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V is volume; α is the alpha factor. The value is between 0 and 1 but closer to 1. As can be inferred from the above formula, if the alpha factor is not taken into account, the calculated volume is an underestimate. ρ specific resistance of blood; L distance between pair of electrodes; G measured conductance; G P parallel conductance
Clinically, the unknown volume is the patient's blood volume, with the tracer having been injected into the patient's blood stream and tagged to the blood plasma. Once the tracer is injected a technician takes five blood samples which undergo microhematocrit centrifugation to extrapolate true blood volume at time 0. The concentration of the I ...
Modalities applied to measurement of ejection fraction is an emerging field of medical mathematics and subsequent computational applications. The first common measurement method is echocardiography, [7] [8] although cardiac magnetic resonance imaging (MRI), [8] [9] cardiac computed tomography, [8] [9] ventriculography and nuclear medicine (gated SPECT and radionuclide angiography) [8] [10 ...
where EBV is the estimated blood volume; 70 mL/kg was used in this model and H i (initial hematocrit) is the patient's initial hematocrit. From the equation above it is clear that the volume of blood removed during the ANH to the H m is the same as the BL s. How much blood is to be removed is usually based on the weight, not the volume.
Perfusion is measured as the rate at which blood is delivered to tissue, [2] or volume of blood per unit time (blood flow) per unit tissue mass. The SI unit is m 3 /(s·kg) [ citation needed ] , although for human organs perfusion is typically reported in ml/min/g. [ 3 ]
Simplified control circuit of human thermoregulation. [8]The core temperature of a human is regulated and stabilized primarily by the hypothalamus, a region of the brain linking the endocrine system to the nervous system, [9] and more specifically by the anterior hypothalamic nucleus and the adjacent preoptic area regions of the hypothalamus.
Wei's equations can be applied to this calculated blood conductance G b to obtain blood volume. [3] Unlike Baan's equation, Wei's equation takes into account the non-linear nature of the electrical field and the dynamic nature of the cardiac cycle to give a more accurate representation of the blood volume.
A photoplethysmogram (PPG) is an optically obtained plethysmogram that can be used to detect blood volume changes in the microvascular bed of tissue. [1] [2] A PPG is often obtained by using a pulse oximeter which illuminates the skin and measures changes in light absorption. [3]