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Biomedical subjects

P Bauerfeind

Publications and source records attributed to P Bauerfeind.

At least 19 recordsLinked to original sources
PubMed2000

Cost analysis of antibiotic prophylaxis for PEG.

BACKGROUND: There are conflicting recommendations regarding the prophylactic use of antibiotics in patients undergoing placement of percutaneous endoscopic gastrostomy tubes. The purpose of this decision analysis was to assess the cost-effectiveness of antibiotic prophylaxis in percutaneous endoscopic gastrostomy. METHODS: A decision tree was modeled using the data of 7 published prospective placebo-controlled trials. Infectious complications were classified as grade I (requiring local care), grade II (requiring intravenous antibiotics), or grade III (requiring surgery). Medication costs were estimated from the United States average wholesale prices of the 1998 Red Book. Physician and facility costs were estimated based on the 1998 Medicare costs. A one-way sensitivity analysis was performed by varying the probability rates of the complications associated with percutaneous endoscopic gastrostomy and the costs of their treatment. RESULTS: The average cost of prophylactic antibiotics was $13.10. Antibiotic prophylaxis led to expected cost savings of $76.72 per percutaneous endoscopic gastrostomy. A sensitivity analysis suggested that antibiotic prophylaxis for percutaneous endoscopic gastrostomy was the preferred strategy unless the average probability of grade III complications dropped below an improbably low threshold value of 0.09%. CONCLUSION: Antibiotic prophylaxis in percutaneous endoscopic gastrostomy is a cost-effective strategy.

Antibiotic Prophylaxis↗
PubMed1999

[New perspectives in 3D MR colonography].

Filling the colon lumen with contrast allows for 3D-MR-colonography. The 3D data set can be postprocessed to multiplanar reconstruction, surface shaded displays as well as virtual colonoscopy. The latter facilitates the differentiation between haustra and polyps and enables detection of polyps down to 6 mm in size. Multiplanar reconstructions provide the assessment of the inner wall contour. The morphology of the colonic wall itself can be assessed on T1- or T2-weighted images. T1-weighted sequences performed before and after i.v. contrast administration and T2-weighted sequences depict pathologies based on their contrast uptake respectively on their tissue water content. This concept of colonic imaging practicable in less than 15 minutes is useful for the assessment of inflammatory disease, for polyp detection as well as for tumour staging.

Colonic Diseases↗
PubMed1999

Contrast optimization for assessment of the colonic wall and lumen in MR colonography.

This report focuses on the optimization of magnetic resonance colonography for combined virtual endoluminal and T2-weighted wall analysis of the colon and demonstrates the potential of the single-shot fast spin-echo (SSFSE) sequence for identifying colorectal pathologies. A 45 degrees flip angle in the three-dimensional spoiled gradient-echo sequence and a TE of 60 msec in the SSFSE sequence in conjunction with a 10 mM gadolinium concentration in the enema results in maximal contrast for the delineation of the colonic lumen in T1-weighted imaging and the colonic wall in T2-weighted imaging. The SSFSE sequence reveals hyperintense signal for inflammatory disease and most polyps exceeding 10 mm in size. It supplements the virtual endoluminal assessment by aiding in the differentiation between mass lesions and fecal matter or residual air.

Colon↗
PubMed1999

Gastric pouch acid secretion in response to physiologic digestive function.

OBJECTIVES: To evaluate acid secretion and histologic features of the gastric segment used for bladder replacement in bladder cancer. METHODS: Nine patients were investigated a mean of 36 months after gastric pouch surgery with modified shamfeeding and feeding. We determined urinary acidity, urinary pH, serum gastrin, and serum pancreatic polypeptide values and tried to find a relationship between feeding and acid secretion in the gastric pouch. In 6 patients, biopsy and histopathologic examination were performed. RESULTS: In 8 patients, urinary acidity increased after feeding following the rise of gastrin; in 1 patient no increase of gastrin or acidity was observed. In 7 patients, urinary acidity did not change after modified shamfeeding, indicating vagal denervation after surgery. This group showed a minimal urinary pH of above 4 after feeding. On the other hand, in 2 patients an increased acid secretion was observed after modified shamfeeding, indicating the possible presence of residual vagal innervation. In this group, the acid secretion in the pouch was higher, reaching the minimal pH level earlier after feeding. Histopathologic examination showed no major structural changes of gastric mucosa. CONCLUSIONS: Most patients are vagally denervated after gastric pouch surgery, and the gastric segment continues its original gastrointestinal function by a hormonal pathway. Our data indicate, however, that in some patients, the gastric pouch keeps a residual vagal innervation. We therefore suggest that nerve fibers present in the blood supply of the gastric segment be interrupted to avoid the complications associated with increased acid secretion of the gastric pouch.

Aged↗
PubMed1999

Is virtual colonoscopy a cost-effective option to screen for colorectal cancer?

OBJECTIVE: Computed tomography (CT) or magnetic resonance (MR) colonography is a new technique that uses data generated from CT or MR imaging to create two- and three-dimensional scans of the colon. It has been advocated to become the new primary technique of screening for colorectal cancer. The economic feasibility of such recommendation, however, has not yet been evaluated. METHODS: The cost-effectiveness of two screening strategies using CT colonography or conventional colonoscopy was compared by computer models based on a Markov process. We supposed that a hypothetical population of 100,000 subjects aged 50 yr undergoes a screening procedure every 10 yr. Suspicious findings of CT colonography are worked-up by colonoscopy. After polypectomy, colonoscopy is repeated every 3 yr until no adenomatous polyps are found. RESULTS: Under baseline conditions, screening by CT colonography costs $24,586 per life-year saved, compared with $20,930 spent on colonoscopy screening. The incremental cost-effectiveness ratios comparing CT colonography to no screening and colonoscopy to CT colonography were $11,484 and $10,408, respectively. Screening by colonoscopy remains more cost-effective even if the sensitivity and specificity of CT colonography both rise to 100%. For the two screening procedures to become similarly cost-effective, CT colonoscopy needs to be associated with an initial compliance rate 15-20% better or procedural costs 54% less than colonoscopy. CONCLUSIONS: To become cost-effective and be able to compete with colonoscopy in screening for colorectal cancer, CT or MR colonography would need be offered at a very low price or result in compliance rates much better than those associated with colonoscopy.

Adult↗
PubMed1998

Detection of mass lesions with MR colonography: preliminary report.

PURPOSE: To evaluate the performance of magnetic resonance (MR) colonography in the detection of colorectal mass lesions. MATERIALS AND METHODS: Twenty-three patients underwent MR colonography preceding colonoscopy. The colon was filled with a gadolinium-water mixture (1:100) with MR imaging guidance, and the patient was imaged prone and supine with a breath-hold three-dimensional spoiled gradient-recalled sequence. In addition, two-dimensional spoiled gradient-recalled images were acquired before and after intravenous administration of gadopentetate dimeglumine. Images were interactively analyzed on the basis of multiplanar reconstruction by two radiologists. For regions that were not conclusively assessable with multiplanar reconstruction, virtual intraluminal endoscopic images of the colon were reconstructed. MR findings were correlated with colonoscopic results. RESULTS: Two patients were excluded from the analysis. Findings in eight of 11 patients were correctly assessed as normal and in six of 10 as mass-positive. In the four patients with false-negative findings, one had two 8-mm polyps and the other three had polyps smaller than 5 mm. All nine mass lesions larger than 10 mm, as well as four of the 10 polyps ranging between 5 and 10 mm, were detected, but all polyps smaller than 5 mm were missed. In contrast to the polyps less than 5 mm, the four missed polyps (5-10 mm) could be identified retrospectively on virtual intraluminal endoscopic images. Contrast enhancement was documented in 13 polyps. CONCLUSION: Three-dimensional MR colonography provided virtual colonoscopic viewing and helped detection of colonic polyps.

Adult↗
PubMed1997

Preliminary assessment of three-dimensional magnetic resonance imaging for various colonic disorders.

BACKGROUND: Improvements in magnetic resonance imaging (MRI) technology have enabled the acquisition of three-dimensional MRI datasets in a single breath hold. We adopted this technique to make a three dimensional intraluminal and extraluminal assessment of the colon in three patients with various colonic disorders. METHODS: One patient was studied after having a double-contrast barium enema. Two patients had MRI scans after colonoscopy, which showed three colonic tumours in one and multiple polyps in the ascending colon of the other. The process of rectal filling with 1.5-2.0 L water mixed with 15-20 mL 0.5 mol/L gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) was monitored with MR fluoroscopic sequence. Three-dimensional datasets of the contrast-filled colon were taken with patients in prone (before and after intravenous administration of 0.1 mmol/kg bodyweight Gd-DTPA) and supine positions. 64 sections with a voxel-resolution of 2.0 x 2.0 x 1.25 mm3-were taken during a 28 s breath hold. Three-dimensional maximum intensity projection, multiplanar reconstruction, and virtual colonoscopic images of the colon were created from these. FINDINGS: Analysis of the coronal source images in conjunction with multiplanar reconstructions revealed all relevant abnormalities, including diverticula, carcinomas, and polyps. Three dimensional maximum-intensity projections gave a morphological overview of the whole colon. Targeted projections, made up of a limited number of coronal source images, showed diverticula and smaller polyps more clearly. After patients were given intravenous contrast all colonic mass lesions were enhanced. Datasets obtained in prone patients gave the best intraluminal views of the colon. Virtual magnetic resonance colonoscopy showed colonic haustra as well as the ileocaecal valve, but did not show clearly the diverticula. All intraluminal mass lesions, on the other hand, were easy to see. INTERPRETATION: The potential of three-dimensional colonic MRI to provide accurate, minimally invasive, cost-effective polyp screening, as well as comprehensive colonic tumour staging, warrants further investigation.

Aged↗
PubMed1997

Virtual colonoscopy with magnetic resonance imaging: in vitro evaluation of a new concept.

BACKGROUND & AIMS: Screening for colonic polyps is desirable. A new concept based on cross-sectional and endoscopic analysis of a magnetic resonance (MR) data set is presented. METHODS: Ex vivo autopsy colonic specimens, containing artificially placed polyps, were obtained and filled with a gadolinium-containing solution. Forty-four thin-section MR images were obtained in a 1.5-T MR scanner in 28 seconds. A three-dimensional endoscopic fly-through of these images was rendered. Fly-throughs and two-dimensional cross-sectional images were analyzed by two observers for the presence of polyps. RESULTS: The average sensitivity and specificity for the detection of polyps based on three-dimensional endoscopic MR colon imaging were 87% and 96%, respectively. Analysis of cross-sectional images showed an overall sensitivity and specificity of merely 57% and 84%, respectively. The difference in the interpretation of three-dimensional MR colonoscopy and two-dimensional cross-sections was statistically significant (P < 0.001). With three-dimensional MR colonoscopy, overall sensitivity for detection of polyps measuring < or =5 mm in length and diameter was 70%; for larger polyps, it increased to 95% (P < 0.01). CONCLUSIONS: The feasibility of an MR-based endoluminal assessment of the colon is shown. Minimal invasiveness, lack of radiation exposure, and high in vitro diagnostic accuracy warrant further investigation of this novel concept.

Colonic Polyps↗
PubMed1997

[3D MRI of the colon: methods and initial results].

PURPOSE: "Exoscopic" and endoscopic identification of colorectal pathologies via MRI. METHODS: 5 patients (36-88 years), two normal and three with different colorectal pathologies (diverticular disease, polyps and carcinoma of the colon), were examined by MRI after colonoscopy. Subsequent to filling of the colon with a gadolinium-water mixture under MRI-monitoring, 3D-data sets of the colon were acquired in prone and supine positions over a 28 sec breath hold interval. Subsequently multiplanar T1-weighted 2D-sequences were acquired before and following i. v. administration of Gd-DTPA (0.1 mmol/kg BW). All imaging was performed in the coronal orientation. The 3D-data were interactively analysed based on various displays: maximum intensity projection (MIP), surface shadowed display (SSD), multiplanar reconstruction (MPR), virtual colonoscopy (VC). RESULTS: All of the colorectal pathologies could be interactively diagnosed by MPR. On MIP images some pathologies were missed. VC presented the morphology of colon haustra as well as of all endoluminally growing lesions in a manner similar to endoscopy. The colon masses showed uptake of contrast media and could thus be differentiated from air or faeces. CONCLUSION: The potential of CMRI in colorectal diagnosis warrants further investigation in a larger series of patients.

Aged↗
PubMed1997

Synthesis and activity of Helicobacter pylori urease and catalase at low pH.

BACKGROUND: Helicobacter pylori produces large amounts of urease presumably to be prepared for the rare event of a sudden acid exposure. The hypothesis that H pylori is acid sensitive and protein production is inhibited by low pH was examined. METHODS: H pylori or its soluble enzymes were incubated buffered or unbuffered at a pH ranging from 2-7 in the presence of 5 mM urea for 30 minutes. After exposure, urease and catalase activities of whole cells, supernatants, and soluble enzyme preparations were measured at pH 6.8. Newly synthesised enzyme was quantified by immunoprecipitation of [35S]-methionine labelled protein. RESULTS: Exposure to buffer below pH 4 resulted in loss of intracellular urease activity. In soluble enzyme preparations and supernatant, no urease activity was measurable after incubation at pH < 5. In contrast, catalase in whole cells, supernatant, and soluble enzyme preparations remained active after exposure to pH > or = 3. Exposure below pH 5 inhibited synthesis of total protein including nascent urease and catalase. At pH 6 or 7, urease represented 10% of total protein, catalase 1.5%. Exposure of H pylori to unbuffered HCl (pH > 2) resulted in an immediate neutralisation; urease and catalase activities and synthesis were unchanged. CONCLUSION: Low surrounding pH reduces activity of urease and synthesis of nascent urease, catalase, and presumably of most other proteins. This suggests that H pylori is not acidophilic although it tolerates short-term exposure to low pH.

Bacterial Proteins↗
PubMed1997

[Peptic ulcer, Helicobacter pylori].

The etiology of gastric or duodenal ulcer defines the choice of treatment. In patients with H. pylori infection but without NSAID treatment of the acute ulcer is achieved by a one week eradication therapy. Prolonged treatment with acid inhibitors is usually not necessary. Eradication should be done by a triple therapy consisting of one acid inhibitor and two antibiotics. Success of the eradication should be controlled 4 weeks after end of the treatment by a C13-urea breath test. Serology is not useful for this matter. NSAID induced ulcers without H. pylori infection should be treated for 4-6 weeks with a potent acid inhibitor, preferably a proton pump inhibitor. If NSAID is continued afterwards prophylaxis against ulcer relapse is necessary. Prostaglandin analog Misoprostol is the only well established drug for that. Proton pump inhibitors seemed also to prevent NSAID ulcer, but solid publications are lacking. H. pylori and NSAID are independent risk factors. Thus. H. pylori eradication does not necessarily prevent relapse of NSAID induced Ulcers. Relapse prophylaxis by Misoprostol or possibly by PPI seems advisable. Ulcer without H. pylori infection and without NSAID is seldom. Other reasons, such as carcinoma, Whipple's disease or Zollinger-Ellison syndrome has to be ruled out. False negative H. pylori tests should be excluded by searching for H. pylori with other methods.

Anti-Bacterial Agents↗
PubMed1996

Metabolic base production and mucosal vulnerability during acid inhibition in a mammalian stomach in vitro.

Acid inhibition increases gastric mucosal susceptibility to damage by luminal acid. This might be due to reduced metabolic CO2 and bicarbonate whereas, during normal acid, secretion cytoprotective CO2/HCO3- production parallels acid production. Metabolic activity and mucosal damage caused by luminal acid perfusion was determined in an in vitro mouse stomach, with and without acid inhibition, and at 0%, 1%, or 5% serosal CO2 supply. Without acid inhibition there was no mucosal damage at any level of serosal CO2/HCO3- supply. Acid inhibition reduced metabolic CO2 production by 29% (P < 0.004) and resulted in microscopic damage to 55% of the mucosal area and perforation in four of five stomachs (P < 0.05). Although, 1% CO2 supply completely replaced the reduction in metabolic CO2, it did not protect against mucosal damage. Overreplacement by 5% serosal CO2/HCO3- was required to prevent damage. There was no correlation between luminal CO2/HCO3- output and mucosal damage. The protection by endogenous or exogenous CO2/HCO3- appears to act intracellularly rather than by intragastric or intercellular neutralization.

Acid-Base Equilibrium↗