Effect of Hæmatocrit on Cerebral Blood-Flow in Man

Thomas, David; Marshall, John; Russell, Richard A.; Wetherley‐Mein, G.; Boulay, G. H. du; Pearson, Thomas C.; Symon, Lindsay; Zilkha, E.

doi:10.1016/s0140-6736(77)90885-6

Cited by 394 publications

(138 citation statements)

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“…Our findings of a reduced cerebral cortical blood flow during hyperviscosity supports previous studies with polycythemic newborns (18,19) and adults (15)(16)(17), and paraproteinemic hyperviscous adults (22,23). Our data are also consistent with the newborn lamb model of Hudak et al (32) in which the independent effect of hematocrit on cerebral cortical blood flow was investigated.…”

Section: Discussionsupporting

confidence: 92%

Cerebral Cortical Blood Flow and Oxygen Metabolism in Normocythemic Hyperviscous Newborn Piglets

et al. 1988

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ABSTRACT. Our study tests the hypothesis that hyper-cerebral blood flow has been demonstrated in adults with primary viscosity independent of arterial 0 2 content reduces cere-polycythemia (1 5-17). In the neonate, polycythemia is associated bra1 cortical blood flow, Oz delivery, and Oz uptake. After with decreased cerebral blood flow velocity and increased pulbaseline determinations, ten 2-to 4-day-old awake spon-satility indices that are reversed by partial plasma exchange hnesusly breathing piglets-ere given an intravenous in-transfusion (18,19). However, Jones et al. (20) emphasized the fusion (5 ml. kg-', body weight) of concentrated cyropre-importance of arterial 0 2 content in the regulation of cerebral cipitate, whereas eight controls received normal saline. blood flow. To maintain a constant 0 2 delivery, an alteration in Cerebral cortical blood flow, arterial and superior sagittal arterial 0 2 content results in a reciprocal change in blood flow. sinus 0 2 content, whole blood viscosity, hematocrit, blood Rosenkrantz et al. (21) showed in newborn lambs that the gases, and plasma fibrinogen concentrations were meas-cerebral blood flow reduction noted with polycythemic hypervisured at baseline and 3 h after infusion. No significant cosity is due to the increased arterial 0 2 content from polycychanges were observed in the control group. Three hours themia and not the result of hyperviscosity. Nevertheless, in after the infusion of concentrated cryoprecipitate the ex-paraproteinemic adults Humphrey and coworkers (22,23), demperimental group showed an increase in whole blood vis-onstrated that 0 2 content and blood viscosity are both independcosity, whereas hematocrit and arterial 0 2 content were ent variables controlling cerebral blood flow. unchanged. There was a decrease in cerebral cortical blood To examine the effect of hyperviscosity independent of polyflow and cerebral cortical 0 2 delivery, whereas cerebral cythemia and arterial O2 content, a normocythemic hyperviscous cortical 0 2 uptake was unchanged. We conclude that hy-animal model was developed. This study is designed to test the perviscosity independent of arterial 0 2 content reduces hypothesis that normocythemic hyperviscosity reduces cerebral cerebral cortical blood flow and that although Oz delivery cortical blood flow, O2 delivery, and 0 2 uptake in newborn was reduced in the newborn piglet cerebral cortical 0 2 piglets. uptake was maintained. (Pediatr Res 24: 486-489,1988) MATERIALS AND METHODS Animals. Eighteen newborn piglets were randomly divided Polycythemia and hyperviscosity occur in 3-5% of newborns into experimental (n = 10) and control (n = 8) groups and (1, 2). Structural and functional CNS abnormalities have been studied between 2 and 4 days of age. ~n i m a l weights on the day associated with polycythernia and hyperviscosity (3-9). The most of study were 1290 * 207 g (mean + SD) and 1280 + 158 g for common etiology of neonatal hyperviscosity is polycythemia. the experimental and control piglets, respectively. However,...

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Section: Discussionsupporting

confidence: 92%

Cerebral Cortical Blood Flow and Oxygen Metabolism in Normocythemic Hyperviscous Newborn Piglets

et al. 1988

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“…The significantly higher blood perfusion volume in participants with lower hematocrit levels is in accordance with findings by Thomas et al (26).…”

Section: Microvasculaturesupporting

confidence: 92%

On the Interplay of Microvasculature, Parenchyma, and Memory in Type 2 Diabetes

et al. 2015

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OBJECTIVEType 2 diabetes is associated with accelerated cognitive decline, especially regarding memory for which the hippocampus plays an essential role. The pathophysiological mechanisms still remain to be elucidated. The purpose of this study is to examine whether hippocampal microvascular and microstructural changes are related to type 2 diabetes (based on status or based on fasting blood glucose [FBG] levels) and verbal memory performance. RESEARCH DESIGN AND METHODSThirty-nine participants with type 2 diabetes (64.5 6 6.1 years old) and 34 participants without type 2 diabetes (58.3 6 9.2 years old) underwent detailed cognitive assessments and 3-Tesla MRI using intravoxel incoherent motion (IVIM) MRI. Multivariate regression analyses controlling for age, sex, education level, BMI, systolic blood pressure, hematocrit level, and relative hippocampal volume were performed to examine associations between hippocampal IVIM measures, type 2 diabetes (status and FBG), and memory performance. RESULTSFor the microvasculature, blood perfusion volume (f) was larger in participants with type 2 diabetes, f and blood flow (fD*) increased with higher FBG levels, and microvascular pseudodiffusion (D*) and fD*, which are indicative of altered microvasculature, were higher in participants with both relatively high FBG levels and low memory performance. In addition, fD* increased with lower memory performance. For the parenchymal microstructure, the diffusion (D), indicative of injured microstructure, was higher with reduced memory performance. CONCLUSIONSIn addition to the parenchymal microstructure, especially the microvascular properties of the hippocampus are altered in participants with both type 2 diabetes and memory problems and possibly hint at an underlying vascular mechanism.Type 2 diabetes is associated with cognitive deficits, accelerated cognitive decline, and an increased risk of dementia and Alzheimer disease (AD) (1-3). A prominently affected cognitive domain in type 2 diabetes is memory (4), for which the hippocampus plays an essential role. In patients with type 2 diabetes and memory problems, reduced hippocampal volumes have previously been reported (5). Furthermore, chronic hyperglycemia has been shown to be associated with altered hippocampal microstructure and memory performance in elderly individuals without diabetes (6). Unfortunately, the exact mechanism underlying hyperglycemia and

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“…Infarcts occurred mainly during childhood and adolescence (mean age 7.7 years) and were often repetitive, as had been observed in previous studies. 2 "Ê xchange transfusion regimes have been used with some success to prevent the recurrence of strokes and to improve existing neurological deficits in the survivors^ even reversing angiographic abnormalities in some cases. 5 Although some early reports described pathological changes in the walls of the larger intracranial arteries, 7 ' 8 later authors generally attributed the ischemic infarction in sickle cell disease to small vessel involvement leading to multiple microinfarcts.…”

Section: Discussionmentioning

confidence: 99%

Hematocrit as a risk factor of cerebral infarction: long-term prospective population survey in a Japanese rural community.

Kiyohara¹,

Ueda²,

Hasuo³

et al. 1986

Stroke

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SUMMARY l b elucidate the relation of hematocrit (Hct) to the incidence of cerebral infarction, a prospective follow-up study of 16 years (1965-81) was performed in a general population sample of 1220 Hisayama residents aged 44 and over, of both sexes. Most of the subjects who died during the follow-up period were autopskd, the rate being 89.0%.Hct decreased with advancing age in men, but not in women. The average value for Hct was significantly lower in women than in men. According to the mean value ± 1 SD of Hct, the subjects were grouped into 3, in each sex as follows: low (<35%), normal (35-45%) and high (2=45%) for men, and, low (<30%), normal (30-40%) and high (2:40%) for women.During the follow-up period, cerebral infarction occurred in 117 patients. The cumulative incidence of cerebral infarction In the low Hct group for men was the lowest, even after adjustments for age and blood pressure. Conversely, the incidence in the low Hct group of women was significantly higher than that in the normal Hct group and was consistently increased with tune during 2-5 years of the follow-up. After the 6th year or later, however, the incidence was gradually but significantly increased hi the Ugh Hct group, compared with the normal Hct group. Since Hct levels were related with other variables such as serum total cholesterol, serum total protein, Quetelet index and prevalence of hypertension in both sexes, heavy alcohol consumption in men, and glucose Intolerance in women, such variables were taken into account using Cox's proportional hazards regression model. The low Hct in women remained important as an independent risk factor of cerebral Infarction.The sex difference hi the role of Hct as a cause of cerebral infarction was discussed, taking into consideration the interrelationship between Hct and other risk factors.

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Effect of Hæmatocrit on Cerebral Blood-Flow in Man

Cited by 394 publications

References 9 publications

Cerebral Cortical Blood Flow and Oxygen Metabolism in Normocythemic Hyperviscous Newborn Piglets

Cerebral Cortical Blood Flow and Oxygen Metabolism in Normocythemic Hyperviscous Newborn Piglets

On the Interplay of Microvasculature, Parenchyma, and Memory in Type 2 Diabetes

Hematocrit as a risk factor of cerebral infarction: long-term prospective population survey in a Japanese rural community.

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