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Biomedical subjects

F E Silverstein

Publications and source records attributed to F E Silverstein.

At least 55 records · Page 3Linked to original sources
PubMed1981

Severe upper gastrointestinal bleeding. Part I: Causes, pathogenesis and methods of diagnosis.

Upper gastrointestinal bleeding is a common gastrointestinal emergency associated with significant socioeconomic impact, morbidity and mortality. The aetiology of upper gastrointestinal bleeding has been reviewed, including the pathophysiological mechanisms of acid peptic and gastric mucosal disease. The initial diagnosis and therapeutic approach to the bleeding patient has been outlined.

Angiography↗
PubMed1981

Evaluation of Nd:YAG photocoagulation using a new experimental ulcer model with a single bleeding artery.

A new model of an acute bleeding gastric ulcer with a single bleeding artery in its base has been developed. A suction ulcer defect is created over a large, submucosal artery. Small bleeding marginal vessels are electrocoagulated with a fine-tipped bipolar forceps. The artery in the base of the ulcer is dissected free and then incised longitudinally; brisk bleeding results. A combination of heparin, aspirin, and dipyridamole is used to prevent spontaneous hemostasis. Bleeding from the incised artery of the single vessel ulcer does not decrease over a 10-min interval. No damage to the muscularis externa of the underlying gastric wall results from preparation of the ulcer. The effect of Nd:YAG laser photocoagulation in this new model was compared with the results of photocoagulation in the standard suction ulcer model. In both models the Nd:YAG laser stopped equivalent bleeding from all ulcers. However, there was a marked difference in the depth of tissue injury, with much less damage observed in the single vessel ulcer. This model may provide a better method to assess depth of tissue injury resulting from endoscopic hemostatic techniques.

Animals↗
PubMed1981

Computer-assisted electrocoagulation: bipolar vs. monopolar in the treatment of experimental canine gastric ulcer bleeding.

A prospective, randomized, controlled experiment using a canine model of severely bleeding gastric ulcer was performed to compare the hemostatic efficacy and tissue damage produced by one bipolar and two monopolar electrodes. Both monopolar electrodes were insulated to their tips; they differed with respect to their surface area (3 mm2 vs. 4 mm2). The force of electrode application was controlled. An analog computer monitored the energy per electrode application and predetermined the duration of each application. Fifty-nine standard acute bleeding ulcers were made and treated one at a time in six heparinized foxhounds at sterile laparotomy. Treatment was randomized to the bipolar or to one of the monopolar electrodes within each of three bleeding strata. No significant difference was observed in hemostatic efficacy among the three electrodes. Treated ulcers were examined histologically after 5 to 7 days to determine the maximum tissue damage produced: Bipolar electrocoagulation caused significantly less damage than electrocoagulation with either monopolar electrode. We conclude that with these electrodes, bipolar electrocoagulation is equally effective for stopping bleeding but results in less tissue injury than monopolar electrocoagulation in this experimental model.

Animals↗
PubMed1980

The evaluation of argon laser photocoagulation in a series of animal models of upper gastrointestinal bleeding.

During the past five years we have evaluated argon laser photocoagulation in various canine models of upper gastrointestinal hemorrhage. In gastric erosions, the eight-watt argon laser was uniformly effective in stopping bleeding. In our standard acute ulcer model the seven-watt argon laser was effective in stopping bleeding from most ulcers and only occasionally produced deep injury. With the addition of a jet of CO2 exiting the laser catheter coaxial to the laser beam, the argon laser was 100% effective and no deep injury resulted. The application of the argon laser in a more physiologic canine bleeding model using a single bleeding vessel in an ulcer base is currently under study. The development of improved animal models of gastrointestinal bleeding should contribute to the identification of effective and safe endoscopic hemostatic methods.

Animals↗
PubMed1979

Evaluation of electrofulguration in control of bleeding of experimental gastric ulcers.

The safety and efficacy of electrofulguration for control of bleeding from standard canine experimental gastric ulcers was studied. At settings of 2, 5, and 8 on a Valleylab SSE-3 generator, 0.5-sec applications provided effective hemostasis. However, a setting of 2 required an excessive number of applications. Settings of 5 and 8 showed deep injury to the muscularis externa when examined histologically. In an attempt to reduce the depth of injury, a more easily ionizable gas mixture of 50% argon gas and 50% CO2 was compared to CO2 alone. At a generator setting of 5 with 0.5-sec applications the argon-CO2 mixture produced slightly less deep injury than CO2 alone, but the difference was not significant. Although electrofulguration was effective in stopping bleeding in these experiments, the tissue injury was unpredictable and deep.

Animals↗
PubMed1979

Significance of the nonopacified gallbladder in endoscopic retrograde cholangiography.

Failure to visualize the cystic duct and gallbladder during endoscopic retrograde cholangiography, while obtaining satisfactory opacification of the rest of the biliary system, is a radiographic sign of undetermined meaning. The diagnostic implication of this finding was analyzed in 63 patients with pathologically proven diagnoses. One patient was normal at surgery. Three groups of abnormal patients had: (1) obstructing lesions of the distal common bile duct (35 patients); (2) primary lesions of the cystic duct or gallbladder (19 patients); or (3) obstructing lesions about the common hepatic/cystic duct junction (8 patients). The results indicate that obstructing lesions of the distal common bile duct may cause stasis of bile within the biliary system, increased biliary pressure, and sludge formation that prevent the flow of contrast material through the cystic duct and into the gallbladder, which can cause nonopacification. If the extrahepatic biliary system is of normal caliber without evidence of an obstructing process, nonfilling of the cystic duct and gallbladder is highly predictive of pathology.

Biliary Tract Diseases↗
PubMed1979

Argon vs. neodymium YAG laser photocoagulation of experimental canine gastric ulcers.

A neodymium YAG (Nd:YAG) laser was evaluated in a dog ulcer model used in the same manner as is recommended for bleeding patients (power 55 W, divergence angle 4 degrees, with CO2 gas-jet assistance). The experiments were performed during sterile laparotomy in heparinized dogs. Bleeding gastric ulcers were photocoagulated until bleeding stopped and then examined histologically 7 days later when depth of tissue injury was maximal. In the first series of experiments, the Nd:YAG laser was compared with the 7-W argon laser in the same dogs. Both lasers stopped bleeding from all experimental ulcers. The 55-W Nd:YAG laser caused full-thickness injury to the gastric wall beneath 11 of the 14 treated ulcers, whereas the 7-W argon laser caused no full-thickness injury beneath 14 treated ulcers. In a second series of experiments, we tried to determine whether varying exposure times with the 55-W Nd:YAG laser would make it less injurious; it did not. In a third series of experiments, the 55-W Nd:YAG laser was tested with and without CO2 gas-jet assistance in order to determine if this would affect the depth of injury; it did not. In the final series of experiments, the wattage of the Nd:YAG laser was varied to see if this would reduce depth of injury; lower wattage did not stop bleeding, and intermediate and higher wattages did stop bleeding but did not reduce depth of injury. We conclude that the 55-W Nd:YAG laser as it is currently used clinically produces deeper tissue damage than the argon laser in our animal model. This damage is not reduced by changes in power, duration of exposure, or the presence of gas-jet assistance.

Animals↗
PubMed1978

Failure of cyanoacrylate tissue glue (Flucrylate, MBR4197) to stop bleeding from experimental canine gastric ulcers.

A plastic tissue adhesive, trifluoroisopropyl 2-cyanoacrylate (Flucrylate (TM), MBR4197), was tested for hemostatic efficacy in acute laparotomy experiments using a canine model of acute bleeding gastric ulcer. An improved delivery system suitable for endoscopic use was developed. Hemostatic efficacy of the adhesive was tested in both briskly bleeding ulcers and in oozing ulcers after partial treatment with a heater probe. In pilot studies at laparotomy, primary and adjunctive cyanoacrylate therapy of 81 bleeding ulcers were evaluated in seven unheparinized foxhounds. Hemostasis was produced in 11% of ulcers treated with cyanoacrylate alone and in 31% of ulcers treated with cyanoacylate as an adjunctive after partial heater-probe treatment; no sham-treated control ulcers stopped bleeding under the conditions of the experiment. To evaluate Flucrylate (TM) using out standard heparinized ulcer model, a randomized study was performed in six heparinized foxhounds at laparotomy. Ulcers were randomized to treatment with cyanoacrylate alone, adjuctive cyanoacrylate, heater probe alone or untreated control. Sham-treated control ulcers or ulcers treated with cyanoacrylate alone did not stop bleeding; 42% of ulcers treated with cyanoacrylate as an adjunctive stopped bleeding; all ulcers treated with a heater probe stopped bleeding. In this experimental model of acute bleeding gastric ulcer, trifluoroisopropyl 2-cyanoacrylate (Flucrylate(TM),MBR4197) did not stop severe bleeding and was unpredictable as an adjunctive treatment.

Animals↗
PubMed1978

Cholangiographic abnormalities in patients with inflammatory bowel disease.

Twenty patients with inflammatory bowel disease, abnormal liver function tests and abnormal endoscopic retrograde cholangiograms were found to have a spectrum of abnormalities affecting the intra- and extrahepatic biliary trees. The intrahepatic systems were abnormal in all patients and demonstrated ductal stenosis, ectasia, decreased arborization and major duct obstruction. The extrahepatic systems were abnormal in 75 percent of cases with stenosis, diverticula formation and mural irregularity being the most frequent abnormalities. The value of endoscopic retrograde cholangiography in this patient group is to exclude extrahepatic obstruction, establish a nonoperative diagnosis, and assist in determining the method of treatment.

Adenoma, Bile Duct↗