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Biomedical subjects

F Ulmer

Publications and source records attributed to F Ulmer.

12 recordsLinked to original sources
PubMed2004

Impact of pressure and gas type on anastomotic wound healing in rats.

BACKGROUND: Laparoscopic techniques in the treatment of various bowel diseases have become more and more popular in today's clinical routine. However, knowledge about the impact of a carbon dioxide (CO(2)) pneumoperitoneum on the quality of healing of the intra-abdominal wound is rare. We therefore investigated the effects of pressure and gas type on anastomosis healing in a rat model. METHODS: Laparotomy and twofold ileo-ileal anastomosis was performed in 78 male Sprague Dawley rats. A CO(2) or a helium pneumoperitoneum of 3 mmHg (each, n=18) or of 6 mmHg (each, n=12) was maintained before and after ileo-ileostomy. Rats in the control group ( n=18) received no pneumoperitoneum. Animals were killed after 5 and 10 days. As indicator of bowel function, mean body weights were compared between the groups. One region of the anastomosis was subjected to computerised bursting-pressure measurements, while the second was explanted for subsequent histopathological examinations: collagen synthesis and degradation was determined by the ratio of collagen type I to type III and by the matrix metalloproteinase MMP-13. The extent of new mucosal layer formation was measured in haematoxylin and eosin (H and E)-stained sections. RESULTS: Alteration in mean body weight and the mean anastomosis bursting pressures did not differ between the groups. Likewise, histological examination revealed no statistically significant differences, either in the values for collagen I/III ratios or in the extent of mucosal proliferation. After 10 days, 6 mmHg helium pneumoperitoneum was associated with a more pronounced expression of MMP-13 than that of controls. CONCLUSIONS: A CO(2) pneumoperitoneum with pressures of 3 mmHg and 6 mmHg was found to have no significant impact upon the healing of anastomosis wounds in rats. Helium pneumoperitoneum offers no advantages over CO(2).

Anastomosis, Surgical↗
PubMed2004

[Foreign body-induced disruption of the gastrointestinal tract-anatomy of the ileocoecal opening].

INTRODUCTION: Over 75% of ingested foreign bodies pass the gastrointestinal tract without any complications. Blunt foreign bodies may lead to a disruption of the intestinal passage, mainly in the area of the ileocoecal opening. The size of the reported foreign bodies varies considerably. The aim of this study was the anatomic investigation to clarify the possible causes of obstruction and its influence on the diameter of the ileocoecal opening. MATERIAL AND METHOD: We investigate anatomically and describe the ileocoecal opening on the basis of 27 specimens. RESULTS: We found not a flap mechanism but a valve mechanism in the ileocoecal junction. The median diameter of the formalin-fixated specimens was 10.9 mm respectively 21.8 mm according to an assumed correction factor of 2. The cause for intestinal obstruction most probably is the ingestion of blunt, angular foreign bodies in the ostium ileale. CONCLUSION: The intraindividual differences as well as the considerable size of foreign bodies that pass the ileoceocal opening support the hypothesis, that the complications described are more a consequence of an ingestion of blunt, cornered foreign bodies in the ostium ileale independent ofn the size of the ileocoecal opening itself.

Cecum↗
PubMed2000

Experimental trial on solo surgery for minimally invasive therapy: comparison of different systems in a phantom model.

BACKGROUND: Robotic aid in minimally invasive surgery (MIS) is becoming more and more common. We designed an experimental trial in a phantom model to verify the feasibility of solo surgery for MIS. By performing laparoscopic cholecystectomy on a phantom model, we compared combinations of different systems available in terms of safety, comfort, and time requirements. METHODS: Two surgeons skilled in endoscopic procedures tested the following systems as endoscope holders: the robotic system (AESOP), foot-controlled (AESOP 1000), and voice-controlled (AESOP 2000); the remote controlled FIPS Endoarm, electrically driven and controlled by a finger-ring joystic; the passive system TISKA Endoarm, a mechanical arm moved by hand and fixed by electromagnetical brakes. All of these systems combined with a second TISKA Endoarm as an instrument holder. A combination of two mechanical Martin arms, c, also was tested. The results were compared with those from a control group involving an assistant surgeon. A total of 70 experiments were performed. RESULTS: The shortest dissection time was registered by the combination of two TISKA Endoarms, with a statistically significant difference as compared with the control group (p < 0.05) and experiments using AESOP 1000 (p < 0.05). The TISKA Endoarm also proved to be more comfortable when used as an instrument holder (p < 0.001 vs Martin arm), and rated second only to AESOP 2000 as an endoscope holder. The rating of AESOP 2000 as endoscope holder was significantly higher than that of all other groups (p < 0.001). The study proved the feasibility of solo surgery. The time needed for dissection was shortest when two TISKA Endoarms were used, demonstrating the possible advantages of solo surgery. The TISKA Endoarm received a subjective positive rating when used as both endoscope holder and instrument holder. The voice control of AESOP 2000 seemed to be a major improvement in the development of an optimal man-machine interface. Nevertheless, the system presents considerable space requirements and does not supply control of 30 degrees optics. The principle of the finger-ring joystick adopted by the FIPS Endoarm seemed very intuitive but lacking in ergonomy. CONCLUSION: Laparoscopic solo surgery can be considered a safe procedure, although further technologic developments should lead to improved ergonomy, intuitiveness of handling, and architecture of the systems, offering the surgeon better control, increased precision of action, and reduction in operation time.

Minimally Invasive Surgical Procedures↗
PubMed2000

A new remote-controlled endoscope positioning system for endoscopic solo surgery. The FIPS endoarm.

In the field of endoscopic solo surgery, the assistance received by the surgeon from ergonomical positioning devices is extremely important. They aid in both the retracting of instruments and the positioning of the endoscope. However, passive systems derived from open surgery have not proved satisfactory. Therefore, we set out to develop a remote-controlled arm capable of moving a rigid endoscope with about four degrees of freedom, while maintaining an invariant point of constraint motion coincident with the trocar puncture site through the abdominal wall. The system is driven by means of speaker-independent voice control or a finger-ring joystick clipped onto the instrument shaft close to the handle. When the joystick is used, the motion of the endoscope is controlled by the fingertip of the operating surgeon, which is inserted into the small ring of the controller in such a way as to make the motion of the fingertip correspond directly to the motion of the tip of the endoscope. A study was performed to compare the two different interfaces available for the system. With both interfaces, the guiding system allows for transparent and intuitive operation. Its set-up is easy; it is safe and reliable to use during the intervention; and it is faster than human assistance. With its improved ergonomy, this new generation of remote-controlled endoscope positioning system represents a further step toward the diffusion of solo surgery techniques in minimally invasive therapy. In our opinion, this prototype creates a valid compromise between human and robotic control of rigid endoscopes.

Animals↗
PubMed2000

[Positioning systems for endoscopic solo surgery].

BACKGROUND: Endoscopic surgery has acquired undisputed importance in the field of both general and specialised surgery. The introduction of robotic technology in surgery has recently led to the development of new positioning systems for endoscopic surgery. These allow direct control of the endoscopic procedures by the surgeon, whose vision currently depends on the assistant in charge of positioning the optic camera in compliance with his wishes. METHODS: We experimented different positioning systems for optics and rigid endoscopic instruments for laparoscopy, some of which were our own design. Over 400 cholecystectomies were carried out by six different surgeons on phantoms containing animal organs. The experimental systems were AESOP (Computer Motion, USA), with both foot-pedal and voice control, ENDOASSIST (Armstrong Healthcare Co. UK), controlled by a device worn by the surgeon, FIPS Endoarm (Karlsruhe Research Centre, Germany), controlled by a joystick and voice, and the passive TISKA Endoarm system (Karlsruhe Research Centre, Germany). Combinations of two systems were compared, using one to position the optic and one to position the retractor instrument. RESULTS: Phantom tests, which are preferable owing to constant conditions, showed the feasibility of experiments in Solo Surgery conditions and highlighted the advantages and drawbacks of the various systems. In particular, the surgeons appreciated the intuitive use of the TISKA Endoarm system as a positioner for the retractor instrument and the optics, in spite of the fact that it was only a passive movement apparatus. Among the remote-control systems tested as an optics positioner, FIPS Endoarm controlled by a joystick was particularly intuitive and produced the best results in terms of time taken to complete the procedure. The time taken was even shorter than that in a large control group with human assistance. CONCLUSIONS: In our experience endoscopic Solo Surgery was found to be applicable to clinical practice. This will bring numerous advantages in terms of the precision of surgical procedures and savings in terms of time and human resources, with a consequent reduction of management costs. There is no doubt that this method represents a step forward in the application of technology to surgery.

Endoscopes↗
PubMedDate not supplied

Influence of mesh materials on collagen deposition in a rat model.

Alterations of the extracellular matrix (ECM) with its major component collagen are increasingly discussed as possible risk factors implicated in the development of abdominal-wall herniation. Because of the widespread use of alloplastic meshes for the surgical repair of hernias, an animal study was performed to analyze the influence of various mesh materials on the quantity and quality of collagen deposition. In 60 male Sprague-Dawley rats an abdominal replacement was performed using three different kinds of mesh materials: polyester (PE), a pure polypropylene (PP), and a composite mesh made of polypropylene and polyglactin (PG). A simple fascia suture repair served as control. The count of fibroblasts, the collagen/protein ratio, the type I/III collagen ratio, and the expression of basic fibroblast growth factor (b-FGF) at the interface were analyzed after 7, 21, and 90 days. The ratio of collagen to overall protein (microg/mg) showed significant differences comparing different mesh materials (sham controls 38.44 +/- 16.33 microg/mg, PE 68.5 +/- 23.8 microg/mg, PP 101.6 +/- 32.3 microg/mg, PG 49.6 +/- 11.6 microg/mg at day 90). The ratio of collagen type I/III increased over time in all groups. However, 90 days after mesh implantation the ratio was always significantly lowered compared to the controls. No significant difference was found comparing different mesh materials. The alteration of the scar composition is closely connected to an increased b-FGF expression. b-FGF and count of fibroblasts highly correlated (r =.95) and showed significant elevated levels compared to simple suture repair. The results of our study strongly support the notion that wound healing is affected by mesh implantation. The quality of the ECM deposition as determined by collagen type I/III ratio is impaired in general, whereas the quantity of ECM deposition is markedly influenced by the kind of mesh material.

Animals↗
PubMedDate not supplied

Does botulinum type-A toxin affect motor activity after proctocolectomy and ileal pouch-anal anastomosis? An experimental study in dogs.

AIM OF THE STUDY: The use of anticholinergic drugs has provided a useful therapeutic approach to reduce stool frequency in patients with proctocolectomy and ileal pouch-anal anastomosis (IPAA). Botulinum type-A (BTA) toxin has been shown to specifically block acetylcholine release in the intestinal wall. Therefore this study investigated the effect of BTA on small intestinal and J-pouch motility after IPAA. MATERIAL AND METHODS: Proctocolectomy and IPAA were performed in 4 dogs. The motility of the small intestine and the ileal pouch was recorded by serosal electrodes and strain gauge transducers. The intestinal transit time was determined radiologically and pouch compliance was determined manometrically. Multiple measurements were performed before and after endoscopic injection of BTA into the pouch wall. RESULTS: This treatment did not significantly influence stool frequency, intestinal transit time or pouch compliance. Intrinsic pouch motility was characterized by irregular contractions, the amplitudes and frequencies of which remained unchanged after BTA administration. With the exception of lower contraction amplitudes directly proximal to the pouch, there were no significant differences in the characteristics of the migrating myoelectric complex or in the fed pattern of the small intestine and ileal pouch. CONCLUSIONS: BTA does not significantly affect ileal pouch motility. The beneficial effects of anticholinergic drugs therefore seem to be due to their multifactorial mode of action and not to the inhibition of cholinergic neurons in the pouch.

Anal Canal↗