The application of surgical procedure manager (SPM): first experience with FESS.

In our hypothesis, the newly developed program SPM (surgical procedure manager) will ensure successful standardization and efficiency of the FESS (functional endoscopic sinus surgery) and therefore make a decisive contribution in terms of economization and improvement of intraoperative quality. Between 27th March 2015 and 8th October 2015, data from 259 FESS procedures were collected using the SPM. The study took place at the surgical desk, an operating room in the ACQUA clinic in Leipzig, Germany. 233 FESS (90%) of the total FESS (n = 259, 100%) were conducted entirely with SPM. 26 SPM terminations (10%) of 259 FESS remain, which are classified as actual SPM terminations-when the surgeon intentionally stops the SPM. The maximum time slot decreased clearly from 1 h 39 min (period A) to 1 h 10 min (period B). A time reduction can also be seen with the minimum duration of 13.5 min compared to 11 min. The variability of the time slot also decreases since the standard deviation is reduced by 4.5 min. On the basis of available recordings it can be postulated that the application of SPM is suitable for standardization for FESS. Standardization by means of SPM and minimal development can be recognized over a period of time. The SPM makes it possible to transfer the general advantages of mechanization on a concrete FESS and do not influence the medical processes nor even restrict the medical freedom. The users are still entirely free in the implementation of the respective procedure.

Less is sometimes more: a comparison of distance-control and navigated-control concepts of image-guided navigation support for surgeons.

Image-guided navigation (IGN) systems provide automation support of intra-operative information analysis and decision-making for surgeons. Previous research showed that navigated-control (NC) systems which represent high levels of decision-support and directly intervene in surgeons' workflow provide benefits with respect to patient safety and surgeons' physiological stress but also involve several cost effects (e.g. prolonged surgery duration, reduced secondary-task performance). It was hypothesised that less automated distance-control (DC) systems would provide a better solution in terms of human performance consequences. N = 18 surgeons performed a simulated mastoidectomy with NC, DC and without IGN assistance. Effects on surgical performance, physiological effort, workload and situation awareness (SA) were compared. As expected, DC technology had the same benefits as the NC system but also led to less unwanted side effects on surgery duration, subjective workload and SA. This suggests that IGN systems just providing information analysis support are overall more beneficial than higher automated decision-support. PRACTITIONER SUMMARY: This study investigates human performance consequences of different concepts of IGN support for surgeons. Less automated DC systems turned out to provide advantages for patient safety and surgeons' stress similar to higher automated NC systems with, at the same time, reduced negative consequences on surgery time and subjective workload.

Potential of the navigated controlled surgery at the lateral skull base with the navigated control unit (NCU 2.0).

Segmentation for navigated control was in the first generation very time consuming. In the present version (NCU 2.0) the risk structure is segmented (instead of the work space), this leads to an enormous decrease in preparation time. In additional, new safety functions were integrated. The segmentation feasibility was tested on patient data and proved to be successful. The automatic stop function was tested on petrous bone models and showed no damage to the facial nerve.

Voice Handicap Index-18 as an Instrument for Assessing Subjective Voice Impairment Between Voice Pre- and Post-treatment.

The Voice Handicap Index (VHI) is today regarded as the gold standard for measuring the subjective impairment of a voice disorder. The aim of our study is to present how the VHI in our version with 18 questions (VHI-18) can be evaluated with other patient collectives (practice visitors or everyday patients). The previous publications have shown that most patient groups were stationary or clinical. A total of 100 adult patients (72 female, 28 male) in our medical practice KOPFZENTRUM were examined. The reliability of the VHI-18 results from a Cronbach's Alpha (0.92). The VHI-18 is suitable as a diagnostic instrument for medical practices or logopaedic practices.

A handheld flexible manipulator system for frontal sinus surgery.

PURPOSE: Draf drainage is the standard treatment procedure for frontal sinus diseases. In this procedure, rigid angled endoscopes and rigid curved instruments are used. However, laterally located pathologies in the frontal sinus cannot be reached with rigid instrumentation. In order to assist surgeons with such complicated cases, we propose a novel handheld flexible manipulator system. METHODS: A cross section of 3 mm × 4.6 mm enables transnasal guiding of a flexible endoscope with 1.4 mm diameter and a standard flexible surgical instrument with up to 1.8 mm diameter into the frontal sinus with increased reachability. The developed system consists of an electrical discharge-machined flexure hinge-based nitinol manipulator arm and a purely mechanical handheld control unit. The corresponding control unit enables upward and left-right bending of the manipulator arm, translation, rolling, actuation and also quick exchange of the surgical instrument. In order to verify the fulfillment of performance requirements, tests regarding reachability and payload capacity were conducted. RESULTS: Reachability tests showed that the manipulator arm can be inserted into the frontal sinus and reach its lateral regions following a Draf IIa procedure. The system can exert forces of at least 2 N in the vertical direction and 1 N in the lateral direction which is sufficient for manipulation of frontal sinus pathologies. CONCLUSION: Considering the fact that the anatomical requirements of the frontal sinus are not addressed satisfactorily in the development of prospective flexible instruments, the proposed system shows great potential in terms of therapeutic use owing to its small cross section and dexterity.

Validation of knowledge acquisition for surgical process models.

OBJECTIVE: Surgical Process Models (SPMs) are models of surgical interventions. The objectives of this study are to validate acquisition methods for Surgical Process Models and to assess the performance of different observer populations. DESIGN: The study examined 180 SPM of simulated Functional Endoscopic Sinus Surgeries (FESS), recorded with observation software. About 150,000 single measurements in total were analyzed. MEASUREMENTS: Validation metrics were used for assessing the granularity, content accuracy, and temporal accuracy of structures of SPMs. RESULTS: Differences between live observations and video observations are not statistically significant. Observations performed by subjects with medical backgrounds gave better results than observations performed by subjects with technical backgrounds. Granularity was reconstructed correctly by 90%, content by 91%, and the mean temporal accuracy was 1.8 s. CONCLUSION: The study shows the validity of video as well as live observations for modeling Surgical Process Models. For routine use, the authors recommend live observations due to their flexibility and effectiveness. If high precision is needed or the SPM parameters are altered during the study, video observations are the preferable approach.

Assessment of technical needs for surgical equipment by surgical process models.

The presented approach introduces a method for estimating the potential benefit of a surgical assist system prior to its actual development or clinical use. The central research question is: What minimal requirements must a future system meet so that its use would be more advantageous than a conventional or already existent method or system, and how can these requirements be obtained from routine clinical data? Forty-three cases of lumbar discectomies were analyzed with regard to activities related to bone ablation in order to predict the temporal requirements for an alternative strategy of using a surgical assist system for bone ablation. The study recorded and analyzed surgical process models (SPM), which are progression models with detailed and exact-to-the-second representations of surgical work steps, as a sensible means for the detailed quantification of the temporal needs of the system. The presented methods can be used for a systematic analysis of such requirements. Implementation of these methods will prove very useful in the future from a medical, technical, and administrative point of view. Manufacturers can use this analytical procedure to derive parameters for their systems that indicate success criteria. Additionally, hospitals can decide, before making actual capital expenditure decisions, if the system of interest is superior to the conventional strategy and therefore worth the investment.

Anatomical Characterization of Frontal Sinus and Development of Representative Models.

This paper presents the methods and the materials towards characterizing frontal sinus anatomy and developing representative anatomical models which reflect the variance of the anatomy with three different sizes: small, medium and large. Anatomical characterization was performed using computer tomography data of up to 50 anonymous patients. Dimensional and volumetric measurements were conducted using the .stl files generated by segmentation and 3-D reconstruction. Three representative data sets were chosen to be realized in the form of models with frontal sinuses of small, medium and large sizes. The models include bone, mucosa and skin structures, whereas bone structures were manufactured by selective laser sintering of polyamide and the soft tissues by casting of gelatin and silicone. To ensure realistic optical and mechanical properties of the mucosa, verification tests were performed and the results were integrated into the manufacturing process.

First clinical application of a navigation-controlled shaver in paranasal sinus surgery.

Conventional, pointer-based navigated Functional Endoscopic Sinus Surgery (FESS) has been shown to have certain limitations: necessity of instrument change for navigation, changes in the surgeon's line-of-sight axis, and limited length of use of the navigation information. These limitations result in negative consequences regarding the surgeon's attentiveness in any given situation, as well as in his cognitive work-load. The principle of Navigated Control offers advantages concerning these problems and limitations of the conventionally navigated FESS. This Chapter analyzes the first clinical deployment of a navigation-controlled shaver in FESS on the basis of the following questions: (1) Is clinical deployment of the navigation-controlled shaver possible with the pre-clinic evaluated set-up? (2) What information relevant to the surgery is relayed in an intraoperative setting by the navigation-controlled shaver? (3) How does deployment of the navigation-controlled shaver affect the ergonomics of the surgery? Ten patients with chronic sinusitis ethmoidalis were included in the study (average age: 48 [22-71], m:w=4:6). The preoperative and intraoperative workflow was documented according to the Innovation Center Computer Assisted Surgery (ICCAS) Workflow protocol. Data regarding the surgical validity of the information and ergonomic characteristics were recorded by means of questionnaires. The average time required for segmentation of the workspace was 14.2 minutes. The shaver switched off through Navigated Control an average 16.5 times during an FESS. From this amount, five shutdowns on average were initiative and six were determined to be provoked. The shutdowns were indicated by the operators to be correct in 199 of 220 (90.5%) events and in agreement with the actual position and planned resection borders. The quality of the relayed navigation information was indicated with an average Level of Quality (LOQ) of 56.4 [50-80]. The most favorable evaluation was attained for navigation in the area of the sphenoid sinus with 71 points on average [60-80]. During an FESS, the navigation information led to a change in the planned surgical strategy an average of 0.9 [0-3] times. Throughout all surgical procedures, the situation awareness was assessed an average of 2.7 points better than with the conventionally navigated FESS. This also was the case for the cognitive workload (Workload shift) with 2.8 [1-3.5] points. This Chapter proves the clinical applicability of a navigation-controlled instrument by means of a shaver in Ears, Nose, and Throat (ENT) surgery for the first time. Reproduction of the dental splint registration, manual segmentation of the working space, and attachment of the registration star still prove to be critical aspects. Data regarding quality of the information relayed by the navigation system and resulting change in surgical strategy lead to the conclusion that the authors are dealing with, in the overall evaluation, supplementary and surgically relevant information. This information is more efficiently transferred to the surgeon by means of Navigated Control that allows, according to the following results, both an improved understanding of the information and cognitive easing of stress for the surgeon.

Virtual endoscopy on a portable navigation system for ENT surgery.

Virtual endoscopy is considered as an ideal aid assessing the complex anatomy of patients and has already been evaluated in several clinical studies. However, due to the increasing quality of modern CT- and MRT-images, present virtual-endoscopy software relies on powerful hardware. In this contribution virtual endoscopy on a portable navigation system for ENT surgery is proposed. The portable navigation system features a tablet pc to ensure a device that does not need much space in the operating room.

Model for nerve visualization in preoperative image data based on intraoperatively gained EMG signals.

While removing bone tissue of the mastoid, the facial nerve is at risk of being injured. In this contribution a model for nerve visualization in preoperative image data based on intraoperatively gained EMG signals is proposed. A neuro monitor can assist the surgeon locating and preserving the nerve. With the proposed model gained EMG signals can be spatially related to the patient resp. the image data. During navigation the detected nerve course will be visualized and hence permanently available for assessing the situs.

The navigation-controlled drill in temporal bone surgery: a feasibility study.

BACKGROUND: This study examines the feasibility of a navigation-controlled (NC) drill for surgery on the petrosal bone in an experimental environment. According to the principle of NC, the drill is to be switched off automatically once the borders of the workspace are exceeded during a mastoidectomy. MATERIALS AND METHODS: The registration is based on an optical navigation system with navigation software (MiMed). As surgery engine, the Unidrive-system (Karl Storz GmbH & CO. Kg, Tuttlingen, Germany) was integrated. The definition of the workspace was performed manually in axial computed tomography (CT) slices of the petrosal bone phantom. The mastoidectomy on the model was accomplished in three runs with 10 trial surgeons altogether (5 experienced [exp.] in otologic (ear) surgery, 5 inexperienced [nonexp.]). During each run, the following were logged: the total length of time for the procedure as well as the number and extent of injuries to the risk structures (facial nerve, horizontal semicircular canal, sigmoid sinus). The resultant petrosal bone cavities were measured on the CT. RESULTS: The time for the segmentation of the workspace for the mastoidectomy amounted to 17 minutes. The mean value of the drilling (e.g., milling) performance ranges from 6.61 mm3/s (group 1 [nonexp. + NC]), 9.62 mm3/s (group 2 [exp. w/o NC]), to 10.08 mm3/s (group 3 [exp. + NC]). The relative deviation to the segmented volume amounts to +7.4% (794.3 mm3) for group 1, -39.9% for group 2, and -34% (3,647.0 mm3) for group 3. In the groups with NC guidance of the drill, no damage to a risk structure could be logged. In the group of exp. ear surgeons without NC assistance, one injury to the facial nerve in the petrosal bone phantom occurred. DISCUSSION: The results that follow prove the fundamental feasibility of an NC drill for surgery of the petrosal bone using the example of the simple mastoidectomy in the laboratory test. When using NC, tissue resection is faster, more precise, and has fewer related complications than the same procedure without. The results offer a very promising basis for the introduction of a newly conceived system to the procedure of NC surgery on the petrosal bone. The device configuration used here was originally conceived for NC guidance of a shaver in functional endoscopic sinus surgery. Individual errors will have to be mitigated through the new version of the control unit presently in development.

Segmentation of neck lymph nodes in CT datasets with stable 3D mass-spring models segmentation of neck lymph nodes.

RATIONALE AND OBJECTIVES: The quantitative assessment of neck lymph nodes in the context of malignant tumors requires an efficient segmentation technique for lymph nodes in tomographic three-dimensional (3D) datasets. We present a stable 3D mass-spring model for lymph node segmentation in computed tomography (CT) datasets. MATERIALS AND METHODS: For the first time our model concurrently represents the characteristic gray value range, directed contour information, and shape knowledge, which leads to a robust and efficient segmentation process. RESULTS: Our model design and the segmentation accuracy were both evaluated with 40 lymph nodes from five clinical CT datasets containing malignant tumors of the neck. CONCLUSION: The segmentation accuracy proved to be comparable to that of manual segmentations by experienced users and significantly reduced the time and interaction needed for the lymph node segmentation.

The impact of haptic learning in telemanipulator-assisted surgery.

BACKGROUND: The use of a telemanipulator requires special training and surgical performance is associated with a learning curve. The aim of this study was to demonstrate the potential value of Haptic-Visual over Visual-Only passive Training in telemanipulator-assisted surgery. METHODS: Two telemanipulator consoles (da Vinci, Intuitive Surgical) were linked through an Application Programer's Interface allowing the applicant at the training console to register the position and passively follow the motions of the instructor's master telemanipulators (MTMs) at the master console (Haptic-Visual Learning group, HVL). The applicant could not actively interfere with the MTM movements. Both the trainee and the instructor shared the same 3-dimensional vision. Alternatively, subjects received only standard visual training without touching the MTMs (Visual-Only Learning group, VL). A standardized demonstration of tasks and the system was given for both groups. Participants (n=20) without previous experience with telemanipulation performed a set of various tasks in a randomized order. Study end points were time and accuracy required to perform the different task. RESULTS: The first task, with moving items to appropriate locations, showed differences in time to perform the task [mean: 4:06 min (HVL) vs. 5:16 min (VL) (P=0.2)] and accuracy differed among groups [mean number of errors 1.7 (VL) vs. 1.3 (HVL) P=0.38]. With more challenging tasks [cut out round figures (cut) and performing double dot suture lines (sti)] the number of errors was less in the HVL group [mean: 1.1 errors (cut) (P=0.05) and 1.8 errors (sti) (P=0.26)] compared with the VL group [mean: 1.8 errors (cut) and 2.3 errors (sti)]. In addition, the time to perform the tasks decreased in the HVL group with mean: 5.42 minutes (cut) (P=0.26) and 9.41 minutes (sti) (P=0.36) compared with the VL group with mean: 7.09 minutes (cut) and 11.43 minutes (sti). CONCLUSIONS: This study demonstrated the impact of haptic-visual passive learning in telemanipulator-assisted surgery which may alter the training for telemanipulator-assisted endoscopic procedures.

[ElePhant: an anatomic-electronic simulation system for the evaluation of computer assisted interventions and surgical education]. / ElePhant: ein anatomisch-elektronisches Simulationssystem für die Evaluation computerassistierter Eingriffe und die chirurgische Ausbildung.

BACKGROUND: Suitable simulation systems providing realistic conditions are required for preclinical evaluation of computer assisted interventions and surgical training. Techniques are necessary for an objective detection of injuries to the structures at risk. The aim of this study was the technical realization of a simulation system for the ENT intervention, mastoidectomy. MATERIALS AND METHODS: The basis of the simulation system was a CT scan of a cadaver skull. Using 3D printing, an anatomical phantom with realistic bone-like properties was created. Electronic detection systems were integrated into the structures at risk. A study with 16 ENT surgeons was conducted to prove the system's suitability for surgical training. RESULTS: The creation of simulation systems for the objective evaluation of surgical intervention qualities is feasible. A modular structure enables economic and simple replacement of the simulation area. The modules are cost effective and reproducible with high accuracy. The present study shows that the simulation system can be applied in surgical education and evaluation as an alternative to cadavers. CONCLUSION: Objective evaluation of injured structures at risk can be realized in real time. The simulation system permits preclinical evaluation studies of computer assisted instruments and surgical education. Reproducibility of the results makes multi-center studies possible.

Evaluation of a navigation system for ENT with surgical efficiency criteria.

The aim of this study is the evaluation of a navigation system (NaviBase) for ENT surgery. For this purpose, a new methodology for the evaluation of surgical and ergonomic system properties has been developed. The practicability of the evaluation instruments will be examined using the example of the overall assessment of the system in comparison with the current surgical standard and with other systems using clinical efficiency criteria. The evaluation is based on 102 ENT surgical applications; of these, 89 were functional endoscopic sinus surgeries (FESS). The evaluation of surgical and ergonomic performance factors was performed by seven ENT surgeons. To evaluate surgical system properties, the Level of Quality (LOQ) in 89 cases of the FESS was determined. It compares the existing information of the surgeon with that of the navigation system on a scale of 0 to 100 and with a mean value of 50 and places it in a relationship to the clinical impact. The intraoperative change of the planned surgical strategy (Change of Surgical Strategy) was documented. The ergonomic factors of the system with the categories of Overall Confidence (Trust), awareness of the situation (Situation Awareness), influence on the operating team, requirements for specific skills (Skill Set Requirement), and cognitive load (Workload Shift) were recorded for all surgical procedures as Level of Reliance (LOR). In the evaluation of the surgical system properties, an average evaluation of the quality of the information, as an LOQ of 63.59, resulted. Every second application of the navigation system (47.9%), on average, led to a change in the surgical strategy. An extension/enhancement of the indication of the endonasal approach through the use of the navigation system was shown in 7 of 102 (6.8%) cases. The completion of the resection in the FESS was rated by 74% of group I and 11% of group II as better in comparison with the standard approach. Total confidence shows a positive evaluation of 3.35 in the LOR. To supplement the evaluation of the navigation system, the technical parameters were included. The maximum deviation, Amax, of the displayed position of the reference value amounted to 1.93 mm. The average deviation was at 1.29 mm with an SD above all values, sd, of 0.29. The subsequent economic evaluation resulted in an effective average extra expenditure of time of 1.35 minutes per case. The overall evaluation of the system imparts application-relevant information beyond the technical details and permits comparability between different assistance systems.

FESS control: realization and evaluation of navigated control for functional endoscopic sinus surgery.

In this paper, a new system for navigated control in functional endoscopic sinus surgery (FESS) is presented. The system allows the safe and convenient use of a shaver that can be enabled by the surgeon only within a specified working space. Preoperatively, the surgeon defines this working space in the axial slices of the CT scan. During the surgery, the positions of the shaver and patient are tracked by an optical navigation system, which calculates whether the shaver is within the working space. The navigated control electronics receives a signal from the navigation system and disables the shaver if it is outside the working space. If the shaver is inside the working space, the surgeon can set its speed freely with a foot pedal. Experimental evaluation shows that the system allows convenient and intuitive safe removal of inflamed tissue while protecting sensitive structures. The clinical applicability was proven in a clinical trial with 10 patients.

Surgical PACS for the digital operating room. Systems engineering and specification of user requirements.

For better integration of surgical assist systems into the operating room, a common communication and processing plattform that is based on the users needs is needed. The development of such a system, a Surgical Picture Aquisition and Communication System (S-PACS), according the systems engineering cycle is oulined in this paper. The first two steps (concept and specification) for the engineering of the S-PACS are discussed.A method for the systematic integration of the users needs', the Quality Function Deployment (QFD), is presented. The properties of QFD for the underlying problem and first results are discussed. Finally, this leads to a first definition of an S-PACS system.

Solving challenges in inter- and trans-disciplinary working teams: Lessons from the surgical technology field.

INTRODUCTION: Engineering a medical technology is a complex process, therefore it is important to include experts from different scientific fields. This is particularly true for the development of surgical technology, where the relevant scientific fields are surgery (medicine) and engineering (electrical engineering, mechanical engineering, computer science, etc.). Furthermore, the scientific field of human factors is important to ensure that a surgical technology is indeed functional, process-oriented, effective, efficient as well as user- and patient-oriented. Working in such trans- and inter-disciplinary teams can be challenging due to different working cultures. The intention of this paper is to propose an innovative cooperative working culture for the interdisciplinary field of computer-assisted surgery (CAS) based on more than ten years of research on the one hand and the interdisciplinary literature on working cultures and various organizational theories on the other hand. METHODOLOGY: In this paper, a retrospective analysis of more than ten years of research work in inter- and trans-disciplinary teams in the field of CAS will be performed. This analysis is based on the documented observations of the authors, the study reports, protocols, lab reports and published publications. To additionally evaluate the scientific experience in an interdisciplinary research team, a literature analysis regarding scientific literature on trans- and inter-disciplinarity was performed. Own research and literature analyses were compared. RESULTS: Both the literature and the scientific experience in an interdisciplinary research team show that consensus finding is not always easy. It is, however, important to start trans- and interdisciplinary projects with a shared mental model and common goals, which include communication and leadership issues within the project teams, i.e. clear and unambiguous information about the individual responsibilities and objectives to attain. This is made necessary due to differing leadership cultures within the cooperating disciplines. Another research outcome is the relevance of a cooperative learning culture throughout the complete duration of the project. Based on this cooperation, new ideas and projects were developed, i.e. a training concept for surgical trainers including technological competence for surgeons. DISCUSSION: An adapted innovative paradigm for a cooperating working culture in CAS is based on a shared mental model and common goals from the very beginning of a project. CONCLUSIONS: All actors in trans- and inter-disciplinary teams need to be interested in cooperation. This will lead to a common view on patients and technology models.

Web-tool to Support Medical Experts in Probabilistic Modelling Using Large Bayesian Networks With an Example of Hinosinusitis.

For many complex diseases, finding the best patient-specific treatment decision is difficult for physicians due to limited mental capacity. Clinical decision support systems based on Bayesian networks (BN) can provide a probabilistic graphical model integrating all necessary aspects relevant for decision making. Such models are often manually created by clinical experts. The modeling process consists of graphical modeling conducted by collecting of information entities, and probabilistic modeling achieved through defining the relations of information entities to their direct causes. Such expert-based probabilistic modelling with BNs is very time intensive and requires knowledge about the underlying modeling method. We introduce in this paper an intuitive web-based system for helping medical experts generate decision models based on BNs. Using the tool, no special knowledge about the underlying model or BN is necessary. We tested the tool with an example of modeling treatment decisions of Rhinosinusitis and studied its usability.