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Annette Fritscher-Ravens

Publications and source records attributed to Annette Fritscher-Ravens.

At least 19 recordsLinked to original sources
PubMed2006

Colon cleaning during colonoscopy: a new mechanical cleaning device tested in a porcine model.

BACKGROUND: Poor colon cleaning frequently impairs colonoscopy. The aim of the study was to develop a method of cleaning the colon during colonoscopy. METHODS: A soft-tipped catheter with a water jet spray at its tip was designed to break up and propel stool contents in the direction of the anus. Stool contents were collected in a container attached to an endoscopy trolley. OBSERVATIONS: In bench tests, colon models filled with porridge were rapidly cleaned. Unprepared colons (n = 15) of anesthetized pigs were cleared in a few minutes by using this device at colonoscopy, by advancing the catheter under direct vision into concretions, which were rapidly broken down. There was minimal trauma to mucosa in these survival studies. CONCLUSIONS: A colon cleaning method for use at colonoscopy was highly effective in cleaning colon models and in unprepared pig colon. This device may have a role in cleaning the colon in unprepared or poorly prepared patients.

Animals↗
PubMed2006

Endoscopic transgastric lymphadenectomy by using EUS for selection and guidance.

BACKGROUND: EUS-guided fine needle aspiration (EUS-FNA) is a reliable tool for tissue diagnosis of unexplained mediastinal or perigastric lymphadenopathy but may be ineffective in sampling a small malignant focus in it or removing an entire node. OBJECTIVE: To develop a new EUS-guided endoscopic-transgastric method to approach (sentinel) lymph nodes, including node marking and lymphadenectomy. DESIGN: Experimental study. SETTING: Animal experiments at an approved university college. SUBJECTS: Six pigs had a linear-array EUS examination 1 week after a transgastric procedure. All had reactive perigastric lymph nodes. INTERVENTIONS: Selected nodes were punctured with a 19-gauge EUS needle. A metal anchor with thread, loaded onto the needle, was placed across the lymph nodes to pull the node toward the stomach. After gastric-wall dissection with a needle knife at the point of emergence of the thread, the nodes were removed by pulling on the thread and the anchor. The gastric incision was closed with an endoscopic suturing system. MAIN OUTCOME AND MEASUREMENTS: Proof of the feasibility to endoscopically remove paragastric lymph nodes by an EUS-guided transgastric approach. RESULTS: In all pigs, lymph-node marking with an anchor and thread was possible. Traction exerted on these nodes showed that they could be pulled against the gastric wall for subsequent removal. In 2 of 6 examinations, the entire sequence of the procedure, node tagging, gastric-wall incision, lymphadenectomy, and wall closure was performed. No serious complication occurred. LIMITATIONS: Animal study throughout, small numbers, no humans to date. CONCLUSIONS: Transgastric lymphadenectomy with EUS for node selection and capturing seems feasible.

Animals↗
PubMed2006

Endoscopic full-thickness resection: circumferential cutting method.

BACKGROUND: Endoscopic full-thickness resection (EFTR) at flexible endoscopy might allow less-invasive removal of more deeply penetrating cancers that have not spread to the serosal surface and more complete histologic examination of the excised tissue. OBJECTIVE: A method for closure of full-thickness defects in the stomach wall would be valuable for other endosurgical applications. SETTING: A method that uses an end cap and band-ligation without prior injection of saline solution to perform EFTR gave good results and was safe in pig studies. There is a size limitation of cancers that can be resected en bloc when using this method. The depth of resection was also variable. DESIGN AND INTERVENTIONS: EFTR was achieved by circumferential cutting with a sphincterotome and a snare. A prototype bidirectional cutter was tested. Sutured closure was accomplished by using a sheathed needle, a metal tag, and a thread at the tip, passed through a 2.8-mm accessory channel. Knot-tying devices secured the sutured defect. MAIN OUTCOME MEASUREMENTS: EFTR was studied in non-survival (n = 4) and survival (n = 8) experiments in pigs. RESULTS: Full-thickness specimens were resected from the gastric wall (100%, 12/12), and the defects were closed by using sewing and knot-tying devices (100%, 12/12). LIMITATIONS: A healing ulcer at the suturing site was evident at follow-up endoscopy in the survival experiments. Bleeding, which was stopped by suturing, occurred in 1 pig (8.3%, 1/12). All pigs survived these experiments without complications (100%, 8/8). CONCLUSIONS: Circumferential EFTR was feasible and appeared safe in survival experiments. This method might allow larger and deeper resection of tumors in the gastric wall.

Animals↗
PubMed2006

The Cath-Cam: a new concept in colonoscopy.

BACKGROUND: Guidewires and catheters exert less force on the gut wall than an endoscope. OBJECTIVE: To develop a guidewire-assisted device for colonoscopy. METHODS: A light-weight flexible catheter illuminated with light-emitting diodes was designed to carry an ultraslim high-resolution videoendoscope of 3 mm. Tip bend stiffness was 5 times less than a colonoscope. Hinged guidewires were passed, folded, through the accessory channel. A loop could be rapidly formed to explore the lumen. RESULTS: The catheter followed curves of excised pig colon and exerted significantly less force on the colon wall than a colonoscope (mean 1.6 +/- 0.23 N vs 3.0 +/- 0.37 N, P < .05; bend-radius, 80 mm). Survival studies in pigs showed that the guidewire loop could be advanced under visual control and the Cath-Cam could be advanced by using much less force than the colonoscope. CONCLUSIONS: A catheter-based colonoscope with a miniature video imager reduced the force required for successful colonoscopy in pigs.

Animals↗
PubMed2006

Endoluminal fundoplication--the Hill procedure.

Endoluminal operations for reflux are currently limited by the inability to visualise and manipulate structures outside the wall of the gut. This may be possible using endoscopic ultrasound (EUS). The aim of this study was to define EUS-anatomy of structures outside the gut which influence reflux; to place stitches in the median arcuate ligament (MAL); to perform posterior gastropexy (Hill procedure) and test the feasibility of crural repair under EUS control in pigs. In survival experiments in 14 pigs, using linear array echo-endoscopes the MAL and part of the right crus were identified and punctured with a needle, which served as a carrier for a tag and thread. These were anchored into the muscle. An endoscopic sewing device was used allowing stitches to be placed through a 2.8 mm accessory channel to any predetermined depth. New methods allowed knot-tying and thread-cutting through the 2.8 mm channel of the echo-endoscope. Stitches were placed through the gastric wall into the MAL and one just beyond the wall of the lower esophageal sphincter (LES). They were tied together and locked against the gastric wall. Preoperative manometry showed a median LES pressure of 11 mm/Hg and 21 mm/Hg after stitch placement (p = 0.0028). The length of the LES increased from median 2.8 cm pre-procedure to 3.5 cm post-procedure. At post mortem, the force to pull the tags out of the MAL was 2.8 kg median. This study shows that transgastric gastro-esophageal reflux surgery using stitching under EUS control can significantly increase the lower oesophageal sphincter pressure in pigs.

Animals↗
PubMed2005

Future therapeutic indications for endoscopic ultrasound.

Attempts to perform therapy guided by endoscopic ultrasound (EUS) are rare. Some new indications for interventional and therapeutic endoscopic procedures performed under EUS control have been developed in areas that have been purely surgical for many years. Indications, procedures, and related tools for EUS-guided endosurgery are described, all of which are experimental but may open a new corridor for endoscopists to enter a variety of transluminal procedures in real time without soiling the peritoneal or mediastinal cavity.

Endosonography↗
PubMed2005

Experimental studies of transgastric gallbladder surgery: cholecystectomy and cholecystogastric anastomosis (videos).

BACKGROUND: Transgastric flexible endoscopic surgery might offer advantages over open and laparoscopic surgery. The aim of this study was to develop methods for performing transgastric biliary endosurgery. METHODS: Cholecystectomies and biliary anastomoses were performed in 8 anesthetized pigs (27-30 kg) in nonsurvival studies. Two endoscopes passed perorally were inserted through the stomach wall after needle-knife incision. Endoscope-induced pneumoperitoneum allowed viewing and manipulation of the gallbladder with both endoscopes independently. The cystic duct was dissected, clipped, and transected. Cholecystectomy was performed with one of two methods: either by using two endoscopes, or a single endoscope and a 5-mm-diameter grasping instrument inserted transabdominally. Clips and sutures were used to attach the gallbladder to the stomach wall, and an incision was made to form a cholecystogastrostomy. In survival experiments in 8 pigs, transgastric incisions were closed with endoscopic sutures. RESULTS: The gallbladder was successfully removed in 8 pigs (nonsurvival experiments). The time for the procedure ranged from 2.5 hours to 40 minutes and decreased with experience. At postmortem examination, clips placed on the cystic duct and the artery were secure. An anastomosis was successfully formed between gallbladder and stomach in 3 pigs. In 8 pigs, full-thickness incisions in the stomach wall were closed with two to 4 stitches. All 8 pigs survived (median follow-up, 22 days; range 14-28 days). CONCLUSIONS: Transgastric gallbladder surgery, including cholecystectomy and biliary anastomosis, is feasible. Full-thickness gastric incisions were safely closed in survival studies. The efficacy and the safety of transgastric surgery merits further study.

Anastomosis, Surgical↗
PubMed2005

Endoscopic full-thickness resection with sutured closure in a porcine model.

BACKGROUND: Some early gastric cancers might be advantageously staged and treated by full-thickness resection if secure methods for closing the defect were available. The aim of this study was to test the feasibility of full-thickness gastric resection. METHODS: Full-thickness gastric resections were performed by using a ligating device without submucosal injection in survival studies in pigs (n = 8). The defects were closed by using new methods for suturing, locking, and cutting thread through a 2.8-mm accessory channel. Stitches (n = 2-4) were placed close to the target area before resection. OBSERVATIONS: Full-thickness resections (n = 8) were performed. The pigs survived without incident for 21 to 28 days. Healing of the suture site was evident at follow-up endoscopy. Suture sites were water tight. The pull-out force with stitches by using this new sewing method was significantly higher than with endoscopic clips (20.3 N +/- 0.94 vs. 2.2 N +/- 0.42, p < 0.05). CONCLUSIONS: Endoscopic full-thickness resection with sutured defect closure was feasible and appeared safe in these survival experiments.

Animals↗
PubMed2005

Three-dimensional linear endoscopic ultrasound-feasibility of a novel technique applied for the detection of vessel involvement of pancreatic masses.

BACKGROUND: Endoscopic ultrasound (EUS) can reliably diagnose and stage pancreatic cancer but is less competent for the differentiation between vascular compression (VC) and invasion (VI). AIM: Prospective comparison of linear EUS with/without three-dimensional (3D) EUS for vessel involvement in pancreatic cancer to evaluate the feasibility of linear 3D ultrasound. MATERIAL AND METHODS: Linear echoendoscopy was used to identify the pancreatic tumor, the tumor-vessel relation and for EUS-FNA to obtain tissue diagnosis. Immediately afterwards, 3D image acquisition was performed using a magnetic tracked 3D sensor. The acquisition time was 10-20 s. RESULTS: EUS results of 22 patients with solid pancreatic lesions were compared to surgical histology. This proved adenocarcinoma in 17 patients and chronic pancreatitis in 5. EUS showed VI in 10 patients, VC in 6, and no vascular involvement (NVI) in 6. Additional 3D evaluation showed VI in 6 patients, VC in 10, and NVI in 6. Surgery proved VI in 7 patients, VC in 9, and NVI in 6. EUS showed VI in 3/5 patients with chronic pancreatitis, 3D showed VC only, while surgery found two patients to have VC and with NVI. In two patients with pancreatic cancer, VI was diagnosed on two dimensional (2D), but VC on 3D evaluation. Surgery showed VC and VI in one each. In the 2D, one patient with NVI had VI on surgery; and on 3D one VC proved to have NVI at surgery. In 1/22 patients the result of 3D was false negative, while 4/22 were false positives and one false negative in conventional EUS. CONCLUSION: Linear 3D EUS seems feasible for pancreatic evaluation. In addition, linear EUS enhanced the evaluation of vascular involvement of pancreatic lesions, especially in chronic pancreatitis.

Adenocarcinoma↗
PubMed2004

Transgastric gastropexy and hiatal hernia repair for GERD under EUS control: a porcine model.

BACKGROUND: Endoluminal operations for gastroesophageal reflux currently are limited by the inability to visualize and manipulate structures outside the wall of the gut. This may be possible by using EUS. The aims of this study were the following: to define the EUS anatomy of structures outside the gut that influence reflux, to place stitches in the median arcuate ligament, to perform posterior gastropexy, and to test the feasibility of crural repair under EUS control in pigs. METHODS: In survival experiments in 22 pigs, by using a linear-array echoendoscope, the median arcuate ligament and part of the right crus were identified and punctured with a needle, which served as a carrier for a tag and thread. These were anchored into the muscle. An endoscopic sewing device was used, allowing stitches to be placed through a 2.8-mm accessory channel to any predetermined depth. New methods allowed knot tying and thread cutting through the 2.8-mm channel of the echoendoscope. RESULTS: Stitches were placed through the gastric wall into the median arcuate ligament, and one stitch was placed just beyond the wall of the lower esophageal sphincter. The stitches were tied together and locked against the gastric wall. Median lower esophageal sphincter pressure, determined manometrically, was 11 mm Hg before surgery and 21 mm Hg after stitch placement (p=0.0002). The length of the lower esophageal sphincter increased from a median of 2.8 cm before the procedure to 3.5 cm after the procedure. At the postmortem, the median force required to pull the tags out of the median arcuate ligament was 2.8 kg. CONCLUSIONS: This study demonstrates that transgastric gastroesophageal reflux surgery, by using stitching under EUS control, can significantly increase lower esophageal sphincter pressure in pigs.

Animals↗
PubMed2003

Endoscopic ultrasound, positron emission tomography, and computerized tomography for lung cancer.

Staging of patients with lung cancer to determine operability is intended to efficiently limit futile thoracotomies without denying possibly curative surgery. Currently available staging tests are imperfect alone and in combination. Imaged suspected metastases often require tissue confirmation before surgery can be denied. Endoscopic ultrasound (EUS) may help identify inoperable patients by providing tissue proof of inoperability in a single staging test, with similar sensitivity for identifying inoperable patients as other staging tests. Therefore, we compared computed tomography, positron emission tomography (PET), and EUS with fine-needle aspiration under conscious sedation, each test interpreted blinded with respect to the other tests, for identifying inoperable patients in a consecutive cohort of 79 potentially operable patients with suspected or proven lung cancer. An economic analysis was also performed. Thirty-nine patients were found inoperable (a 40th patient's inoperability was missed by all preoperative staging tests). The sensitivity of computerized tomography was 43%. PET and EUS each had similar sensitivities (68 and 63%, respectively) and similar negative predictive values (64 and 68%, respectively), but EUS's superior specificity (100 vs. 72% for PET) and considerably lower expense means it may be preferred to PET early in staging to identify inoperable patients.

Adult↗
PubMed2003

Transluminal endosurgery: single lumen access anastomotic device for flexible endoscopy.

BACKGROUND: Forming anastomoses between two hollow organs at flexible endoscopy might reduce the need for surgery for obstructing malignancy. Current methods require access to both lumens. The aim of this work was to develop methods of forming an anastomosis at flexible endoscopy, such as a gastrojejunostomy or cholecystoduodenostomy, when access to only one lumen is feasible. METHODS: A modified needle was passed through a large-channel echoendoscope from the accessible lumen into the target hollow organ. An anastomotic device was formed by using two 7F catheter segments, which were pushed over a guidewire into the target, the less accessible lumen. When released, by withdrawing the guidewire, the catheters formed a cross shape and created an anastomosis when compressed against a plate from the accessible side. OBSERVATIONS: These devices were tested in live animal experiments. With an echoendoscope in the stomach, it was repeatedly possible to place needles, threaded tags, and guidewires into the small intestine and gallbladder. In 4 to 7 days, anastomoses were formed in 16 pigs between the small intestine and the stomach, and between the gallbladder and the stomach. The initial diameter of the anastomoses ranged from 3 to 9 mm. No complication occurred. CONCLUSIONS: It is feasible to form anastomoses at flexible endoscopy when access is limited to a single side.

Anastomosis, Surgical↗
PubMed2003

Endoscopic ultrasound evaluation in the diagnosis and staging of lung cancer.

The detection of mediastinal lymph node metastases in patients with lung cancer is most important. These nodes may be used for tissue diagnosis of the malignancy, if sampling techniques of the primary have failed. Their presence implies a stage III disease and may exclude a patient from surgery. CT is the standard imaging, but is relatively poor at staging the mediastinum (overall sensitivity: 50-70%), and is especially unreliable for lesions <1 cm. PET is a new physiological imaging technique, which seems to be superior to CT (sensitivity: 67-100%). Transesophageal EUS delivers high resolution imaging, offers the advantage of simultaneous tissue sampling (EUS-FNA sensitivity: 84-94%), but is limited to the posterior mediastinum. This review compares the diagnostic value of CT, PET and EUS as well as the different tissue sampling methods for mediastinal metastases with EUS-FNA. The technique of EUS and FNA is described, and a special interest is taken to stress out the different areas of the mediastinum accessible for each of the tissue sampling methods as well as the pros and cons for its use. Advantages and disadvantages of EUS-FNA are shown and the new efforts described to improve the outcome of EUS-FNA by adding molecular methods for the detection of micrometastases.

Endosonography↗
PubMed2003

Critical care transesophageal endosonography and guided fine-needle aspiration for diagnosis and management of posterior mediastinitis.

BACKGROUND: Acute mediastinitis is a serious complication; it occurs after esophageal perforation and thoracic surgery and is rarely due to infections. Clinical and computed tomographic scan signs may be nonspecific, especially in postoperative patients. DESIGN: We prospectively evaluated the value of transesophageal endosonography with guided fine-needle aspiration in the diagnosis and identification of etiologic agents in critically ill patients with suspected posterior mediastinitis. SETTING: University hospital. PATIENTS AND METHODS: Transesophageal endosonography/fine-needle aspiration was performed at the bedside in the intensive care unit with a Pentax 34UX echo-endoscope and a portable Hitachi console (EUB 525). Eighteen patients with clinically suspected mediastinitis were examined with intensive care team support. RESULTS: Computed tomography was performed before transesophageal endosonography in all 18 patients and was inconclusive in 9. Transesophageal endosonography detected mediastinal lesions in 16 (89%) of 18 patients and was more accurately diagnostic than computed tomography (p =.0082). Fifteen patients had undergone surgery (11 esophagectomy, 1 other esophageal surgery, 1 head/neck cancer surgery, 1 complication after dilatational tracheostomy, and 1 with intervention after polytrauma). Three patients were suspected to have nonpostoperative mediastinitis. In 16 patients, infectious organisms were detected (bacterial, n = 14; fungal, n = 1; tuberculosis, n = 1). Culture and sensitivity of transesophageal endosonography/fine-needle aspiration specimens led to appropriate drug therapy. In two patients, methicillin-resistant Staphylococcus aureus was detected, leading to isolation care. Twelve patients improved; six died. Of the two patients in whom transesophageal endosonography did not detect a mediastinitis, one was false negative on autopsy. There were no complications. CONCLUSION: Bedside transesophageal endosonography/fine-needle aspiration of posterior mediastinal lesions in critically ill patients was an effective and relatively noninvasive way to detect mediastinitis and provide material to identify the etiologic agent. It was particularly useful in postesophagectomy patients.

Abscess↗
PubMed2003

Endoscopic ultrasound-guided biopsy for the diagnosis of focal lesions of the spleen.

OBJECTIVES: Needle biopsy of splenic lesions using computed tomography (CT) or ultrasound (US) is difficult if the size of the lesion is small. It may be dangerous if the lesion is adjacent to the splenic hilum or located peripherally. We used endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) to elucidate the tissue diagnosis of splenic abnormalities. METHODS: EUS-FNA was performed in 12 patients when US- or CT-guided biopsy was inconclusive (n = 5), was not attempted because of small tumor size (0.9-1.4 cm; N = 4), or was considered dangerous (n = 3). A linear echo-endoscope and 22-gauge needles were used for cytology and bacteriology. RESULTS: The age of the patients was 19-68 yr (median 32 yr). Seven patients were male and five female. The size of the lesions was 0.8-4.2 cm (median 1.4 cm). Cytology was inadequate in one patient. Bacteriology was positive for Staphylococcus aureus and Serratia in one patient each, and cultures were positive for Mycobacterium tuberculosis in two patients. A positive diagnosis was made in 10 of 12 patients (83%). Final diagnoses were tuberculosis in two patients, Hodgkin's disease in two, sarcoidosis in two, abscesses in two, metastatic colon cancer in one, and infarction in one. Suspected recurrence of non-Hodgkin's lymphoma was not confirmed in one case. One patient experienced pain after puncture, but no hematoma was demonstrated on subsequent US examination. CONCLUSIONS: EUS-FNA cytodiagnosis in patients with unknown splenic lesions seems feasible, even in very small foci, when CT- or US-guided biopsy fails. Additional material for bacteriology may show benign treatable diseases such as abscesses or tuberculosis.

Adult↗