A mathematical model of cerebral blood flow chemical regulation. II. Reactivity of cerebral vascular bed

1989 ◽  
Vol 36 (2) ◽  
pp. 192-201 ◽  
Author(s):  
M. Ursino ◽  
P. Di Giammarco ◽  
E. Belardinelli
Keyword(s):  
Mathematical Model ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Chemical Regulation ◽  
Vascular Bed ◽  
Cerebral Vascular

Interaction among autoregulation, CO2 reactivity, and intracranial pressure: a mathematical model

1998 ◽  
Vol 274 (5) ◽  
pp. H1715-H1728 ◽  
Author(s):  
Mauro Ursino ◽  
Carlo Alberto Lodi
Keyword(s):  
Mathematical Model ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Intracranial Pressure ◽  
Nonlinear Interaction ◽  
Cerebral Blood Volume ◽  
Cerebral Hemodynamics ◽  
Pial Arteries ◽  
Arterial Circulation ◽  
Neurosurgical Patients

The relationships among cerebral blood flow, cerebral blood volume, intracranial pressure (ICP), and the action of cerebrovascular regulatory mechanisms (autoregulation and CO2 reactivity) were investigated by means of a mathematical model. The model incorporates the cerebrospinal fluid (CSF) circulation, the intracranial pressure-volume relationship, and cerebral hemodynamics. The latter is based on the following main assumptions: the middle cerebral arteries behave passively following transmural pressure changes; the pial arterial circulation includes two segments (large and small pial arteries) subject to different autoregulation mechanisms; and the venous cerebrovascular bed behaves as a Starling resistor. A new aspect of the model exists in the description of CO2 reactivity in the pial arterial circulation and in the analysis of its nonlinear interaction with autoregulation. Simulation results, obtained at constant ICP using various combinations of mean arterial pressure and CO2 pressure, substantially support data on cerebral blood flow and velocity reported in the physiological literature concerning both the separate effects of CO2 and autoregulation and their nonlinear interaction. Simulations performed in dynamic conditions with varying ICP underline the existence of a significant correlation between ICP dynamics and cerebral hemodynamics in response to CO2 changes. This correlation may significantly increase in pathological subjects with poor intracranial compliance and reduced CSF outflow. In perspective, the model can be used to study ICP and blood velocity time patterns in neurosurgical patients in order to gain a deeper insight into the pathophysiological mechanisms leading to intracranial hypertension and secondary brain damage.

scholarly journals Dynamics of the speed of blood flow in the arteries of the bone regenerate of the limbs and in the brain arteries during functional tests and changes in the treatment mode

2019 ◽  
Vol 17 (4) ◽  
pp. 51-56 ◽  
Author(s):  
V. A. Schurov
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Velocity ◽  
Treatment Regimen ◽  
Blood Flow Velocity ◽  
Outpatient Treatment ◽  
Lower Leg ◽  
Temporary Increase ◽  
Functional Tests ◽  
Vascular Bed

The results of a comparative study of the linear velocity of blood flow in the arteries of the bone regenerate in patients with fractures of the leg and shoulder bones and in the process of Ilizarov treatment are analyzed. Studies were conducted at rest and when performing a number of functional tests (orthostatic, muscular and with a dosed axial load on the limb). The effect of stress on the state of regional and cerebral blood flow in the conditions of inpatient treatment and after the transfer of patients to the outpatient treatment regimen was assessed.Material and methods. 41 adult patients with a closed diaphyseal fracture of the humerus and 57 patients with a fracture of the tibia bones during Ilizarov treatment were examined. The blood flow in the regenerate and along the middle cerebral arteries was determined by the method of ultrasonic doppler sonography.Results. With an increase in the functional load on the limb in patients with fractures of the humerus and tibial bones, respectively, up to 10 and 30 kgf, a temporary increase in the blood flow velocity in the arteries of the bone regenerate was observed. Large values of the load on the lower leg, accompanied by the acceleration of blood flow, indicate a better protection of the vascular bed of the tibial regenerate. The magnitude of the decrease in blood flow velocity in the regeneration of the lower leg arising from the behavior of an orthostatic test in the course of treating patients increased from 21 to 37 %, and indicated an increase in the reactivity of the vascular bed. In patients with injuries of the shoulder and lower leg, the transfer to the outpatient treatment regimen was accompanied by a statistically significant (p≤0.001) increase in the duration of the fixation period, respectively, to 82±3 and 94±7 days, a decrease in the increased blood flow velocity in the middle cerebral artery on the contralateral side by 43 % and 57 % and an increase in the magnitude of changes in cerebral blood flow rate during functional muscle test by 50 and 67 %. 

Abstract P531: Cerebral Blood Flow Analysis Using Flow Wire Measurements and CFD Analysis

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Aichi Chien ◽  
Huy Dinh ◽  
Viktor Szeder ◽  
Fernando Vinuela
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Velocity ◽  
Cfd Simulation ◽  
Cfd Analysis ◽  
Flow Data ◽  
Velocity Data ◽  
Mean Flow ◽  
Good Agreement ◽  
Cerebral Vascular

Introduction: Clinical reports show that cerebral blood flow conditions are indicative of cerebral vascular disease. While methods for characterizing cerebral vascular flow have been extensively reported in the past, comparative analyses between direct flow measurements (DM) and computational flow dynamic (CFD) analysis remain limited. We hypothesize that flow data can be reliably measured both directly and through CFD in normal vessels. Methods: A left heart replicator was used as a realistic cardiac pump which maintained systolic pressure at 120 mmHg and diastolic pressure at 80 mmHg. A stenotic model with 50% stenosis for the ICA was connected to the replicator. A ComboWire was used for DM and recorded flow pressure and velocity. CFD was used to study flow. Results: In areas at the proximal end of the stenosis, the pressure and flow velocity derived from DM and CFD were in good agreement. At the end of systole and diastole, DM pressure were 145.42 mmHg and 73.53 mmHg, respectively. CFD simulation for the same system obtained the pressure at the end of systole and diastole of 147.16 mmHg and 74.64 mmHg, respectively. The velocity data collected from DM was at 15.40 cm/s and 7.74 cm/s for systolic flow and mean flow velocity. CFD measured flow was 17.85 cm/s and 11.37 cm/s, respectively. In areas at the distal end of the stenosis, pressure data showed good agreement between DM and CFD analysis. The DM were 138 and 70.81 mmHg at the end of systole and diastole, respectively; CFD simulation yielded 145.95 and 74.51 mmHg, respectively. Variations in the velocity data were observed at this location (Fig, pink arrows). Conclusion: DM of pressure showed good agreement with CFD simulation in all areas of the vessel. DM of velocity using the flow wire were highly affected by location of the measurement. CFD analysis can provide more consistent flow data for flow information collection along the vasculature.

Vasopressin and prostanoid mechanisms in control of cerebral blood flow in hypotensive newborn pigs

1990 ◽  
Vol 258 (2) ◽  
pp. H408-H413 ◽  
Author(s):  
W. M. Armstead ◽  
C. W. Leffler ◽  
D. W. Busija ◽  
R. Mirro
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Metabolic Rate ◽  
Vascular Resistance ◽  
Brain Regions ◽  
Cerebral Metabolic Rate ◽  
Cerebral Vasoconstriction ◽  
Newborn Pigs ◽  
Cerebral Vascular Resistance ◽  
Cerebral Vascular

The interaction between vasopressinergic and prostanoid mechanisms in the control of cerebral hemodynamics in the conscious hypotensive newborn pig was investigated. Indomethacin treatment (5 mg/kg) of hypotensive piglets caused a significant decrease in blood flow to all brain regions within 20 min. This decrease in cerebral blood flow resulted from increased cerebral vascular resistances of 52 and 198% 20 and 40 min after treatment, respectively. Cerebral oxygen consumption was reduced from 2.58 +/- 0.32 ml.100 g-1.min-1 to 1.01 +/- 0.12 and 0.29 +/- 0.08 ml.100 g-1.min-1 20 and 40 min after indomethacin, respectively, in hemorrhaged piglets. Treatment with the putative vascular (V1) receptor antagonist [1-(beta-mercapto-beta, beta-cyclopentamethylene propionic acid-2-(O-methyl)tyrosine]arginine vasopressin (MEAVP) had no effect on regional cerebral blood flow, calculated cerebral vascular resistance, or cerebral metabolic rate either before or during hemorrhagic hypotension. However, decreases in cerebral blood flow and metabolic rate and increases in vascular resistance on treatment with indomethacin were blunted markedly in animals treated with MEAVP. These data are consistent with the hypothesis that the prostanoid system contributes to the maintenance of cerebral blood flow and cerebral metabolic rate during hypotension in the newborn pig, as reported previously, and implicate removal of vasopressinergic modulation by prostanoids as a potential mechanism for indomethacin-induced cerebral vasoconstriction in hypotensive newborn piglets.

scholarly journals Interrelationships Among Regional Cerebral Blood Flow, Mean Transit Time, Vascular Volume and Cerebral Vascular Resistance

Stroke ◽  
1974 ◽  
Vol 5 (6) ◽  
pp. 719-724 ◽  
Author(s):  
YOSHIHIRO KURIYAMA ◽  
TAKASHI AOYAMA ◽  
KUNIHIKO TADA ◽  
SHOTARO YONEDA ◽  
TADAATSU NUKADA ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Vascular Resistance ◽  
Transit Time ◽  
Regional Cerebral Blood Flow ◽  
Mean Transit Time ◽  
Regional Cerebral Blood ◽  
Vascular Volume ◽  
Cerebral Vascular Resistance ◽  
Cerebral Vascular

scholarly journals Adenosine Deaminase Inhibitors Enhance Cerebral Anoxic Hyperemia in the Rat

1985 ◽  
Vol 5 (2) ◽  
pp. 295-299 ◽  
Author(s):  
J. W. Phillis ◽  
R. E. DeLong ◽  
J. K. Towner
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Adenosine Deaminase ◽  
Reactive Hyperemia ◽  
Low Doses ◽  
Venous Outflow ◽  
Vascular Regulation ◽  
Vascular Insufficiency ◽  
Basal Flow ◽  
Cerebral Vascular

Cerebral blood flow in the rat was monitored by a venous outflow technique with an extracorporeal circulation, which allows for the continuous recording of flow over periods of several hours. The adenosine deaminase inhibitors erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) (1.0–100 μg/kg) and deoxycoformycin (0.1–1 μg/kg) potentiated the reactive hyperemia elicited by a brief (24-s) anoxic challenge. Basal flow rate was unaltered by EHNA administration and slightly enhanced by deoxycoformycin. The results are consistent with the hypothesis that adenosine plays a significant role in cerebral vascular regulation and suggest that low doses of these deaminase inhibitors may be useful in the treatment of cerebral vascular insufficiency.

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