Search results for "Cerebral blood flow"
showing 10 items of 138 documents
Impaired Cerebrovascular Autoregulation in Large Vessel Occlusive Stroke after Successful Mechanical Thrombectomy: A Prospective Cohort Study
2020
Abstract Introduction: Successful thrombectomy improves morbidity and mortality after stroke. The present prospective, observational cohort study investigated a potential correlation between the successful restoration of tissue perfusion by mechanical thrombectomy and intact cerebrovascular autoregulation (CA). Objective: Status of CA in patients with large vessel occlusive stroke after thrombectomy. Methods: After thrombectomy CA was measured using transcranial Doppler ultrasound. For this purpose a moving correlation index (Mxa) based on spontaneous arterial blood pressure fluctuations and corresponding cerebral blood flow velocity changes was calculated. CA impairment was defined by Mxa …
Arterial and Venous Cerebral Blood Flow Velocities and Their Correlation in Healthy Volunteers and Traumatic Brain Injury Patients.
2020
Few studies have explored the cerebral venous compartment or the correlation between venous and arterial cerebral blood flows. We aimed to correlate cerebral blood flow velocities in the arterial (middle cerebral artery) and venous (straight sinus) compartments in healthy volunteers and traumatic brain injury (TBI) patients. In addition, we determined the normative range of these parameters.A total of 122 healthy volunteers and 95 severe TBI patients of both sexes were included and stratified into 3 age groups as follows: group 1 (aged, 18 to 44 y); group 2 (aged, 45 to 64 y); group 3 (older than 65 y). Transcranial Doppler systolic cerebral blood flow velocity, diastolic cerebral blood flo…
Transcranial Doppler sonography in dementia of Alzheimer type.
1994
The intention of this study was to examine the relation of clinical variables and cognitive dysfunction to cerebrovascular blood flow in a sample of patients with Alzheimer''s disease without any sign or symptom of cardiovascular or cerebrovascular disease. The patients met DSM-III-R criteria for dementia of Alzheimer type. Blood flow velocities in the anterior, middle (MCA) and posterior cerebral arteries were recorded using transcranial Doppler sonography. Several psychometric tests including the Mini-Mental State Examination (MMSE) were performed. The patients’ age correlated significantly with the systolic flow velocity in the left MCA (r = –0.57) explaining 24% of the total variance; t…
Regional blood flow in deep structures of the brain measured in acute cat experiments by means of a new beta-sensitive semiconductor needle detector.
1967
Regional cerebral blood flow was measured by means of isotope clearance with a new type of solid state beta-sensitive needle detector (diameter 0.9 mm) introduced into the brain tissue in acute cat experiments. The flow values obtained within the cortex were compared with values recorded above the same cortical region with the same needle detector, or with a small GM-tube. The insertion of the needle detector into the brain tissue gave rise to injury (checked histologically) which deformed the clearance curves in a manner suggesting that the normal circulation had been destroyed within the tissue from which the measurements were made.
Initiation of high-frequency oscillatory ventilation and its effects upon cerebral circulation in pigs: an experimental study
2006
BACKGROUND: Current practice at high-frequency oscillatory ventilation (HFOV) initiation is a stepwise increase of the constant applied airway pressure to achieve lung recruitment. We hypothesized that HFOV would lead to more adverse cerebral haemodynamics than does pressure controlled ventilation (PCV) in the presence of experimental intracranial hypertension (IH) and acute lung injury (ALI) in pigs with similar mean airway pressure settings. METHODS: In 12 anesthetized pigs (24-27 kg) with IH and ALI, mean airway pressure (P(mean)) was increased (to 20, 25, 30 cm H(2)O every 30 min), either with HFOV or with PCV. The order of the two ventilatory modes (cross-over) was randomized. Mean art…
Nonlinear effects of respiration on the crosstalk between cardiovascular and cerebrovascular control systems.
2016
Cardiovascular and cerebrovascular regulatory systems are vital control mechanisms responsible for guaranteeing homeostasis and are affected by respiration. This work proposes the investigation of cardiovascular and cerebrovascular control systems and the nonlinear influences of respiration on both regulations through joint symbolic analysis (JSA), conditioned or unconditioned on respiration. Interactions between cardiovascular and cerebrovascular regulatory systems were evaluated as well by performing correlation analysis between JSA indexes describing the two control systems. Heart period, systolic and mean arterial pressure, mean cerebral blood flow velocity and respiration were acquired…
Sevoflurane Impairs Cerebral Blood Flow Autoregulation in Rats: Reversal by Nonselective Nitric Oxide Synthase Inhibition
2005
UNLABELLED In this study, we investigated the effects of 1.0 and 2.0 minimum alveolar anesthetic concentration (MAC) sevoflurane on cerebral blood flow (CBF) autoregulation before and after nonselective inhibition of nitric oxide (NO) synthase in rats. Rats were randomly assigned as follows: Group 1 (n = 8): 1.0 MAC sevoflurane; Groups 2 and 3 (n = 8 per group): 2.0 MAC sevoflurane. Assessment of autoregulation within a mean arterial blood pressure range of 140-60 mm Hg was performed by graded hemorrhage before and after administration of l-arginine methyl ester (l-NAME, 30 mg/kg IV, Groups 1 and 2) or during hypocapnia (Group 3). In 10 additional animals, brain tissue NO(2)(-) concentratio…
Local H2-Clearance and PO2-Measurements in Microareas of the Brain Tissue in Rats
1969
Lubbers [5], as well as others, measured the oxygen partial pressure of the exposed cerebral cortex by means of small platinum microelectrodes. They registered low pO2 values between 1 and 3 mmHg in certain areas of the cortex, despite the fact that the EEG was of normal pattern. In order to decide whether these low pO2 values are a result of low rCBF, or high local oxygen consumption of brain tissue, we developed a new method. Using the same platinum needle, we measured both local pO2 values and H2-clearance curves in microareas of the brain tissue. Cater and Silver [2], Lubbers [4, 5], and others used glass-insulated platinum microelectrodes to measure local pO2. Further, Aukland, Bower a…
Neuroimaging for the anesthesiologist.
2007
Neuroimaging is essential in the treatment of cerebral nervous system disorders or in patients in the ICU with deterioration of their neurologic function. Leading clinical symptoms are acute neurologic deficits with different stages of hemisymptomatology, primary or progressing loss of consciousness or vigilance deficit, focal or generalized seizures, sometimes combined with an acute respiratory or circulatory insufficiency. The resulting questions can be summarized in those of intracranial space occupying hemorrhage; acute infarction; and signs for reduced cerebral blood flow, cerebrovascular vasospasm, or intracranial mass. Recent evolutions in imaging have contributed to an increase in d…
Relaxant effects of sodium nitroprusside and NONOates in goat middle cerebral artery: delayed impairment by global ischemia-reperfusion.
1999
Global cerebral ischemia and subsequent reperfusion induce early impairment of the vasodilator responses to hypercapnia and vasoactive substances. Nitric oxide (NO) is involved in the regulation of cerebral blood flow (CBF) in both health and disease. The present study was designed to assess possible changes in the cerebrovascular reactivity to NO donors induced by cerebral ischemia-reperfusion in goats. Female goats (n = 9) were subjected to 20 min global cerebral ischemia under halothane/N2O anesthesia. Sixteen additional goats were sham-operated as a control group. One week later the effects of ischemia-reperfusion on relaxations to NO donors sodium nitroprusside (SNP), diethylamine/NO (…