Biomedical subjects

W Schwizer

Publications and source records attributed to W Schwizer.

53 records · Page 3Linked to original sources

PubMed1995

Conscious sedation for gastroscopy: patient tolerance and cardiorespiratory parameters.

BACKGROUND/AIMS: Most patients receive conscious sedation for gastroscopy. However, the benefit of the most often used combination of low-dose intravenous midazolam and topical lidocaine on patient tolerance remains poorly defined and has not been shown to outweigh cardiorespiratory risks. To respond to these issues, a randomized, double-blind, placebo-controlled prospective study was performed. METHODS: Two hundred outpatients undergoing diagnostic gastroscopy were assigned to receive either (1) midazolam (35 micrograms/kg) and lidocaine spray (100 mg), (2) midazolam and placebo lidocaine, (3) placebo midazolam and lidocaine, or (4) placebo midazolam and placebo lidocaine. RESULTS: Tolerance (visual analogue scale, 0-100 points; 0, excellent; 100, unbearable) improved as compared with placebo midazolam and placebo lidocaine by 23 points (95% confidence interval, 15-32) in group 1, 15 points (95% confidence interval, 7-24) in group 2, and 10 points (95% confidence interval, 2-18) in group 3. Increasing age (P < 0.001), low anxiety (P < 0.001), and male sex (P < 0.03), but not amnesia, were associated with better patient tolerance. Oxygen desaturation (< 1 minute) occurred in 8.2% and was not more frequent after midazolam treatment. Hypotension was rare (2.1%), and no adverse outcome occurred. CONCLUSIONS: Both low-dose midazolam (35 micrograms/kg) and lidocaine spray have an additive beneficial effect on patients tolerance and rarely induce significant alterations in cardiorespiratory monitoring parameters, thus supporting the widespread use of conscious sedation.

Adult↗

PubMed1995

Cerulein-induced changes in plasma amino acid concentrations are not a valid test for pancreatic insufficiency.

OBJECTIVES: There is controversy about the cholecystokinin (CCK)-induced decrease of plasma amino acids for the diagnosis of pancreatic insufficiency in that it is unclear whether the conflicting results are due to different degrees of stimulation by CCK. We have therefore evaluated the amino acid consumption test by examining the dose-response relation among increasing doses of cerulein and plasma amino acids compared with the release of pancreatic polypeptide in six healthy volunteers and six patients with severe pancreatic insufficiency proven by a pathological para-aminobenzoic acid test. METHODS: Stepwise increasing doses of cerulein (10-80 pmol/kg/h) were given i.v., each for 60 min with a secretin background (1 CU/kg/h). In the volunteer group, an additional experiment with infusion of placebo (saline 0.9%) was performed. RESULTS: CCK-induced amino acid changes were small in volunteers (maximum decrease: 8.4 +/- 0.9%; mean +/- SEM), tended to be more pronounced in patients (maximum decrease: 13.8 +/- 2.8%; NS), and did not permit a distinction among volunteers and patients. There was no dose-response relationship between CCK and plasma amino acids in either group. In contrast, pancreatic polypeptide levels increased markedly and dose-dependently in volunteers and patients and tended to be lower in patients with pancreatic insufficiency. CONCLUSIONS: The decrease of plasma amino acid levels in response to cerulein does not reflect pancreatic function and does not permit the diagnosis of pancreatic insufficiency.

Adult↗

PubMed1994

Gd-DOTA as a gastrointestinal contrast agent for gastric emptying measurements with MRI.

Current MR meal markers may interfere with gastric motility and secretion restricting the use of MRI in the measurement of gastric physiology. We therefore evaluated Gd-DOTA as a liquid phase marker, in vitro by determining dissociation, and adherence to the solids, and in vivo by simultaneous MRI (0.35 T scanner, multiple T1-weighted sections of the upper abdomen) and double indicator (perfusion marker PEG 4000, meal marker 99mTc-DTPA) measurements of emptying and secretion, following ingestion of 500 ml 10% glucose. In vitro Gd-DOTA was stable at a pH > 2 with < 2% dissociation at 24 h during incubation with HCl. Dissociation during incubation with HCl was linearly dependent on H+ concentration (0.77 < pH < 2.02). Less Gd-DOTA was absorbed onto the solid phase than 99mTc-DTPA (25% cf 36%). In vivo Gd-DOTA marked gastric contents provided strong positive contrast. Similar emptying curves were observed with both MRI and double-indicator techniques (r = 0.987, P < 0.001). Gd-DOTA has the potential to be a useful liquid phase contrast agent in MR studies on gastric function.

Adult↗

PubMed1994

Gastric motility measurement by MRI.

The motor mechanisms associated with gastric emptying of nutrient liquids are unclear. Gastric emptying and motility were determined in seven healthy volunteers using an MRI technique following ingestion of 500 ml of (1) 10% and (2) 25% dextrose labeled with 1 mM Gd-DOTA. Emptying was determined with transaxial scans and motility during fast coronal scans 1.2 sec apart. Emptying was slower after ingestion of 25% dextrose. Following both meals, proximal gastric diameter remained relatively constant, while antral contractile frequency and depth varied markedly. These variations were greater after 10% dextrose. These studies suggest that antral motility changes contribute to slowing of gastric emptying by nutrient meals.

Animals↗

PubMed1994

Measurement of gastric emptying and gastric motility by magnetic resonance imaging (MRI).

Hitherto it has been impossible to measure noninvasively gastric emptying and motility from multiple regions of the stomach in humans. We describe the development of a novel methodology to achieve this using magnetic resonance imaging (MRI). Initial validation studies performed in five healthy volunteers demonstrated similar gastric emptying curves and secretion rates after ingestion of 10% dextrose labeled with [Gd]DOTA, assessed by MRI ([Gd]DOTA as meal marker) and a simultaneous double-indicator technique. Comparison between MRI and scintigraphy in five patients also gave similar results. Application of newer MRI technology allowing a series of coronal scans 1.2 sec apart permitted quantification of wall motion in the proximal and distal stomach in seven healthy volunteers. These results indicate that MRI provides new insights into the mechanisms responsible for both normal and disordered emptying.

Contrast Media↗

PubMed1994

Gastric emptying of liquid meals measured noninvasively in humans with [13C]acetate breath test.

The aim of the present study was to develop a breath test to measure liquid gastric emptying rates that would be without radiation exposure and applicable to field testing. Four different test meals were investigated: a glucose meal, an amino acid meal, a fat meal, and a mixed meal (Ensure). The test meals were labeled with two markers, [13C]acetate and PEG-4000 (polyethylene glycol 4000). Gastric emptying rates were measured simultaneously by both breath test and the double-indicator technique in eight healthy male subjects. The appearance of 13CO2 in the breath closely reflected gastric emptying of the four test meals as measured by the double-indicator technique. It is concluded that the [13C]acetate breath test is a reliable, noninvasive test to measure gastric emptying rates of liquid test meals.

Acetates↗

PubMed1993

[Motility disorders and assessment methods of the esophagus].

Esophageal diseases frequently cause symptoms such as heartburn, epigastric pain and dysphagia. This article discusses the indications, techniques and limitations of currently available diagnostic procedures. Investigation of symptoms should proceed in a logical stepwise manner, beginning with endoscopy to exclude esophagitis or neoplasia. Symptoms due to acid reflux can be identified by 24h esophageal pH-metry to document a temporal association between symptoms and episodes of esophageal acidification. Stationary or ambulatory manometric recording of esophageal pressures can be used to diagnose esophageal motor disorders such as achalasia, nutcracker esophagus, diffuse esophageal spasm, or dysfunction of the upper or lower esophageal sphincter. Combined 24 h pH-manometry should be used to test the temporal association between pain, reflux, or abnormal motility in patients with non-cardiac chest pain. Video-fluoroscopy is the most appropriate technique to diagnose swallowing disorders. Pulmonary aspiration of gastro-esophageal reflux can be documented with scintigraphy.

Deglutition Disorders↗

PubMed1992

Foreign body entrapment in the esophagus of healthy subjects--a manometric and scintigraphic study.

Foreign body entrapment and mucosal injury caused by oral medications are increasingly reported to occur in the upper esophagus in apparently normal subjects. We performed esophageal manometry in 40 normal volunteers to determine whether a unique motility pattern in the upper third of the esophagus predisposes to entrapment of foreign bodies at this site; 18 normal volunteers also had transit scintigraphy of a gelatin capsule filled with a radionuclide. The esophageal body was divided into five consecutive segments starting proximally, with each segment corresponding to 20% of the total length. Amplitude, slope, and velocity of the esophageal contraction were markedly decreased in the second segment compared with the other segments. Entrapment and dissolution of a gelatin capsule occurred in 39% of volunteers in the proximal esophagus correlating to the second segment, i.e., the segment with the lowest amplitude, slope, and velocity of esophageal contractions. The observation that wet swallows have greater amplitudes (P less than 0.01) and steeper slopes (P less than 0.05) than dry swallows explains why the occurrence of pill entrapment was reduced when taken with sufficient water. However, even with a water chaser of 120 mL, pill entrapment occurred at the second segment of the esophagus in 1 of 18 volunteers. The observed motility pattern in the proximal esophagus provides a better explanation for the entrapment of foreign bodies at this site than compression of the esophagus by the left main stem bronchus, aortic arch, or left atrium as suggested by other investigators.

Adult↗

PubMed1992

Measurement of gastric emptying by magnetic resonance imaging in humans.

A new noninvasive radiation-free method to measure gastric emptying in humans was developed. The upper abdomen was recorded with a magnetic resonance imager after administration of a liquid meal containing Gadolinium tetraazacyclododecane tetraacetic acid as a magnetic resonance image (MRI) marker. Meal volumes, total gastric volumes, and secretory rates were measured. The MRI technique was validated simultaneously by the double indicator method in 5 healthy volunteers and in 5 patients with symptoms of disordered gastric emptying applying gamma camera scintigraphy and MRI in randomized order. Similar gastric meal emptying curves were obtained in volunteers and in patients by MRI and the reference methods as assessed by linear (r greater than 0.90; P less than 0.001) and intraclass correlation analysis (r greater than 0.905) for T1/2, areas under the curve, and percent of gastric meal retained. Furthermore, similar total gastric volumes and gastric secretory rates were measured by MRI and the double indicator technique. The new MRI method correctly reflected gastric emptying disorders in patients. Thus for the first time it is possible to combine these measurements of gastric functions in a single method and to relate them to gastric morphology visualized by the generation of three-dimensional images.

Adult↗

PubMed1992

Ambulatory 24-h esophageal pH monitoring: normal values, optimal thresholds, specificity, sensitivity, and reproducibility.

Ambulatory 24-h esophageal pH monitoring is increasing in popularity as the means to measure esophageal exposure to gastric juice and document the presence of gastroesophageal reflux disease, particularly before surgical therapy. Normal values for pH exposure were obtained from 50 asymptomatic healthy subjects. Receiver operating characteristic curves constructed from another 25 asymptomatic healthy subjects and 25 selected patients with other markers of increased esophageal acid exposure showed that a composite score and the percent total time pH less than 4 provide the most efficient interpretation of the test with a sensitivity of 96%, a specificity of 100% and an accuracy of 98% for the composite score, and a sensitivity, specificity, and accuracy of 96% for the percent total time pH less than 4. Repeat monitoring of healthy volunteers and symptomatic subjects in the inpatient and outpatient environment showed no significant difference, with the exception that the number of reflux episodes was significantly greater during the outpatient recording in volunteers. This did not affect the clinical accuracy of the test. Esophageal pH probes were well tolerated, but caused belching and coughing during the early part of the monitored period. We conclude that computerized ambulatory 24-h esophageal pH monitoring in the outpatient setting provides accurate and reproducible results.

Adult↗

PubMed1991

Physiological role of cholecystokinin on postprandial insulin secretion and gastric meal emptying in man. Studies with the cholecystokinin receptor antagonist loxiglumide.

Cholecystokinin was previously proposed to play an important role in the regulation of postprandial insulin secretion either indirectly, by inhibiting gastric meal emptying, or directly, by acting as an incretin promoting the release of insulin. The aim of this investigation was therefore to clarify the role of endogenous cholecystokinin in the regulation of insulin release and gastric emptying applying the highly potent and specific cholecystokinin receptor antagonist loxiglumide. Five healthy volunteers were examined after an overnight fast. Gastric meal emptying was measured by the double indicator technique using a multiple lumen tube in the duodenum and 99mTc-diethylenetriamine pentaacetate as a meal marker and polyethylene glycol 4000 as a duodenal perfusion marker. Postprandial insulin, C-peptide, cholecystokinin and glucose levels were measured after ingestion of two isocaloric meals of a) Ensure (containing fat, protein and glucose), and b) a pure glucose meal (1.11 mol/l). The meals were given either with an intravenous infusion of loxiglumide (22 mumol.kg-1.h-1) or placebo. The infusion of loxiglumide markedly accelerated the gastric emptying of the mixed meal (area under curve, 5576 +/- 352 min vs 3498 +/- 109 min; p less than 0.001) and the pure glucose meal (area under curve 5662 +/- 537 min vs 3551 +/- 534 min; p less than 0.05). Simultaneously, loxiglumide induced a more rapid rise in postprandial insulin levels after both meals resulting in significantly higher (p less than 0.05) insulin levels during the first postprandial hour, but similar insulin levels in the second postprandial hour. Accordingly, we found a close correlation between meal emptying and insulin release (r = 0.748, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Role of cholecystokinin in the regulation of gastric emptying and pancreatic enzyme secretion in humans. Studies with the cholecystokinin-receptor antagonist loxiglumide.

The role of cholecystokinin (CCK) in the regulation of gastric emptying and pancreatic enzyme secretion was evaluated by infusing the CCK-receptor antagonist loxiglumide. Gastric emptying rates and pancreatic secretory outputs were measured in five healthy volunteers by the double-indicator perfusion technique using a multiple-lumen tube in the duodenum. Placebo or loxiglumide (22 mumol.kg-1.h-1) was infused throughout each experiment. Five hundred-milliliter liquid intragastric meals of (a) fat, protein, and glucose (Ensure; Abbott, Chicago, IL); (b) glucose, 20 g/dL; and (c) guar gum, 1.1 g/dL, were given in random order. In addition, the effect of a physiologic CCK-8 dose (20 pmol.kg-1.h-1) after an intragastric 500-mL saline meal (0.154 mol/L) was tested. Intravenous CCK-8 induced a marked retardation of the gastric emptying rate of the saline solution (P less than 0.05) while stimulating pancreatic secretory outputs; both effects were completely abolished by the infusion of loxiglumide. Loxiglumide markedly accelerated the gastric emptying rates (by approximately 40%) and simultaneously diminished lipase (by approximately 75%) and trypsin (by approximately 50%) outputs of both the mixed meal (P less than 0.01) and the pure glucose meal (P less than 0.05). Additional experiments using gamma camera scintigraphy confirmed the accelerating effect of loxiglumide on gastric emptying of the mixed meal (P less than 0.01). The gastric emptying rate of the guar meal, which did not release CCK, was not influenced by the infusion of loxiglumide. Loxiglumide distinctly augmented plasma CCK levels after the mixed (2.6 times) and the pure glucose (2.1 times) meals while markedly reducing (approximately 76%) pancreatic polypeptide release (P less than 0.02). It is concluded that endogeneous CCK exerts a major role in the regulation of both gastric liquid emptying and pancreatic secretion in humans.

Adult↗

PubMed1989

Does delayed gastric emptying contribute to gastroesophageal reflux disease?

We studied 76 patients with symptoms of heartburn, regurgitation, or both and 38 asymptomatic control subjects by measuring the gastric emptying of technetium-99m-labeled oatmeal. In addition, we performed 24-hour esophageal pH monitoring and manometric studies of the esophagus on all study participants. Endoscopy was performed on all patients. Patients with proved reflux on 24-hour pH monitoring, in comparison to those without reflux and the control subjects, had a shorter lower esophageal segment with a lower pressure and more esophagitis. Delayed gastric emptying occurred with equal frequency in patients with and without reflux. Esophageal reflux was not associated with delayed gastric emptying. Delayed emptying was associated with less esophagitis than found in those with normal gastric emptying, suggesting that the prolonged presence of food in the stomach may have a buffering effect on gastric acidity. We concluded that delayed emptying is not a major factor in the pathophysiology of gastro-esophageal reflux disease and that therapy aimed at speeding gastric emptying cannot be supported by our results.

Adult↗

PubMed1988

The lower esophageal sphincter in health and disease.

The ability of the lower esophageal sphincter to protect the esophageal mucosa from exposure to gastric juice depends on its resting pressure, length exposed to abdominal pressure, and overall length. Mechanical incompetency of the sphincter can occur when one or more of these components fail. The purpose of this study was to measure manometrically the normal percentile values for these components, and to identify the point differentiating a mechanically competent from an incompetent sphincter. The results show that a mechanically incompetent sphincter can be identified by a sphincter pressure below the 2.5 percentile, an abdominal length below the fifth percentile, and an overall length below the 2.5 percentile of normal values. Sixty percent of the patients with documented increased esophageal exposure to acid gastric juice had a mechanically incompetent sphincter.

Adolescent↗

PubMed1987

Drug-induced esophageal strictures.

A retrospective study of 55 patients with a benign esophageal stricture showed that in 11 patients (20%) the cause was a drug-induced lesion due to potassium chloride (3), tetracyclines (3), aspirin (2), vitamin C (1), phenytoin (1), and quinidine (1). Five of the 11 patients would have been diagnosed as having a reflux etiology of their stricture if 24-hour esophageal pH monitoring was not performed. Six patients responded to dilatation and five patients required resection or bypass. A prospective study of 18 asymptomatic volunteers showed a high incidence of esophageal lodgment of a radiolabeled medicinal capsule, with subsequent dissolution and release of the isotope. This occurred most frequently in elderly subjects and was reduced by increasing the volume of water chaser. The sites of lodgment correspond to the location of the observed strictures in the patient population. An in vitro study showed that, when the causative drugs were mixed with saliva, dissolution occurred within 60 minutes and was associated with significant changes in pH. These investigations show that drug-induced esophageal strictures are more common than previously appreciated, and can be confused with a reflux etiology. Diagnosis is suggested by a history of drug ingestion, location of the stricture, and a normal esophageal acid exposure on 24-hour pH monitoring. The severity of the esophageal injury is variable and requires dilatation to resection for therapy.

Adolescent↗

PubMed1984

Myogenic activity relationship between the lower esophageal sphincter and pylorus of the cat in normal peristalsis and provoked retroperistalsis.

Electrodes were chronically implanted in some of 14 cats and acutely inserted in others in the muscle of the high pressure zone of the lower esophagus (LEHPZ), in the duodenum, pylorus and antrum at identical location to register the myogenic electrical activity of the LEHPZ. Simultaneously the intraluminal pressure of the LEHPZ and swallowing contractions were recorded on a 6 channel Beckman R 611 ink-pen polygraph using stationary perfusion manometry. A clear basic electrical rhythm with slow wave activity was regularly found in the LEHPZ. Strong electrical changes (action potentials) were superimposed on the slow waves which were associated with relaxation in the LEHPZ and muscle contraction in the esophagus. Electric stimulation of the duodenum and pylorus with rectangular impulses produced retrograde peristalsis in the antrum but no response in the LEHPZ. Direct stimulation of the LEHPZ and gastric fundus, however, caused a strong transient contraction of the LEHPZ.

Action Potentials↗

PubMedDate not supplied

MR defecography: depiction of anorectal anatomy and pathology.

With the advent of open-configuration MR systems, enabling image acquisition in a vertical patient position, MR defecography has become possible. MR defecography permits analyses of the anorectal angle, opening of the anal canal, functioning of the puborectal muscle, and descent of the pelvic floor during defecation. The rectal walls are well delineated on the GRE images, permitting visualization of intussusceptions and rectoceles. The concomitant depiction of structures surrounding the anorectal canal is helpful in the assessment of a spastic pelvic floor and the descending perineum syndrome and in permitting visualization of enteroceles. Dynamic MR defecography is an attractive alternative in the evaluation of defecation disorders.

Adult↗