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Search Results: 1 - 10 of 16235 matches for " Transit time "
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Transit-Time Flow Measurement: Letter to The Editor  [PDF]
Elsayed Elmistekawy
Open Journal of Thoracic Surgery (OJTS) , 2012, DOI: 10.4236/ojts.2012.22007
Abstract: Transit-time flow technology is considered as a quality of care in bypass surgery especially in off pump revascularization. Transit time flow measurement is a real time, direct, easy and handy tool for assessment quality of anastomosis and graft blood flow.
Mechanism of Cuff-Less Blood Pressure Measurement Using MMSB  [PDF]
Yibin Li, Yangyu Gao, Ning Deng
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B025

Continuous measurement of blood pressure based on pulse transit time (PTT) using GMR sensors is the state-of-art non-invasive cuffless method in which modulated magnetic signature of blood (MMSB) is used. In this paper, the mechanism of MMSB is investigated. According to the experimental results, it is found that both blood pulse flowing through the applied magnetic field and the displacement of the GMR sensor caused by blood pulse contribute to the disturbance of magnetic field detected by GMR sensors. The feasibility of MMSB method is discussed as well.

Early peak of hydrogen during lactose breath test predicts intestinal motility  [PDF]
Veronica Ojetti, Teresa Antonella Di Rienzo, Giovanna D’Angelo, Emidio Scarpellini, Gianluca Rizzo, Maria Chiara Campanale, Antonio Gasbarrini
Open Journal of Gastroenterology (OJGas) , 2014, DOI: 10.4236/ojgas.2014.41007
Abstract: Lactose breath test (LBT) is considered the gold standard for the diagnosis of lactose malabsorption. The test is considered positive for a peak of hydrogen (H2) 20 parts per million (ppm) above the baseline. Some patients (pts) showed a rapid peak between 30 and 90 minutes after lactose ingestion. The aim of this study was to evaluate the predictive value of an early peak during a LBT and an accelerated oro-cecal transit time (OCTT). We retrospectively analyzed all pts who referred to our Gastroenterology unit for Irritable Bowel Syndrome, from January to September 2012, who performed LBT, glucose and lactulose breath test. We consider a positive LBT for a peak of H2 > 20 ppm, a positive GHBT for a peak >12 ppm and we considered a normal OCCT a peak of H2 ≥ 10 ppm between 75 ± 105 min after lactulose load. The correlation between LBT and OCTT was evaluated by Pearson score. 93 pts (65 F/28 M mean age 47 ± 6 years) with a positive LBT, without small intestinal bacterial overgrowth were analyzed: 46 pts (32 F/14 M; mean age 48 ± 6 years) with an early peak (<90 min) of H2 (≥20 ppm) were enrolled as case, and 47 pts matched for sex and age with a peak of H2 after 90 min were enrolled as controls. 72% (33/46) of the group with an early peak showed an accelerated, 17% (8/46) a normal and 11% (5/46) a delayed OCTT. Meanwhile, in control group 40.4% (19/47) showed a normal, 57.5% (27/47) a delayed and just 1 pts an accelerated OCTT. The specificity and sensibility of LBT for an accelerated OCTT were 97.9% and 71.7% respectively. The positive predictive value of LBT for an accelerated OCTT is 97.1%; the negative predictive value is 78%. There is a significant correlation between LBT and OCTT (p < 0.05). The presence of an early peak of H2 between 30 and 90 min after the ingestion of 25 gr of lactose could predict the presence of an accelerated OCTT in 97% of pts. If confirmed by further study, in this subset of pts, lactulose breath test for evaluating OCTT could be avoided.
A Probabilistic Method of Characterizing Transit Times for Quantum Particles in Non-Stationary States  [PDF]
Hae-Won Kim, Karl Sohlberg
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.48145

We present a probabilistic approach to characterizing the transit time for a quantum particle to flow between two spatially localized states. The time dependence is investigated by initializing the particle in one spatially localized “orbital” and following the time development of the corresponding non-stationary wavefunction of the time-independent Hamiltonian as the particle travels to a second orbital. We show how to calculate the probability that the particle, initially localized in one orbital, has reached a second orbital after a given elapsed time. To do so, discrete evaluations of the time-dependence of orbital occupancy, taken using a fixed time increment, are subjected to conditional probability analysis with the additional restriction of minimum flow rate. This approach yields transit-time probabilities that converge as the time increment used is decreased. The method is demonstrated on cases of two-state oscillations and shown to produce physically realistic results.

Transit Time Flowmetry in Coronary Artery Bypass Grafting-experience at Queen Alia Heart Institute, Jordan
Basel Harahsheh
Oman Medical Journal , 2012,
Abstract: Objectives: To assess the results of transit time flowmetry (TTF) on a consecutive group of coronary artery bypass grafting (CABG) patients at Queen Alia Heart Institute.Methods: Intraoperative flow measurements of a consecutive group of 436 CABG patients. The flow pattern for each coronary artery system was assessed including mean flows, pulsatility index (PI) and the need for revision.Results: A total of 1394 grafts in 436 patients were assessed (3.2 grafts per patient), wherein 100 grafts showed inadequate flowmetry results (7.2%); most of which were in the circumflex and right coronary artery systems with a percentage of 9.4% and the least in the LAD system with a percentage of 4.4%. The mean flow of grafts to the LAD system was 33.4±5.3 mL/min with a PI of 2.4±0.4; while the mean for grafts to the circumflex artery systemwas 35.1±7.2 mL/min with a PI of 3.5±0.7. The mean for theright coronary artery was 38.4±5.9 mL/min with a PI of 2.6±0.6. Revisions occurred in five patients (1.1%). Suboptimal grafts to the LAD system exhibited a flow of 14.1±7.4 mL/min with a PI of 6.9±1.7. While for the circumflex system a flow of 5.5±3.6 mL/min was reported with a PI of 10.4±7.8; and for the right coronary system a flow of 7.2±5.3 mL/min with a PI of 9.1±5.7 was reported.Conclusion: Grafts to the LAD system showed the best flowmetry results compared to grafts to the circumflex and right coronary systems. A proportion of poor grafts were revised.
Assessment of Colon Transit Time in Idiopathic Chronic Constipation
MK Amirbaigy,H Salman Roughani,N Hosaini,Z Bootorabi
Journal of Shahid Sadoughi University of Medical Sciences , 2006,
Abstract: Introduction: Treatment in chronic constipation is highly dependent on colon transit time (CTT), which not only determines the cause but also determines the correct treatment policy. The aim of this study was evaluation of CTT in constipated patients. Methods: 43 patients with chronic constipation who did not respond to high fiber diet were enrolled in the study. Patients with history of drug induced constipation, Parkinson disease, multiple sclerosis, cerebrovascular accident, hypothyroidism, diabetic mellitus, opium addiction or previous abdominal surgery were excluded from the study. The subjects were administered 30 radio opaque markers orally (capsule form) in the morning and X.Ray was done 120 hours later. In normal patients we expect only 20% of markers (6 markers) to be retained in the colon lumen after 120 hours. Patients with more than 6 markers in colon lumen after 120 hourswere defined as abnormal CTT and were classified as colon inertia or abnormal defecation according to the position of the retained markers in the colon lumen. Results: 40 patients completed the study. 16 patients were male and 24 were female. 22(55%) patients had normal CTT. 7 patients (17.5%) had colon inertia and 3 (7.5%) had abnormal defecation, while 8 patients (20%) had both of them. No significant difference was observed between males and females. Conclusion: The pattern of CTT in constipated patients can be determined cost effectively.
Changes in cerebral perfusion detected by dynamic susceptibility contrast magnetic resonance imaging: normal volunteers examined during normal breathing and hyperventilation  [PDF]
Ronnie Wirestam, Christian Engvall, Erik Ryding, Stig Holtas, Freddy Stahlberg, Peter Reinstrup
Journal of Biomedical Science and Engineering (JBiSE) , 2009, DOI: 10.4236/jbise.2009.24034
Abstract: Global cerebral perfusion parameters were measured using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) in eight healthy volunteers examined during normal breathing and spontaneous hyperventilation. DSC-MRI-based cerebral blood flow (CBF) de-creased during hyperventilation in all volun-teers (average decrease 29%), and the corre-sponding global CBF estimates were 73±19ml/ (min100g) during normal breathing and 52± 7.9ml/(min100g) during hyperventilation (mean ±SD, n=8). Furthermore, the hypocapnic condi-tions induced by hyperventilation resulted in a prolongation of the global mean transit time (MTT) by on average 14%. The observed CBF estimates appeared to be systematically over-estimated, in accordance with previously pub-lished DSC-MRI results, but reduced to more reasonable levels when a previously retrieved calibration factor was applied.
Dietary fiber intake, stool frequency and colonic transit time in chronic functional constipation in children
Guimar?es, E.V.;Goulart, E.M.A.;Penna, F.J.;
Brazilian Journal of Medical and Biological Research , 2001, DOI: 10.1590/S0100-879X2001000900007
Abstract: the objective of the present study was to evaluate associations between fiber intake, colonic transit time and stool frequency. thirty-eight patients aged 4 to 14 years were submitted to alimentary evaluation and to measurement of colonic transit time. the median fiber intake of the total sample was age + 10.3 g/day. only 18.4% of the subjects presented a daily dietary fiber intake below the levels recommended by the american health foundation. in this group, the median left colonic transit time was shorter than in the group with higher dietary fiber intake (11 vs 17 h, p = 0.067). the correlation between stool frequency and colonic transit time was negative and weak for left colon (r = -0.3, p = 0.04), and negative and moderate for rectosigmoid and total colon (r = -0.5, p<0.001 and r = -0.5, p<0.001, respectively). the stool frequency was lower in the group with slow transit time (0.8 vs 2.3 per week, p = 0.014). in conclusion, most patients with chronic functional constipation had adequate dietary fiber intake. the negative correlation between stool frequency and colonic transit time increased progressively from proximal segments to distal segments of the colon. patients with normal and prolonged colonic transit time differ in terms of stool frequency.
Motilidade esofagiana: ensaio iconográfico sobre cintilografia dinamica do es?fago
Penas, Maria Expósito;
Radiologia Brasileira , 2007, DOI: 10.1590/S0100-39842007000600012
Abstract: this study is an interesting selection of esophageal dynamic images and respective activity/time curves to demonstrate motility ranging from normal to the opposite extreme (advancedstage achalasia). the technique employed was: 4-hour fast, with restriction of smoking, alcohol and caffeine products; anterior 0.5-second imaging during 2 minutes, covering the region from the mouth to the gastric fundus, followed by a planar 20-second image from the same region (normal transit time: < 10 seconds). the collection is based on a twenty-year experience employing a systematization including several parameters, which is able to discriminate patients with normal total esophageal transit time independently of symptoms.
Um novo método de avalia??o do "tempo esofágico" com ultra-sonografia por abordagem externa
Sakate, Makoto;Teixeira, Altamir Santos;Yamashita, Seizo;Medeiros, Thais Ricardo;Silva, Pedro Gabriel da;Henry, Maria Aparecida Coelho de Arruda;
Radiologia Brasileira , 2008, DOI: 10.1590/S0100-39842008000500008
Abstract: objective: to utilize ultrasonography for evaluating the esophageal transit time as well as the esophagus capability of differentiating among non-solid substances ingested (water and yoghurt). materials and methods: twenty-two young adults of both sexes with no gastric or esophageal complaint were evaluated, with a b-mode 3.5 mhz, convex transducer placed over the epigastric area. the esophageal transit time was determined by means of a chronometer activated when the deglutition was initiated (glottic movement), and stopped upon visualization of the bolus through the intra-abdominal esophagus. results: the mean esophageal transit time for water was 6.64 ± 1.83 sec, and 8.59 ± 2.70 sec for yoghurt. the comparative statistical analysis by a t-paired test has demonstrated statistically significant differences between the mean esophageal transit times for the two substances. conclusion: this new experimental method for evaluating the esophageal transit time by ultrasonography demonstrates significant differences in the time required for a determined liquid or pasty food passing through the esophagus, elucidating clinical suspicions and allowing a more precise indication for further, more complex clinical studies.
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