Transcranial Doppler measurement of middle cerebral artery blood flow velocity: a validation study.

Bishop, Christopher; Powell, Sherry; Rutt, D L; Browse, N L

doi:10.1161/01.str.17.5.913

Cited by 752 publications

(394 citation statements)

References 14 publications

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“…16,21 Significant correlations between mean blood velocity in the middle cerebral artery and cerebral blood flow at rest in healthy subjects has been published by several authors. [22][23][24] This correlation, however, could not be substantiated by other investigations. 25 There is no data regarding these features in patients with liver diseases.…”

Section: Discussioncontrasting

confidence: 59%

Increased cerebrovascular resistance in cirrhotic patients with ascites

et al. 1998

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Studies assessing regional hemodynamics in patients with cirrhosis and ascites have shown vasodilation in the splanchnic circulation and vasoconstriction in the renal circulation and in the brachial and femoral artery vascular territories. The aim of this study was to assess the cerebral vascular resistance in cirrhotic patients with ascites. The resistive index in the middle cerebral artery (an index of the cerebral vascular resistance) and in a renal interlobar artery were measured by Doppler ultrasonography in 7 healthy subjects: 13 patients with compensated cirrhosis and 24 patients with ascites (13 with renal failure). The arterial blood pressure and the activity of the renin-angiotensin and sympathetic nervous systems, as estimated by plasma renin activity and plasma norepinephrine concentration, respectively, were also measured. The resistive index in the middle cerebral artery was significantly increased in patients with ascites (0.68 ؎ 0.05, mean ؎ SD) as compared with patients without ascites (0.60 ؎ 0.01, P F .05) and with healthy patients (0.52 ؎ 0.01, P F .01). Renal resistive index was also increased in patients with ascites (0.77 ؎ 0.01) compared with the other two groups (0.68 ؎ 0.02 and 0.62 ؎ 0.00, respectively; P F .001). The resistive index in the middle cerebral artery showed a direct correlation with renal resistive index (r ‫؍‬ .73, P F .01), plasma renin activity (r ‫؍‬ .61, P F .01), and norepinephrine (r ‫؍‬ .53, P F .01). The resistive index in the middle cerebral artery showed an inverse correlation with mean arterial pressure (r ‫,54.؊؍‬ P F .01). These results indicate that in patients with cirrhosis and ascites there is a cerebral vasoconstriction which is probably related with the arterial hypotension and the overactivity of vasoconstrictor systems. (HEPATOL-OGY 1998;28:39-44.)Portal hypertension in cirrhosis is associated with a hyperdynamic circulation, which is characterized by hypervolemia, high cardiac output, arterial hypotension, and low peripheral vascular resistance. 1 These circulatory abnormalities are thought to be secondary to a splanchnic arteriolar vasodilation related to the increase in portal pressure. Portal hypertension in experimental animals is associated with a generalized splanchnic arteriolar vasodilation. 2,3 There is indirect evidence that this also occurs in human cirrhosis, as hepatic blood flow is usually normal or increased in these patients, even though 60% to 80% of portal flow is shunted through the collateral circulation. 4 In addition, the mean transit time in the splanchnic vascular bed is substantially reduced in alcoholic cirrhotic patients, which indicates a hyperkinetic splanchnic circulation in these patients. 5 Finally, studies using echo-Doppler have documented increased splenic and mesenteric blood flow in patients with cirrhosis. 6,7 Investigations assessing regional circulations in human cirrhosis are also consistent with that concept. Renal blood flow is reduced and renal vascular resistance is increased in most patients with cirrhosi...

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Section: Discussioncontrasting

confidence: 59%

Increased cerebrovascular resistance in cirrhotic patients with ascites

et al. 1998

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“…28 During cardiopulmonary bypass and in patients with cerebrovascular diseases, correlations between CBF and V MCA values are rather weak with wide betweenpatient variation. 14,29 In a number of previous studies, relative changes in CBF were reflected by changes in V MCA in a proportional manner, suggesting that MCA diameter remains constant. 30 Nevertheless, other investigations could show that illness and interventions as orthostasis, migraine attacks, CO 2 -rebreathing, or vasoactive medicine could change the MCA diameters by 5% to 12%.…”

Section: Discussionmentioning

confidence: 95%

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

Grüne

Kazmaier

Stolker

et al. 2015

J Cereb Blood Flow Metab

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In addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO 2 -induced changes in CBF, CVR, CPPe, ZFP, and RAP is not fully understood. In a controlled crossover trial, we investigated 10 anesthetized patients aiming at PaCO 2 levels of 30, 37, 43, and 50 mm Hg. Cerebral blood flow was measured with a modified Kety-Schmidt-technique. Zero flow pressure and RAP was estimated by linear regression analysis of pressure-flow velocity relationships of the middle cerebral artery. Effective cerebral perfusion pressure was calculated as the difference between mean arterial pressure and ZFP, CVR as the ratio CPPe/CBF. Statistical analysis was performed by one-way RM-ANOVA. When comparing hypocapnia with hypercapnia, CBF showed a significant exponential reduction by 55% and mean V MCA by 41%. Effective cerebral perfusion pressure linearly decreased by 17% while ZFP increased from 14 to 29 mm Hg. Cerebrovascular resistance increased by 96% and RAP by 39%; despite these concordant changes in mean CVR and Doppler-derived RAP correlation between these variables was weak (r = 0.43). In conclusion, under general anesthesia hypocapnia-induced reduction in CBF is caused by both an increase in CVR and a decrease in CPPe, as a consequence of an increase in ZFP.

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“…However, studies measuring 133 Xe clearance and radioactive microspheres have shown that relative changes in CBFV correlate well with changes in cerebral blood flow. 21,22 TCD sonography is now widely used as a surrogate measure of cerebral blood flow. 23 Interpatient variability in CBFV measurements can be due to variations in Doppler probe positioning, resulting in different angles of insonation (i.e., the angle at which the Doppler beam impacts on the artery).…”

Section: Objectifmentioning

confidence: 99%

Propofol decreases cerebral blood flow velocity in anesthetized children

Karsli

Luginbuehl

Farrar

et al. 2002

Can J Anesth/J Can Anesth

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P Pu ur rp po os se e: : Propofol, by virtue of its favourable pharmacokinetic profile, is suitable for maintenance of anesthesia by continuous infusion during neurosurgical procedures in adults. It is gaining popularity for use in pediatric patients. To determine the effects of propofol on cerebral blood flow in children, middle cerebral artery blood flow velocity (Vmca) was measured at different levels of propofol administration by transcranial Doppler (TCD) sonography.M Me et th ho od ds s: : Twelve ASA I or II children, aged one to six years undergoing elective urological surgery were randomized to receive one of two propofol dosing regimens. Half of the patients received propofol in an escalating fashion, initially targeting an estimated steady-state serum concentration of 3 µg·mL -1 , which was then doubled. The other half received propofol designed initially to target the high concentration followed by the lower one. In each child anesthesia was induced and maintained with propofol according to the protocol, rocuronium was given to facilitate tracheal intubation, and a caudal epidural block was performed. A TCD probe was placed appropriately to measure Vmca. Cerebral blood flow velocity (CBFV), mean arterial pressure (MAP) and heart rate (HR) were recorded simultaneously at both levels of propofol administration.R Re es su ul lt ts s: : Twelve patients were studied. At the higher estimated target serum propofol concentration there were significant decreases in Vmca (17%, P < 0.001), MAP (6%, P < 0.002) and HR (8%, P < 0.05) when compared to the lower targeted concentration.C Co on nc cl lu us si io on n: : This study shows that a higher rate of propofol infusion is associated with lower CBFV and MAP values in children. Propofol's cerebral vasoconstrictive properties may be responsible for this finding. Vacm (17 %, P < 0,001), de TAM (6 %, P < 0,002) et de FC (8 %, P < 0,05) Objectif Résultats : Des baisses significatives de

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Transcranial Doppler measurement of middle cerebral artery blood flow velocity: a validation study.

Cited by 752 publications

References 14 publications

Increased cerebrovascular resistance in cirrhotic patients with ascites

Increased cerebrovascular resistance in cirrhotic patients with ascites

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

Propofol decreases cerebral blood flow velocity in anesthetized children

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