Effects of Venesection on Leg Blood Flow in Claudicants with High-Normal Haematocrit

1988 ◽  
Vol 33 (4) ◽  
pp. 298-299 ◽  
Author(s):  
A.R. Turner ◽  
G.D.O. Lowe ◽  
C.D. Forbes ◽  
J. G. Pollock
Keyword(s):  
Blood Flow ◽  
Intermittent Claudication ◽  
Carrying Capacity ◽  
Blood Viscosity ◽  
Oxygen Delivery ◽  
Peak Flow ◽  
Haemoglobin Concentration ◽  
Leg Blood Flow ◽  
Calf Blood Flow ◽  
Oxygen Carrying Capacity

Patients with intermittent claudication frequently have high-normal levels of haematocrit and hence blood viscosity, which may contribute to decreased calf blood flow on exercise, and hence to the symptom of claudication. Reduction in haematocrit and viscosity by serial venesection in eight patients with stable claudication and high-normal haematocrit (mean 0.50) was performed, and the effects on claudication, calf blood flow, and calf oxygen delivery were studied. Following reduction in haematocrit to low-normal levels (mean 0.44), resting calf blood flow was unchanged; peak flow after ischaemic exercise increased slightly (+17%), but peak oxygen delivery (peak flow × haemoglobin concentration) was unchanged. Hence any increase in calf blood flow in the symptomatic leg is balanced by a decrease in oxygen-carrying capacity after venesection. No increase in claudication time would therefore be expected, and none was observed in the present study.

Haemorheology of the eastern grey kangaroo and the Tasmanian devil

2011 ◽  
Vol 59 (1) ◽  
pp. 26 ◽  
Author(s):  
Michael J. Simmonds ◽  
Oguz K. Baskurt ◽  
Herbert J. Meiselman ◽  
Michael Pyne ◽  
Michael Kakanis ◽  
...  
Keyword(s):  
Surface Charge ◽  
Carrying Capacity ◽  
Blood Viscosity ◽  
Haemoglobin Concentration ◽  
Scanning Electron Micrographs ◽  
Tasmanian Devil ◽  
Grey Kangaroo ◽  
Rbc Aggregation ◽  
Oxygen Carrying Capacity ◽  
Rbc Deformability

The blood of two Australian marsupials, the eastern grey kangaroo (Macropus giganteus) and the Tasmanian devil (Sarcophilus harrisii), has been reported to have greater oxygen-carrying capacity (i.e. haemoglobin content) when compared with that of placental mammals. We investigated whether alterations of blood rheological properties are associated with the increased oxygen-carrying capacity of these marsupials. Eastern grey kangaroos (n = 6) and Tasmanian devils (n = 4) were anaesthetised for blood sampling; human blood (n = 6) was also sampled for comparison. Laboratory measurements included blood and plasma viscosity, red blood cell (RBC) deformability, RBC aggregation and the intrinsic tendency of RBC to aggregate, RBC surface charge and haematological parameters. Scanning electron micrographs of RBC from each species provided morphological information. High-shear blood viscosity at native haematocrit was highest for the Tasmanian devil. When haematocrit was adjusted to 0.4 L L–1, lower-shear blood viscosity was highest for the eastern grey kangaroo. RBC deformability was greatly reduced for the Tasmanian devil. Eastern grey kangaroo blood had the highest RBC aggregation, whereas Tasmanian devil RBC did not aggregate. The surface charge of RBC for marsupials was ~15% lower than that of humans. The dependence of oxygen-delivery effectiveness on haemoglobin concentration (i.e. oxygen content) and blood viscosity was quantitated by calculating the haematocrit to blood viscosity ratio and was 15–25% lower for marsupials compared with humans. Our results suggest that environmental pressures since the marsupial–monotreme divergence have influenced the development of vastly different strategies to maintain a match between oxygen demand and delivery.

Circadian Periodicity of Calf Blood Flow in Subjects With Intermittent Claudication

Angiology ◽  
1970 ◽  
Vol 21 (4) ◽  
pp. 215-223 ◽  
Author(s):  
B. Dorigo ◽  
E. Tedeschi ◽  
G.P. Biti ◽  
M.R. Voegelin ◽  
Vittorio Bartoli
Keyword(s):  
Blood Flow ◽  
Intermittent Claudication ◽  
Circadian Periodicity ◽  
Calf Blood Flow

Oxygen delivery at high blood viscosity and decreased arterial oxygen content to brains of conscious rats

2001 ◽  
Vol 280 (6) ◽  
pp. H2591-H2597 ◽  
Author(s):  
A. Rebel ◽  
C. Lenz ◽  
H. Krieter ◽  
K. F. Waschke ◽  
K. Van Ackern ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Oxygen Content ◽  
Blood Viscosity ◽  
Oxygen Delivery ◽  
Brain Structures ◽  
Arterial Oxygen ◽  
Cerebral Oxygen ◽  
Compensatory Mechanisms ◽  
Arterial Oxygen Content

We addressed the question to which extent cerebral blood flow (CBF) is maintained when, in addition to a high blood viscosity (Bvis) arterial oxygen content (CaO2 ) is gradually decreased. CaO2 was decreased by hemodilution to hematocrits (Hct) of 30, 22, 19, and 15% in two groups. One group received blood replacement (BR) only and served as the control. The second group received an additional high viscosity solution of polyvinylpyrrolidone (BR/PVP). Bvis was reduced in the BR group and was doubled in the BR/PVP. Despite different Bvis, CBF did not differ between BR and BR/PVP rats at Hct values of 30 and 22%, indicating a complete vascular compensation of the increased Bvis at decreased CaO2 . At an Hct of 19%, local cerebral blood flow (LCBF) in some brain structures was lower in BR/PVP rats than in BR rats. At the lowest Hct of 15%, LCBF of 15 brain structures and mean CBF were reduced in BR/PVP. The resulting decrease in cerebral oxygen delivery in the BR/PVP group indicates a global loss of vascular compensation. We concluded that vasodilating mechanisms compensated for Bvis increases thereby maintaining constant cerebral oxygen delivery. Compensatory mechanisms were exhausted at a Hct of 19% and lower as indicated by the reduction of CBF and cerebral oxygen delivery.

Chronic hypoxia and the cerebral circulation

2006 ◽  
Vol 100 (2) ◽  
pp. 725-730 ◽  
Author(s):  
Kui Xu ◽  
Joseph C. LaManna
Keyword(s):  
Blood Flow ◽  
Carrying Capacity ◽  
Hemoglobin Concentration ◽  
Capillary Density ◽  
Hypoxic Exposure ◽  
Blood Oxygen ◽  
Brain Capillary ◽  
Blood Flow Increase ◽  
Time Courses ◽  
Oxygen Carrying Capacity

Exposure to mild hypoxia elicits a characteristic cerebrovascular response in mammals, including humans. Initially, cerebral blood flow (CBF) increases as much as twofold. The blood flow increase is blunted somewhat by a decreasing arterial Pco2 as a result of the hypoxia-induced hyperventilatory response. After a few days, CBF begins to fall back toward baseline levels as the blood oxygen-carrying capacity is increasing due to increasing hemoglobin concentration and packed red cell volume as a result of erythropoietin upregulation. By the end of 2 wk of hypoxic exposure, brain capillary density has increased with resultant decreased intercapillary distances. The relative time courses of these changes suggest that they are adjusted by different control signals and mechanisms. The CBF response appears linked to the blood oxygen-carrying capacity, whereas the hypoxia-induced brain angiogenesis appears to be in response to tissue hypoxia.

scholarly journals Reduction of Oxygen-Carrying Capacity Weakens the Effects of Increased Plasma Viscosity on Cardiac Performance in Anesthetized Hemodilution Model

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Surapong Chatpun ◽  
Pedro Cabrales
Keyword(s):  
Cardiac Output ◽  
Carrying Capacity ◽  
Oxygen Delivery ◽  
Maximum Rate ◽  
Systolic Pressure ◽  
Pressure Change ◽  
Plasma Viscosity ◽  
Cardiac Performance ◽  
Dextran 70 ◽  
Oxygen Carrying Capacity

We investigated the effects of reduced oxygen-carrying capacity on cardiac function during acute hemodilution, while the plasma viscosity was increased in anesthetized animals. Two levels of oxygen-carrying capacity were created by 1-step and 2-step hemodilution in male golden Syrian hamsters. In the 1-step hemodilution (1-HD), 40% of the animals' blood volume (BV) was exchanged with 6% dextran 70 kDa (Dx70) or dextran 2000 kDa (Dx2M). In the 2-step hemodilution (2-HD), 25% of the animals' BV was exchanged with Dx70 followed by 40% BV exchanged with Dx70 or Dx2M after 30 minutes of first hemodilution. Oxygen delivery in the 2-HD group consequently decreased by 17% and 38% compared to that in the 1-HD group hemodiluted with Dx70 and Dx2M, respectively. End-systolic pressure and maximum rate of pressure change in the 2-HD group significantly lowered compared with that in the 1-HD group for both Dx70 and Dx2M. Cardiac output in the 2-HD group hemodiluted with Dx2M was significantly higher compared with that hemodiluted with Dx70. In conclusion, increasing plasma viscosity associated with lowering oxygen-carrying capacity should be considerably balanced to maintain the cardiac performance, especially in the state of anesthesia.

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