Superior fitting of arterial resistance and compliance parameters with genetic algorithms in models of dynamic cerebral autoregulation

2021 ◽  
pp. 1-1
Author(s):  
Felipe-Andres Bellorobles ◽  
Ronney Panerai ◽  
Emmanuel Katsogridakis ◽  
Max Leonardo Chacon
Keyword(s):  
Genetic Algorithms ◽  
Cerebral Autoregulation ◽  
Arterial Resistance ◽  
Dynamic Cerebral Autoregulation

scholarly journals Impaired Cerebrovascular Hemodynamics are Associated with Cerebral White Matter Damage

2013 ◽  
Vol 34 (2) ◽  
pp. 228-234 ◽  
Author(s):  
Sushmita Purkayastha ◽  
Otite Fadar ◽  
Aujan Mehregan ◽  
David H Salat ◽  
Nicola Moscufo ◽  
...  
Keyword(s):  
White Matter ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Cerebral Autoregulation ◽  
Structural Integrity ◽  
Cerebral White Matter ◽  
Elderly Individuals ◽  
Transfer Function Analysis ◽  
Dynamic Cerebral Autoregulation ◽  
Cerebrovascular Hemodynamics

White matter hyperintensities (WMH) in elderly individuals with vascular diseases are presumed to be due to ischemic small vessel diseases; however, their etiology is unknown. We examined the cross-sectional relationship between cerebrovascular hemodynamics and white matter structural integrity in elderly individuals with vascular risk factors. White matter hyperintensity volumes, fractional anisotropy (FA), and mean diffusivity (MD) were obtained from MRI in 48 subjects (75±7years). Pulsatility index (PI) and dynamic cerebral autoregulation (dCA) was assessed using transcranial Doppler ultrasound of the middle cerebral artery. Dynamic cerebral autoregulation was calculated from transfer function analysis (phase and gain) of spontaneous blood pressure and flow velocity oscillations in the low (LF, 0.03 to 0.15 Hz) and high (HF, 0.16 to 0.5 Hz) frequency ranges. Higher PI was associated with greater WMH ( P<0.005). Higher phase across all frequency ranges was associated with greater FA and lower MD ( P<0.005). Lower gain was associated with higher FA in the LF range ( P=0.001). These relationships between phase and FA were significant in the territories limited to the middle cerebral artery as well as across the entire brain. Our results show a strong relationship between impaired cerebrovascular hemodynamics (PI and dCA) and loss of cerebral white matter structural integrity (WMH and DTI metrics) in elderly individuals.

scholarly journals Acute hypoxia impairs dynamic cerebral autoregulation: results from two independent techniques

2009 ◽  
Vol 107 (4) ◽  
pp. 1165-1171 ◽  
Author(s):  
Andrew W. Subudhi ◽  
Ronney B. Panerai ◽  
Robert C. Roach
Keyword(s):  
Cerebral Autoregulation ◽  
Acute Hypoxia ◽  
Latin Squares ◽  
Differential Sensitivity ◽  
Experimental Session ◽  
Assessment Techniques ◽  
Frequency Components ◽  
Autoregulation Index ◽  
Single Experimental Session ◽  
Dynamic Cerebral Autoregulation

We investigated the effect of acute hypoxia (AH) on dynamic cerebral autoregulation (CA) using two independent assessment techniques to clarify previous, conflicting reports. Twelve healthy volunteers (6 men, 6 women) performed six classic leg cuff tests, three breathing normoxic (FiO2 = 0.21) and three breathing hypoxic (FiO2 = 0.12) gas, using a single blinded, Latin squares design with 5-min washout between trials. Continuous measurements of middle cerebral artery blood flow velocity (CBFv; DWL MultiDop X2) and radial artery blood pressure (ABP; Colin 7000) were recorded in the supine position during a single experimental session. Autoregulation index (ARI) scores were calculated using the model of Tiecks et al. (Tiecks FP, Lam AM, Aaslid R, Newell DW. Stroke 26: 1014–1019, 1995) from ABP and CBFv changes following rapid cuff deflation (cuff ARI) and from ABP to CBFv transfer function, impulse, and step responses (TFA ARI) obtained during a 4-min period prior to cuff inflation. A new measure of %CBFv recovery 4 s after peak impulse was also derived from TFA. AH reduced cuff ARI (5.65 ± 0.70 to 5.01 ± 0.96, P = 0.04), TFA ARI (4.37 ± 0.76 to 3.73 ± 0.71, P = 0.04), and %Recovery (62.2 ± 10.9% to 50.8 ± 9.9%, P = 0.03). Slight differences between TFA and cuff ARI values may be attributed to heightened sympathetic activity during cuff tests as well as differential sensitivity to low- and high-frequency components of CA. Together, results provide consistent evidence that CA is impaired with AH. In addition, these findings demonstrate the potential utility of TFA ARI and %Recovery scores for future CA investigations.

Dynamic Cerebral Autoregulation After Mild Dehydration to Simulate Microgravity Effects

2009 ◽  
Vol 80 (5) ◽  
pp. 443-447 ◽  
Author(s):  
Yojiro Ogawa ◽  
Ken-ichi Iwasaki ◽  
Ken Aoki ◽  
Takashi Saitoh ◽  
Jitsu Kato ◽  
...  
Keyword(s):  
Cerebral Autoregulation ◽  
Dynamic Cerebral Autoregulation

Midlife Aerobic Exercise and Dynamic Cerebral Autoregulation: Associations with Baroreflex Sensitivity and Central Arterial Stiffness

2021 ◽  
Author(s):  
Tsubasa Tomoto ◽  
Justin Repshas ◽  
Rong Zhang ◽  
Takashi Tarumi
Keyword(s):  
Arterial Stiffness ◽  
Aerobic Exercise ◽  
Cerebral Autoregulation ◽  
Baroreflex Sensitivity ◽  
Function Analysis ◽  
Middle Aged ◽  
Age Related ◽  
Transfer Function Analysis ◽  
Carotid Distensibility ◽  
Dynamic Cerebral Autoregulation

Midlife aerobic exercise may significantly impact age-related changes in the cerebro- and cardiovascular regulations. This study investigated the associations of midlife aerobic exercise with dynamic cerebral autoregulation (dCA), cardiovagal baroreflex sensitivity (BRS), and central arterial stiffness. Twenty middle-aged athletes (MA) who had aerobic training for >10 years were compared with 20 young (YS) and 20 middle-aged sedentary (MS) adults. Beat-to-beat cerebral blood flow velocity, blood pressure (BP), and heart rate were measured at rest and during forced BP oscillations induced by repeated sit-stand maneuvers at 0.05 Hz. Transfer function analysis was used to calculate dCA and BRS parameters. Carotid distensibility was measured by ultrasonography. MA had the highest peak oxygen uptake (VO2peak) among all groups. During forced BP oscillations, MS showed lower BRS gain than YS, but this age-related reduction was absent in MA. Conversely, dCA was similar among all groups. At rest, BRS and dCA gains at low frequency (~0.1 Hz) were higher in the MA compared with MS and YS groups. Carotid distensibility was similar between MA and YS groups, but it was lower in the MS. Across all subjects, VO2peak was positively associated with BRS gains at rest and during forced BP oscillations (r=0.257~0.382, p=0.003~0.050) and carotid distensibility (r=0.428~0.490, p=0.001). Furthermore, dCA gain at rest and carotid distensibility were positively correlated with BRS gain at rest in YS and MA groups (all p<0.05). These findings suggest that midlife aerobic exercise improves central arterial elasticity and BRS which may contribute to CBF regulation through dCA.

scholarly journals How many squat–stand manoeuvres to assess dynamic cerebral autoregulation?

2018 ◽  
Vol 118 (11) ◽  
pp. 2377-2384 ◽  
Author(s):  
S. C. Barnes ◽  
N. Ball ◽  
V. J. Haunton ◽  
T. G. Robinson ◽  
R. B. Panerai
Keyword(s):  
Cerebral Autoregulation ◽  
Dynamic Cerebral Autoregulation

scholarly journals Dynamic cerebral autoregulation: A marker of post-operative delirium?

2019 ◽  
Vol 130 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Juliana R. Caldas ◽  
Ronney B. Panerai ◽  
Edson Bor-Seng-Shu ◽  
Graziela S.R. Ferreira ◽  
Ligia Camara ◽  
...  
Keyword(s):  
Cerebral Autoregulation ◽  
Dynamic Cerebral Autoregulation
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