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Biomedical subjects

K Knyrim

Publications and source records attributed to K Knyrim.

At least 19 recordsLinked to original sources
PubMed1992

[Metal or plastic endoprostheses in malignant obstructive jaundice. A randomized and prospective comparison].

In a prospective randomized trial 58 patients (24 men, 34 women, mean age 67 +/- 13 [42-89] years) with inoperable malignant jaundice were treated with synthetic (S; n = 29) or expanding metal endoprostheses (M; n = 29). After endoscopic retrograde cholangiopancreatography patients were divided into a group with hilar (K: n = 7; M: n = 6) or distal involvement (K: n = 22, M: n = 23). In two cases with hilar involvement (28%) a synthetic endoprosthesis could not be implanted, while early prosthesis occlusion (after 2 days) was observed in one case. But in this group it was possible to implant all metal stents. In the group with distal involvement both synthetic and metal endoprostheses were successfully implanted. In the M group the proportion of patients with prosthesis failure (13.6%) was significantly higher than in the S subgroup (40.9%). The cholangitis incidence was 9% in the M group, significantly less (P less than 0.05) than in the K group (40.9%). Duration of hospital stay to treat prosthesis-related complications was significantly less in the M group (average 2.9 days) than the K group (12.9 days). It would be a great advance in palliative tumour treatment if it were possible significantly to reduce, by means of metal stents, the incidence of late cholangitis and the duration of hospital stay necessary to treat late complications. But improvement in the technique of implanting metal stents would be essential before their general use in distal lesions can be recommended.

Adult↗
PubMed1992

[The palliative therapy of malignant esophageal obstruction with self-expanding metal endoprostheses].

A total of 23 self-expanding metal stents were implanted in 17 patients (12 men, 5 women; mean age 66 [44-83] years) with inoperable malignant obstruction of the oesophagus or the oesophago-gastric junction. A primary success was achieved in all, a good functional result in 16 (94%). There were no complications. In the follow-up period (mean of 15.2 +/- 13 weeks) re-obstruction by the tumour process occurred in three patients. Twelve patients died after a mean survival time of 15.8 +/- 14 weeks. In ten of these the stent was still patent at death, while two had again developed dysphagia. The cumulative patency rate of the stents was 79%. These observations indicate that self-expanding metal stents can achieve satisfactory palliation in dysphagia due to a malignancy. The mortality and morbidity rates of the method seem to be less than those of other palliative measures.

Adenocarcinoma↗
PubMed1992

Bile composition, microspheroliths, antinucleating activity, and gallstone calcification.

This study examined if abnormalities in bile composition and antinucleating activity are associated with gallstone calcification. Nineteen controls without gallbladder disease and 42 patients with cholesterol stones were studied. Bile was obtained at surgery and analyzed for pH and PCO2, ionized calcium, and total calcium. The pH and carbonate concentrations of gallbladder bile were significantly higher in patients with calcified stones than in patients with noncalcified stones and in controls, resulting in significantly higher levels of the ion product in patients with calcified gallstones. Microspheroliths of calcium carbonate, seen on microscopic examination of bile, predicted stone calcification with a sensitivity of 86%, a specificity of 86%, and a predictive value of 86%. Bile from control subjects completely inhibited precipitation of calcium carbonate from a supersaturated solution, whereas bile from subjects with calcified and noncalcified gallstones did not. It is concluded that gallstone calcification is related to elevated bile pH and carbonate concentrations, resulting in an elevated ion production of calcium carbonate in gallbladder bile. In addition, bile from subjects with calcified and noncalcified gallstones lacks antinucleating activity for calcium carbonate.

Absorption↗
PubMed1992

Technical failure of biliary metal stent deployment in a series of 116 applications.

Biliary metal stents are thought to offer improved long-term palliation of malignant biliary obstruction due to a lower incidence of migration and clogging. Placement of these stents is technically more complicated than that of plastic endoprostheses and requires two experienced physicians. We report the incidence and reasons for apparent malfunction of expandable metal stent deployment (Wallstents and Strecker stents). In 116 applications of 82 Wallstents (endoscopic approach: n = 33, transhepatic approach: n = 49), we observed 19 cases of stent malfunction due to technical problems of stent delivery. In 13 cases (15.8%), the restraining membrane of the Wallstent could not be retracted sufficiently to deliver the stent. There were 6 (17.6%) failures in 34 cases of Strecker stent deployment. In 3 cases, we noted difficult balloon removal, including avulsion of the balloon catheter shaft within the endoscope during attempted balloon removal in one case. In one case, the Strecker stent could only be released partially, requiring subsequent endoscopic extraction. In two patients, only partial expansion of one end of the Strecker stent could be achieved. Given the significant malfunction rate of expandable metal stents during stent delivery, further improvements in the delivery system of the metal stents are required.

Cholestasis, Extrahepatic↗
PubMed1992

Self-expanding metal stents for palliation of malignant esophageal obstruction--a pilot study of eight patients.

We sought to determine whether the application of a self-expanding metal stent enables palliation of malignant dysphagia with minimal risk. The results of pilot studies from two centers are reported. We treated 8 inoperable patients with a 14 mm self-expanding metal stent (Wallstent). The stent was applied without general anesthesia under mild i.v. sedation. The procedure was successful in all cases. No side effects were noted. In one patient, tumor ingrowth through the meshes of the stent occurred. This patient was additionally treated with a percutaneous gastrostomy. One patient experienced tumor overgrowth of the proximal end, necessitating laser treatment. Three patients were still alive after three months. The mean number of cumulative endoscopic interventions per patient was 2.2 (SD: +/- 2; median 2). The mean observation time was 10.7 weeks +/- 2 (median 12). Dysphagia was graded from 0 (normal swallowing) to 4 (inability to swallow saliva). Dysphagia was significantly (p less than 0.0005) reduced from grade 3.1 (SD: +/- 0.35) to 0.5 (SD: +/- 0.5) immediately after stenting. 62.5% of the patients were able to manage a virtually normal diet (in one of these patients dysphagia recurred six weeks after stent placement due to tumor ingrowth). Six patients (75%) were able to ingest all necessary calories orally. The application of a 14 mm self-expanding metal stent in cases of inoperable malignant esophageal obstruction seems to offer safe and effective palliation of malignant dysphagia.

Adenocarcinoma↗
PubMed1991

The appreciation of colour in endoscopy.

The perception of colour at endoscopy has been taken for granted since the discovery of the fibreoptic bundle and the advent of fibreoptic endoscopy. Fibreoptic and lens assemblies can distort the impression of colour by selectively absorbing some wavelengths of light. In the case of electronic endoscopes, the principal sensor is the charge-coupled device (CCD), a small microelectronic device that converts an image into a sequence of electronic signals which, after appropriate processing, are transformed into an image on the monitor screen. The image is therefore visualized as a mosaic of small images, one from each sensing element. Colour is synthesized by using sequential illumination using filters or by filters placed over the CCD. Fibre-endoscopes may alter colour by selectively transmitting certain portions of the visible spectrum, while electronic endoscopes are susceptible to errors due to poor calibration of the instrument and manipulation of the colour controls by endoscopists. Colour information provides the endoscopist with clues to the nature of the lesion and also a site for biopsy. In experimental situations, colour information has been used to determine blood flow and classify lesions. Much work needs to be done to define normal and abnormal colour in the gastrointestinal tract and to develop a standard terminology for colour nomenclature in endoscopy.

Color Perception↗
PubMed1990

The effects of synthetic human secretin on calcium carbonate solubility in human bile.

This study sought to determine the effects of synthetic human secretin on ionized calcium and carbonate concentrations in human hepatic bile. Five patients with a nasobiliary drain in the right hepatic duct were studied. Three basal samples of bile were collected, each over a 15-minute period. Synthetic human secretin was then infused IV at 0.05 micrograms.kg-1.h-1 for 45 minutes followed by 0.5 micrograms.kg-1.h-1 for 45 minutes. Bile was sampled over 15-minute periods. To document return to baseline conditions, two further samples of bile were obtained over 15-minute periods 2 hours after the infusion was terminated. Bile acid concentration was determined by an enzymatic method; pH and PCO2 were measured with an automated analyzer. Total calcium was determined by inductively coupled plasma emission spectrometry and ionized calcium by an ion-specific electrode. Bicarbonate and carbonate concentrations were calculated using Henry's law and the Henderson-Hasselbalch equation. The fraction of bile sampled by the catheter was determined by Indocyanin Green recovery at the end of the experiment. Secretin caused an increase in bile flow and bicarbonate output. Bicarbonate concentrations increased from 26 +/- 3 mmol/L to 41 +/- 3 mmol/L (P less than 0.05), and chloride concentrations decreased. Mean bile acid concentrations declined significantly from 14.6 +/- 2 mmol/L to 4.7 +/- 1 mmol/L (P less than 0.05). Ionized calcium concentrations decreased from 0.7 +/- 0.005 mmol/L to 0.5 +/- 0.02 mmol/L (P less than 0.05) while pH increased significantly from 7.44 +/- 0.06 to 7.6 +/- 0.04 (P less than 0.05). Carbonate concentrations increased significantly from 0.15 +/- 0.02 mmol/L to 0.26 +/- 0.03 mmol/L, and the ion product for calcium carbonate increased significantly from 0.099 +/- 0.002 (mmol/L)2 to 0.135 +/- 0.015 (mmol/L)2 (P less than 0.05). Synthetic human secretin augments the ion product of calcium and carbonate in human hepatic bile, increasing the tendency for calcium carbonate precipitation.

Analysis of Variance↗
PubMed1990

Perspectives in "electronic endoscopy". Past, present and future of fibers and CCDs in medical endoscopes.

Electronic endoscopy has undergone considerable evolution in recent years. Early instruments had poorer resolution than fiberscopes, and distorted colors significantly. The second generation of electronic endoscopes has been considerably improved, and electronic endoscopy is expected to play a major role in endoscopy in the next decade, with its enhanced teaching abilities, permanent image storage, reproduction and retrieval. An important new development has been the development of a high-resolution colonoscope & gastroscope. Electronic endoscopes are now able to produce better resolution than fiberscopes, and the future should bring further improvements in resolution with electronic instruments. A number of problems still remain to be solved with electronic endoscopy. Irregular reflection from secretions, food and blood at short focus (less than 1 cm) results in a loss of resolution, which makes electronic endoscopy particularly difficult when bleeding is brisk. Electronic endoscopes synthesize color from a strobed signal of red, blue and green in a processor. Color is dependent on brightness, and at close focus, excessive brightness in the center of the field results in erratic color reproduction. Images acquired at electronic endoscopy may be digitized for storage and processing in a computer--which, however, is not a straightforward task at the present time. Image processing in electronic endoscopy is still in its early stages, but we anticipate that new developments in early diagnosis, classification and measurement of lesions will take place. Digitized images can also be transmitted via telephone lines, and it will soon be possible to instantaneously send images across the world.

Color↗
PubMed1989

The effects of intraduodenal bile acid administration on biliary secretion of ionized calcium and carbonate in man.

The importance of calcium in gallstone formation is increasingly recognized. Calcium carbonate is an important constituent of gallbladder stones and may be present in the nidus of cholesterol stones. Secondary deposition of calcium carbonate on the surface of cholesterol gallstones is an important reason for failure of oral bile acid dissolution therapy. We sought to determine the effects of bile acids on the crystallization conditions of calcium carbonate in bile. We studied 18 patients with choledocholithiasis with a percutaneous or endoscopically placed catheter high in the biliary tree. Samples of bile in the basal state and following replacement of the bile acid pool with cholic acid, chenodeoxycholic acid and ursodeoxycholic acid were analyzed for total calcium, ionized calcium, bicarbonate and carbonate, and the saturation index for calcium carbonate was calculated. Hepatic bile in the basal state was supersaturated with calcium carbonate. Total calcium concentrations rose linearly with rising bile acid concentrations but ionized calcium was maintained in a relatively narrow range. These data are consistent with an important role for bile acids in binding calcium. Extrapolation of the linear regressions between bile acid concentration and calcium concentrations suggested that in the absence of bile acids, biliary calcium concentrations are in passive equilibrium with plasma. Chenodeoxycholic acid and ursodeoxycholic acid caused a bicarbonate-rich choleresis and significantly augmented the saturation index for calcium carbonate, whereas cholic acid caused no change. In contrast with animal models, the apparent choleretic activity of cholic acid, chenodeoxycholic acid and ursodeoxycholic acid was similar, and no hyper-choleresis was observed with ursodeoxycholic acid. Chenodeoxycholic acid and ursodeoxycholic acid therefore increase the thermodynamic possibility for calcium carbonate precipitation.

Aged↗
PubMed1989

Optical performance of electronic imaging systems for the colon.

Electronic (video) endoscopes are a significant new development in gastroenterology, offering the potential of enhanced teaching and permanent storage of pictorial data. The primary concern of gastroenterologists is the resolution and color performance of these instruments, as these parameters have important bearings on the ability to discern pathological changes in mucosa. We sought to determine the resolution and color capabilities of electronic colonoscopes and compare them with a conventional fiber colonoscope. Resolution was determined using a standard test chart at various distances and the number of picture elements (a measure of resolution) was calculated. The mean number of picture elements was Fujinon (219), Fiber (172), Pentax (169), Toshiba (142), Olympus (140), and Welch Allyn (133). In close focus examination (target distances less than 1 cm), the Fujinon and Toshiba endoscopes had significantly higher resolution than the other instruments. Color was measured quantitatively using a standard color chart and a color analyzer. Color polygons were plotted for each endoscope on a reference chromaticity diagram. All systems had an acceptable overall performance but color was undersaturated with some systems. The optical performance of electronic endoscopes has improved considerably since the inception of electronic endoscopy.

Colonoscopes↗
PubMed1987

Electronic endoscopy--the latest technology.

At present, video endoscopic systems (VE) are available from four companies. We have had an opportunity to test these instruments in clinical practice. In principle, all the VE's are similar in that they employ charge coupling devices (CCD-chips) as image sensors, but they differ significantly in CCD chip technology and in the color acquisition technique. The basic aspects of CCD chip and transmission technology of relevance to the endoscopist are discussed. The mechanical properties of the endoscopes are listed. Finally, we provide an outlook on the determinants of the optical performance of VE's. The optical performance of a VE can be characterized by its resolution and color performance.

Colonoscopes↗
PubMed1987

Video-endoscopes in comparison with fiberscopes: quantitative measurement of optical resolution.

The subject of this study was the optical performance of video-endoscopic systems (VE) in terms of maximal resolving power and resolvable picture elements. Olympus, Toshiba/Machida, Fujinon, and Welch Allyn video gastroscopes were tested. A GIF Q 10 fiberscope from Olympus was also included for comparison. The resolution measurements were made at various distances using two independent methods--electronic analysis of the TV signal, and visual evaluation of the resolution, of a standardized test target. The results obtained with the two methods were in perfect agreement. The resolution of fine details clearly depends on the distance between the distal end and the target because of decreasing image scale. Depending on the individual optical design, the various VE's show maxima at different distances. At shorter distances, the image is degraded by defocusing. An optimal distance which is as small as possible is desired for clinical routine. Apart from the fiberscope this requirement is best met by the Fuji system. The greatest resolution is obtained with the Toshiba system but at the cost of the viewing angle which is the smallest of all the systems. Fuji combines relatively high resolution with a large viewing angle. Because of the widely varying viewing angle a comparison based solely on resolution cannot represent the true imaging capability of the system. We therefore eliminated purely optical parameters and calculated the number of resolvable picture elements per line. We regard this number to be a fair characterization of both TV and fiber systems.

Fiber Optic Technology↗
PubMed1987

Color performance of video endoscopes: quantitative measurement of color reproduction.

We have conducted a study aimed at testing the color performance of video endoscopes in quantitative terms for the first time. The video endoscopes investigated were from Fuji, Olympus, Toshiba/Machida, and Welch-Allyn. The tests were carried out with an opto-electronic color analyser using standardized color charts and a neutral grey chart. Hue and chroma of the reproduced colors were measured. The Olympus video endoscope reproduces the hue very well, showing only slight color desaturation. The Fuji video endoscope had a yellowish tint, whereas the picture obtained with the WA video endoscope produced an inhomogeneous picture with a pronounced red/purplish cast at the top of the screen and almost neutral reproduction at the lower half. The Toshiba video endoscope was the only one with a color chip, and reproduced hue fairly well, but its colors were weakly saturated.

Color↗
PubMed1987

Computer-aided formulation of physician's reports and storage of ERCP data.

In the 2nd Medical Dept. of the Technical University of Munich, endoscopic retrograde cholangiopancreatography (ERCP) reports are written with the aid of a computer. The doctor doing the examination enters the ERCP data into screen masks. The data are stored at once in a data bank. This data bank system permits immediate error checks of the variables entered, singly and in combination. Errors can be corrected in a loop. Generating of ERCP reports is controlled by a text file, which contains both control statements and standard phrases. A special program for the document generating was developed by the authors and has been used for 15 years in various applications.

Cholangiopancreatography, Endoscopic Retrograde↗