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Biomedical subjects

F E Silverstein

Publications and source records attributed to F E Silverstein.

At least 73 records · Page 4Linked to original sources
PubMed1978

Laser photocoagulation for gastrointestinal bleeding.

Endoscopic laser photocoagulation is one of the exciting developments in the field of gastrointestinal endoscopic therapy. However, much work needs to be done before these techniques should be allowed to proliferate into widespread use. There are few controlled randomized clinical studies evaluating any endoscopic treatment of bleeding, including argon laser and Nd:YAG laser photocoagulation. Despite this, uncontrolled clinical trials of both argon and Nd:YAG laser photocoagulation have begun. Laser photocoagulation of bleeding upper gastrointestinal lesions should be considered a procedure in an experimental stage of development, to be performed only under protocol studies at endoscopic research centres. Only after this or any other haemostatic technique has been proven effective and safe in thorough animal trials and then in controlled clinical trial should it be considered ready for general clinical use.

Animals↗
PubMed1977

Endoscopic laser treatment. II. Comparison of the efficacy of high and low power photocoagulation in control of severely bleeding experimental ulcers in dogs.

The coagulative efficacy of a "high power" argon laser which delivers 6.5 +/- 1.0 w was compared to that of a "low power" argon laser which delivers 1.0 +/- 0.1 w. The wave-guide angle of divergence was 8 degrees. For the high power laser, the distance between the wave-guide tip and the mucosa varied from 1.0 to 1.5 cm with a delivered power density range of 160 to 487 w per cm2. For the low power laser, the distance between the tip and mucosa varied from 0.7 to 1.3 cm with a power density of 35 to 146 w per cm2. Group A consisted of acute experiments in 6 heparinized dogs in which 51 standard-sized acute gastric ulcers extending into the submucosa were made at laparotomy via a large gastrotomy. Ulcer bleeding rates were quantified into three categories of severity. Within each category, ulcers were randomized to high power, low power, or untreated control. All 19 low power-treated ulcers and 16 untreated controls continued bleeding; 13 of 16 high power-treated ulcers stopped bleeding completely. Representative ulcers were examined histologically. Group B consisted of chronic experiments on 31 ulcers in 7 unheparinized dogs. These ulcers were either treated with high power or left as untreated controls. Dogs were killed and the ulcers were examined histologically at 7, 14, and 28 days. Only rarely did the laser injury penetrate into the muscularis externa. There were no perforations. By 14 days, all lesions were covered with normal surface epithelium. These data encourage further development of congruent to 7.0 w argon laser photocoagulation for eventual clinical use in man.

Animals↗
PubMed1976

Operative and endoscopic pancreatography in the diagnosis of pancreatic cancer.

X-rays of the pancreatic duct can now be obtained by a nonoperative endoscopic approach (endoscopic retrograde cholangiopancreatography-ERCP). After more than 2 years experience we have found that the pancreatic duct can be visualized in 85 to 90% of patients. This test is used to detect pancreatic carcinoma in the symptomatic patient and in searching for an operative pancreatic lesion in a patient with known recurrent or chronic pancreatitis. Many of these patients have pain or a transiently elevated amylase; a few have steatorrhea or abnormalities of the duodenal sweep on barium meal. Stenosis or obstruction of the main pancreatic duct with or without proximal duct dilation are the characteristic abnormalities noted in pancreatic carcinoma. A rare pancreatic tumor which is not in juxtaposition with the duct will have a normal pancreatogram although the common duct may be obstructed by cholangiography as it passes through the head of the pancreas. In patients with chronic pancreatitis it may be difficult to differentiate an inflammatory from a neoplastic stricture by either operative or endoscopic pancreatography. In the future, cytologic and biochemical examination of the pancreatic secretions obtained at ERCP may increase the accuracy of diagnosing carcinoma.

Adult↗
PubMed1976

The new look into the gastrointestinal tract.

Esophagogastroduodenoscopy has proved to be the most accurate method of diagnosing disese of the upper gastrointestinal tract. Endoscopic technics already are being employed for the treatment of gastric polyps. Experimental work on endoscopic treatment of upper gastrointestinal bleeding is under way in several medical centers. A variety of methods are being tested: laser photocoagulation, suture clip placement and the use of bioco+mpatible tissue glues. Endoscopic retrograde cholangiopancreatography now is established as a useful technic in the diagnosis of biliary tract disease. Its diagnostic usefulness in the pancreas is confined to certain diseases in which it is desirable to determine the need for operative intervention. The initial success of endoscopic papillotomy and stone extraction promises further future therapeutic uses for ERCP. Colonoscopy may well prove to be the most useful of the gastrointestinal endoscopic methods. It is particularly helpful in diagnosing colonic cancer, in determining the source of occult colonic bleeding and in providing information regarding idiopathic colonic inflammatory disease. The success of polypectomy indicates the possibility of substituting endoscopic treatment for invasive surgery. Laparoscopy in conscious patients is a well-established technic that is useful in gastroenterology, hepatology, oncology and gynecology. Its usefulness has long been appreciated in other countries and the method merits wide use in the United States. Endoscopy is a rapidly changing and evolving field. This monograph has attempted to outline the current state of the art, but many changes are expected in the next 5-10 years.

Biliary Tract Diseases↗
PubMed1976

High power argon laser treatment via standard endoscopes. I. A preliminary study of efficacy in control of experimental erosive bleeding.

With minimal transmission loss a high power argon laser (10 w) was coupled to a waveguide consisting of a flexible, single, coated, quartz fiber encased in a protective polyethylene tube. This waveguide can be passed down the biopsy channel of any standard fiberoptic endoscope. An aiming light improves accuracy. Safety devices were developed to protect the subject and the operator. Each of 8 heparinized mongrel dogs had three superficial erosions created endoscopically in the fundal gland mucosa by a jet of warm 0.1 N HC1. In each animal two lesions were photocoagulated with the laser and the third was left as a control. The animals were killed at 0, 4, 7, 10, and 14 days, and the erosions were examined histologically. By 14 days all lesions were covered by normal surface epithelium. Parietal and chief cells had returned to untreated erosions at 14 days but not to all lasered lesions. Only rarely did the lasered lesions penetrate through the muscularis mucosae into the submucosa. High power argon laser photocoagulation is now feasible through standard endoscopes. These data are sufficiently promising to encourage further evaluation of laser photocoagulation in a variety of animal models.

Animals↗
PubMed1976

A reproducible animal model of acute bleeding ulcer-the "ulcer maker".

An instrument has been developed which creates an experimental model of an acute bleeding gastric ulcer. The diameter and depth of these gastric ulcers are reproducible. The instrument can be used endoscopically or at laparotomy. Using this ulcer model nonsurgical modalities for the treatment of upper gastrointestinal bleeding can be compared in a controlled manner. This standard experimental model may also facilitate comparison of results among different research groups.

Animals↗
PubMedDate not supplied

An endoscopic Doppler probe for assessing intestinal vasculature.

Flexible fiberoptic endoscopes permit the physician to inspect the mucosal surface of the upper gastrointestinal tract and colon. However, this visual inspection provides little information about the underlying vascular supply to the intestinal wall. We tested the hypothesis that a Doppler probe could be constructed small enough to pass through the biopsy channel of a fiber endoscope and be used with it while performing endoscopy. The purpose would be to determine the location of patent arteries or veins, determine the magnitude and waveforms of the velocity in them, and estimate their contribution or potential contribution to intestinal bleeding. For this purpose, a miniature catheter probe (1.8 mm O.D. and 2 m in length) and an electronic range limited pulsed Doppler unit were developed. This probe and unit were studied in a series of 13 dogs to determine efficacy of detecting arterial and venous flow and to test the safety of the device. The duodenum was surgically exposed and opened in the region of the common bile duct (CBD). Arteries and veins surrounding the CBD were studied. Particular attention was directed to arterial structures which clinically pose a risk of bleeding when performing endoscopic papillotomy, a therapeutic technique in which the papilla of Vater is cut to release bile duct stones. The results of the study revealed that the probe could indeed detect arterial and venous structures accurately. There was no evidence that the probe produced any injury to the common bile duct or pancreas by histological or serum amylase studies and the device was determined safe and suitable for clinical evaluation.

Animals↗
PubMedDate not supplied

An endoscopic Doppler probe: preliminary clinical evaluation.

A new pulsed Doppler catheter has been developed for use during gastrointestinal fiberendoscopy. Modern gastrointestinal endoscopy allows inspection of the wall of the entire esophagus, stomach, duodenum, and colon. Diagnosis is performed by inspecting the surface of the mucosa, biopsy, and cytology. However, it is not possible to determine the characteristics of the blood vessels of the wall beneath the mucosa with available techniques. We have developed a Doppler system which is miniature and can be passed down the biopsy channel of standard fiberendoscopes. This 8 MHz device incorporates range limiting to select the depth of interrogation by Doppler. The length of the probe is 2 m, and the diameter is 1.8 mm. This device has been tested in animal studies for efficacy and safety and is now being tested clinically in patients. The probe has been tested for two indications: the detection of the retroduodenal artery prior to endoscopic papillotomy for retained bile duct stones (90 patients); and the detection of flow in esophageal varices before and after endoscopic sclerotherapy (33 patients). Preliminary results are encouraging and suggest that this device can give information about submucosal blood vessels which cannot be detected using other methods.

Ampulla of Vater↗