Biomedical subjects
Publications and source records attributed to G Buess.
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.
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.
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.
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.
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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.
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.
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.
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.
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.
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.
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.
Local therapy of rectal carcinoma with the method of TEM was performed in 98 patients during the period from August 1, 1989 to January 31, 1994. 56 of the patients had pT1, 27 pT2, and 15 pT3 tumours. There was no lethality. The rate of complications, which required operative intervention, was 8%. No lymph node metastases were found in the specimens of the patients with pT1 tumours, who were re-resected, because the margin of the primary specimen were judged to be not free of tumour. In the specimens of the re-resected patients with pT2 carcinomas, lymph node involvement was more common than remnants of the primary tumour. Two of the patients with local therapy of pT1 low-risk carcinomas developed a recurrence so far. A secondary procedure for cure according to oncologic criteria could be performed in both cases. In selected cases the local therapy of rectal carcinoma avoids the high morbidity and mortality of the classical operation. Live quality will be improved, especially if an artificial anus can be avoided. In case of a recurrence the chance of a secondary procedure for cure is not to be underestimated.
Patients with pT1 low-risk rectal carcinomas seem to be overtreated by a classical radical operation. A total of 170 patients with rectal carcinomas were locally treated with the transanal endoscopic microsurgery (TEM) technique. Four of the group with pT1 low-risk tumours with local therapy developed a recurrence, three of whom underwent a curative secondary procedure, bringing the failure rate to one out of 81. Two recurrences were diagnosed among the 22 patients who were re-resected after local treatment in stage pT1 low risk. Both patients died of the tumour disease, another due to dehiscence of the suture, bringing the failure rate in the re-resected group to three of 22.
Local excision of colorectal tumour may be palliative or curative. Recent advances in minimal access techniques have allowed curative excision to be offered to a wider range of patients. Absolute indications for potentially curative local excision include mobile tumours, T1 tumours (assessed by ultrasonography), well or moderately differentiated histology (determined by biopsy) and tumour size less than 3 cm. Relative indications include T2 and T3 tumours (by ultrasonography), poorly differentiated histology (by biopsy) and tumour size greater than 3 cm depending on patient fitness. The rationale for these recommendations is described in detail.
One of the keys to safe laparo-endoscopic surgery is an expeditious, reliable, and safe access to the operative field. Aside from appropriate surgical technique, the technology of trocars, cannulae, and other endoscopically guided insertion techniques plays a decisive role for safe identification of and access to the peritoneal cavity. This report takes a close look at critical features of trocar and cannula design for blind insertion with the focus on the biomechanical principles involved in traversing the abdominal wall. Particular attention has been paid to techniques minimizing the risk of accidental injury to major vessels, intestine, and other important structures. The principle of controlled visualized access led to several developments in the field of trocars, cannulae, and puncture techniques. Aside from blind and open access with the Veress needle, conventional trocars and cannulae, a selected variety of endoscopically assisted ports such as the optical Veress needle, optical trocars and optical scalpel, and a vacuum-supported access system are described in detail.
The increasing use of the laparoscopic approach in colorectal surgery depends not only on the indications but also on technological development. Better visualization of the operative field is available using a three-chip camera or three-dimensional system. Alternative port positionings together with curved instruments increase the degree of freedom during operation. Complex laparoscopic procedures need highly specific instruments. We have developed atraumatic bowel graspers, different types of retractors, and innovative combination instruments. OREST II, a new multipurpose system that assists the organization of laparascopic surgery is described.
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