384 research outputs found

    Assessment of the Effect of Granisetron on the Gastric Cross-Sectional Area By Ultrasound on Patients Undergoing Elective Cesarean Section: A Randomized Double-Blind Study

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    Background: Gastric ultrasound is considered a valuable tool for the assessment of gastric volume preoperatively. Materials and Methods: The goal of this study was to assess the effect of granisetron on the gastric cross-sectional area by ultrasound estimation of its cross-sectional area for elective Cesarean Section. Sixty patients were assigned randomly into one of 2 groups; Granisetron group (n=30): received 1 mg granisetron diluted in 10 mL normal saline 0.9%. Control (n=30): received 10 mL of normal saline 0.9%. Cross-sectional area and volume of stomach contents were measured using ultrasound immediately before administration of the study drug and one hour later. Results: No statistical difference was detected in post-treatment antral CSA nor gastric residual volume between the two groups (4.8±1.4 vs 4.6±2.1, P: 0.8) and (50±19 vs 57±27, P: 0.3) for antral CSA and gastric volume comparison between both groups. However, a significant statistical difference was found in antral CSA pre and post-granisetron administration (4.8±1.4 vs 4 ±1.2; P<0.001). The Granesitron group had a statistically significantly lower rate of nausea and vomiting than the control group. Conclusion: Based on ultrasonographic measurement granesitron could effectively reduce the gastric cross-sectional area when administered preoperatively to parturients undergoing elective CS

    Exploring gastrointestinal variables affecting drug and formulation behavior: methodologies, challenges and opportunities

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    Various gastrointestinal (GI) factors affect drug and formulation behavior after oral administration, including GI transfer, motility, pH and GI fluid volume and composition. An in-depth understanding of these physiological and anatomical variables is critical for a continued progress in oral drug development. In this review, different methodologies (invasive versus non-invasive) to explore the impact of physiological variables on formulation behavior in the human GI tract are presented, revealing their strengths and limitations. The techniques mentioned allow for an improved understanding of the role of following GI variables: gastric emptying (magnetic resonance imaging (MRI), scintigraphy, acetaminophen absorption technique, ultrasonography, breath test, intraluminal sampling and telemetry), motility (MRI, small intestinal/colonic manometry and telemetry), GI volume changes (MRI and ultrasonography), temperature (telemetry) and intraluminal pH (intraluminal sampling and telemetry)

    A multi-compartmental mathematical model of the postprandial human stomach : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Anatomy and Physiology at Massey University, Palmerston North, New Zealand

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    Computational fluid dynamics of the human stomach helps to understand the gastric processes such as trituration, mixing, and transit of digesta. Their outcomes give greater insight into the design of food and orally dosed drug delivery system. Current models of gastric contractile activity are primarily limited to the gastric antrum and assume global values for the various physiological characteristics. This thesis developed a unified compartmental gastric model with correctly informed anatomical and physiological data. The gastric geometry incorporated the actions of multiple compartments, such as the gastric fundus, body, antrum, pyloric canal, proximal duodenal cap, and the small intestinal brake. Lattice-Boltzmann Method (LBM) is used to simulate the fluid dynamics within the stomach. This thesis quantified the effects of transgastric pressure gradient (TGPG) between the fundus and the duodenum, the effect of antral propagating contraction (APC) amplitude, and the viscosity of the gastric contents on gastric flow, mixing, and gastric emptying. The results of this work suggest that TGPG influences gastric emptying where as APCs do not play major role in gastric emptying. Flow rate without TGPG obtained in this work agrees with previous work (Pal et al., 2004); however, it is higher in the presence of a TGPG. Results show that APCs promote recirculation, and the amplitude of APC is vital in this regard. The 'pendulating' flow of gastric content observed in this work is reported previously in duplex sonography experiments (Hausken et al., 1992). This work quantified the gastric shear rates (0.6 - 2.0 /s). This work also suggests that the viscosity of the content influences gastric fluid dynamics. This work is a simplified first step towards a 3D gastric model. Hence, these simulation studies were performed under two simplifications: dimensionality and rheology, i.e., we have assumed a Newtonian fluid flow in 2D gastric geometry. A 3D gastric model with more rheologically realistic fluid to explore the pseudoplastic fluid dynamics within the stomach in the future is recommended

    Risk factors for the preservation of morphological changes in the gastric mucosa after eradication therapy for Helicobacter pylori infection in children with chronic gastritis

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    We conducted a clinical, morphofunctional examination and standard treatment of 155 children with chronic gastroduodenitis associated with Helicobacter pylori (HP) infection. It was кevealed that after 6 months lymphoplasmacytic infiltration of the gastric mucosa (GM) preserved in 37% of cases, and unspecified atrophy - in 9%, increased C3 and C4 components of the compliment - in 19% of children, antroduodenal discoordination on the background of postprandial secretin and cholecystokinin level - in 25%, as well as disorders of the intestinal microbiot

    Biomechanics of the Small Intestinal Contractions

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    The small intestine is a part of the gastrointestinal segment comprising of the duodenum, jejunum, and ileum. They help to process the gastric contents for further digestion, which involves mixing with duodeno-biliary-pancreatic (DBP) secretions to facilitate the chemical digestion, and homogenization of the luminal contents through contractions of the circular and longitudinal smooth muscle fibers of the intestine. The contractions of these smooth muscle fibers develops the mechanical forces at the mucosal wall, which as a consequence, transfers its momentum to the underlying fluid to develop the fluid flows, suggesting relevance of mechanics in physiology. The resulting flows are what drive the digestion. Changes in contractility of wave shapes of circular and longitudinal smooth muscle contractions and fluid rheology are known to affect the digestive process through generation of various flow patterns that differ in luminal pressure, peak velocity, extent of shearing/ mixing, volume of mixing, and flow rate. Recent studies indicate that the digestive process can be very specific such as to cause lipid digestion through segmental contractions and transport by eliciting propagating contractions, suggesting that the intestine manages to digest a variety of food in an efficient manner by eliciting appropriate contractions

    MODELING AND SIMULATION OF THE PERISTALTIC FLOW OF NEWTONIAN AND NON-NEWTONIAN FLUIDS WITH APPLICATION TO THE HUMAN BODY

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    Computational models are developed to investigate peristaltic motion in the human gastro-intestinal tract. The peristaltic motion is simulated by means of traveling waves which deform the boundary of the tubes. An axisymmetric tube of uniform diameter is used to model the small intestines, and an axisymmetric conical geometry is developed to model the lower part of the human stomach. The conical geometry represents a simplification of the more complicated three-dimensional models of the human stomach that have been used in other studies. Also, they seeks to reduce computational costs and circumvent difficulties of mesh generation. The computations are performed within the open source CFD environment OpenFOAM. Whenever possible, comparisons are made to the predictions of other geometrical models from the literature to validate our results. First, the transport of fluids via peristaltic motion in a cylindrical or a conical tube is investigated. The effect of fluid, and geometrical parameters on the ow behavior is determined. Of particular interest is the transport efficiency, ow patterns, and strain rates. Second, the mixing characteristics of peristalsis is investigated for the human stomach when the pylorus is closed. Using the axisymmetric conical geometry, the effect of parameters such as wave speed, wave shape, relative occlusion, and fluid viscosity of Newtonian and non-Newtonian fluids on the ow behavior are determined. The focus of these investigations is on the quantification of the retropulsive jet induced at the pylorus, as well as on the induced vorticities between peristaltic waves, both of which contribute to the mixing efficiency. Moreover, particle tracking techniques are used to determine strain rates along particle paths which allows the investigation of stresses experienced by food particles

    Relationship between postprandial changes in cardiac left ventricular function, glucose and insulin concentrations, gastric emptying, and satiety in healthy subjects

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    Background: The digestion of food is known to alter the hemodynamics of the body significantly. The purpose of this study was to study the postprandial changes in stroke volume (SV), cardiac output (CO) and left ventricular (LV) longitudinal systolic and diastolic functions measured with tissue Doppler imaging, in relation to gastric emptying rate (GER), satiety, and glucose and insulin concentrations in healthy subjects. Methods: Twenty-three healthy subjects were included in this study. The fasting and postprandial changes at 30 min and 110 min in CO, heart rate (HR) and blood pressure were measured. Moreover, tissue Doppler imaging systolic (S'), early (E') and late (A') mitral annular diastolic velocities were measured in the septal (s) and lateral (l) walls. Glucose and insulin concentrations, and satiety were measured before and 15, 30, 45, 60, 90, and 120 min after the start of the meal. The GER was calculated as the percentage change in the antral cross-sectional area 1590 min after ingestion of the meal. Results: This study show that both CO, systolic longitudinal ventricular velocity of the septum (S's) and lateral wall (S'l), the early diastolic longitudinal ventricular velocity of the lateral wall (E'l), the late diastolic longitudinal ventricular velocity of the septum (A's) and lateral wall (A'l) increase significantly, and were concomitant with increased satiety, antral area, glucose and insulin levels. The CO, HR and SV at 30 min were significantly higher, and the diastolic blood pressure was significantly lower, than the fasting. The satiety was correlated to HR and diastolic blood pressure. The insulin level was correlated to HR. Conclusions: This study shows that postprandial CO, HR, SV and LV longitudinal systolic and diastolic functions increase concomitantly with increased satiety, antral area, and glucose and insulin levels. Therefore, patients should not eat prior to, or during, cardiac evaluation as the effects of a meal may affect the results and their interpretation

    Verification and Validation of Numerical Modelling Approaches Pertinent to Stomach Modelling

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    The digestive system is vital to the human body. Over many decades, scientists have been investigating the food breakdown mechanisms inside the stomach through in vivo human and animal studies and in vitro experiments. Due to recent improvements in computing speed and algorithm development, computational modelling has become a viable option to investigate in-body processes. Such in silico models are more easily controlled to investigate individual variables, do not require invasive physical experiments, and can provide valuable insights into the local physics of gastric flow. There is a huge potential for numerical approaches in stomach modelling as they can provide a comprehensive understanding of the complex flow and chemistry in the stomach. However, to make sure the numerical methods are accurate and reliable, rigorous verification and validation are essential as part of model development. A significant focus of this thesis was on verifying and validating the numerical modelling approaches pertinent to stomach modellin
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