Measurement of Liver Blood Flow by Means of a Single Injection of Bromosulphthalein, without Hepatic Venous Catheterization

1976 ◽  
Vol 51 (2) ◽  
pp. 141-150 ◽  
Author(s):  
M. J. Clarkson ◽  
Anne Hardy-Smith ◽  
T. G. Richards
Keyword(s):  
Blood Flow ◽  
Single Dose ◽  
Colloidal Particles ◽  
Single Injection ◽  
Liver Blood Flow ◽  
Flow Rates ◽  
Fick Principle ◽  
The Third ◽  
Venous Catheterization ◽  
Wide Range

1. A method is described for the measurement of liver blood flow without hepatic venous catheterization by the injection of a single dose of bromosulphthalein and the analysis of the graph of the plasma disappearance of the indicator. 2. The rationale of the method was tested in three systems which covered a wide range of flow rates. The first system was a physical model with a haemodialyser in which the calculated flow could be compared with the flow measured directly. The second was in anaesthetized dogs, in which the calculated flow was compared with that measured by continuous infusion and hepatic venous catheterization, based on the Fick principle. The third system was in unanaesthetized turkeys, in which metabolism of bromosulphthalein does not occur. The calculated flow was compared with the flow measured simultaneously by the uptake of colloidal particles by the Kupffer cells. 3. In all three systems the correspondence between the two methods of measuring liver blood flow was good, the differences between them being not statistically significant. 4. The method has been applied to measurements of liver blood flow in man and animals and gives results comparable with those reported by other workers.

Measurement of pulmonary blood flow during exercise using nitrous oxide

1962 ◽  
Vol 17 (4) ◽  
pp. 579-586 ◽  
Author(s):  
Margaret R. Becklake ◽  
C. J. Varvis ◽  
L. D. Pengelly ◽  
S. Kenning ◽  
M. McGregor ◽  
...  
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Dilution Technique ◽  
Fick Principle ◽  
Pulmonary Capillary Blood Flow ◽  
Time Period ◽  
Pulmonary Capillary ◽  
Wide Range ◽  
Pulmonary Capillary Blood ◽  
The Difference

Pulmonary capillary blood flow (Qc) in the exercising subject was calculated from the rate of disappearance of N2O during steady state breathing of an N2O-He-O2 mixture. Measurements were made after alveolar rinsing (reciprocal of N2 washout) had occurred, and up to 30 sec, a time period accompanied by minimal recirculation, since FaNN2O during this period did not rise significantly. Repeatability of the method, judged as the difference of a second estimate from a first on the same subject, was comparable to that reported for the direct Fick technique in resting subjects (31 of 33 paired observations agreed within 20%). Results over a wide range agreed with almost simultaneous measurements by a dye dilution technique (24 of 26 paired observations agreed within 20%), and when related to pulse rate and to Vo2, were comparable to those of the other workers whose subjects were studied in a similar posture. Indeed, this technique (using the indirect Fick principle under “steady state” conditions) probably attains its greatest accuracy during exercise when other methods become less easily applicable. Submitted on December 18, 1961

A mathematical model for measuring blood flow in skeletal muscle with the microdialysis ethanol technique

1995 ◽  
Vol 79 (2) ◽  
pp. 648-659 ◽  
Author(s):  
F. Wallgren ◽  
G. Amberg ◽  
R. C. Hickner ◽  
U. Ekelund ◽  
L. Jorfeldt ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Tissue ◽  
Theoretical Calculations ◽  
Microdialysis Probe ◽  
Flow Rates ◽  
Perfusate Flow ◽  
Wide Range ◽  
Theory And Experiments ◽  
Good Agreement

A theoretical analysis of the microdialysis ethanol technique in skeletal muscle is presented, and a model governing the transport of ethanol from the microdialysis probe to the capillaries in the muscle tissue is proposed. The model is derived under the assumption of a steady-state situation, and an analytical solution is found for the outflow-to-inflow ratio of ethanol in the perfusate. Theoretically calculated results are compared with experiments, and for at least one of the two probe types used good agreement is achieved in a wide range of blood flow and perfusate flow rates. The main uncertainty factor in the theoretical calculations is the diffusivity of ethanol in muscle tissue, and the value for best agreement between theory and experiments has been used. Error estimates show that for a constant relative error in the outflow-to-inflow ratio of ethanol in the perfusate, low perfusate flow rates give better predictions of the blood flow.

Derecruitment in cat liver: extension of undistributed parallel tube model to effects of low hepatic blood flow on ethanol uptake

1989 ◽  
Vol 67 (10) ◽  
pp. 1225-1231 ◽  
Author(s):  
C. V. Greenway ◽  
L. Bass
Keyword(s):  
Blood Flow ◽  
Hepatic Blood Flow ◽  
Venous Pressure ◽  
Liver Blood Flow ◽  
Hepatic Uptake ◽  
Tube Model ◽  
Low Flows ◽  
Wide Range ◽  
Parallel Tube ◽  
Parallel Tube Model

Previous studies showed two deviations from the predictions of the undistributed parallel tube model for hepatic uptake of substrates: a small deviation at high flows and a large deviation at low flows. We have examined whether these deviations could be described by a single correction factor. In cats anesthetized with pentobarbital, a hepatic venous long-circuit technique with an extracorporeal reservoir was used to vary portal flow and hepatic venous pressure, and allow repeated sampling of arterial, portal, and hepatic venous blood without depletion of the cat's blood volume. Hepatic uptake of ethanol was measured over a wide range of blood flows and when intrahepatic pressure was increased at low flows. This uptake could be described by the parallel tube model with a correction for hepatic blood flow: [Formula: see text]. In 22 cats, [Formula: see text], k = 0.021 ± 0.0015 when flow (F) was in millilitres per minute per 100 g liver, and Km = 150 ± 20 μM when ĉ is the log mean sinusoidal concentration. (1 − e−kF) represents the proportion of sinusoids perfused and metabolically active. A dynamic interpretation of this proportion is related to intermittency (derecruitment) of sinusoidal flow. Half the sinusoids were perfused at a flow of 33 mL/(min∙100 g liver) and the liver was essentially completely perfused (> 95%) at the normal flow of 150 mL/(min∙100 g liver). Derecruitment was not changed by raising hepatic venous pressure, and it was not related to hepatic venous resistance.Key words: liver circulation, ethanol metabolism, liver blood flow, sinusoidal perfusion, portal pressure.

Validation of miniature ultrasonic transit-time flow probes for measurement of renal blood flow in rats

1995 ◽  
Vol 268 (1) ◽  
pp. F175-F178 ◽  
Author(s):  
W. J. Welch ◽  
X. Deng ◽  
H. Snellen ◽  
C. S. Wilcox
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Transit Time ◽  
Ex Vivo ◽  
High Flow ◽  
Flow Rates ◽  
Time Flow ◽  
Wide Range ◽  
Transit Time Flowmeter

This study validates the accuracy of miniature ultrasonic transit-time flow probes for measuring renal blood flow (RBF) in the rat. Probes for 1-mm and 2-mm vessels were calibrated ex vivo using excised arteries at varying flow rates and hematocrit (Hct). Correlation between measured and true flow rates for the 2-mm probe were identical (r = 1.0) at both normal and subnormal Hct values. Correlation for the 1-mm probe was high (r = 0.994) at normal Hct, but varied at both high flow rates and subnormal Hct values. In vivo correlation of RBF measurements using the 1-mm probe with the clearance and extraction of p-aminohippuric acid showed a high correlation (r = 0.84; n = 72, P < 0.0001) over a wide range of flow rates (0.5-21 ml/min) and Hct (36-74%). Zero flow levels remained steady, averaging -0.2 +/- 0.2 ml/min during occlusion in the living animal and -0.1 +/- 0.3 ml/min after exsanguination. This study shows that the ultrasonic transit-time flowmeter (1-mm and 2-mm probes) is a reasonably accurate and reliable method with which to measure RBF in the anesthetized, acute-instrumented rat.

scholarly journals Effect of Propranolol on Local Cerebral Blood Flow under Normocapnic and Hypercapnic Conditions

1981 ◽  
Vol 1 (4) ◽  
pp. 429-436 ◽  
Author(s):  
Nils Dahlgren ◽  
Martin Ingvar ◽  
Bo K. Siesjö
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Single Dose ◽  
Constant Infusion ◽  
Local Cerebral Blood Flow ◽  
Flow Rates ◽  
Adrenergic Mechanisms

The effect of propranolol (2.5 mg kg−1, i.v.) on local cerebral blood flow (CBF) in normocapnia was studied in rats maintained artificially ventilated on 70% N2O and 30% O2. The method used was autoradiography with [14C]iodoantipyrine. Although a single dose of propranolol, given 30 min prior to CBF measurements, somewhat reduced mean CBF values in all of the 22 structures analysed, none of the changes were significant. The results confirm previous ones, in which overall CBF was measured, in showing that β-adrenergic mechanisms have little effect on normal cerebrovascular tone. Following a single dose of propranolol, results obtained in hypercapnia were equally negative; neither did CBF fall significantly when propranolol was given by constant infusion during 15 min. Furthermore, local CBF did not differ between animals infused with dl-propranolol and d-propranolol. It is concluded that in the rat, propranolol has but small effects on the CBF response to hypercapnia, if any. The results reveal that local CO2 responsiveness, calculated as ΔCBF/ΔPco2, varies with normocapnic flow rates.

Effect of vascular pressure and blood flow on CO diffusion in the perfused dog lung

1963 ◽  
Vol 18 (4) ◽  
pp. 722-728 ◽  
Author(s):  
Benjamin Burrows ◽  
Albert H. Niden
Keyword(s):  
Blood Flow ◽  
Diffusing Capacity ◽  
Perfusion Rate ◽  
Flow Rates ◽  
Pulmonary Capillaries ◽  
Transit Times ◽  
Wide Range ◽  
Per Se ◽  
Lung Capillaries ◽  
Intravascular Pressure

The effects of blood flow and vascular pressure on the pulmonary diffusing capacity for carbon monoxide have been studied independently in 18 isolated perfused dog lungs, using the “equilibration technique” for Dl determination. The Dl is a function of mean vascular pressure over a wide range of vascular tensions, suggesting that there are some lung capillaries with high closing pressures or that patent pulmonary capillaries are capable of dilating in response to an increase in their transmural pressure. A maximum Dl could not be obtained. Measured Dl is reduced with low rates of pulmonary blood flow, but its dependence on perfusion rate becomes slight as physiologic flow rates are approached. Nonuniform diffusing capacity: lung volume ratios throughout the lung are noted at both low intravascular pressure and low blood flow, indicating nonuniformity of capillary filling and/or nonuniformity of capillary erythrocyte transit times. Under the conditions of these experiments, Dl appears to be dependent on blood flow per se as well as related to changes in pulmonary vascular resistance. Submitted on November 14, 1962

Vancomycin and Tobramycin Clearance in an Infant during Continuous Hemofiltration

1993 ◽  
Vol 27 (2) ◽  
pp. 224-227 ◽  
Author(s):  
Deborah K. Armstrong ◽  
Hanneli A. Hidalgo ◽  
Maher Eldadah ◽  
MICHAEL D. Reed
Keyword(s):  
Blood Flow ◽  
Case Report ◽  
Serum Concentration ◽  
Flow Rate ◽  
Drug Concentration ◽  
Serum Concentrations ◽  
Continuous Hemofiltration ◽  
Flow Rates ◽  
Fick Principle ◽  
Flow Through

Objective To report a case of vancomycin and tobramycin clearance by continuous veno-venous hemofiltration in an infant. Hemofiltration clearance (ClHF) was calculated by two methods and compared for ease and reliability. Methodology Case report of a hospitalized four-month-old infant With method A, ClHF calculation for vancomycin and tobramycin was determined by accurate collection of ultrafiltrate in five 24-hour periods and a midpoint serum sample. With method B, C1HF calculation was determined by obtaining prefilter sample, postfilter sample, and blood flow through filter (Fick principle) over three study periods, correlating to three of five study periods in method A. Results The infant received continuous veno-venous hemofiltration. With method A, vancomycin C1HF ranged from 0.27 to 0.80 mL/min; tobramycin C1HF ranged from 0.32 to 0.91 mL/min. With method B, ClHF for vancomycin ranged from 0 to 2.08 mL/min. Tobramycin ClHF ranged from 0 to 1.6 mL/min when calculated with method B. Conclusions Continuous veno-venous hemofiltration increased the clearance of vancomycin and tobramycin requiring dosage modifications. It appears that method A, which uses the ultrafiltration concentration compared with the serum concentration is more accurate than method B, as it averages fluctuations in ultrafiltrate flow rates. Method B compares a single pre- to postfilter drug concentration and relies on an accurate measurement of ultrafiltration flow rate. Determining ClHF based upon one point in time may overestimate ClHF when the ultrafiltration flow rate varies, as it does in the critically ill. Daily serum concentrations for vancomycin and tobramycin are recommended during continuous veno-venous hemofiltration.

Liver Blood Flow as a Major Determinant of the Clearance of Recombinant Human Tissue-Type Plasminogen Activator

1992 ◽  
Vol 67 (01) ◽  
pp. 083-087 ◽  
Author(s):  
A de Boer ◽  
C Kluft ◽  
J M Kroon ◽  
F J Kasper ◽  
H C Schoemaker ◽  
...  
Keyword(s):  
Blood Flow ◽  
Rat Liver ◽  
Healthy Subjects ◽  
Liver Blood Flow ◽  
Major Determinant ◽  
Tissue Type ◽  
Perfused Rat Liver ◽  
Liver Model ◽  
Type Plasminogen Activator ◽  
Proportional Change

SummaryThe influence of changes in liver blood flow on the clearance of rt-PA was studied both in healthy subjects and in a perfused rat liver model. Liver blood flow in healthy subjects was documented indirectly by the clearance of indocyanine green (ICG). Exercise reduced liver blood flow on average by 57% with a 95% confidence interval (95% Cl) ranging from 51% to 62% (n = 5) and increased plasma levels of rt-PA activity (after an i. v. infusion of 18 mg of rt-PA over 120 min) by 119% (95% Cl, 58% - 203%) and rt-PA antigen by 91% (95% Cl, 30% - 140%). In the perfused rat liver model it was shown that halving or doubling of the physiological flow rate of a perfusate, containing rt-PA caused a proportional change in the clearance of rt-PA, while the extraction of rt-PA by the liver remained similar. In conclusion, liver blood flow is a major determinant of the clearance of rt-PA. This may have important implications for dosage of rt-PA in patients with myocardial infarction.

How to use alum with cationic dispersed rosin size

TAPPI Journal ◽  
2016 ◽  
Vol 15 (5) ◽  
pp. 331-335 ◽  
Author(s):  
LEBO XU ◽  
JEREMY MYERS ◽  
PETER HART
Keyword(s):  
Zeta Potential ◽  
Colloidal Particles ◽  
Streaming Potential ◽  
Excessive Amount ◽  
Paper Machine ◽  
Optimum Amount ◽  
Potential Measurement ◽  
Streaming Current ◽  
Wide Range ◽  
Laboratory Results

Retention of cationic dispersed rosin size was studied via turbidity measurements on stock filtrate with different alum and dispersed rosin size dosages. Stock charge characteristics were analyzed using both an analysis of charge demand determined via a streaming current detector and an evaluation of zeta potential of the fibers by streaming potential measurement. The results indicated that an optimum amount of alum existed such that good sizing retention was maintained throughout a wide range of dispersed rosin size dosages. However, when an excessive amount of alum was used and fines and colloidal particles were transitioned from anionic to cationic, the cationic size retention was reduced. Laboratory results were confirmed with a paper machine trial. All data suggested that a stock charge study was necessary to identify optimal alum dosage for a cationic dispersed rosin sizing program.

Automation of Process Control in Chemical Plant

2015 ◽  
Vol 2 (1) ◽  
pp. 6-12
Author(s):  
Agus Sugiarta ◽  
Houtman P. Siregar ◽  
Dedy Loebis
Keyword(s):  
Process Control ◽  
Pid Control ◽  
Control Algorithm ◽  
Chemical Engineering ◽  
Chemical Plant ◽  
Raw Material ◽  
Flow Rates ◽  
Material Supply ◽  
Wide Range ◽  
Inherent Problem

Automation of process control in chemical plant is an inspiring application field of mechatronicengineering. In order to understand the complexity of the automation and its application requireknowledges of chemical engineering, mechatronic and other numerous interconnected studies.The background of this paper is an inherent problem of overheating due to lack of level controlsystem. The objective of this research is to control the dynamic process of desired level more tightlywhich is able to stabilize raw material supply into the chemical plant system.The chemical plant is operated within a wide range of feed compositions and flow rates whichmake the process control become difficult. This research uses modelling for efficiency reason andanalyzes the model by PID control algorithm along with its simulations by using Matlab.

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