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Biomedical subjects

O H Gilja

Publications and source records attributed to O H Gilja.

At least 19 recordsLinked to original sources
PubMed2006

A multimodal laser Doppler and endosonographic distension device for studying mechanosensation and mucosal blood flow in the oesophagus.

We describe the development of a multimodal device combining bag distension, manometry, high frequency intraluminal ultrasound, laser Doppler flowmetry and symptom registration. Bench tests showed that the different modalities did not influence each other. During bag distension we obtained high quality images of the oesophageal wall for computing biomechanical parameters, and laser Doppler signals showing variation in mucosal perfusion. We conclude that the principle of measurement is sound and that the device can provide a basis for further studies.

Animals↗
PubMed2005

Mechanosensory properties in the human gastric antrum evaluated using B-mode ultrasonography during volume-controlled antral distension.

The aims of this study were to evaluate gastric antral mechanical behavior and distension-induced sensorimotor responses in the human gastric antrum using transabdominal ultrasound scanning. Ten healthy volunteers underwent volume-controlled ramp inflation of a bag located in the antrum with volumes up to 125 ml. The active and passive circumferential tensions and stresses were calculated from measurements of pressure, diameter, and wall thickness before and during the administration of the anticholinergic drug butylscopolamine. The bag distensions elicited contractions in the antrum and sensory responses below the pain threshold. Butylscopolamine abolished the contractions and significantly reduced the sensory response. The length-tension diagram known from in vitro studies of smooth muscle strips could be reproduced as tension-volume diagrams in the human gastric antrum. The number of induced contractions and the contraction pressure amplitude (afterload) showed a parabolic behavior as function of the distension volume (preload), with maximum approximately at 70 ml. At the sensation threshold, the luminal circumference showed the lowest variation coefficient (13-25%), whereas the variation coefficient was more than 100% for the pressure, tensions, and stresses. We conclude that the muscle length-tension diagram and typical preload-afterload curves ad modem the Frank-Starling cardiac law can be obtained in the human gastric antrum. The sensory responses were most closely associated with the luminal circumference, indicating that the sensation during antral distension depends on deformation rather than on tension.

Adult↗
PubMed2004

Analysis of surface geometry of the human stomach using real-time 3-D ultrasonography in vivo.

The objective of this study was to develop an analytical method to describe the three-dimensional (3-D) geometry of the gastric antrum, gastric fundus and the whole stomach. The Fourier series method was used to simulate the organ surface geometry obtained from a 3-D ultrasound system. Data generated from eight antrums and three whole stomachs, at pressures of approximately 7 cm H(2)O, were used for lumen curvature calculations. The principal curvatures spatial distributions were non-homogeneous in the gastric antrum, gastric fundus and the stomach due to their complex geometry. The maximum longitudinal principal curvature in the antrum, fundus and total stomach were, respectively, 0.460 +/- 0.066, 0.583 +/- 0.087 and 1.123 +/- 0.328, whereas the maximum circumferential curvature were 1.192 +/- 0.090, 3.649 +/- 1.574 and 8.444 +/- 3.424, respectively. The present study provides an analytical tool for characterizing the complex 3-D geometry of an organ-like the human stomach reconstructed by clinical imaging modalities. Providing an average tension for the stomach does not reflect the large variation in tension throughout the stomach wall.

Adult↗
PubMed2003

Intragastric maldistribution of a liquid meal in children with recurrent abdominal pain assessed by three-dimensional ultrasonography.

BACKGROUND: Using two-dimensional (2D) ultrasonography, we previously found indications of impaired adaptive relaxation of the proximal stomach in children with recurrent abdominal pain (RAP). In the present study, we applied a new three-dimensional (3D) ultrasonographic method to investigate intragastric volumes and distribution of a liquid meal in another group of children with RAP. METHODS: Twenty patients with RAP (age 10-15 years) and 20 healthy subjects (age 11-15 years) underwent ultrasonographic measurements of the stomach. A position sensor was used based on magnetic scanhead tracking for acquisition of 3D images after a liquid meal. The children scored abdominal symptoms before and after the meal. RESULTS: Expressed as a fraction of ingested volume, the patients had a smaller volume of the proximal stomach and a larger antral volume at 2 min postprandially compared to healthy subjects (P = 0.03 and P = 0.001, respectively). The patients also showed a decreased proximal to distal gastric volume ratio at 2 min postprandially (P = 0.001). Patients experienced more pain in response to the meal than healthy subjects (P = 0.04), but there was no correlation between pain and proximal or distal gastric volumes. CONCLUSIONS: RAP in children may be associated with an early intragastric maldistribution of a meal.

Abdominal Pain↗
PubMed2002

Intragastric maldistribution of a liquid meal in patients with reflux oesophagitis assessed by three dimensional ultrasonography.

BACKGROUND AND AIMS: Our aim was to study intragastric volume and distribution of a liquid meal in patients with reflux oesophagitis using three dimensional ultrasonography. METHODS: Twenty patients and 20 healthy controls underwent ultrasonographic measurements of the stomach using a position sensor based on magnetic scanhead tracking for acquisition of three dimensional images. In vivo accuracy of the method was evaluated by scanning a soup filled barostat bag positioned in the proximal stomach of six healthy subjects. RESULTS: In the volume range 100-700 ml, our three dimensional system showed excellent correlation (r=0.99) between estimated and true volumes (limits of agreement -3.4 to 11.0 ml) and a low interobserver variation (limits of agreement -10.9 to 6.7 ml). After ingestion of a 500 ml meat soup meal, patients with reflux oesophagitis revealed a larger volume of the total and proximal stomach at two and 10 minutes (p=0.05; p=0.01, respectively), and an increased proximal/distal intragastric volume ratio at 10 minutes (p=0.04). Patients also experienced more epigastric fullness than controls (p=0.0006). CONCLUSIONS: The present three dimensional ultrasound system showed excellent agreement with true volumes and low interobserver variation. Soon after a liquid meal, patients with reflux oesophagitis have abnormal pooling of the ingested liquid in the proximal stomach.

Adult↗
PubMed2002

Mechanical properties in the human gastric antrum using B-mode ultrasonography and antral distension.

The aims of this study were to investigate gastric antral geometry and stress-strain properties by using transabdominal ultrasound scanning during volume-controlled distensions in the human gastric antrum. Seven healthy volunteers underwent stepwise inflation of a bag located in the antrum with volumes up to 60 ml. The stretch ratio and Cauchy stress and strain were calculated from measurements of pressure, diameter, and wall thickness. A second distension series was conducted in three volunteers during administration of the anticholinergic drug butylscopolamine. Analysis of stretch ratios demonstrated positive strain in the circumferential direction, negative strain in the radial direction, and no strain in the longitudinal direction. The stress-strain relation was exponential and did not differ without or with the administration of butylscopolamine. The wall stress was decomposed into its active and passive components. The well-known length-tension diagram from in vitro studies of smooth muscle strips was reproduced. The maximum active tension appeared at a volume of 50 ml, corresponding to a stretch ratio of 1.5. We conclude that the method provides measures of antral biomechanical wall properties and can be used to reproduce the muscle length-tension diagram in humans.

Aged↗
PubMed2001

Gastric accommodation studied by ultrasonography in patients with reflux esophagitis.

The aim of this study was to investigate gastric accommodation to a meal in patients with reflux esophagitis using ultrasonography. Twenty consecutive patients with reflux esophagitis of grade I (14) or II (6) and 20 healthy subjects underwent ultrasonographic measurements of the stomach before and after ingestion of a 500 ml soup meal. Reflux esophagitis patients revealed a significantly larger sagittal area of the proximal stomach at 5 min (P = 0.002) and 15 min (P = 0.007) postprandially and experienced more epigastric fullness after the meal (P = 0.0006). Postprandial fullness and sagittal area of the proximal stomach correlated significantly (r = 0.69; P = 0.0007). We conclude that patients with mild or moderate reflux esophagitis have a larger sagittal area of the proximal stomach and more postprandial fullness in response to a soup meal than healthy subjects. Postprandial distension of the proximal stomach may be a pathogenetic factor in reflux esophagitis.

Adult↗
PubMed2001

Controversies in dyspepsia.

Even in the absence of visible lesions like an ulcer, cancer or oesophagitis, patients with functional dyspepsia may complain of severe dyspeptic symptoms and have a poor quality of life. Characteristically, these patients also often have a low estimate of their own health and have complaints from several organ systems. The cause of the disease is not known. Both central nervous system and gastric disturbances appear to be involved, and their relative importance is controversial. There is no clear beneficial effect of acid suppression or H. pylori eradication although effects of such therapy may be seen in minor subgroups. New findings emphasise the importance of distinguishing between functional dyspepsia and gastro-oesophageal reflux disease, which exhibit completely different gastric accommodation patterns to a meal and have very different therapeutic potential. The effect of drugs like glyceryl trinitrate, glucagon, sumatriptan and buspirone which all concomitantly improve symptoms and gastric accommodation support the important role of abnormal gastric accommodation to meals in patients with functional dyspepsia. A hypothetical model for the pathogenesis of functional dyspepsia is presented. It incorporates four established abnormalities: various psychological abnormalities, low vagal tone, impaired gastric relaxation, and visceral hypersensitivity, in a logical interplay along the brain-gut axis.

Dyspepsia↗
PubMed2000

Influence of a 5HT1 receptor agonist on gastric accommodation and initial transpyloric flow in healthy subjects.

Sumatriptan, a 5HT1 receptor agonist, inhibits antral motor activity, delays gastric emptying and relaxes the gastric fundus. The aim of this study was to characterize the effect of sumatriptan on transpyloric flow and gastric accommodation during and immediately after ingestion of a liquid meal using duplex sonography. Ten healthy subjects were investigated twice on separate days. In random order either sumatriptan 6 mg (Imigran 0.5 mL) or a placebo were given s.c. 15 min before ingesting 500 mL of a meat soup. The subjects were examined during the 3-min period before ingestion of the liquid meal, the 3-min spent drinking the meal and 10 min postprandially. Sumatriptan caused a significant widening of both the gastric antrum (P=0.02) and the proximal stomach (P=0.01) 10 min postprandially as compared with placebo. It caused no significant differences in time to initial gastric emptying (P=0.2), but significantly delayed commencement of peristaltic-related transpyloric flow (P=0.04). Sumatriptan had no significant effect on mean abdominal symptom scores, but after sumatriptan there was a significant negative correlation between width of postprandial antral area and postprandial nausea and between width of postprandial antral area and postprandial bloating. We therefore conclude that sumatriptan causes a postprandial dilatation of both the distal and the proximal stomach with no change in dyspeptic symptoms nor in length of time to first gastric emptying. Time to commencement of peristaltic-related emptying is delayed.

Adult↗
PubMed2000

[Intraluminal sonography in the diagnosis of gastrointestinal diseases].

Endosonography is an imaging method whereby a high frequency ultrasound probe is inserted into a body cavity with or without under endoscopic control. Examination of the gastrointestinal tract is performed using special echo-endoscopes or trans-endoscopic mini-probes. The gastrointestinal wall, mediastinum, pancreas, bile ducts, retroperitoneum, and other structures surrounding the gastrointestinal tract are target organs for endosonography. A detailed image of pathological processes can thus be obtained. The method can be used both for primary diagnosis of lesions and in follow-up of gastrointestinal diseases. It is accurate in local staging of cancer and in detecting small lesions. There are some limitations for optimal examination like stenoses or other factors prohibiting a precise positioning of the ultrasound transducer. The clinical importance of endo-sonographic examinations must be continuously evaluated on the basis of new technical modalities and changes in therapeutic procedures.

Endosonography↗
PubMed2000

Impaired accommodation of the proximal stomach in children with recurrent abdominal pain.

BACKGROUND: A new ultrasonographic method was applied in children with recurrent abdominal pain, to study accommodation of the proximal stomach to a meal. METHODS: After an overnight fast, 20 patients with recurrent abdominal pain (age, 7-14 years) and 23 healthy control subjects (age, 7-13 years), were scanned by a 5-MHz transducer positioned in the epigastrium, to monitor the size of the proximal stomach before and after a test meal of meat soup. RESULTS: Children with recurrent abdominal pain had a significantly smaller sagittal area of the proximal stomach at 10 and 20 minutes after the meal than in healthy control subjects (P = 0.01 for both) and significantly higher emptying fraction of the proximal stomach at 10 minutes after the meal than in healthy control subjects (P = 0.02). There was no significant difference in emptying of the distal stomach between the patients and healthy control subjects. Children with recurrent abdominal pain experienced more symptoms (pain, bloating) in response to the test meal than did healthy control subjects. CONCLUSION: The results support the view that recurrent abdominal pain in children may be a motility disorder that can be detected in the proximal stomach as an impairment of adaptive relaxation in response to a meal. This new ultrasonographic method may become a valuable diagnostic tool in patients with recurrent abdominal pain.

Abdominal Pain↗
PubMed1999

In vitro volume estimation of kidneys using three-dimensional ultrasonography and a position sensor.

OBJECTIVE: A new 3D ultrasound system using a position sensor based on magnetic scanhead tracking and new software utilising automatic contour tracing between manually traced contours was tested for volume estimation of kidneys in vitro. METHODS: Kidneys from piglets and pigs were fixed in formaldehyde. A reservoir with 0.9% saline kept at 37 degrees C was used. The kidneys were scanned either by a linear translational movement along the organ or by a tilting movement. The outer contour of the kidneys was traced manually, by two independent investigators. The volume of each kidney was also measured using the Archimedes principle (true volumes). RESULTS: Good agreement between 3D ultrasound volume estimates and true volumes was found for both probe movements. For translational movement of the transducer, the mean errors between the methods were 4.17 and 4.31 ml for the two independent investigators, and the volume range was 96-203 ml. The corresponding error values for tilting movement were 1.10 and 0.19 ml. The interobserver variation was also small, there was no difference in the volumes obtained by the two investigators, or by the two scanning movements. CONCLUSION: Volume estimates using this 3D ultrasound method showed very good agreement with true volumes, both mean errors and interobserver variation were low.

Analysis of Variance↗
PubMed1999

3D-endosonography in gastroenterology: methodology and clinical applications.

Endoluminal ultrasonography allows detailed imaging of the gastrointestinal wall and adjacent structures. Three-dimensional (3D) imaging may improve visualisation of topographic relations and the nature of pathologic lesions. The objective of this report is to summarise current status of 3D-endosonography and to discuss the possible clinical impact of this new modality. 3D ultrasonographic images are usually generated from a series of digitised two-dimensional ultrasound pictures acquired in a manner that enables registration of their relative spatial position. Such acquisition can be accomplished with different ultrasound probes, but in most cases of endosonography, a controlled pullback of radial-scanning probes has been applied. Digital ultrasound images are obtained by frame grabbing of analogue video recordings or by direct transmission from digital scanners. Dedicated software programs have been developed for 3D reconstruction and visualisation, allowing interactive display and measurements. 3D endosonography provides new possibilities for clinical imaging, but the impact on therapeutic strategies and clinical outcome has yet to be established.

Digestive System↗
PubMed1999

Hydrosonography of the small intestine: comparison with radiologic barium study.

BACKGROUND: Transabdominal ultrasonography of the small intestine is hampered by luminal gas. We have developed a new sonographic method (hydrosonography) that largely eliminates the gas problem and have compared this method with radiologic barium study. METHODS: Fifty-six patients admitted for X-ray examination of the small bowel because of abdominal pain, diarrhoea, weight loss and/or known inflammatory bowel disease were examined. To remove luminal gas before performing transabdominal ultrasonography, 21 of polyethylene glycol solution was inserted through a nasojejunal tube by means of a peristaltic pump. Wall thickness, peristalsis, luminal narrowing, prestenotic dilatation, and extraintestinal complications were recorded. RESULTS: On ultrasonography we were able to visualize the terminal part of the ileum in 98% of the patients. Perfect agreement between hydrosonography and barium studies was seen in 50 of 55 patients. However, 44 patients had normal findings on both examinations. The sensitivity and specificity of hydrosonography were 64% and 100%, respectively. The positive predictive value was 100%. For X-ray examination sensitivity and specificity were 91% and 100%, respectively. Four patients with minor mucosal abnormalities or pathologic findings in the upper part of the small intestine accounted for the relatively low overall sensitivity found for hydrosonography compared with roentgenography. However, important extraintestinal complications were disclosed by ultrasound. CONCLUSIONS: Hydrosonography of the small bowel is a new, convenient, and reliable method for examining the lower part of the small intestine. However, it cannot replace barium studies in patients with mucosal abnormalities. especially in the upper part of the small bowel.

Adolescent↗
PubMed1999

Measurements of organ volume by ultrasonography.

In a clinical context, measurements of organ volume are often performed in the diagnosis and follow-up of patients with a variety of diseases. Ultrasonography is a cheap, widely available and non-hazardous imaging modality to use for estimation of volumes, and a range of two- and three-dimensional methods have emerged to accomplish this task. This paper reviews some of the ultrasound methods available in cardiology, gastroenterology, nephrology/urology and gynaecology/obstetrics. Using two-dimensional (2D) ultrasound, the simplest method of calculating the volume of an organ is based on the multiplication of three diameters perpendicular to each other. These 2D methods are often based on geometrical assumptions which may introduce significant errors in volume estimation. Therefore, volume estimation based on three-dimensional (3D) ultrasound has been developed to increase accuracy and precision. At present, the process of making 3D images based on ultrasonography is divided into five steps: data acquisition, data digitization, data storage, data processing and data display. In conclusion, ultrasonography is a useful and reliable tool to calculate volumes of organs. In particular, 3D ultrasonography seems promising in this respect and appears to be superior to 2D ultrasonography in accuracy and precision in volume measurements.

Cardiac Volume↗
PubMed1998

In vitro evaluation of three-dimensional ultrasonography based on magnetic scanhead tracking.

The objective of this study was to evaluate the accuracy and precision of a magnetic position sensor system for acquisition of three-dimensional (3D) ultrasound images in volume estimation of phantoms in vitro. Installation of either 0.9% solution of saline at 37 degrees C or distilled water at 20 degrees C to a condom was performed. Scanning was performed either by a continuous or stepwise acquisition. This 3D ultrasound system demonstrated good correlation (r = 0.99-1.0, n = 8) between estimated (EV) and true volumes (TV). The errors were in the range 1.3%+/-0.3% (SEM) to 1.9%+/-0.6%, independent of sound velocity. Scanning through a porcine abdominal wall positioned at the fluid surface yielded a systematic underestimation of the volume: mean (EV - TV) = -7.2+/-0.8 ml. Eight repeated scans of the same volume yielded a coefficient of variation of 1.1%. Interobserver error of the tracing procedure was 2.6%+/-0.9%. This 3D ultrasound system gave high accuracy and precision in volume estimation in vitro, and yielded low interobserver error. A change in ultrasound velocity of approximately 60 m/s did not influence the accuracy significantly. Scanning through an abdominal wall underestimated volumes slightly.

Abdomen↗
PubMed1998

Gastric meal accommodation studied by ultrasound in diabetes. Relation to vagal tone.

BACKGROUND: Disturbed gastric meal accommodation may cause abdominal symptoms in patients with functional dyspepsia and diabetes mellitus who have poor vagal control of gastric motility. In the present study we aimed to explore the relation between gastric meal accommodation and vagal tone in diabetic patients with vagal neuropathy. METHODS: Twenty patients with diabetes (DM) (insulin-dependent type; 10 men and 10 women, aged 35.3 +/- 7.6 years) and 20 healthy controls (HC) (10 men and 10 women; aged 34.7 +/- 10.7 years) were studied. Proximal gastric size was assessed with ultrasound in a sagittal area and a frontal diameter. Distal gastric (antrum) size was assessed in a sagittal area. Vagal tone was assessed non-invasively by recording of respiratory sinus arrhythmia (RSA) in beats per minute. RESULTS: Proximal sagittal area was significantly (P = 0.03) smaller in DM (18.5 +/- 5.5 cm2) than in HC (22.2 +/- 4.6 cm2). Proximal frontal diameter did not differ significantly (P = 0.60) between DM and HC (5.9 +/- 1.1 cm versus 5.7 +/- 0.8 cm). Antral area, too, did not differ significantly (P = 0.59) between DM and HC (14.5 +/- 4.1 cm2 versus 13.6 +/- 5.8 cm2). Proximal/distal meal distribution ratio, defined as proximal sagittal area/distal sagittal area, was significantly (P = 0.05) smaller in DM (6.8 +/- 0.6) than in HC (9.9 +/- 5.5). Vagal tone was significantly (P = 0.03) lower in DM (4.5 +/- 1.9 beats/min) than in HC (6.3 +/- 2.7 beats/min). Vagal tone tended (r = 0.33, P = 0.06) to correlate with proximal sagittal area in DM and HC pooled. Vagal tone correlated (r = 0.34, P = 0.05) with proximal frontal diameter in DM and HC pooled. A significant negative correlation (r = -0.39, P = 0.03) was observed between vagal tone and antral area in DM and HC pooled. CONCLUSIONS: Patients with diabetes and low vagal tone have an impaired postprandial gastric meal distribution characterized by a small proximal stomach and a small proximal/distal meal distribution ratio.

Adult↗