Blood volume measurement, functional

Hamberg LM, Hunter GJ, Kierstead D, Lo EH, Gilberto Gonzalez R, Wolf GL. Measurement of cerebral blood volume with subtraction three-dimensional functional CT. Am J Neuroradiol 1996 17 1861-1869. 

Left ventricular ejection fraction—Also known simply as the ejection fraction, it is the fraction or percentage of the end diastolic blood volume ejected by the left ventricle during systole. It is a measurement of cardiac systolic function with a normal ejection being >60%. It can be determined noninvasively by an echocardiogram. 

The CO diffusing capacity, DPco, of sheep was measured at various 02 tensions in a hyperbaric chamber using a method similar to that outlined above (12). DPco varied as a function of the oxygen tension. In Figure 2 the reciprocal of DPco is plotted as a function of the reciprocal of the diffusing capacity of the maternal and fetal red blood cells. From the plot the slope is the reciprocal of the value of V, the maternal and fetal capillary blood volume while the intercept is the reciprocal of Dmco- From these studies we calculated that the resistance of maternal and fetal red blood cells was approximately one-third of the total resistance while the resistance of the placental membrane per se was about two-thirds of the total resistance to 02 diffusion (12). This is in contrast to previous studies which assumed that the placental membrane per se constituted the total resistance to diffusion. 

A novel technique is now available, CT perfusion (see Sect. 31.2.3), which offers a measure of tumor neoangiogenesis. It provides functional information represented by blood volume, blood flow, mean transit time, and permeabihty surface area (Fig. 31.8). In tumors, compared with normal tissue, blood volume, blood flow, and permeability surface area are usually increased, whereas mean transit time (representing an indirect measure of arteriovenous shunts) is reduced because of the higher number of shunts compared with normal tissue (Fig. 31.9) (Sahani et al. 2005). 

---