Cerebral Artery Flow Research Articles

Reference values for cerebral blood flow velocities in critically ill, sedated children.

Transcranial Doppler ultrasound (TCD) is increasingly being used in the pediatric intensive care unit to assess cerebral hemodynamics during critical illness. However, no normative data in this patient population have been published to date. Therefore, we aimed to describe the anterior and posterior cerebral blood flow velocities in critically ill children undergoing mechanical ventilation and sedation. A prospective, observational cohort study was performed. Children with known or suspected acute or chronic neurologic conditions were excluded. Participants underwent TCD measurement of middle cerebral and basilar artery flow velocities. One hundred and forty children newborn to 17years of age were enrolled. Measured values were lower in this cohort of children than the previously published cerebral flow velocities of normal, healthy children. Cerebral blood flow velocities of the basal cerebral arteries in critically ill, mechanically ventilated, sedated children are lower than in healthy children of the same age and gender published in previous studies. As such, the cerebral blood flow velocity (CBFV) values reported here may serve as a more accurate reference point when using TCD as a clinical tool to diagnose CBFV abnormalities and guide therapy in this patient population.

Blood flow in cerebral arteries – automated way from Computed Tomography to ANSYS Fluent

<p style="text-align: justify;">With the constant growth of computer simulation significance in science and engi-neering, many new fields are gaining access to these powerful tools. One of these new disciplines is medicine. Human body provides many fascinating areas that could be researched from completely different angle and could gain all the benefits that computer simulation offers. For example blood flow in human arteries can be stud-ied using Computational Fluid Dynamics. Researchers of cerebrovascular disorders can get an insight view on physical phenomena of blood flow and study risk factors of embolism or cerebral aneurysm.</p><p style="text-align: justify;">Main issue in using computer simulation in medical research is the complexity and uniqueness of geometry that needs to be handled. After all, human body is one of the most sophisticated engineering systems created by nature. In this paper, a workflow for creating a numerical mesh for CFD simulation purposes is shown. Application shown in the example focus on cerebral arteries blood flow simulation. Numerical mesh is generated based on CT scan of patient’s head, using freeware tools Slicer3D and AutoIt3 as well as commercial software ANSYS Fluent Meshing 15.0.</p>

Estimación de valores hemodinámicos mediante el uso del doppler transcraneal en un grupo de voluntarios habitantes de Cali (Colombia), una ciudad a 995 m sobre el nivel del mar

Transcranial doppler measures the velocity of blood flow in cerebral arteries and the pulsatility index for each artery. The aim of this study was to determine the hemodynamic behaviour in a city located 995 m above sea level, and its association with gender, age and body mass index. The test was performed by an expert on a group of volunteers with no cerebrovascular disease.The study was performed on 51 volunteers (24 men, mean age 46.2 years, and 27 women, mean age: 48.5 years, standard deviation 6.2 years). There were insufficient readings in 6 participants due to an inadequate acoustic window. Statistical differences (P<.01) in the arteries of the left region of the middle cerebral arteries (P<.01), anterior cerebral (P<.1), and extracranial internal carotid (P<.01) suggest the need for gender differentiation among participants. A slower blood flow in male participants compared to female participants is associated with age (P<.05).While the value of the mean in some results is suggestive of a difference between groups, the standard deviations are wide, thus this difference does not have enough power to be considered. Future studies are suggested with a larger number of participants.

ProSeal Laryngeal Mask Airway Attenuates Systemic and Cerebral Hemodynamic Response During Awakening of Neurosurgical Patients: A Randomized Clinical Trial.

Extubation and emergence from anesthesia may lead to systemic and cerebral hemodynamic changes that endanger neurosurgical patients. We aimed to compare systemic and cerebral hemodynamic variables and cough incidence in neurosurgery patients emerging from general anesthesia with the standard procedure (endotracheal tube [ETT] extubation) or after replacement of the ETT with a laryngeal mask airway (LMA). Forty-two patients undergoing supratentorial craniotomy under general anesthesia were included in a randomized open-label parallel trial. Patients were randomized (sealed envelopes labeled with software-generated randomized numbers) to awaken with the ETT in place or after its replacement with a ProSeal LMA. We recorded mean arterial pressure as the primary endpoint and heart rate, middle cerebral artery flow velocity, regional cerebral oxygen saturation, norepinephrine plasma concentrations, and coughing. No differences were found between groups at baseline. All hemodynamic variables increased significantly from baseline in both groups during emergence. The ETT group had significantly higher mean arterial pressure (11.9 mm Hg; 95% confidence interval [CI], 2.1-21.8 mm Hg) (P=0.017), heart rate (7.2 beats/min; 95% CI, 0.7-13.7 beats/min) (P=0.03), and rate-pressure product (1045.4; 95% CI, 440.8-1650) (P=0.001). Antihypertensive medication was administered to more ETT-group patients than LMA-group patients (9 [42.9%] vs. 3 [14.3%] patients, respectively; P=0.04). The percent increase in regional cerebral oxygen saturation was greater in the ETT group by 26.1% (95% CI, 9.1%-43.2%) (P=0.002), but no between-group differences were found in MCA flow velocity. Norepinephrine plasma concentrations rose in both groups between baseline and the end of emergence: LMA: from 87.5±7.1 to 125.6±17.3 pg/mL; and ETT: from 118.1±14.1 to 158.1±24.7 pg/mL (P=0.007). The differences between groups were not significant. The incidence of cough was higher in the ETT group (87.5%) than in the LMA group (9.5%) (P<0.001). Replacing the ETT with the LMA before neurosurgical patients emerge from anesthesia results in a more favorable hemodynamic profile, less cerebral hyperemia, and a lower incidence of cough.

Effects of adding remifentanil to propofol anesthesia on systemic hemodynamics, cardiac output, and middle cerebral artery flow velocity during electroconvulsive therapy: a pilot study.

The purpose of this study was to examine the effects of adding remifentanil to propofol anesthesia on systemic hemodynamics, cardiac output, and middle cerebral artery (MCA) blood flow velocity during electroconvulsive therapy (ECT). Twelve patients undergoing ECT were enrolled in this study. The patients received anesthesia by one of the following 2 methods: either propofol alone at a dose of 1.0 mg/kg, or propofol 0.75 mg/kg with remifentanil 1.0 μg/kg in turn during successive ECT sessions, immediately before the administration of succinylcholine. All patients were monitored for blood pressure, heart rate, cardiac output, and MCA flow velocity by transcranial Doppler sonography. Middle cerebral artery flow velocity increased after ECT in both anesthesia method groups and lasted for 2 minutes after ECT. No difference in MCA flow velocity was observed between the 2 methods at any time point. Seizure duration was longer under propofol with remifentanil than under propofol alone [propofol with remifentanil, 32 (3) seconds; propofol alone, 24 (4) seconds; P < 0.01]. In contrast, no difference in time to awakening (time from the ECT stimulus to the patient's ability to open eyes) was observed between the 2 groups [propofol with remifentanil, 183 (19) seconds; propofol alone, 185 (21) seconds]. The addition of remifentanil (1 μg/kg) is suitable for reduction of the propofol dose during ECT, without any adverse hemodynamic effects, including on cerebral blood flow.

Principles of cerebral hemodynamics when intracranial pressure is raised: lessons from the peripheral circulation.

Background: The brain is highly vascular and richly perfused, and dependent on continuous flow for normal function. Although confined within the skull, pressure within the brain is usually less than 15 mmHg, and shows small pulsations related to arterial pulse under normal circumstances. Pulsatile arterial hemodynamics in the brain have been studied before, but are still inadequately understood, especially during changes of intracranial pressure (ICP) after head injury.Method: In seeking cohesive explanations, we measured ICP and radial artery pressure (RAP) invasively with high-fidelity manometer systems, together with middle cerebral artery flow velocity (MCAFV) (transcranial Doppler) and central aortic pressure (CAP) generated from RAP, using a generalized transfer function technique, in eight young unconscious, ventilated adults following closed head trauma. We focused on vascular effects of spontaneous rises of ICP (‘plateau waves’).Results: A rise in mean ICP from 29 to 53 mmHg caused no consistent change in pressure outside the cranium, or in heart rate, but ICP pulsations increased in amplitude from 8 to 20 mmHg, and ICP waveform came to resemble that in the aorta. Cerebral perfusion pressure (=central aortic pressure – ICP), which equates with transmural pressure, fell from 61 to 36 mmHg. Mean MCAFV fell from 53 to 40 cm/s, whereas pulsatile MCAFV increased from 77 to 98 cm/s. These significant changes (all P < 0.01) may be explained using the Monro–Kellie doctrine, because of compression of the brain, as occurs in a limb when external pressure is applied.Conclusion: The findings emphasize importance of reducing ICP, when raised, and on the additional benefits of reducing wave reflection from the lower body.

Ontogeny of cerebrovascular critical closing pressure.

Premature infants are at risk of vascular neurologic insults. Hypotension and hypertension are considered injurious, but neither condition is defined with consensus. Cerebrovascular critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow (CBF) ceases. CrCP may serve to define subject-specific low or high ABP. Our objective was to determine the ontogeny of CrCP. Premature infants (n = 179) with gestational age (GA) from 23-31 wk had recordings of ABP and middle cerebral artery flow velocity twice daily for 3 d and then daily for the duration of the first week of life. All infants received mechanical ventilation. CrCP was calculated using an impedance-model derivation with Doppler-based estimations of cerebrovascular resistance and compliance. The association between GA and CrCP was determined in a multivariate analysis. The median (interquartile range) CrCP for the cohort was 22 mm Hg (19-25 mm Hg). CrCP increased significantly with GA (r = 0.6; slope = 1.4 mm Hg/wk gestation), an association that persisted with multivariate analysis (P < 0.0001). CrCP increased significantly from 23 to 31 wk gestation. The low CrCP observed in very premature infants may explain their ability to tolerate low ABP without global cerebral infarct or hemorrhage.

Inability to Process Negative Emotions in Cerebellar Damage: a Functional Transcranial Doppler Sonographic Study.

Recent studies have implicated the cerebellum as part of a circuitry that is necessary to modulate higher order and behaviorally relevant information in emotional domains. However, little is known about the relationship between the cerebellum and emotional processing. This study examined cerebellar function specifically in the processing of negative emotions. Transcranial Doppler ultrasonography was performed to detect selective changes in middle cerebral artery flow velocity during emotional stimulation in patients affected by focal or degenerative cerebellar lesions and in matched healthy subjects. Changes in flow velocity during non-emotional (motor and cognitive tasks) and emotional (relaxing and negative stimuli) conditions were recorded. In the present study, we found that during negative emotional task, the hemodynamic pattern of the cerebellar patients was significantly different to that of controls. Indeed, whereas relaxing stimuli did not elicit an increase in mean flow velocity in any group, negative stimuli increased the mean flow velocity in the right compared with left middle cerebral artery only in the control group. The patterns by which mean flow velocity increased during the motor and cognitive tasks were similar within patients and controls. These findings support that the cerebellum is part of a network that gives meaning to external stimuli, and this particular involvement in processing negative emotional stimuli corroborates earlier phylogenetic hypotheses, for which the cerebellum is part of an older circuit in which negative emotions are crucial for survival and prepare the organism for rapid defense.

Abstract 168: Intra-arterial Stem Cell Treatment Reduces Ischemic Brain Injury In Reproductively Senescent Female Rats

Background: Cell therapy is emerging as a promising treatment for stroke. We recently we demonstrated the efficacy of intra-arterial delivery of MSCs (IA MSCs) at 24h after a reversible middle cerebral artery occlusion (MCAo). Our study also identified a maximum tolerated dose of MSCs that could be delivered IA without compromising middle cerebral artery flow. The IA approach avoids first-pass trapping of MSCs in the lungs and liver as seen with intravenous delivery. Intra-arterial treatment is also minimally invasive and widely available in clinical practice and thus appealing for clinical translation. Since majority of ischemic strokes in women occur after onset of menopause it is crucial that we test the efficacy of IA MSCs in reproductively senescent females consistent with STAIR recommendations. We aimed to validate the efficacy of IA MSCs in reproductively senescent female rats. Methods: Retired breeder female (9-11 months; 280-350 g) Sprague-Dawley rats showing estrous acyclicity were exposed to MCAo (90 min). A day later, rats were treated with IA MSCs (1x10^5 cells) or phosphate-buffered saline (PBS). MSCs or PBS treated rats were sacrificed at 28-30 days for infarct volume measurement using histology. To test motor function, the rotarod test was performed. Rats were trained for 3 consecutive days for the rotarod test before undergoing the MCAo procedure. The mean duration (in seconds) on the device was recorded from 3 rotarod measurements 1 day before surgery. The rats were tested at 1, 7, 15 and 28-30 days after MCAo. Results: We observed significantly lower mean infarct volume in the MSC-treated group (12 ± 3 mm3; n=6) compared to the PBS-treated group (29 ± 7 mm3; Mean ± SEM; n=4, p&lt;0.05). Treatment at 1 day after MCAO with MSCs significantly improved functional recovery, as evidenced by improved rotarod test results and neurological scores at 7, 15 and 30 days (P&lt;0.05) compared with the PBS-treated group. Conclusions: Intra-arterial stem cell treatment reduces ischemic brain injury and improves functional outcomes in reproductively senescent female rats. Validating the efficacy of IA MSC treatment using a reproductively senescent animal stroke model suggests high potential for future clinical translation in a population at high risk for stroke.

Intracranial blood flow changes after extracranial carotid artery stenting.

Carotid artery stenting is an endovascular treatment option for patients with extracranial carotid stenosis. However, intracranial blood flow changes following stenting have not been established. To determine the effects of stenting on intracranial blood flow. Records of patients who underwent stenting at our institution between 2004 and 2012 and had flow rates obtained pre- and poststenting by the use of quantitative magnetic resonance angiography were retrospectively reviewed. Percentage stenosis, stenosis length, and minimum vessel diameter were measured from cerebral angiography images. Eighteen patients were included. Mean age was 65 years with 67% presenting with symptomatic stenosis. Degree of stenosis ranged from 60% to 90%. Internal carotid artery (ICA) mean flow improved significantly poststenting from 174.9 ± 83.6 mL/min to 250.7 ± 91.2 mL/min (P = .011). Ipsilateral middle cerebral artery (MCA) flow, however, was not significantly altered poststenting (107.8 ± 41.6 mL/min vs 114.3 ± 36.3 mL/min; P = .28). Univariate analysis revealed that improved minimum vessel diameter after stenting, but not percentage stenosis (P = .18) or stenosis length (P = .45), is significantly associated with increased ICA flow (P = .02). However, improved percentage stenosis, stenosis length, minimum vessel diameter, and ICA flow poststenting were not significantly associated with increased MCA flow (P = .64, .38, .13, .37, respectively). ICA flow was compromised at baseline, improving 43% on average poststenting. Increased minimum vessel diameter was the factor most significantly associated with increased flow. Conversely, MCA flow was not significantly compromised at baseline nor altered after stenting, suggesting compensatory intracranial collateral supply prestenting that redistributes following ICA revascularization.

Blood flow distribution in cerebral arteries.

High-resolution phase-contrast magnetic resonance imaging can now assess flow in proximal and distal cerebral arteries. The aim of this study was to describe how total cerebral blood flow (tCBF) is distributed into the vascular tree with regard to age, sex and anatomic variations. Forty-nine healthy young (mean 25 years) and 45 elderly (mean 71 years) individuals were included. Blood flow rate (BFR) in 21 intra- and extracerebral arteries was measured. Total cerebral blood flow was defined as BFR in the internal carotid plus vertebral arteries and mean cerebral perfusion as tCBF/brain volume. Carotid/vertebral distribution was 72%/28% and was not related to age, sex, or brain volume. Total cerebral blood flow (717 ± 123 mL/min) was distributed to each side as follows: middle cerebral artery (MCA), 21%; distal MCA, 6%; anterior cerebral artery (ACA), 12%, distal ACA, 4%; ophthalmic artery, 2%; posterior cerebral artery (PCA), 8%; and 20% to basilar artery. Deviating distributions were observed in subjects with 'fetal' PCA. Blood flow rate in cerebral arteries decreased with increasing age (P<0.05) but not in extracerebral arteries. Mean cerebral perfusion was higher in women (women: 61 ± 8; men: 55 ± 6 mL/min/100 mL, P<0.001). The study describes a new method to outline the flow profile of the cerebral vascular tree, including reference values, and should be used for grading the collateral flow system.

INSTRUMENTAL AND DIAGNOSTIC CRITERIA OF HEMODYNAMIC DISORDERS AND ENDOTHELIAL DYSFUNCTION CORRECTION IN PREGNANTS WITH ARTERIAL HYPERTENSION

&lt;p&gt;&lt;strong&gt;Background&lt;/strong&gt;. According to the WHO, hypertension is associated with 20-33 % of maternal death during pregnancy within extragenital pathology statistics. There are complications of the fetus and newborn associated with hypertension at 140/90 mm Hg and higher.&lt;br /&gt;&lt;strong&gt;Objective.&lt;/strong&gt; A comparative analysis of antihypertensive therapy effectiveness in pregnants with arterial hypertension was performed using modern clinical and instrumental methods of endothelial function diagnostic, central and utero-placental hemodynamic estimation.&lt;br /&gt;&lt;strong&gt;Methods.&lt;/strong&gt; We examined 63 pregnant women with hypertension at 28 to 32 weeks of gestation. Women were randomized into three groups:group I (control group – 20 women), that included pregnant women with hypertension treated with basic antihypertensive therapy as recommended by Health Ministry of Ukraine standards (metildofa and nifedipin); group II – 21 pregnant women receiving metildofa and metoprolol; group III (22 pregnant women) receiving metildofa and nebivolol.&lt;br /&gt;&lt;strong&gt;Conclusions.&lt;/strong&gt; It was found that the brachial artery ultrasound measuring and occlusive plethysmography procedure by Dietz is an early and safe method of endothelial dysfunction diagnostic in pregnants with hypertension. Doppler ultrasound of blood flow in uterine, umbilical arteries, and middle cerebral arteries of the fetus allows timely diagnosis of the side effect of antihypertensive drugs on the fetus. The therapy of choice for pregnants with Stage II Arterial Hypertension should be based on methyldopa and calcium channel antagonists or selective beta-blockers combination. Highly selective beta-blockers with vasodilative effect (nebivolol hydrochloride) and L-arginine (Tivortin) allow to prevent perinatal adverse effects of antihypertensive therapy, to correct hemodynamic disorders and endothelial dysfunction in pregnants with arterial hypertension.&lt;/p&gt;&lt;p&gt;&lt;br /&gt;&lt;strong&gt;KEY WORDS:&lt;/strong&gt; arterial hypertension, uterine-placental hemodynamics, endothelial dysfunction&lt;/p&gt;

Middle cerebral arterial flow changes on transcranial color and spectral Doppler sonography in patients with increased intracranial pressure.

Intracranial pressure usually increases after severe brain injury. However, a method for noninvasive evaluation of intracranial pressure is still lacking. The purpose of this study was to explore the potential role of transcranial color Doppler sonography in assessing intracranial pressure by observing the middle cerebral artery blood flow parameters in patients with increased intracranial pressure of varying etiology. The hemodynamic changes in the middle cerebral artery in patients with varying degrees of increased intracranial pressure were investigated by transcranial color Doppler sonography in 93 patients who had emergency surgery for brain injury. Middle cerebral artery Doppler flow spectra changed regularly as intracranial pressure increased. The pulsatility index (PI) and resistive index (RI) had a significantly positive correlation with intracranial pressure (r = 0.90 and 0.89, respectively; P< .001), whereas the middle cerebral artery diastolic velocity showed a significant negative correlation with intracranial pressure (r = -0.52; P< .01). A receiver operating characteristic curve showed that the RI and PI cutoff values were 0.705 and 1.335, respectively, for predicting increased intracranial pressure, with sensitivity of 0.885 and specificity of 0.970. In addition to the PI and RI, middle cerebral artery diastolic flow velocity measurement by transcranial color Doppler sonography may also be a useful variable for evaluating intracranial pressure in patients with acute brain injury.

Influence of parity on fetal hemodynamics and amniotic fluid volume at term

Pregnancy complications, particularly those associated with placental dysfunction, occur more frequently in nulliparous than in parous women. This difference may be a consequence of improved trophoblastic invasion and, as a result, improved placental function following previous pregnancy. Placental dysfunction in cases of fetal growth restriction may be identified by ultrasound assessment of fetoplacental hemodynamics and amniotic fluid volume. In this prospective observational study, we investigated whether differences in these measures of placental function exist between nulliparous and parous women, prior to active labor. Over a 2-year period, 456 nulliparous and 152 parous women with uncomplicated singleton pregnancies were recruited to this prospective observational study. Each participant underwent an ultrasound assessment prior to active labor, during which fetal biometry, umbilical artery, middle cerebral artery and umbilical venous Dopplers, as well as amniotic fluid volume, were assessed. All cases were followed up within 48 h of delivery. Ultrasound parameters and intrapartum outcomes were then compared between the nulliparous and parous groups. Compared with nulliparous women, parous women had significantly higher fetal middle cerebral artery pulsatility index, cerebroplacental ratio and amniotic fluid volume. In nulliparous women, middle cerebral artery flow rate was also significantly higher and represented a greater percentage of umbilical venous flow than was observed in parous women. Prior to the active phase of labor, ultrasound parameters indicative of placental function differ significantly between nulliparous and parous pregnancy, even amongst an uncomplicated, low-risk cohort.

Cerebral oxygenation in health and disease.

Monitoring cerebral blood flow (CBF) and oxygenation has implications for both clinical practice and research interests; e.g., to provide insight into functional neurovascular coupling, to better understand orthostatic hypotension, and to evaluate the influence of vasopressors on cerebral oxygenation during anesthesia and/or surgery. These topics, and others, are addressed in this e-book by presenting original research, reviews, and opinion papers covering new, exciting but also controversial issues related to cerebral oxygenation in health and disease as evaluated by near-infrared spectroscopy (NIRS).

Transcranial Doppler-based assessment of cerebral autoregulation in critically ill children during diabetic ketoacidosis treatment.

Impaired cerebral autoregulation may be associated with poor outcome in diabetic ketoacidosis. We examined change in cerebral autoregulation during diabetic ketoacidosis treatment. Prospective observational cohort study. Tertiary care children's hospital. Children admitted to the ICU with diabetic ketoacidosis (venous pH < 7.3, glucose > 300 mg/dL, HCO3 < 15 mEq/L, and ketonuria) constituted cases, and children with type I diabetes without diabetic ketoacidosis constituted controls. None. Between 2005 and 2009, 32 cases and 50 controls were enrolled. Transcranial Doppler ultrasonography was used to measure middle cerebral artery flow velocities, and cerebral autoregulation testing was achieved via tilt-table testing. Cases underwent two and controls underwent one cerebral autoregulation test. Cerebral autoregulation was quantified by the autoregulatory index (autoregulatory index < 0.4 = impaired and autoregulatory index 0.4-1.0 = intact autoregulation). The first autoregulation test was obtained early (time 1, 12-24 hr; median [interquartile range], 8 hr [5-18 hr]) during diabetic ketoacidosis treatment, and a second autoregulation test was obtained during recovery (time 2, 36-72 hr; median [ interquartile range], 46 hr [40-59 hr]) from time 0 (defined as time of insulin start). Cases had lower autoregulatory index at time 1 than time 2 (p < 0.001) as well lower autoregulatory index than control subjects (p < 0.001). Cerebral autoregulation was impaired in 40% (n = 13) of cases at time 1 and in 6% (n = 2) of cases at time 2. Five cases (17%) showed persistent impairment of cerebral autoregulation between times 1 and 2 of treatment. All control subjects had intact cerebral autoregulation. Impaired cerebral autoregulation was common early during diabetic ketoacidosis treatment. Although the majority improved during diabetic ketoacidosis treatment, 17% of subjects had impairment between 36 and 72 hours after start of insulin therapy. The observed impaired cerebral autoregulation appears specific to the diabetic ketoacidosis process in patients with type I diabetes.

Effects of acupuncture at GB20 on CO2 reactivity in the basilar and middle cerebral arteries during hypocapnia in healthy participants.

The acupoint GB20 is known to affect vertebrobasilar blood flow regulation. However, no previous study has used transcranial Doppler imaging to examine whether acupuncture at GB20 has a selective effect on blood flow in various cerebral arteries, such as the basilar artery (BA) and the middle cerebral arteries (MCAs). Therefore, this study sought to determine the specific effects of GB20 acupuncture on cerebral blood flow (CBF). Blood flow velocity and CO(2) reactivity were measured by transcranial Doppler imaging with a 2-MHz pulsed Doppler probe observed through both temporal windows for the MCAs and through the suboccipital window for the BA before and after GB20 acupuncture treatment in 15 healthy young male volunteers. The changes in hyperventilation-induced CO(2) reactivity and corrected blood flow velocities at 40 mmHg (CV40) were assessed for the BA and both MCAs. Blood pressure and heart rate were measured before and after the acupuncture treatment. CO(2) reactivity in the BA increased significantly after GB20 acupuncture treatment compared with baseline (p=0.041). In contrast, CO(2) reactivity in both MCAs remained unchanged. The CV40 in the BA and the MCAs showed no change after the GB20 acupuncture treatment. The mean heart rate decreased significantly after the GB20 acupuncture, whereas the mean blood pressure showed no change. This study demonstrated that acupuncture treatment on GB20 increases CO(2) reactivity specifically in the BA, with no effect in the MCAs. These results clinically support the use of GB20 to treat disorders of posterior cerebral circulation and support the idea that particular acupoints affect specific brain regions and cerebral arteries.

Effects of extracranial carotid stenosis on intracranial blood flow.

The hemodynamic effects of extracranial carotid stenosis on intracranial blood flow are not well characterized. We sought to determine the impact of degree of stenosis, stenosis length, and residual lumen on intracranial blood flow in patients with extracranial carotid stenosis. Carotid stenosis patients who had undergone both vessel flow rate measurements using quantitative magnetic resonance angiography and digital subtraction angiography were examined. The impact of the anatomic measurements of the stenosis relative to ipsilateral internal carotid artery (ICA) flow and ipsilateral-to-contralateral middle cerebral artery (MCA) flow ratio were assessed. Forty-four patients (mean age, 67 years; 64% symptomatic) were included. Higher percentage stenosis and smaller residual lumen were associated with a significant decrease in ICA flow (P<0.01 and 0.04, respectively). On multivariate analysis, percentage stenosis remained as the primary predictor of ICA flow (P<0.001). MCA flow ratio was not significantly associated with percentage stenosis, stenosis length, or residual lumen. However, mean MCA flow ratio was significantly lower in symptomatic compared with asymptomatic patients (0.92 versus 1.22; P=0.001). In contrast, mean ICA flow ratio was similar among these 2 groups (0.55 versus 0.55; P=0.99). Percentage stenosis and residual lumen are significantly associated with ICA but not MCA flow, suggesting that local hemodynamic effects of carotid stenosis do not translate directly to distal vasculature, because intracranial flows can be maintained through collaterals. The lower MCA flow ratio in symptomatic patients highlights the potential importance of distal hemodynamics in symptomatic presentation.

Optimal dose of landiolol for preventing abrupt changes in both cardiac output and middle cerebral artery flow velocity after electroconvulsive therapy.

The purpose of this study was to examine the dose-dependent effects of landiolol on systemic hemodynamics, cardiac output, and cerebral artery blood flow. Eight patients undergoing electroconvulsive therapy (ECT) received 1 of the 3 drugs/doses (saline, 0.125 mg/kg of landiolol, 0.25 mg/kg of landiolol), in turn, for 3 ECT sessions, immediately after the administration of succinylcholine. In the case of 0.25 mg/kg of landiolol, heart rate, mean arterial pressure, and cardiac output remained unchanged throughout the study period.We believe that 0.25 mg/kg of landiolol may be suitable for preventing the increase in systemic hemodynamics, including cardiac output after ECT.

P05.15: Massive fetal subdural hemorrhage presented with elevated middle cerebral artery flow velocity and reverse end‐diastolic flow

<scp>P</scp>05.15: Massive fetal subdural hemorrhage presented with elevated middle cerebral artery flow velocity and reverse end‐diastolic flow