Influence of diffusion on dispersion of indicators in blood flow.

Bate, H; Rowlands, Sam; Sirs, John A.

doi:10.1152/jappl.1973.34.6.866

Cited by 30 publications

(21 citation statements)

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“…5 do not fall on the line ut/x = 1 0, is also at variance with accepted indicator dilution theory. This discrepancy, of the indicator dilution theory in laminar flow, was noted by Bate & Sirs (1971) and Bate et al (1973) and has recently been given a theoretical basis by Lane & Sirs (1974). This investigation is supported by a grant from the Wellcome Trust.…”

Section: Discussionmentioning

confidence: 68%

“…The simplest situation is to consider solute dispersion to be due to the combined effects of solute diffusion and laminar convection by a parabolic velocity profile. Bate, Rowlands & Sirs (1973), extending the analysis first proposed by Taylor (1953), showed that the dispersion during flow through a tube was determined by a parameter a2iftDx, where D is the diffusion coefficient, a the tube radius, t2 the mean velocity and x the distance 690 D. A. LANE AND J.…”

Section: Introductionmentioning

confidence: 59%

“…The implications of the results have then been extrapolated to whole blood, despite the non-Newtonian and heterogeneous nature of blood flow. In this paper it is proposed to re-examine the model of Bate et al (1973) for various solutes in plasma and whole blood during flow down a straight tube. Particularly, it seemed necessary to examine the possibility of mixing induced by the rolling and tumbling of the erythrocytes (Bloch, 1962;Wells & Schmid-Schdnbein, 1969;Goldsmith & Marlow, 1972).…”

Section: Introductionmentioning

confidence: 99%

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The dispersion of solutes during blood flow through a straight tube

Lane¹,

Sirs²

1974

The Journal of Physiology

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SUMMARY1. The dispersion of solutes in plasma and blood has been studied by observing the clearance at a point down-stream of a bolus of labelled solution by the steady flow of unlabeled solution.2. With a low molecular weight solute the clearance curve is qualitatively similar in 2N-KCI solution, plasma and whole blood.3. The dispersion of a high molecular weight protein, [131I]HSA, in plasma is dominated by the velocity profile of the flow.4. The clearance curves for HSA in whole blood are similar to those of plasma, except that the red blood cells speed the clearance of protein in the tail region of the curve.5. An analysis of the data suggests that the dispersion of solutes during blood flow through a straight tube can be attributed to the combined effects of solute diffusion and laminar convection. There is no evidence that induced motion of the erythrocytes produces significant mixing, in the bulk of the flow.

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Section: Discussionmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

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The dispersion of solutes during blood flow through a straight tube

Lane¹,

Sirs²

1974

The Journal of Physiology

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“…7 Some other authors have also discussed problematic aspects, mostly by use of flow pipe models. [8][9][10][11][12][13][14] The IDT has also been formulated by use of concepts borrowed from the theory of linear ͑stable͒ systems. 2,3,7,15 The use of such a formulation does not, however, demonstrate the validity of the IDT, especially not for all kinds of detectors and labeling processes.…”

Section: Discussionmentioning

confidence: 99%

Is the indicator dilution theory really the adequate base of many blood flow measurement techniques?

Doriot

Dorsaz

et al. 1997

Medical Physics

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The indicator dilution theory is the underlying model of many blood flow measurement techniques used daily in hospitals, for instance in cardiac catheterization laboratories. The basic version of this theory applies to a "stationary" flow system with one inlet and one outlet, into which a small amount M of indicator is injected "suddenly" at time t = 0 at the inlet. The quintessence of the theory consists in three equations, which themselves result from some apparently simple assumptions about the considered flow systems. The first equation states that the (constant) flow Q through the system can be calculated by use of the known amount of indicator, M, and of the indicator concentration-time curve c(t) recorded at the outlet. The second one allows the calculation of the "mean transit time" t* of fluid and indicator particles through the system from the curve c(t). The third equation, V = Qt*, yields the system volume V. It is generally believed that these three equations would be absolutely valid if the assumptions of the theory could be perfectly fulfilled. We show, by considering a simple model, that all three equations are actually incorrect for most flow systems when the detector used to record the curve c(t) is of the "trans-illumination" type, as is the case for instance in dye dilution methods and in many angiographic or CT techniques. A further consequence is that t*, which is truly the "center of mass" of the concentration-time curve c(t), does not have the well known property of being the adequate parameter for flow determinations. Many flow measurement techniques thus appear to have no theoretical base.

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“…[30e33] and Bate et al [36,37] to obtain solutions related to other regions. Equation 3.4, expressed in terms of Peclet number ðPe ¼ aF=D m Þ, reduced distance ðe ¼ D m x=a 2 F 0 Þ and reduced time (s ¼ D m t/a 2 ), was numerically integrated for all values of s < 0.8 that corresponded to the region of interest for unsegmented flow analysis.…”

Section: Sample Dispersionmentioning

confidence: 99%

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Influence of diffusion on dispersion of indicators in blood flow.

Cited by 30 publications

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The dispersion of solutes during blood flow through a straight tube

The dispersion of solutes during blood flow through a straight tube

Is the indicator dilution theory really the adequate base of many blood flow measurement techniques?

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