Oxygen and carbon dioxide transport in time-dependent blood flow past fiber rectangular arrays

2009 ◽  
Vol 21 (3) ◽  
pp. 033101 ◽  
Author(s):  
Jennifer R. Zierenberg ◽  
Hideki Fujioka ◽  
Ronald B. Hirschl ◽  
Robert H. Bartlett ◽  
James B. Grotberg
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Time Dependent ◽  
Carbon Dioxide Transport ◽  
Flow Past ◽  
Rectangular Arrays

scholarly journals A Model of Brain Arteriolar Oxygen and Carbon Dioxide Transport during Anemia

1993 ◽  
Vol 13 (5) ◽  
pp. 872-880 ◽  
Author(s):  
Richard S. Schacterle ◽  
Robert J. Ribando ◽  
J. Milton Adams
Keyword(s):  
Carbon Dioxide ◽  
Mathematical Model ◽  
Blood Flow ◽  
Tissue Oxygenation ◽  
Normal Values ◽  
Experimental Studies ◽  
Limited Information ◽  
Carbon Dioxide Transport ◽  
Theoretical Evidence ◽  
Predicted Values

Existing experimental and theoretical evidence suggests that precapillary diffusion of O2 and CO2 occurs between arterioles and tissue under normal physiologic conditions. However, limited information is available on arteriolar gas transport during anemia. With use of a mathematical model of an arteriolar network in brain tissue, anemic hematocrits of 35, 25, and 15% were modeled to determine the effect of anemia on the exchange, the change in the equilibrium tissue O2 and CO2 tensions, and the increase in blood flow needed to restore tissue oxygenation. We found that the blood Po2 exiting the network fell from 66 mm Hg normally to 48 mm Hg during the severest anemia. Concurrently, the equilibrium tissue O2 tensions dropped from 44 to 23 mm Hg. For CO2 the exit blood Pco2 was 58 mm Hg for a 15% hematocrit, an increase of 4 mm Hg from the normal value, and equilibrium tissue Pco2 increased from 56 to 61 mm Hg. Blood flow increases from normal values necessary to offset the effects of the decreased O2 delivery to the tissue were 26, 86, and 222%, respectively, for hematocrits of 35, 25, and 15%. We compared our model results with recent experimental studies that have suggested that the amount of O2 diffusion is much higher than predicted values. We found that these experimental O2 gradients are three to four times larger than theoretical.

scholarly journals CLINICAL SIGNIFICANCE OF CARDIAC AND RESPIRATORY ADJUSTMENTS IN CHRONIC ANEMIA

Blood ◽  
1948 ◽  
Vol 3 (4) ◽  
pp. 329-348 ◽  
Author(s):  
HERRMAN L. BLUMGART ◽  
MARK D. ALTSCHULE
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Carbonic Anhydrase ◽  
Carrying Capacity ◽  
Vital Capacity ◽  
The Body ◽  
Carbon Dioxide Transport ◽  
Chronic Anemia ◽  
Arterial Blood ◽  
Oxygen Carrying Capacity

Abstract The cardiac and respiratory adjustments in chronic anemia and their clinical manifestations have been reviewed. When the oxygen carrying capacity of the blood is diminished, an adequate supply of oxygen to the tissues is maintained by an increased cardiac output, an increased velocity of blood flow, and a relatively more complete abstraction of the oxygen from the blood as it passes through the capillaries. With the increased blood flow, the average peripheral resistance is decreased but the state of the small blood vessels is not uniform everywhere; the blood flow in the hands and kidneys, for instance, may be reduced, while that of other parts of the body is increased. The total oxygen consumption of the body in anemia is not strikingly altered. The blood volume generally is slightly reduced but the plasma volume is normal. The deviations from the normal values vary from patient to patient, but generally are definite when the hemoglobin values are less than 50 per cent and are greatest at the lowest levels of hemoglobin concentration. The close interrelationship between the cardiovascular and respiratory systems is exemplified by the coincident changes in the respiratory system in anemia. The rate and depth of respiration often are increased together with a lowering in the vital capacity and its subdivisions, the reserve and complemental air volumes. The resid- ual air is somewhat increased. These deviations from the normal are similar to those observed in pulmonary congestion or edema and denote a loss of elasticity and expansibility favoring the occurrence of exertional dyspnea. The arterial blood saturation is usually normal at rest but, during exertion, a significant lowering becomes apparent. The importance of hemoglobin in the transport of carbon dioxide is reviewed; the decreased availability of hemoglobin as a buffer in carbon dioxide transport in anemia is compensated by the increased ventilation of the blood in the lungs, rendering the arterial blood somewhat alkalotic. The red cells also play an important role in regard to the respiratory enzyme, carbonic anhydrase. In the anemias due to blood loss, malnutrition, chronic infection, uremia, or leukemia, the blood carbonic anhydrase activity is parallel to the decrease in hemoglobin level leading to a deficiency not only of oxygen carrying capacity but also a decreased ability to absorb carbon dioxide from the tissues and to release it in the lungs. The following factors, many of which are closely interrelated, are operative in the production of dyspnea in anemic patients: the increased respiratory minute volume, the decreased vital capacity and its subdivisions, the abnormalities in carbon dioxide transport and dissociation, the reduced arterial oxygen capacity and the decreased blood oxygen saturation during effort, and the frequently observed elevated blood lactic acid values. The symptoms and signs exhibited by anemic patients, including palpitation and breathlessness on exertion, tachycardia, cardiac dilatation and hypertrophy, are described. In addition to an apical systolic murmur, other systolic and diastolic murmurs are occasionally heard. The arterial blood pressure is frequently lowered in anemia; the venous pressure is generally within the limits of normal. Electrocardiographic abnormalities occur in approximately one-quarter of anemic patients but are minor and not specific in character. The occurrence of angina pectoris, congestive failure, and intermittent claudication in some patients with the development of anemia, and disappearance of these conditions as the anemia is alleviated, is discussed with particular reference to the underlying physiologic mechanisms.

Impact of transient hypotension on regional cerebral blood flow in humans

2015 ◽  
Vol 129 (2) ◽  
pp. 169-178 ◽  
Author(s):  
Nia C.S. Lewis ◽  
Kurt J. Smith ◽  
Anthony R. Bain ◽  
Kevin W. Wildfong ◽  
Tianne Numan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Vertebral Artery ◽  
Regional Cerebral Blood Flow ◽  
Internal Carotid ◽  
Regional Cerebral Blood

Diameter reductions in the internal carotid artery (ICA) and vertebral artery (VA) contribute to the decline in brain blood with hypotension. The decline in vertebral blood flow with hypotension was greater when carbon dioxide was low; this was not apparent in the ICA.

scholarly journals Contrast‐enhanced ultrasound imaging can be used to evaluate fetal cerebral perfusion: potential implications for fetal surgery

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Kendall M. Lawrence ◽  
Barbara E. Coons ◽  
Anush Sridharan ◽  
Avery C. Rossidis ◽  
Marcus G. Davey ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Cerebral Perfusion ◽  
Fetal Surgery ◽  
Time Dependent ◽  
Contrast Enhanced Ultrasound ◽  
Acid Base ◽  
Fetal Sheep ◽  
Contrast Enhanced ◽  
Support Device ◽  
Acid Base Status

Abstract Background Fetal surgery is increasingly performed to correct congenital defects. Currently, fetal brain perfusion cannot be assessed intra-operatively. The purpose of this study was to determine if contrast-enhanced ultrasound (CEUS) could be used to monitor fetal cerebral perfusion during fetal surgery and if parameters correlate with fetal hemodynamics or acid/base status. Methods Cannulated fetal sheep were insufflated with carbon dioxide gas in an extra-uterine support device and in utero to mimic fetal surgery. Fetal heart rate, mean arterial pressure, and arterial blood gases were serially measured. CEUS examinations of the brain were performed and time-dependent metrics were quantified to evaluate perfusion. The relationships between measured parameters were determined with mixed linear effects models or two-way repeated measures analysis of variance. Results 6 fetal sheep (113 ± 5 days) insufflated at multiple time-points (n = 20 experiments) in an extra-uterine support device demonstrated significant correlations between time-dependent perfusion parameters and fetal pH and carbon dioxide levels. In utero, 4 insufflated fetuses (105 ± 1 days) developed hypercarbic acidosis and had reductions in cerebral perfusion parameters compared to age-matched controls (n = 3). There was no significant relationship between cerebral perfusion parameters and fetal hemodynamics. Conclusions CEUS-derived cerebral perfusion parameters can be measured during simulated fetal surgery and strongly correlate with fetal acid/base status.

The effect of five per cent carbon dioxide on the response of muscle blood flow to isoproterenol in man

1973 ◽  
Vol 14 (1) ◽  
pp. 21-25 ◽  
Author(s):  
C. Xanalatos ◽  
Lindsay MacDonell ◽  
E. Larbi ◽  
I. M. James
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Muscle Blood Flow ◽  
Cent Carbon Dioxide

Carbon dioxide transport in crustal magmatic systems

2011 ◽  
Vol 307 (3-4) ◽  
pp. 470-478 ◽  
Author(s):  
Shumpei Yoshimura ◽  
Michihiko Nakamura
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Transport
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