scholarly journals Estimation Methods for Viscosity, Flow Rate and Pressure from Pump-Motor Assembly Parameters

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1451
Author(s):  
Martin Elenkov ◽  
Paul Ecker ◽  
Benjamin Lukitsch ◽  
Christoph Janeczek ◽  
Michael Harasek ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Pressure Difference ◽  
Mean Squared Error ◽  
Blood Flow Rate ◽  
Estimation Methods ◽  
In Vitro Test ◽  
Motor Speed ◽  
Term Operation

Blood pumps have found applications in heart support devices, oxygenators, and dialysis systems, among others. Often, there is no room for sensors, or the sensors are simply unreliable when long-term operation is required. However, control systems rely on those hard-to-measure parameters, such as blood flow rate and pressure difference, thus their estimation takes a central role in the development process of such medical devices. The viscosity of the blood not only influences the estimation of those parameters but is often a parameter that is of great interest to both doctors and engineers. In this work, estimation methods for blood flow rate, pressure difference, and viscosity are presented using Gaussian process regression models. Different water–glycerol mixtures were used to model blood. Data was collected from a custom-built blood pump, designed for intracorporeal oxygenators in an in vitro test circuit. The estimation was performed from motor current and motor speed measurements and its accuracy was measured for: blood flow rate r2 = 0.98, root mean squared error (RMSE) = 46 mL.min−1; pressure difference r2 = 0.98, RMSE = 8.7 mmHg; and viscosity r2 = 0.98, RMSE = 0.049 mPa.s. The results suggest that the presented methods can be used to accurately predict blood flow rate, pressure, and viscosity online.

scholarly journals In vivo / in vitro Correlation of Pharmacokinetics of Gentamicin, Vancomycin, Teicoplanin and Doripenem in a Bovine Blood Hemodialysis Model

2021 ◽  
Vol 12 ◽  
Author(s):  
M G Vossen ◽  
S Pferschy ◽  
C Milacek ◽  
M Haidinger ◽  
Mario Karolyi ◽  
...  
Keyword(s):  
Blood Flow ◽  
Renal Replacement Therapy ◽  
Protein Binding ◽  
Replacement Therapy ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Bovine Blood ◽  
Flow Rates ◽  
Dialysate Flow Rate

Background: Elimination of a drug during renal replacement therapy is not only dependent on flow rates, molecular size and protein binding, but is often influenced by difficult to predict drug membrane interactions. In vitro models allow for extensive profiling of drug clearance using a wide array of hemofilters and flow rates. We present a bovine blood based in vitro pharmacokinetic model for intermittent renal replacement therapy.Methods: Four different drugs were analyzed: gentamicin, doripenem, vancomicin and teicoplanin. The investigated drug was added to a bovine blood reservoir connected to a hemodialysis circuit. In total seven hemofilter models were analyzed using commonly employed flow rates. Pre-filter, post-filter and dialysate samples were drawn, plasmaseparated and analyzed using turbidimetric assays or HPLC. Protein binding of doripenem and vancomycin was measured in bovine plasma and compared to previously published values for human plasma.Results: Clearance values were heavily impacted by choice of membrane material and surface as well as by dialysis parameters such as blood flow rate. Gentamicin clearance ranged from a minimum of 90.12 ml/min in a Baxter CAHP-170 diacetate hemofilter up to a maximum of 187.90 ml/min in a Fresenius medical company Fx80 polysulfone model (blood flow rate 400 ml/min, dialysate flow rate 800 ml/min). Clearance of Gentamicin vs Vancomicin over the F80s hemofilter model using the same flow rates was 137.62 mL vs 103.25 ml/min. Doripenem clearance with the Fx80 was 141.25 ml/min.Conclusion: Clearance values corresponded very well to previously published data from clinical pharmacokinetic trials. In conjunction with in silico pharmacometric models. This model will allow precise dosing recommendations without the need of large scale clinical trials.

Fluid Dynamics Analysis by CT Imaging Technique of New Sorbent Cartridges for Extracorporeal Therapies

2019 ◽  
Vol 48 (1) ◽  
pp. 18-24
Author(s):  
Anna Lorenzin ◽  
Mauro Neri ◽  
Massimo de Cal ◽  
Giordano Pajarin ◽  
Giuseppe Mansi Montenegro ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Pressure Drop ◽  
Flow Rate ◽  
Imaging Technique ◽  
Blood Purification ◽  
Ct Imaging ◽  
Flow Profile ◽  
In Vitro Test

Background: Recent innovations in biomaterials technology have led to the development of innovative sorbents adopted as adsorbing devices in the field of extracorporeal blood purification therapies. As removal mechanism, adsorption allows to remove specific molecules, selectively binding them to sorbent materials. In addition to the material properties, a quintessential aspect influencing device properties is blood flow distribution within the sorbent particles. Objectives: In order to adequately characterize the potential adsorbing properties for an effective blood purification therapy, an in vitro study assessing the fluid dynamics inside 3 new cartridges, HA130, HA230 and HA330 (Jafron, Zhuhai City, ­China) was conducted through CT imaging technique. ­Methods: The cartridges were placed in vertical position in the CT ­gantry. Dye solution was circulated through the cartridges at 250 mL/min, longitudinal sections, 0.5 cm thick, were recorded for 60 s. Furthermore, an in vitro test was conducted to build pressure drop profiles. Blood was circulated at a different flow rate, 100–400 mL/min, step 50 mL/min. Pre and post cartridges pressures were acquired and pressure drop calculated. Results: Sequential images demonstrated an excellent distribution of the flow inside the cartridges. Average flow velocity was 0.37 cm/s for the 3 cartridges. HA130 had a homogeneous flow profile along the entire length of the device; HA230 and HA330 showed minimal differences between central and peripheral regions. Pressure drop profiles resulted linear, increasing proportionally with blood flow rate and packing density. Conclusions: We may conclude that the structural and functional design of the studied cartridges is adequate for haemoperfusion with no channelling phenomena. This ensures maximum and optimal utilization of the sorbent contained in the devices.

Non-parametric dynamical estimation of blood flow rate, pressure difference and viscosity for a miniaturized blood pump

2021 ◽  
pp. 039139882110067
Author(s):  
Martin Elenkov ◽  
Benjamin Lukitsch ◽  
Paul Ecker ◽  
Christoph Janeczek ◽  
Michael Harasek ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Pressure Difference ◽  
Rotation Speed ◽  
Blood Flow Rate ◽  
Blood Pump ◽  
Motor Current ◽  
Hydrodynamic Parameters ◽  
Error Formula ◽  
Blood Pumps

Blood pumps are becoming increasingly important for medical devices. They are used to assist and control the blood flow and blood pressure in the patient’s body. To accurately control blood pumps, information about important hydrodynamic parameters such as blood flow rate, pressure difference and viscosity is needed. These parameters are difficult to measure online. Therefore, an accurate estimation of these parameters is crucial for the effective operation of implantable blood pumps. In this study, in vitro tests with bovine blood were conducted to collect data about the non-linear dependency of blood flow rate, flow resistance (pressure difference) and whole blood viscosity on motor current and rotation speed of a prototype blood pump. Gaussian process regression models are then used to model the non-linear mappings from motor current and rotation speed to the hydrodynamic variables of interest. The performance of the estimation is evaluated for all three variables and shows very high accuracy. For blood flow rate – correlation coefficient ([Formula: see text] = 1, root mean squared error ([Formula: see text]) = 0.31 ml min−1, maximal error ([Formula: see text]) = 9.31 ml min−1; for pressure [Formula: see text] = 1, [Formula: see text] = 0.09 mmHg, [Formula: see text] = 8.34 mmHg; and for viscosity [Formula: see text] = 1,[Formula: see text] = 0.09 mPa.s, [Formula: see text] = 0.31 mPa⋅s. The current findings suggest that this method can be employed for highly accurate online estimation of essential hydrodynamic parameters for implantable blood pumps.

The Effect of Furosemide on the Intrarenal Blood Flow Distribution in the Dog

1972 ◽  
Vol 50 (8) ◽  
pp. 774-783 ◽  
Author(s):  
Serge Carrière ◽  
Michel Desrosiers ◽  
Jacques Friborg ◽  
Michèle Gagnan Brunette
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Urine Volume ◽  
Flow Distribution ◽  
Blood Flow Rate ◽  
Initial Distribution ◽  
Blood Flow Distribution ◽  
Intrarenal Blood Flow ◽  
Femoral Blood ◽  
Furosemide Administration

Furosemide (40 μg/min) was perfused directly into the renal artery of dogs in whom the femoral blood pressure was reduced (80 mm Hg) by aortic clamping above the renal arteries. This maneuver, which does not influence the intrarenal blood flow distribution, produced significant decreases of the urine volume, natriuresis, Ccreat, and CPAH, and prevented the marked diuresis normally produced by furosemide. Therefore the chances that systemic physiological changes occurred, secondary to large fluid movements, were minimized. In those conditions, however, furosemide produced a significant increase of the urine output and sodium excretion in the experimental kidney whereas Ccreat and CPAH were not affected. The outer cortical blood flow rate (ml/100 g-min) was modified neither by aortic constriction (562 ± 68 versus 569 ± 83) nor by the subsequent administration of furosemide (424 ± 70). The blood flow rate of the outer medulla in these three conditions remained unchanged (147 ± 52 versus 171 ± 44 versus 159 ± 54). The initial distribution of the radioactivity in each compartment remained comparable in the three conditions. In parallel with the results from the krypton-85 disappearance curves, the autoradiograms, silicone rubber casts, and EPAH did not suggest any change in the renal blood flow distribution secondary to furosemide administration.

The Effect of Hematocrit on the Clearance of Small Molecules during Hemodialysis

1983 ◽  
Vol 6 (3) ◽  
pp. 127-130 ◽  
Author(s):  
C. Woffindin ◽  
N.A. Hoenich ◽  
D.N.S. Kerr
Keyword(s):  
Blood Flow ◽  
Regression Analysis ◽  
Small Molecules ◽  
Flat Plate ◽  
Flow Rate ◽  
Distribution Curve ◽  
Blood Flow Rate ◽  
Hollow Fibre ◽  
Urea Clearance ◽  
Flow Rates

Data collected during the evaluation of a series of hemodialysers were analysed to see the effect of hematocrit on the clearance of urea and creatinine. All evaluations were performed on patients with a range of hematocrits with a mean close to 20%. The urea clearance of those in the upper half of the distribution curve (mean hematocrit 29.4%) was not significantly different from that of patients in the lower half of the distribution curve (mean hematocrit 16.9%) whether the clearance was studied at high or low blood flow rates and with hollow fibre or flat plate disposable hemodialysers. Likewise, there was no correlation between hematocrit and urea clearance by regression analysis. In contrast, the clearance of creatinine was affected by hematocrit being greater at lower hematocrit values. This difference was independent of blood flow rate and dialyser type and was confirmed by regression analysis.

Anoxia and adenosine induce increased cerebral blood flow rate in crucian carp

1994 ◽  
Vol 267 (2) ◽  
pp. R590-R595 ◽  
Author(s):  
G. E. Nilsson ◽  
P. Hylland ◽  
C. O. Lofman
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Crucian Carp ◽  
Blood Flow Rate ◽  
Fold Increase ◽  
Liver Glycogen ◽  
Glycolytic Flux ◽  
Brain Blood Flow ◽  
Atp Production ◽  
The Brain

The crucian carp (Carassius carassius) has the rare ability to survive prolonged anoxia, indicating an extraordinary capacity for glycolytic ATP production, especially in a highly energy-consuming organ like the brain. For the brain to be able to increase its glycolytic flux during anoxia and profit from the large liver glycogen store, an increased glucose delivery from the blood would be expected. Nevertheless, the effect of anoxia on brain blood flow in crucian carp has never been studied previously. We have used epireflection microscopy to directly observe and measure blood flow rate on the brain surface (optic lobes) during normoxia and anoxia in crucian carp. We have also examined the possibility that adenosine participates in the regulation of brain blood flow rate in crucian carp. The results showed a 2.16-fold increase in brain blood flow rate during anoxia. A similar increase was seen after topical application of adenosine during normoxia, while adenosine was without effect during anoxia. Moreover, superfusing the brain with the adenosine receptor blocker aminophylline inhibited the effect of anoxia on brain blood flow rate, clearly suggesting a mediatory role of adenosine in the anoxia-induced increase in brain blood flow rate.

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