Waveform Shape Analysis: Extraction of Physiologically Relevant Information from Doppler Recordings

1994 ◽  
Vol 86 (5) ◽  
pp. 557-565 ◽  
Author(s):  
Margaret M. Ramsay ◽  
Fiona Broughton Pipkin ◽  
Peter C. Rubin ◽  
Robert Skidmore
Keyword(s):  
Laplace Transform ◽  
Pulsatility Index ◽  
Flow Characteristics ◽  
Resistance Index ◽  
Relevant Information ◽  
Peripheral Circulation ◽  
Valsalva Manoeuvre ◽  
Flow Conditions ◽  
Physiological Relevance ◽  
Healthy Female

1. Doppler recordings were made from the brachial artery of healthy female subjects during a series of manoeuvres which altered the pressure—flow characteristics of the vessel. 2. Changes were induced in the peripheral circulation of the forearm by the application of heat or icepacks. A sphygmomanometer cuff was used to create graded occlusion of the vessel above and below the point of measurement. Recordings were also made whilst the subjects performed a standardized Valsalva manoeuvre. 3. The Doppler recordings were analysed both with the standard waveform indices (systolic/diastolic ratio, pulsatility index and resistance index) and by the method of Laplace transform analysis. 4. The waveform parameters obtained by Laplace transform analysis distinguished the different changes in flow conditions; they thus had direct physiological relevance, unlike the standard waveform indices.

scholarly journals Post-exercise pulsatility index indicates treatment effects in peripheral arterial occlusive disease (PAOD)

2021 ◽  
Author(s):  
Andrej Udelnow ◽  
Maria Hawemann ◽  
Ivo Buschmann ◽  
Frank Meyer ◽  
Zuhir Halloul
Keyword(s):  
Repeated Measures ◽  
Pulsatility Index ◽  
Treatment Effects ◽  
Resistance Index ◽  
Peak Systolic Velocity ◽  
Arterial Tree ◽  
Post Exercise ◽  
Diastolic Velocity ◽  
Before And After ◽  
Healthy Persons

Summary Background Hypothesis: Post-exercise measurements better discriminate PAOD-patients from healthy persons and they more sensitively detect hemodynamic improvements after treatment procedures than resting measurements. Methods A total of 19 healthy volunteers and 23 consecutive PAOD-patients underwent measurements of peak systolic velocity (PSV), end-diastolic velocity (EDV), minimal diastolic velocity (MDV), time-averaged maximum velocities (TAMAX), resistance index (RI) and pulsatility index (PI) before and after a standard exercise test (at 1, 2, 3, 4 and 5 min) before and after treatment (incl. epidemiological data, PAOD risk factors and comorbidities). Results In resting values, healthy persons and PAOD-patients did not differ significantly in any of the hemodynamic parameters. PSV increased after treatment in PAOD-patients by 5 cm/s (paired t‑test, p: 0.025); however, when the amplitude of autoregulatory changes related to the resting values were calculated, PAOD-patients showed clearly less hemodynamic changes after exercise than healthy persons (p: 0.04; 0.002; <0.001 for PSV, TAMAX and PI, resp.). The time course after exercise was compared by repeated measures of ANOVA. Healthy persons differed significantly in PI, RI and PSV from PAOD patients before and after treatment (p<0.001 each). The PAOD-patients revealed a significantly improved PI after treatment (p: 0.042). The only factor contributing significantly to PI independently from grouping was direct arterial vascularization as compared to discontinuous effects by an obstructed arterial tree. Conclusion Healthy persons cannot be well differentiated from PAOD-patients solely by hemodynamics at rest but by characteristic changes after standard exercise. Treatment effects are reflected by higher PI-values after exercise.

99mTc-Szintigraphie versus Farbduplex-Sonographie

2013 ◽  
Vol 52 (05) ◽  
pp. 186-191 ◽  
Author(s):  
P. N. Truong ◽  
B. Bockisch ◽  
K. Zaplatnikov ◽  
W. T. Kranert ◽  
H. Korkusuz ◽  
...  
Keyword(s):  
Pulsatility Index ◽  
Thyroid Nodules ◽  
Resistance Index ◽  
Duplex Sonography ◽  
Flow Speed ◽  
Statistic Analysis ◽  
Thyroid Scintigraphy ◽  
Focal Lesions ◽  
Thyroid Autonomy ◽  
Blood Tests

SummarySince the development of colour coded duplex-sonography (ccds), several attempts have been made to implement this technique for diagnosis of focal lesions in the thyroid. There are controversial discussions on whether ccds might replace thyroid scintigraphy in diagnosis of hyperfunctional thyroid nodules. Aim of this study was the comparison of ccds and thyroid scintigraphy in diagnosis of functional thyroid autonomy. Patients, material and methods: 192 patients with thyroid nodules > 10mm detected by conventional sonography underwent thyroid scintigraphy. Additionally, these patients were subjected to ccds of the thyroid. In total, 286 thyroid nodules were examined by scintigraphy, ccds and blood tests. Results: Thyroid scintigraphy showed 67% of thyroid nodules as hyperfunctional, 19% indifferent and 14% as hypofunctional. Mean 99mTc uptake of hyperfunctional nodules was 2.19%, of indifferent nodules 1.12% and of hypofunctional nodules 1.06% respectively. The ccds allowed perinodular measurement of flow speed (hyperfunctional: 0.23 ± O.1 m/s; hypofunctional: 0.22 ± 0.1; indifferent: 0.21 ± 0.09), resistance index (hyperfunctional: 1.21 ± 1.16; hypofunctional: 0.62 ± 0.48; indifferent: 0.93 ± 1.02) and pulsatility index (hyperfunctional: 0.97 ± 0.45; hypofunctional: 0.84 ± 0.4; indifferent: 1.04 ± 0.6) in all nodules as well as intranodular measurement in some of the nodules (24% in hyperfunctional, 2% in indifferent and 15% in hypofunctional nodules). Statistic analysis of the obtained ccds data did not show any practically relevant correlations (p>0.05) with 99mTc uptake, basal TSH, fT3 or fT4. Conclusion: Thyroid scintigraphy cannot be replaced by ccds for diagnosis of functional thyroid autonomy. Reliable diagnostics still require a combination of thyroid scintigraphy, sonography and blood tests.

A particle image velocimetry study on the pulsatile flow characteristics in straight tubes with an asymmetric bulge

2000 ◽  
Vol 214 (5) ◽  
pp. 655-671 ◽  
Author(s):  
S C M Yu ◽  
J B Zhao
Keyword(s):  
Particle Image Velocimetry ◽  
Steady Flow ◽  
Pulsatile Flow ◽  
Flow Condition ◽  
Particle Image ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Flow Conditions ◽  
Image Velocimetry

Flow characteristics in straight tubes with an asymmetric bulge have been investigated using particle image velocimetry (PIV) over a range of Reynolds numbers from 600 to 1200 and at a Womersley number of 22. A mixture of glycerine and water (approximately 40:60 by volume) was used as the working fluid. The study was carried out because of their relevance in some aspects of physiological flows, such as arterial flow through a sidewall aneurysm. Results for both steady and pulsatile flow conditions were obtained. It was found that at a steady flow condition, a weak recirculating vortex formed inside the bulge. The recirculation became stronger at higher Reynolds numbers but weaker at larger bulge sizes. The centre of the vortex was located close to the distal neck. At pulsatile flow conditions, the vortex appeared and disappeared at different phases of the cycle, and the sequence was only punctuated by strong forward flow behaviour (near the peak flow condition). In particular, strong flow interactions between the parent tube and the bulge were observed during the deceleration phase. Stents and springs were used to dampen the flow movement inside the bulge. It was found that the recirculation vortex could be eliminated completely in steady flow conditions using both devices. However, under pulsatile flow conditions, flow velocities inside the bulge could not be suppressed completely by both devices, but could be reduced by more than 80 per cent.

scholarly journals The endocrine effects of bitter tastant administration in the gastrointestinal system - Intragastric versus intraduodenal administration

2021 ◽  
Author(s):  
Wout Verbeure ◽  
Eveline Deloose ◽  
Joran Tóth ◽  
Jens F. Rehfeld ◽  
Lukas Van Oudenhove ◽  
...  
Keyword(s):  
Feeding Tube ◽  
Gut Peptides ◽  
Nasogastric Feeding ◽  
Physiological Relevance ◽  
Quinine Hydrochloride ◽  
Healthy Female ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Acyl Ghrelin ◽  
Intraduodenal Administration

Bitter tastants are recently introduced as potential hunger-suppressive compounds, the so-called "Bitter pill". However, the literature about bitter administration lacks consistency in methods and findings. We want to test whether hunger ratings and hormone plasma levels are affected by: 1) the site of administration: intragastrically (IG) or intraduodenally (ID), 2) the bitter tastant itself, quinine hydrochloride (QHCl) or denatonium benzoate (DB), and 3) the timing of infusion. Therefore, 14 healthy, female volunteers participated in a randomized, placebo-controlled six-visit crossover study. After an overnight fast, DB (1µmol/kg), QHCl (10µmol/kg) or placebo were given IG or ID via a nasogastric feeding tube. Blood samples were taken 10 min prior to administration and every 10 min after administration for a period of 2 hours. Hunger was rated at the same timepoints on a visual analogue scale (VAS). ID bitter administration did not affect hunger sensations, motilin or acyl-ghrelin release compared with its PLC infusion. IG QHCl infusion tended to suppress hunger increase, especially between 50-70 minutes after infusion, simultaneously with reduced motilin values. Here, acyl-ghrelin was not affected. IG DB did not affect hunger or motilin, however acyl-ghrelin levels were reduced 50-70 minutes after infusion. Plasma values of glucagon-like peptide 1 and cholecystokinin were too low to be properly detected or to have any physiological relevance. In conclusion, bitter tastants should be infused into the stomach to reduce hunger sensations and orexigenic gut peptides. QHCl has the best potential to reduce hunger sensations, and it should be infused 60 minutes before food intake.

scholarly journals Relation between Fetal Renal Artery Doppler ‎Indices and Non-PROM Oligohydramnios in ‎Third Trimester of Pregnancy

2021 ◽  
pp. 1-8
Author(s):  
Asmaa Ibrahim Laag ◽  
Nareman Mahmoud Elhamamy ◽  
Amr‏ ‏Mohamed Tawfek Elbadry ◽  
Atef Hammad Teama
Keyword(s):  
Amniotic Fluid ◽  
Renal Artery ◽  
Flow Velocity ◽  
Pulsatility Index ◽  
Resistance Index ◽  
Normal Amount ◽  
Amniotic Fluid Index ◽  
Group I ◽  
Significant Difference ◽  
Artery Flow

Background: Amniotic fluid is the liquid which surround the fetus after the first few weeks of gestation. Amniotic fluid is derived mostly from the fetus and has many functions that are essential for normal growth and development. The aim of this work is to study the relation between fetal renal artery flow velocity waveforms and amniotic fluid volume in normal pregnancies and those complicated by oligohydramnios. Methods: This prospective observational study was carried out on 40pregnant women (10) of them were with normal amount of amniotic fluid (group I), while (30) of them suffered from oligohydramnios (group II).By using color doppler ultrasound imaging, the fetal renal circulation can be assessed. Intermittent assessment of renal artery flow velocity waveforms during the early stages of pregnancy may help in predicting changes in amniotic fluid dynamics. Results: There was a non-significant difference between cases with normal amount of amniotic fluid and cases with oligohydramnios in Gestational age, Maternal age, fetal femur length, bi parietal diameter, abdominal circumference and Fetal weight. There were increased values of fetal renal artery Resistance index (RI) and Pulsatility index (PI) in cases of oligohydramnios than cases with normal amount of amniotic fluid. There was no correlation between Peak systolic velocity (PSV) and Amniotic fluid index (AFI). There was a significant difference in End diastolic velocity (EDV) between cases with normal amount of amniotic fluid and cases with oligohydramnios. Also, there was a significant difference in Systolic diastolic ratio (S/D) and Amniotic fluid index (AFI) between cases with normal amount of amniotic fluid and cases with oligohydramnios. Conclusions: There is a relation between renal artery flow velocity waveforms and oligohydramnios using Pulsed wave Doppler Ultrasonography. There are higher values of renal artery Resistance index and Pulsatility index in cases of oligohydramnios more than cases with normal amount of amniotic fluid.

Estimating the hydrodynamic and morphodynamic characteristics using Entropy theory at the confluence of Negro and Solimões Rivers

2021 ◽  
Author(s):  
Farhad Bahmanpouri ◽  
Silvia Barbetta ◽  
Carlo Gualtieri ◽  
Marco Ianniruberto ◽  
Naziano Filizola ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Flow Characteristics ◽  
Low Flow ◽  
Entropy Theory ◽  
Velocity Data ◽  
Flow Conditions ◽  
Mean Velocity ◽  
Discharge Data ◽  
Confluence Zone ◽  
Error Percentage

&lt;p&gt;When two mega rivers merge the mixing of two flows results in a highly complex three-dimensional flow structure in an area known as the confluence hydrodynamic zone. In the confluence zone, substantial changes occur to the hydrodynamic and morphodynamic features which are of significant interest for researchers. The con&amp;#64258;uence of the Negro and Solim&amp;#245;es Rivers, as one of the largest river junctions on Earth, is the study area of the present research. During the EU-funded Project &amp;#8220;Clim-Amazon&amp;#8221; (2011-2015), velocity data were collected using an ADCP vessel operating under high and low flow conditions in different locations at that confluence (Gualtieri et al., 2019). By applying the Entropy theory developed by Chiu (1988) for natural channels and simplified by Moramarco et al. (2014), the two-dimensional velocity distribution, as well as depth-averaged velocity, were calculated at the different transects along the confluence zone, using only the surface velocities observation. The estimated data yielded 6.6% and 6.9% error percentage for the discharge data related to high and low flow conditions, respectively, and 8.4% and 8.3% error percentage for the velocity data related to high and low flow conditions, respectively. Regardless of the flow condition, these preliminary results also suggest the potential points at the confluence zone for the maximum local scouring. The findings of the current research highlighted the potential of Entropy theory to estimate the flow characteristics at the large river&amp;#8217;s confluence, just starting from the measure of surface velocities. This is of considerable interest for monitoring high flows using&amp;#160;no-contact technology, when ADCP or other contact equipment cannot be used for the safety of operators and risks for equipment loss.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Keywords: Amazon River, Negro/Solim&amp;#245;es Confluence, Entropy Theory, Velocity Distribution, Local Scouring&lt;/p&gt;&lt;p&gt;References&lt;/p&gt;&lt;p&gt;Gualtieri, C., Ianniruberto, M., Filizola, N. (2019). On the mixing of rivers with a difference in density: the case of the Negro/Solim&amp;#245;es confluence, Brazil. Journal of Hydrology, 578(11), November 2019, 124029,&lt;/p&gt;&lt;p&gt;Chiu, C. L. (1988). &amp;#8220;Entropy and 2-D velocity distribution in open channels&amp;#8221;. Journal of Hydrologic Engineering, ASCE, 114(7), 738-756&lt;/p&gt;&lt;p&gt;Moramarco, T., Saltalippi, C., Singh, V.P. (2004). &amp;#8220;Estimation of mean velocity in natural channels based on Chiu&amp;#8217;s velocity distribution equation&amp;#8221;. Journal of Hydrologic Engineering, ASCE, 9 (1), pp. 42-50&lt;/p&gt;

scholarly journals Influence of Rigid Emerged Vegetation in a Channel Bend on Bed Topography and Flow Velocity Field: Laboratory Experiments

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 118 ◽  
Author(s):  
Hossein Hamidifar ◽  
Alireza Keshavarzi ◽  
Paweł M. Rowiński
Keyword(s):  
Laboratory Experiments ◽  
Flow Characteristics ◽  
Maximum Velocity ◽  
Flow Conditions ◽  
Mean Flow ◽  
Bed Topography ◽  
Channel Bend ◽  
Bed Erosion ◽  
Flow Hydraulics ◽  
The Mean

Trees have been used extensively by river managers for improving the river environment and ecology. The link between flow hydraulics, bed topography, habitat availability, and organic matters is influenced by vegetation. In this study, the effect of trees on the mean flow, bed topography, and bed shear stress were tested under different flow conditions. It was found that each configuration of trees produced particular flow characteristics and bed topography patterns. The SR (single row of trees) model appeared to deflect the maximum velocity downstream of the bend apex toward the inner bank, while leading the velocity to be more uniformly distributed throughout the bend. The entrainment of sediment particles occurred toward the area with higher values of turbulent kinetic energy (TKE). The results showed that both SR and DR (double rows of trees) models are effective in relieving bed erosion in sharp ingoing bends. The volume of the scoured bed was reduced up to 70.4% for tests with trees. This study shows the effectiveness of the SR model in reducing the maximum erosion depth.

scholarly journals Fish responses to flow velocity and turbulence in relation to size, sex and parasite load

2014 ◽  
Vol 11 (91) ◽  
pp. 20130814 ◽  
Author(s):  
F. A. Hockley ◽  
C. A. M. E. Wilson ◽  
A. Brew ◽  
J. Cable
Keyword(s):  
Poecilia Reticulata ◽  
Flow Characteristics ◽  
Parasite Load ◽  
Hydrodynamic Drag ◽  
Flow Conditions ◽  
Low Velocity ◽  
Heterogeneous Flow ◽  
High Turbulence ◽  
Balance Energy ◽  
Riverine Fish

Riverine fish are subjected to heterogeneous flow velocities and turbulence and may use this to their advantage by selecting regions that balance energy expenditure for station holding while maximizing energy gain through feeding opportunities. This study investigated microhabitat selection by guppies Poecilia reticulata in terms of flow characteristics generated by hemisphere boulders in an open channel flume. Velocity and turbulence influenced the variation in swimming behaviour with respect to size, sex and parasite intensity. With increasing body length, fish swam further and more frequently between boulder regions. Larger guppies spent more time in the areas of high-velocity and low-turbulence regions beside the boulders, whereas smaller guppies frequented the low-velocity and high-turbulence regions directly behind the boulders. Male guppies selected the regions of low velocity, indicating possible reduced swimming ability owing to hydrodynamic drag imposed by their fins. With increasing Gyrodactylus turnbulli burden, fish spent more time in regions with moderate velocity and lowest turbulent kinetic energy which were the most spatially and temporally homogeneous in terms of velocity and turbulence. These findings highlight the importance of heterogeneous flow conditions in river channel design owing to the behavioural variability within a species in response to velocity and turbulence.

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