treatment (odds ratio [OR], 0.302; p = 0.001) and tumor type (OR, 0.304; p = 0.002) to be independent risk factors. The systematic review included 12 studies. Chylothorax occurred for 2.6 % of the patients. Treatment favored reoperation in five studies (70-100 %) and a conservative approach in four studies (58-72 %), with equal mortality rates. No significant difference was found between the transthoracic and transhiatal approaches. CONCLUSION: Chylothorax rates are low in high-volume centers (2-3 %). No significant difference was noted between the transthoracic and transhiatal approaches. Neoadjuvant treatment and tumor type were shown to be independent risk factors. Treatment concept (reoperation vs conservative treatment) did not affect long-term survival.

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.

Real-time monitoring for detection of retained surgical sponges and team motion in the surgical operation room using radio-frequency-identification (RFID) technology: a preclinical evaluation.

BACKGROUND: Technical progress in the surgical operating room (OR) increases constantly, facilitating the development of intelligent OR systems functioning as "safety backup" in the background of surgery. Precondition is comprehensive data retrieval to identify imminent risky situations and inaugurate adequate security mechanisms. Radio-frequency-identification (RFID) technology may have the potential to meet these demands. METHODS: We set up a pilot study investigating feasibility and appliance reliability of a stationary RFID system for real-time surgical sponge monitoring (passive tagged sponges, position monitoring: mayo-stand/abdominal situs/waste bucket) and OR team tracking (active transponders, position monitoring: right/left side of OR table). RESULTS: In vitro: 20/20 sponges (100%) were detected on the mayo-stand and within the OR-phantom, however, real-time detection accuracy declined to 7/20 (33%) when the tags were moved simultaneously. All retained sponges were detected correctly. In vivo (animal): 7-10/10 sterilized sponges (70%-100%) were detected correctly within the abdominal cavity. OR-team: detection accuracy within the OR (surveillance antenna) and on both sides of the OR table (sector antenna) was 100%. Mean detection time for position change (left to right side and contrariwise) was 30-60 s. No transponder failure was noted. CONCLUSION: This is the first combined RFID system that has been developed for stationary use in the surgical OR. Preclinical evaluation revealed a reliable sponge tracking and correct detection of retained textiles (passive RFID) but also demonstrated feasibility of comprehensive data acquisition of team motion (active RFID). However, detection accuracy needs to be further improved before implementation into the surgical OR.

Emergency Telemedicine Mobile Ultrasounds Using a 5G-Enabled Application: Development and Usability Study.

BACKGROUND: Digitalization affects almost every aspect of modern daily life, including a growing number of health care services along with telemedicine applications. Fifth-generation (5G) mobile communication technology has the potential to meet the requirements for this digitalized future with high bandwidths (10 GB/s), low latency (<1 ms), and high quality of service, enabling wireless real-time data transmission in telemedical emergency health care applications. OBJECTIVE: The aim of this study is the development and clinical evaluation of a 5G usability test framework enabling preclinical diagnostics with mobile ultrasound using 5G network technology. METHODS: A bidirectional audio-video data transmission between the ambulance car and hospital was established, combining both 5G-radio and -core network parts. Besides technical performance evaluations, a medical assessment of transferred ultrasound image quality and transmission latency was examined. RESULTS: Telemedical and clinical application properties of the ultrasound probe were rated 1 (very good) to 2 (good; on a 6 -point Likert scale rated by 20 survey participants). The 5G field test revealed an average end-to-end round trip latency of 10 milliseconds. The measured average throughput for the ultrasound image traffic was 4 Mbps and for the video stream 12 Mbps. Traffic saturation revealed a lower video quality and a slower video stream. Without core slicing, the throughput for the video application was reduced to 8 Mbps. The deployment of core network slicing facilitated quality and latency recovery. CONCLUSIONS: Bidirectional data transmission between ambulance car and remote hospital site was successfully established through the 5G network, facilitating sending/receiving data and measurements from both applications (ultrasound unit and video streaming). Core slicing was implemented for a better user experience. Clinical evaluation of the telemedical transmission and applicability of the ultrasound probe was consistently positive.

New technologies for information retrieval to achieve situational awareness and higher patient safety in the surgical operating room: the MRI institutional approach and review of the literature.

BACKGROUND: Technical progress in the operating room (OR) increases constantly, but advanced techniques for error prevention are lacking. It has been the vision to create intelligent OR systems ("autopilot") that not only collect intraoperative data but also interpret whether the course of the operation is normal or deviating from the schedule ("situation awareness"), to recommend the adequate next steps of the intervention, and to identify imminent risky situations. METHODS: Recently introduced technologies in health care for real-time data acquisition (bar code, radiofrequency identification [RFID], voice and emotion recognition) may have the potential to meet these demands. This report aims to identify, based on the authors' institutional experience and a review of the literature (MEDLINE search 2000-2010), which technologies are currently most promising for providing the required data and to describe their fields of application and potential limitations. RESULTS: Retrieval of information on the functional state of the peripheral devices in the OR is technically feasible by continuous sensor-based data acquisition and online analysis. Using bar code technologies, automatic instrument identification seems conceivable, with information given about the actual part of the procedure and indication of any change in the routine workflow. The dynamics of human activities also comprise key information. A promising technology for continuous personnel tracking is data acquisition with RFID. Emotional data capture and analysis in the OR are difficult. Although technically feasible, nonverbal emotion recognition is difficult to assess. In contrast, emotion recognition by speech seems to be a promising technology for further workflow prediction. CONCLUSION: The presented technologies are a first step to achieving an increased situational awareness in the OR. However, workflow definition in surgery is feasible only if the procedure is standardized, the peculiarities of the individual patient are taken into account, the level of the surgeon's expertise is regarded, and a comprehensive data capture can be obtained.

Effective operating room (OR) utilization by performing low-complex surgical procedures during the 2020 corona pandemic.

PURPOSE: The SARS-CoV-2 pandemic has almost stopped all elective surgical treatment throughout the world. As operating room (OR) capacities are reduced everywhere to ensure availability of intensive care capacities, especially low-complex surgical procedures are often postponed. These include totally implantable central-venous access ports which are important for the oncologic treatment of cancer patients. METHODS: In our study, we investigated the potential of an outpatient surgical centre (OSC) in terms of workflow effectiveness compared to the central operating room complex (COR) of a university hospital using low-complex surgical procedures as an example. Data of 524 consecutive patients who received a Port-a-cath procedure (422 implantations (80.5%) and 102 explantations (19.5%)) in our department between February 2019 and February 2020 were evaluated. RESULTS: A total of 277 patients were operated in outpatient surgical centre (OSC), and 247 patients received the procedure in the central OR (COR) complex. Grade II and III complications according to the Clavien-Dindo classification occurred in 5.2% (OSC) and 7.3% (COR) of patients. Incision-to-suture time was significantly quicker in the OSC group (36 vs. 42 min., p < 0.032). Total OR time (01:08 vs. 01:20 h) and preparation-to-incision time were also shorter in the OSC group (12 vs. 17 min., p < 0.002). CONCLUSION: In order to ensure effective OR utilization especially in times of the corona pandemic, the use of smaller decentralized OR units, e.g., outpatient surgical centres, for performing low-complex surgical cases is beneficial. Our study revealed shorter total OR and preparation-to-incision times.

Feasibility of opto-electronic surgical instrument identification.

One essential precondition of workflow analysis in minimally invasive surgery is a continuous data inflow in real time, in particular on the instruments in use. However, reliable identification systems are missing to date. We developed an automatic identification system which detects and registers the individual instrument during insertion into the trocar. The system is based on an opto-electronic object detection system using barcode 2/5 interleaved (printed out vs. lasered) which is detected by a micro endoscopic camera and light device. Evaluation was performed in vitro (laparoscopic training simulator) and in vivo (animal experiment) on 5 mm and 10 mm instruments with different insertion velocities into the trocar (20/10/1 cm/sec.). Furthermore, registration accuracy with a 1 - 5 sec. barcode retention period was evaluated. The best results were achieved with a 5 sec. static retention period of the barcode in the camera focus with a printed barcode. Retention periods of less than 5 sec. and dynamic insertions led to a significant decline of the detection rate. Opto-electronic barcode registration could be a promising technology for an automatic instrument registration. Although not yet mature for clinical application, the introduced system showed reliable results under static conditions.

CT-navigated real-time ultrasonography: evaluation of registration accuracy for clinical application.

Ultrasound examination is a valuable diagnostic tool in almost all medical disciplines. However, the results are highly dependent on the experience and performance of the individual examiner and the technical conditions of the examination. Since computed tomography (CT) is not affected by these factors, the combination of real-time ultrasound images and previously compiled CT scans with identical cross-sections displayed simultaneously during transcutaneous ultrasonography could be advantageous. To evaluate the practical applicability and reliability of CT-supported transcutaneous ultrasonography, we examined 10 patients with a Real-Time Virtual Sonography Unit using a previously compiled CT scan as a reference. The results were evaluated by 10 sonographers with different levels of experience. By using the 3-point registration method almost identical ultrasound and CT cross-sections were displayed throughout the examination. However, there was a constant lateral and height deviation of the CT image detected. The crucial point is the correct and reliable referencing of the real-time ultrasound. In conclusion, the CT-navigated ultrasound seems not yet complete for clinical applications. Although helpful for training purposes, it is not accurate enough yet to play a role in routine clinical diagnostic work up.

Enhanced Visualization: From Intraoperative Tissue Differentiation to Augmented Reality.

BACKGROUND: Optimal visualization of the operative field and methods that additionally provide supportive optical information form the basis for target-directed and successful surgery. This article strives to give an overview of current enhanced visualization techniques in visceral surgery and to highlight future developments. METHODS: The article was written as a comprehensive review on this topic and is based on a MEDLINE search and ongoing research from our own group and from other working groups. RESULTS: Various techniques for enhanced visualization are described comprising augmented reality, unspecific and targeted staining methods, and optical modalities such as narrow-band imaging. All facilitate our surgical performance; however, due to missing randomized controlled studies for most of the innovations reported on, the available evidence is low. CONCLUSION: Many new visualization technologies are emerging with the aim to improve our perception of the surgical field leading to less invasive, target-oriented, and elegant treatment forms that are of significant benefit to our patients.

Surgical data processing for smart intraoperative assistance systems.

Different components of the newly defined field of surgical data science have been under research at our groups for more than a decade now. In this paper, we describe our sensor-driven approaches to workflow recognition without the need for explicit models, and our current aim is to apply this knowledge to enable context-aware surgical assistance systems, such as a unified surgical display and robotic assistance systems. The methods we evaluated over time include dynamic time warping, hidden Markov models, random forests, and recently deep neural networks, specifically convolutional neural networks.

Developments in flexible endoscopic surgery: a review.

Flexible endoscopy is increasingly developing into a therapeutic instead of a purely diagnostic discipline. Improved visualization makes early lesions easily detectable and allows us to decide ad hoc on the required treatment. Deep enteroscopy allows the exploration of even the small bowel - for long a "white spot" for gastrointestinal endoscopy - and to perform direct treatment. Endoscopic submucosal dissection is a considerable step forward in oncologically correct endoscopic treatment of (early) malignant lesions. Though still technically challenging, it is increasingly facilitated by new manipulation techniques and tools that are being steadily optimized. Closure of wall defects and hemostasis could be improved significantly. Even the anatomy beyond the gastrointestinal wall is being explored by the therapeutic use of endoluminal ultrasound. Endosonographic-guided surgery is not only a suitable fallback solution if conventional endoscopic retrograde cholangiopancreatography fails, but even makes necrosectomy procedures, abscess drainage, and neurolysis feasible for the endoscopist. Newly developed endoscopic approaches aim at formerly distinctive surgical domains like gastroesophageal reflux disease, appendicitis, and cholecystitis. Combined endoscopic/laparoscopic interventional techniques could become the harbingers of natural orifice transluminal endoscopic surgery, whereas pure natural orifice transluminal endoscopic surgery is currently still in its beginnings.

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.