scholarly journals Model Estimation of Cerebral Hemodynamics Between Blood Flow and Volume Changes: A Data-Based Modeling Approach

2009 ◽  
Vol 56 (6) ◽  
pp. 1606-1616 ◽  
Author(s):  
Hua-Liang Wei ◽  
Ying Zheng ◽  
Yi Pan ◽  
D. Coca ◽  
Liang-Min Li ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Hemodynamics ◽  
Model Estimation ◽  
Volume Changes ◽  
Modeling Approach

Abstract 9934: High Mean Arterial Pressure Aggravates Cerebral Hemodynamics After Extracorporeal Resuscitation in Swine

Circulation ◽  
2021 ◽  
Vol 144 (Suppl_2) ◽  
Author(s):  
Yael Levy ◽  
Alice Hutin ◽  
Nicolas Polge ◽  
fanny lidouren ◽  
Matthias Kohlhauer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Arrest ◽  
Oxygen Consumption ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Cerebral Hemodynamics ◽  
Reactivity Index ◽  
Extracorporeal Cardiopulmonary Resuscitation ◽  
Standard Map ◽  
Arterial Blood

Introduction: Extracorporeal cardiopulmonary resuscitation (E-CPR) is used for the treatment of refractory cardiac arrest but the optimal target to reach for mean arterial pressure (MAP) remains to be determined. Hypothesis: We hypothesized that MAP levels modify cerebral hemodynamics during E-CPR. Accordingly, we tested two MAP targets (65-75 vs 80-90 mmHg) in a porcine model of E-CPR. Methods: Pigs were anesthetized and instrumented for the evaluation of cerebral and systemic hemodynamics. They were submitted to 15 min of untreated ventricular fibrillation followed by 30 min of E-CPR. Electric attempts of defibrillation were then delivered until resumption of spontaneous circulation (ROSC). Extracorporeal circulation was initially set to an average flow of 40 ml/kg/min with a standardized volume expansion in both groups. The dose of epinephrine was set to reach either a standard or a high MAP target level (65-75 vs 80-90 mmHg, respectively). Animals were followed during 120 min after ROSC. Results: Six animals were included in both groups. After cardiac arrest, MAP was maintained at the expected level (Figure). During E-CPR, high MAP transiently improved carotid blood flow as compared to standard MAP. This blood flow progressively decreased after ROSC in high vs standard MAP, while intra-cranial pressure increased. Interestingly, this was associated with a significant decrease in cerebral oxygen consumption (26±8 vs 54±6 L O 2 /min/kg at 120 min after ROSC, respectively; p<0.01) (Figure). The pressure reactivity index (PRx), which is the correlation coefficient between arterial blood pressure and intracranial pressure, became positive in high MAP (0.47±0.02) vs standard MAP group (-0.16±0.10), demonstrating altered cerebral autoregulation with high MAP. Conclusion: Increasing MAP above 80 mmHg with epinephrine aggravates cerebral hemodynamics after E-CPR. Figure: Mean arterial pressure (MAP), cerebral blood flow and oxygen consumption (*, p<0.05)

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 Effects of short-term exposure to head-down tilt on cerebral hemodynamics: a prospective evaluation of a spaceflight analog using phase-contrast MRI

2016 ◽  
Vol 120 (12) ◽  
pp. 1466-1473 ◽  
Author(s):  
Karina Marshall-Goebel ◽  
Khalid Ambarki ◽  
Anders Eklund ◽  
Jan Malm ◽  
Edwin Mulder ◽  
...  
Keyword(s):  
Blood Flow ◽  
Phase Contrast ◽  
Cerebral Hemodynamics ◽  
Arterial Blood Flow ◽  
Ambient Atmosphere ◽  
Phase Contrast Mri ◽  
Jugular Veins ◽  
Cross Sectional ◽  
Arterial Blood ◽  
Short Term Exposure

Alterations in cerebral hemodynamics in microgravity are hypothesized to occur during spaceflight and could be linked to the Visual Impairment and Intracranial Pressure syndrome. Head-down tilt (HDT) is frequently used as a ground-based analog to simulate cephalad fluid shifts in microgravity; however, its effects on cerebral hemodynamics have not been well studied with MRI techniques. Here, we evaluate the effects of 1) various HDT angles on cerebral arterial and venous hemodynamics; and 2) exposure to 1% CO2 during an intermediate HDT angle (−12°) as an additional space-related environmental factor. Blood flow, cross-sectional area (CSA), and blood flow velocity were measured with phase-contrast MRI in the internal jugular veins, as well as the vertebral and internal carotid arteries. Nine healthy male subjects were measured at baseline (supine, 0°) and after 4.5 h of HDT at −6°, −12° (with and without 1% CO2), and −18°. We found a decrease in total arterial blood flow from baseline during all angles of HDT. On the venous side, CSA increased with HDT, and outflow decreased during −12° HDT ( P = 0.039). Moreover, the addition of 1% CO2 to −12° HDT caused an increase in total arterial blood flow ( P = 0.016) and jugular venous outflow ( P < 0.001) compared with −12° HDT with ambient atmosphere. Overall, the results indicate decreased cerebral blood flow during HDT, which may have implications for microgravity-induced cerebral hemodynamic changes.

Abnormal Cerebral Hemodynamics in Preterm Infants with Patent Ductus Arteriosus

PEDIATRICS ◽  
1982 ◽  
Vol 69 (6) ◽  
pp. 778-781
Author(s):  
Brian Lipman ◽  
Gerald A. Serwer ◽  
Jane E. Brazy
Keyword(s):  
Blood Flow ◽  
Patent Ductus Arteriosus ◽  
Preterm Infants ◽  
Ductus Arteriosus ◽  
Cerebral Arteries ◽  
Flow Patterns ◽  
Cerebral Hemodynamics ◽  
Ductal Closure ◽  
Blood Flow Patterns ◽  
Patent Ductus

Blood flow patterns in the anterior cerebral arteries were studied in eight preterm infants with patent ductus arteriosus and left-to-right shunts. A noninvasive Doppler technique was used to obtain the blood flow patterns and to calculate a pulsatility index. Advancing diastolic blood flow was decreased in all eight infants, and two demonstrated retrograde anterior cerebral artery flow during diastole. Following ductal closure, the diastolic flow in the anterior cerebral arteries increased significantly, reaching levels seen in normal infants. These observations demonstrate that infants with patent ductus arteriosus and left-to-right shunts may have abnormal cerebral hemodynamics which return to normal following ductal closure.

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