Biomedical subjects
Publications and source records attributed to H Raestrup.
Transanal endoscopic microsurgery, although technically challenging, offers a viable and perhaps superior outcome to radical abdominal or traditional transanal excision of rectal neoplasia. Appropriate training and case selection, as with any new technology, are mandatory to help ensure optimal results.
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.
An adequate fundic wrap is fundamental to the success of conventional and laparoscopic Nissen fundoplications. Nevertheless, up to now there has been no standardized method for the surgeon to determine intraoperatively the width and tension of the fundic wrap according to objective criteria. With the support of Rüsch (Kernen, Germany), we developed a measurement balloon for use in laparoscopic Nissen fundoplication. The balloon allows the surgeon to define the width of the wrap and predetermine its length, as well as to measure its tension. Depending on the measured balloon pressure, the surgeon can perform fundic sutures more or less tightly. On the basis of 41 fundoplication model tests, we found that a fundic wrap typically described as "loose and floppy" produced a balloon pressure of 50-60 mmHg. In 10 laparoscopic Nissen fundoplications on domestic pigs, we were able to adjust the fundic wrap intraoperatively to a balloon pressure in this range (mean; 53.5; SD; 2.25). After the optimal intraoperative balloon pressure in humans has been investigated in a prospective study that is in progress, the Tübingen balloon is expected to serve as an instrument for quality assurance in reflux surgery.
Following a laparoscopic cholecystectomy 400 patients have been interviewed with a questionnaire on the late results of the surgery (15 to 40 months postop.). The cholecystectomies had been performed within the time from March 7, 1990 to April 30, 1992 in Tübingen. After a mean of 16.8 days the patients returned to work, while they themselves felt reduced for an average of 10.6 days. 11.9% of the patients complained of slight wound healing problems and in 3.1% wound infections have been registered. Although 97% of the patients were satisfied with the results of surgery, 8.7% still complained of upper abdominal trouble. Slight persistent problems like light pain or flatulence have been reported by 19%.
Transanal Endoscopic Microsurgery (TEM) was introduced into clinical practice by the Buess group in 1983. Since then vast experience has been gained in removing tumours of the rectum by the operative rectoscope. Though the indication in benign lesions for TEM as a local resection therapy is undisputed, the indication for resection of T1 or advanced carcinomas has to be evaluated. By using a 40 mm operating rectoscope sealed with a gastight working insert to prevent pressure loss after creation of a pneumorectum and a stereoscopic optic with sixfold magnification, exact visualisation of a rectal tumour can be achieved. The insertion of endoscopic surgical instruments like the high frequency knife, forceps, scissors, and suction device allows precise excision of the lesion as well as suture closure of the wound. Recently a bipolar multifunctional combination instrument has been developed for more precise dissection, less blood loss and shorter operation times.
From August 1st 1989 to May 1st 1993, 190 rectal adenomas and 75 carcinomas were locally excised with the TEM technique. The mortality was 0.4%, the rate of complications which required surgical re-intervention was 3% in adenomas and 8% in carcinomas. The final histology of the removed carcinomas revealed 44 pT1, 23 pT2 and eight pT3 stages. In two of the eight re-resected patients with pT1 low-risk tumours, residual primary tumour but no lymph node metastases were found. In contrast to this, three of the eleven re-resected patients with pT2 low-risk tumours had already developed lymph node metastases. After an average follow-up time of 14 months, two recurrences were observed in the group of the only locally treated patients with pT1 low-risk carcinomas. Both underwent a secondary procedure for cure but in late tumour stages. No recurrence was diagnosed so far among the re-resected patients.
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Conventional transhiatal dissection of the oesophagus is usually performed without visual control. The attendant danger of this is that complications such as bleeding and tracheal lesions may be overlooked. This problem can be avoided by the use of an endoscopic operation system. This report describes a new technique of endoscopic microsurgical dissection of the oesophagus (EMDOE) and the results of the first 35 cases. Under visual control with a specially designed mediastinoscope the soft tissue surrounding the oesophagus is carefully dissected, and the oesophageal blood vessels can be safely exposed, coagulated and divided. The dissection begins cervically and proceeds along the oesophagus down to the oesophagocardiac junction. A simultaneously working abdominal team helps remove the oesophagus, which is then replaced by a stomach tube. Although the method is still under evaluation, results to date have been especially good for small distal tumors, especially adenocarcinomas.
Techniques for intrathoracal stapler anastomosis under thoracoscopic control were studied and developed in an experimental program. Since this procedure is possible from two directions, both directions were evaluated. Two different techniques, a transoral and a transhiatal, resulted. For the transoral technique the stapler is inserted from above. The anvil, which is connected to a wire, is drawn into the abdomen together with the distal oesophagus. Retracting the wire pulls both the anvil and the stomach tube up into the thorax after the insertion of the anvil. The second technique requires a special attachment to introduce the anvil transhiatally into the thorax and into the oesophageal stump. The gastric tube is pushed into the thorax by the stapler gun, which is inserted into the stomach through an antrostomy. The insertion of the anvil into the oesophageal stump can also be achieved with the support of a flexible endoscope including a polyp snare.
In order to save time for changing instruments and minimize thermal damage in underlying tissue caused by monopolar high frequency in transanal endoscopic microsurgery (TEM), we have developed a new electrosurgical instrument, in which four functions are integrated: bipolar cutting, monopolar coagulation, suction and irrigation. The new device and the conventional monopolar knife were tested during both in vitro and in vivo experiments to compare the thermal alterations and effects on operating time. In vitro experiments demonstrated that the extent of thermal alterations created by bipolar cutting was less than in the case of monopolar cutting in the fresh porcine liver and bovine rectum. The mean severity scores for carbonization, coagulation and vacuolization in the resected mucosae obtained during in vivo animal operations by the bipolar procedure were 2.09, 2.27 and 1.36, respectively, whereas those obtained using the monopolar technique were 2.64, 2.82 and 2.36, respectively. The new device required an average operation time of 673.5 seconds, whereas the conventional setup required 701.9 seconds to resect the same diameter of rectal mucosa. Reduced operation time with the new device was mainly attributable to the reduced time needed for changing the instruments for hemostasis. The decreased thermal damage to the underlying bowel wall produced by the bipolar procedure should reduce the incidence of such operative complications in TEM (Transanal Endoscopic Microsurgery, developed in 1983 by Buess, Theis and Hutterer) as perforation, dehiscence in the suture line or post-polypectomy coagulation syndrome. By quickly switching between the multiple functions of this new device a clear operative field can always be achieved, thus decreasing operation time and bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)
To evaluate the feasibility of laparoscopic transcystic lithotripsy of common bile duct stones, a phantom model comprising bovine liver and biliary tract tissue integrated within a laparoscopic trainer was built. A 9 French cholangioscope was introduced via the cystic duct into the common bile duct in which a human gall stone of known composition had been introduced. Lithotripsy was performed using either a laser or electrohydraulic probe passed through the working channel of the cholangioscope following which the stone fragments were manipulated into the duodenum through the papilla of Vater using the choledochoscope. A total of 20 lithotripsies with each energy form were performed. Lithotripsy was successful in breaking the stones into fragments smaller than 6 mm. The energy expenditure was comparable with a mean of 49 J for laser lithotripsy (range 9 to 159 J), and 53 J (range 16 to 160 J) for electrohydraulic wave lithotripsy. The lithotripsy time measured from introduction of the cholangioscope until its removal was a mean of 30 minutes for electrohydraulic wave lithotripsy and 41 minutes for dye laser lithotripsy. This difference was statistically significant. Macroscopic tissue damage to the common bile duct wall was not observed following any procedure. An additional experiment was performed to evaluate damage that could be caused to the wall of the common bile duct. Both electrohydraulic shock wave and pulsed dye laser lithotripsy without optical feedback regulation caused severe tissue defects when there was tissue contact or distance less than 2 mm. With optical feedback regulation however, no tissue damage was induced by laser lithotripsy.(ABSTRACT TRUNCATED AT 250 WORDS)