Functional blood volume and distribution of specific blood flow in the kidney of man

Abstract

A method has been devised to determine the distribution of blood flow through the kidney in man and animals. The studies reported here have been accomplished in humans by using catheterization of renal artery and vein so as to administer a dye indicator at the entrance of the system and measure its behavior at the exit. Through a transformation of the equation of the dye curve the distribution of specific blood flow is inferred. The distribution function seems to be superimposable from one individual to another. The ratio of the half width to the first moment of the distribution function remains nearly constant under widely variable physiological conditions. Renal blood volume and renal capillary surface area are also measured. specific renal blood flow; functional renal blood volume; renal blood volume; capillary blood volume; renal capillary surface area Submitted on October 9, 1964

Physiology and theory of tracer washout techniques for the estimation of myocardial blood flow: Flow estimation from tracer washout

“…Similarity has been demonstrated for transorgan transport functions in the kidney by Gomez et al, 22 in the lung over a very limited range of alveolar and left atrial pressures by Knopp and Bassingthwaighte,23 and in the coronary bed by Knopp et al 17 Data from the latter study are plotted in Fig. 11, showing a fair degree of similarity.…”

“…For the concentration-time curves, recalling that h(t) = F · C(t)/m i , (equation 2), then: (22) and for the constant volume system: (23) Equations 22 and 23 show that for a system with stable dispersive properties, a change in F doesn't affect the peak heights of C(t) but does change the spread of the curve, the areas being inversely related to F. Similarly, C(t D2 ) = C(t D1 ) and C(t E2 ) = C(t E1 ) while t D2 = F 1 t D1 /F 2 and t E2 = F 1 t E1 /F 2 . This may be viewed merely as normalization of the time scale of t/t.…”

Transcoronary intravascular transport functions obtained via a stable deconvolution technique

“…3, indicates that the relative dispersion, σ/t, the skewness, and the kurtosis are all quite constant over a wide range of mean transit times. This basic feature, the "similarity" of the transport functions, was found in the kidney (Gomez et al, 1965) and over a limited range of flow in the lung (Knopp et al, 1969) and in the leg-arterial system (Bassingthwaighte, 1966a) and can be expected to be a feature of any vascular bed in which there are no dramatic changes in geometry at different flows. Figure 4 shows the relationship of the transport function dispersion to mean transit time for a variety of organs (Bassingthwaighte et al, 1966a(Bassingthwaighte et al, , 1967Knopp et at., 1969).…”

“…Of particular interest is the deviation of the form of h from simple unimodal models, which clearly could not provide nearly .as good descriptions of h. The commonly used unimodal density functions such as the lagged normal density curve (Bassingthwaighte et al, 1966a(Bassingthwaighte et al, , 1966b, a gamma variate (Gomez et al, 1965), or the log normal density function all have downslopes which are virtually indistinguishable from a single exponential in the tail region below 30% of peak height. The lagged normal density functions describing arterial transport functions (Bassingthwaighte, 1966a) had skewnesses of about 1.0, in accordance with a monoexponential downslope.…”

“…For the description of the transcoronary transport functions, fitting functions were selected that would most reasonably approximate the transport function for a single blood pathway through the coronary bed. The assumption of a unimodal right-skewed distribution for h i is based on the work of Bassingthwaighte (1966a), who described dispersion in the human leg artery with the lagged normal density function; Knopp et al (1969), who used this function to describe plasma dispersion in the lung; and Gomez et al (1965), who used the log normal function to describe dispersion in the human kidney. Lagged normal density functions were arbitrarily chosen to describe the individual pathway transport functions, although there is no question that gamma variates or log normals will do as well; and the choice has no influence on the shape of the calculated h's.…”