Our model accounts for O2 diffusion out of the circulation before blood arriving to the nutritional circulation and for changes in blood flow velocity. We analyzed the effects of transfusing 0.5 or more units of 300 cc of packed red blood cells (PRBCs) at an Hct of 65% and calculated microcirculatory DO2 after accounting for increased blood viscosity and assuming no change in blood pressure. We hypothesized that increasing Hct would increase DO2 and tested our hypothesis by mathematically modeling DO2 in the circulation.Ĭalculations were made assuming a normal cardiac output (5 L/min) with degrees of anemia ranging from 5% to 80% Hct deficit. The net effect of transfusion on DO2 in this system can be analyzed by using the relationship between Hct and systemic blood viscosity of circulating blood at the posttransfusion Hct to calculate DO2 and comparing this value with pretransfusion DO2. However, increasing Hct also increases blood viscosity, which may thus lower DO2 if the arterial circulation is a rigid hydraulic system as the resistance to blood flow will increase. 1 From the *Departments of Mechanical Engineering †Bioengineering, University of California, San Diego, La Jolla, California ‡Department of Experimental Medicine, School of Medicine, Universidad Nacional Autónoma de México, México, DF, México §Department of Odontology, Universidad Juárez del Estado de Durango, Durango, Dgo, México ‖School of Surgery, Faculty of Medicine Dentistry and Health Sciences, University of Western Australia, and Centre for Population Health Research, Curtin University, Perth, Western Australia, Australia ¶Institute of Anesthesiology, University of Zurich and University Hospital Zurich, Zurich, Switzerland #Clinic of Anesthesiology and Intensive Care, Faculty of Medicine, Kepler University Linz, Austria **Department of Anesthesiology, Critical Care Medicine, Pain Management and Hyperbaric Medicine at Englewood Hospital & Medical Center, Director TeamHealth Research Institute, Englewood, New Jersey and ††Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York.īlood transfusion is used to treat acute anemia with the goal of increasing blood oxygen-carrying capacity as determined by hematocrit (Hct) and oxygen delivery (DO2).The increase blood viscosity noted in the hypoxic and diseased groups could lead to a decreased blood flow and oxygen delivery to the tissues. No significant difference was observed among the four groups in mean cell volume, mean cell hemoglobin, and mean cell hemoglobin concentration. The diseased group had a significantly higher PCV than all other groups resulting in a significant increase in blood viscosity. At packed cell volumes (PCV) of 30% and 40% and at high shear rates (75 s -1 and 150 s -1) the hypoxic group had a significantly higher apparent blood viscosity when compared to healthy fish, likely the result of a significant increase in the total plasma protein concentration in this group. Plasma and apparent (whole) blood viscosity measurements were made using a Wells-Brookfield cone/plate viscometer at ten different shear rates. Twenty-seven adult striped bass weighing between 1040 g and 1800 g were divided into four groups: (1) healthy fish (2) short-term hypoxia, fish exposed to oxygen concentrations of 4 mg/L for four hours (3) simulated transport, exposed to crowding with oxygen concentrations of approximately 8.4 mg/L and (4) diseased fish, infected with henneguya causing inflammation of the gill surface leading to hypoxemia in these animals. Blood viscosity and blood parameters were studied in striped bass, Morone saxatilis (Walbaum) under various fish hatchery conditions.
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