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Biomedical subjects

G Buess

Publications and source records attributed to G Buess.

At least 19 recordsLinked to original sources
PubMed2005

Ergonomic testing of two different types of handles via virtual reality simulation.

BACKGROUND: Ergonomics in laparoscopic surgery is an unsolved problem. Deficiencies of the instrument handles are well-known and described in several reports and studies. Today, virtual training modules for laparoscopic surgery are available. The aim of this study was to evaluate the ability of a virtual reality (VR) simulator to determine the ergonomic properties of two different laparoscopic instrument handles. METHODS: Two different types of handles, a ring and an axial handle from Richard Wolf, were used to perform the short clip and cut task of the Xitact 500 LS simulator. The task was repeated every 2 days for a period of 5 weeks. After every trial the volunteers were asked structured questions about their preferences while using the two handles. RESULTS: The axial handle was superior or equal to the ring handle in all criteria. Learning curves over the entire time and day by day were similar. No differences were found for travel distances and error rates, but task times were different for both handles. The subjects preferred the axial handle at the end of the study. CONCLUSION: It is possible to determine differences in ergonomics of handle design with a VR trainer. In this study, the Richard Wolf axial handle was superior to the ring handle.

Computer Simulation↗
PubMed2005

Monitor position in laparoscopic surgery.

BACKGROUND: One of the key problems in laparoscopy is the ergonomic positioning of the monitor. In this study we tested task performance and muscle strain of subjects in relation to monitor position during laparoscopic surgery. METHODS: Eighteen subjects simulated laparoscopic suturing by threading tiny pearls with a curved needle. This was repeated in three monitor positions (15 min each): frontal at eye level (A), frontal in height of the operating field (B), and 45 degrees to the right side at eye level (C). Subjects were not allowed to turn their heads during these sessions. After the test they were asked for their preferred monitor position. During all tests the electromyographic (EMG) activity of the main neck muscles was recorded and the number of pearls was counted. RESULTS: The EMG activity was significantly lower for position A compared to positions C and B (p < 0.05). No significant difference was found between positions B and C. The number of threaded pearls as an indicator for task performance was highest for position B. The difference was statistically significant compared to position C (p = 0.0008) but not between positions A and C (p = 0.0508) or A and B (p = 0.0575). When asked for the preferred monitor position, nine subjects chose two monitors in the frontal positions A and B. No subject preferred the monitor at the side position (C). CONCLUSION: Regarding EMG data, the monitor positioned frontal at eye level is preferable. Reflecting personal preferences of subjects and task performance, it should be of advantage to place two monitors in front of the surgeon: one in position A for lowest neck strain and the other in position B for difficult tasks with optimal task performance. The monitor position at the side is not advisable.

Computer Terminals↗
PubMed2004

New model for skills assessment and training progress in minimally invasive surgery.

BACKGROUND: With the spread of minimally invasive surgery and training in this field, development of metrics for skills assessment and training progress has become increasingly important. Our approach was to use the tracking of motion for the definition of objectives metrics. METHODS: We have developed an inanimate model and tracked the 3D coordinates of the instrument tips with an ultrasound system. Besides already validated parameters (time, error time, and distance efficiency ratio) we examined the transit and the speed profile for their evidentiary power. Performances of experts (who have already performed >100 laparoscopic operations) and novices (<20 laparoscopic operations) were evaluated. RESULT: The standardized time, the error time as a precision indicator, and the transit profile parameter for spatial perception could significantly ( p < 0.05) distinguish between experts and novices. Furthermore, these parameters and the distance efficiency ratio improved significantly during a training course in laparoscopic surgery. CONCLUSION: Our model showed changes of the mentioned parameters with experience. According to our results, it can be used for skills assessment and as a training progress measurement system. We propose transit profile as an additional important parameter for assessment.

Adult↗
PubMed2003

Laparoscopic sutured anastomosis of the bowel.

BACKGROUND: Even though the safety and efficacy of sutured anastomosis have been proved in open surgery, laparoscopic sutured anastomosis is rarely performed because it is difficult and time-consuming. We aim at description of a standardized technique for laparoscopic sutured anastomosis of the bowel and definition of its learning curve. METHODS: Fifty-six laparoscopic sutured anastomoses of cow small intestine were performed in a laparoscopic simulator. In a survival animal trial, 10 end-to-end, 2 gastrojejunostomy, 2 cholecystojejunostomy, 2 colocolic, and one side-to-side anastomoses were performed, using the same technique. RESULTS: In the survival cases, we had no leaks or obstruction, minimal adhesions, and only one stenotic gastrojejunostomy. The mean end-to-end anastomotic time was 50 min. The technique was suitable for most sites in the GIT. The learning phase required 40 anastomoses in the simulator. CONCLUSIONS: The described technique seems relatively fast, safe, and universal, and it needs about 40 anastomoses to be mastered.

Anastomosis, Surgical↗
PubMed2001

[Dissection technique--is ultrasound the best method?].

Preventive hemostasis is extremely important in endoscopic surgery. Ultrasonic dissectors are used very often. We tested the occlusion safety of bipolar forceps and ultrasonic dissector for porcine vessels. Thermographic videos showed maximum temperature up to 200 degrees C when using one ultrasonic dissector. The lateral damage zone in vivo and in vitro measured between 2 and 6 mm.

Animals↗
PubMed2000

Robotics and telemanipulation technologies for endoscopic surgery. A review of the ARTEMIS project. Advanced Robotic Telemanipulator for Minimally Invasive Surgery.

In endoscopic surgery, the ability to guide the instrument is significantly decreased compared with open surgery. Rigid laparoscopic instruments offer only four of the six degrees of freedom required for the free handling of objects in space. Robotics technology can be used to restore full mobility of the endoscopic instrument. Therefore, we designed a master-slave manipulator system (ARTEMIS) for laparoscopic surgery as a prototype. The system consists of two robotic arms holding two steerable laparoscopic instruments. These two work units are controlled from a console equipped with two master arms operated by the surgeon. The systems and its components were evaluated experimentally. Laparoscopic manipulations were feasible with the ARTEMIS system. The placement of ligatures and sutures and the handling of catheters were possible in phantom models. The surgical practicability of the system was demonstrated in animal experiments. We conclude that robotic manipulators are feasible for experimental endoscopic surgery. Their clinical application requires further technical development.

Animals↗
PubMed1999

Ultrasonic dissection for endoscopic surgery. The E.A.E.S. Technology Group.

With the development of endoscopic surgery, new hazards of high-frequency (HF) electrosurgery have been recognized. The potential risks of monopolar electrosurgery, the limitations of bipolar technique, and the need to reduce instrument interchange have favored the use of ultrasonic technology, which becomes more and more popular. This work aims at presenting the main features of the currently available ultrasonically activated scalpels, as well as their advantages, limitations, and indications.

Dissection↗
PubMed1999

The role and future of endoscopic imaging systems.

Visual perception is the main sensory input from the environment in most situations of daily life. It is the only sensory input from the operating field in endoscopic surgery, and thus the qualities of the optical imaging system have a considerable impact on the course of the surgical intervention. Significant improvements have been made recently in various fields of science and engineering, influencing endoscopic imaging systems in experimental and clinical use. Among these are technologies that improve the endoscope itself in terms of providing new visual features, such as fogging prevention and plastic images, using new illumination techniques. Other developments concern the improvement of image resolution and color fidelity through new charge-coupled device (CCD) sensors or alternative techniques for image creation. Finally, the combination of endoscopic technologies with robotics provides for intuitive and more efficient direction of the line of sight.

Endoscopes↗
PubMed1998

Robotics and allied technologies in endoscopic surgery.

The human hand-arm system provides seven degrees of freedom for the manipulation of objects in space. In open surgery these motion axes can be used fully when guiding the surgical instrument. In endoscopic procedures the surgical instrument is fixed to the point of trocar insertion, resulting in only four degrees of freedom. This leads to a loss of instrumental functionality in endoscopic procedures. Robotics and telemanipulator technology can be used to restore the full spatial mobility of the endoscopic instrument. A functional model of an endoscopic master-slave manipulator system has been developed and is under experimental surgical evaluation. Allied technologies include new tactile sensor and vision systems that can enhance the application of robotic systems in surgery for the future.

Journal Article↗
PubMed1998

Complications following transanal endoscopic microsurgery.

Transanal Endoscopic Microsurgery (TEM) was clinically introduced by Buess et al. In 1983 for the removal of adenomas from the rectal cavity. Later, the indications were extended to the excision of pT1 low-risk carcinomas in curative and to tumors in higher stages in palliative intent. Training courses for this method have been conducted since 1985 and several hundred surgeons have been taught this procedure in Germany and other countries. Because TEM is gaining international recognition it is worthwhile to review the complications of the method.

Journal Article↗
PubMed1997

Indications and results of local treatment of rectal cancer.

BACKGROUND: Local therapy of early rectal carcinoma has become an alternative to the classical radical operation which has a higher morbidity and mortality rate. METHODS: Rectal carcinoma was treated by transanal endoscopic microsurgery (TEM) in 113 patients. The indications for the procedure were pT1 low-risk tumour, advanced tumour in high-risk patients, and patients who refused more radical surgery based on oncological guidelines. RESULTS: Sixty-four patients had pT1, 33 pT2 and 16 pT3 tumours. No patient died as a result of TEM. The rate of complications which needed operative intervention was 7 per cent. So far, two of the patients treated by local resection of pT1 low-risk tumours have had a recurrence. In both cases, a secondary procedure was possible with curative intent. CONCLUSION: Patients with pT1 rectal tumours represent a suitable group for local treatment because of the acceptability of the procedure and the low recurrence rate.

Adult↗
PubMed1996

[First results of transanal endoscopic surgery (sec. Buess) in Hungary].

The operative technic, the instrumentation, the indication field and the first domestic results of the transanal endoscopic microsurgery (TEM) is presented. The method is suitable to the removal of the benign and the well or intermediately differentiated T1-2N0M0 stage low risk carcinomas taking place under the reflection of the pelvic peritoneum. The procedure is equally favourable comparing to the previously applied operative methods in respect of the oncological criteria, the anal sphincter preservation and the operative risk. The median tumour surface of the 17 (12 benign, 5 malignant) rectum tumours operated on till the March 1996 was between 9.2 and 16.7 cm2. The level of the tumours from the dentate line was between 3 and 13 cm, the greatest tumour diameter was about 7 cm. During the 14.1 month long median follow up period only one local recurrence of a T1N0M0 carcinoma has been observed and was reoperated with the TEM technic again. The TEM method seems to solve the problem of the oncologically reliable, anal sphincter saving, proportional to the severity of the illness operation of the benign and small malignant tumours in the middle and lower part of the rectum.

Anal Canal↗
PubMed1996

Local therapy of rectal tumors.

PURPOSE: The aim of the study is to outline the rising importance of local treatment of rectal tumors and a changing strategy in therapy of early rectal cancer. METHODS: As the surgical procedure, transanal endoscopic microsurgery was used. Indications for the local procedure were pT1 low-risk tumors and tumors of higher stages in patients with severe risk factors and of those who refused the operation according to oncologic guidelines. RESULTS: A total of 236 rectal adenomas and 98 carcinomas were locally excised using the transanal endoscopic microsurgery technique. Mortality rate was 0.3 percent, and rate of complications requiring surgical reintervention was 5.5 percent in adenomas and 8 percent in carcinomas. Final histology of removed carcinomas revealed 56 pT1, 27 pT2, and 15 pT3 stages. After an average follow-up time of 24 months, two recurrences were observed in the group of patients with pT1 low-risk carcinomas who only underwent local therapy. In both cases, a second intervention for cure was undertaken but for tumors in a late stage. CONCLUSIONS: In selected cases, local therapy of rectal carcinoma avoids high morbidity and mortality of the classical operation. Quality of life will be improved, especially if an artificial anus can be avoided. In case of recurrence, the chance of a secondary procedure for cure is not to be underestimated.

Adenoma↗
PubMed1996

Combined endoscopic closure of rectourethral fistula.

PURPOSE: Rectourethral fistula formation is a rare complication of radical prostatectomy and other pelvic surgical procedures. MATERIALS AND METHODS: In 2 patients endoscopic closure of the fistula was performed by combined transrectal endoscopic excision of the fistula, endoscopic suture, and simultaneous transurethral fulguration and fibrin application. RESULTS: This combined approach resulted in closure of the fistula in both patients as proved by rectoscopy, retrograde urethrography and disappearance of all clinical symptoms. The latest postoperative followup was 18 months. CONCLUSIONS: Any open procedure to correct a rectourethral fistula is considered major surgery. Therefore, the minimally invasive approach described should be attempted first in patients with a small rectourethral fistula.

Aged↗
PubMed1996

Experimental telemanipulation in endoscopic surgery.

Today's rigid endoscopic instruments limit the intracorporeal mobility of the surgical tool and are a severe impediment for the further spread of endoscopic techniques in operative medicine. Since 1992 flexible, steerable instruments with additional links for pivoting and rotating the tip have been developed and experimentally evaluated. The latest versions of this series of instruments are equipped with electromotors for better handling. The next aim in this development is a fully mobile telemanipulator with six motion axes dedicated to use in endoscopic surgery. Its first tests are planned for 1995. For successful operation of an electric telemanipulator, the man-machine interface (MMI) is of cardinal importance. For the definition of surgical requirements for the MMI, a conventional master-slave manipulator designed for technical application was modified for use in guiding a laparoscopic instrument. Master and slave sites of the system were 1.3 km apart and linked by means of a fiber-optic cable. Using this modified telepresence system, remote laparoscopic cholecystectomy was feasible in a phantom model. In a standardized test series using a test parcours, different parameters of the control system were modified, and their influence on the execution time of the parcours tasks was recorded. Well-suited parameter configurations were found and allowed experimental verification and completion of the important aspects of our concepts for development of an endoscopic manipulator MMI.

Cholecystectomy, Laparoscopic↗
PubMed1996

[Minimally invasive ENT surgery. Progress due to modern technology].

Three fundamentals have to be fulfilled to optimize minimally, invasive surgery: three-dimensional imaging, free maneuverability of the instruments, sensorial feedback. Projection of two pictures from a stereoendoscope and subsequent separation with a LCD shutter allows three-dimensional videoendoscopy to be performed. A high-frequency shutter technique (100/120 Hz) presents pictures from the two video cameras to the right and left eye, respectively, so that the surgeon has spatial vision of the operative field. Steerable instruments have four component: a control unit, rigid shaft, steerable multi-joints, distal effector. The steerable multi-joints give two additional degrees of freedom compared to conventional rigid instruments in endoscopic surgery. For intuitive movements, however, an electronic control system is necessary that is comparable to the "master-slave" principle in remote technology. A remote manipulator system with six degrees of freedom is now available. Additionally, a multifunctional distal tip permits different surgical steps to be performed without changing the instrument. For better control of the instrument and the operative procedure tactile feedback can be achieved with appropriate microsensor systems. Recent projects suggest that an artificial sensor system can be established within the foreseeable future.

Endoscopes↗
PubMed1996

[Technique and indications for sphincter-saving transanal resection in rectal carcinoma].

Using a transanal procedure, two different operative techniques are possible: the TEM technique (Transanal Endoscopic Microsurgery), which is more and more accepted in the world as method of choice for the local resection of adenomas and carcinomas pT1 "low risk" in the rectum and the lower sigma. The technically difficult procedure requires much experience. It should therefore only be practiced in centers to reach an acceptable number of clinical cases. In the lower third of the rectum, especially in locations close to the dentate line, the conventional transanal resection of tumours is also an adequate procedure.

Anal Canal↗