The hemodynamics of the microcirculation reflect system properties of the involved components. The blood itself is a complex suspension of water, small and large molecules and different cell types. Under most conditions, its rheologic properties are dominated by the different behaviour of fluid and cellular compartments. When perfused through small-bore tubes or vessels, the suspension exhibits specific emergent properties. The Fahraeus-effect and the Fahreaeus-Lindqvist-effect result from the interaction of cellular particles with each other and with the vessel wall. Additional phenomena occur in vascular networks due to the uneven distribution of blood cells and blood plasma at divergent microvascular bifurcations. In order to understand microvascular hemodynamics in vivo but also in artificial microfluidic geometries it is thus necessary to recognize the pertinent system properties on the level of the blood, the microvessels and the microvascular networks or perfused structures.
GoldsmithHLMasonSG. Axial migration of particles in Poiseuille flow. Nature. 1961;190:1095–6.
2.
GoldsmithHLCokeletGRGaehtgensP. Robin Fahraeus: Evolution of his concepts in cardiovascular physiology. Am J Physiol. 1989;257:H1005–15.
3.
BarbeeJHCokeletGR. The Fahraeus effect. Microvasc Res. 1971;3:6–16.
4.
PriesARSecombTW. Blood flow in microvascular networks. Handbook of Physiology: Microcirculation. In: TumaRFDuránWNLeyK (eds) San Diego: Academic Press, Elsevier; 2008. pp. 3–36.
5.
AlbrechtKHGaehtgensPPriesARHeuserM. The Fahraeus effect in narrow capillaries (i.d. 3.3 to 11.0 um). Microvasc Res. 1979;18:33–47.
6.
PriesARSecombTWGaehtgensPGrossJF. Blood flow in microvascular networks - experiments and simulation. Circ Res. 1990;67:826–34.
7.
SecombTWPriesAR. The microcirculation: Physiology at the mesoscale. J Physiol. 2011;589:1047–52.
8.
SecombTWHsuRPriesAR. Blood flow and red blood cell deformation in nonuniform capillaries: Effects of the endothelial surface layer. Microcirculation. 2002;9:189–96.
9.
SecombTW. Flow-dependent rheological properties of blood in capillaries. Microvasc Res. 1987;34:46–58.
10.
LipowskyHHZweifachBW. Methods for the simultaneous measurement of pressure differentials and flow in single unbranched vessels of the microcirculation for rheological studies. Microvasc Res. 1977;14:345–61.
11.
LipowskyHHUsamiSChienS. In vivo measurements of “apparent viscosity” and microvessel hematocrit in the mesentery of the cat. Microvasc Res. 1980;19:297–319.
12.
PriesARSecombTWGessnerTSperandioMBGrossJFGaehtgensP. Resistance to blood flow in microvessels in vivo. Circ Res. 1994;75:904–15.
13.
PriesARSecombTW. Microvascular blood viscosity in vivo and the endothelial surface layer. Am J Physiol Heart Circ Physiol. 2005;289:H2657–64.
14.
ReitsmaSSlaafDWVinkHvan ZandvoortMAoude EgbrinkMG. The endothelial glycocalyx: Composition, functions, and visualization. Pflugers Arch. 2007;454:345–59.
15.
PriesARSecombTWGaehtgensP. The endothelial surface layer. Pflugers Arch. 2000;440:653–66.
16.
DesjardinsCDulingBR. Heparinase treatment suggests a role for the endothelial cell glycocalyx in regulation of capillary hematocrit. Am J Physiol. 1990;258:H647–54.
17.
ParkIChoeKSeoHHwangYSongEAhnJHwanJYKimP. Intravital imaging of a pulmonary endothelial surface layer in a murine sepsis model. Biomed Opt Express. 2018;9:2383–93.
18.
CurryFE. The molecular structure of the Endothelial Glycocalyx Layer (EGL) and Surface Layers (ESL) modulation of transvascular exchange. Adv Exp Med Biol. 2018;1097:29–49.
19.
MarkiAErmilovEZakrzewiczAKollerASecombTWPriesAR. Tracking of fluorescence nanoparticles with nanometre resolution in a biological system: Assessing local viscosity and microrheology. Biomech Model Mechanobiol. 2014;13:275–88.
20.
RasmussenPMSecombTWPriesAR. Modeling the hematocrit distribution in microcirculatory networks: A quantitative evaluation of a phase separation model. Microcirculation. 2018;25(3):e12445.
21.
GambarutoAM. Flow structures and red blood cell dynamics in arteriole of dilated or constricted cross section. J Biomech. 2016;49:2229–40.
22.
YeTPhan-ThienNLimCT. Particle-based simulations of red blood cells-A review. J Biomech. 2016;49:2255–66.
23.
HyakutakeTNagaiS. Numerical simulation of red blood cell distributions in three-dimensional microvascular bifurcations. Microvasc Res. 2015;97:115–23.
24.
JuMYeSSNamgungBChoSLowHTLeoHLKimS. A review of numerical methods for red blood cell flow simulation. Comput Methods Biomech Biomed Engin. 2015;18:130–40.
25.
SecombTWStyp-RekowskaBPriesAR. Two-dimensional simulation of red blood cell deformation and lateral migration in microvessels. Ann Biomed Eng. 2007;35:755–65.
26.
PriesARSecombTWJacobsHSperandioMOsterlohKGaehtgensP. Microvascular blood flow resistance: Role of endothelial surface layer. Am J Physiol. 1997;273:H2272–79.
27.
PriesARKueblerWM. Normal endothelium. Handb Exp Pharmacol. 2006;1–40.
28.
ChienSTvetenstrandCDEpsteinMAFSchmid-SchönbeinGW. Model studies on distributions of blood cells at microvascular bifurcations. Am J Physiol. 1985;248:H568–76.
29.
BugliarelloGHsiaoGCC. Phase separation in suspensions flowing through bifurcations: A simplified hemodynamic model. Science. 1964;143:469–71.
30.
PriesARAlbrechtKHGaehtgensP. Model studies on phase separation at a capillary orifice. Biorheology. 1981;18:355–67.
31.
FentonBMCarrRTCokeletGR. Nonuniform red cell distribution in 20 to 100 um bifurcations. Microvasc Res. 1985;29:103–26.
32.
PriesARLeyKClaassenMGaehtgensP. Red cell distribution at microvascular bifurcations. Microvasc Res. 1989;38:81–101.
33.
EdenGPopelAS. A numerical study of plasma skimming in small vascular bifurcations. J Biomech Eng. 1994;116:79–88.
34.
CarrRTWickhamLL. Influence of vessel diameter on red cell distribution at microvascular bifurcations. Microvasc Res. 1991;41:184–96.
35.
BarberJOAlberdingJPRestrepoJMSecombTW. Simulated two-dimensional red blood cell motion, deformation, and partitioning in microvessel bifurcations. Ann Biomed Eng. 2008;36:1690–8.
36.
LevinMDawantBPopelAS. Effect of dispersion of vessel diameters and lengths in stochastic networks. II. Modeling of microvascular hematocrit distribution. Microvasc Res. 1986;31:223–34.
37.
PriesARLeyKGaehtgensP. Generalization of the Fahraeus principle for microvessel networks. Am J Physiol. 1986;251:H1324–32.
38.
PriesARGaehtgensP. Dispersion of blood cell flow in microvascular networks. Microvascular Mechanics. Hemodynamics of Systemic and Pulmonary Microcirculation. In: LeeJSSkalakTC (eds) New York: Springer; 1989. pp. 39–49.
39.
LeyKPriesARGaehtgensP. Topological structure of rat mesenteric microvessel networks. Microvasc Res. 1986;32:315–32.
40.
PriesARFritzscheALeyKGaehtgensP. Redistribution of red blood cell flow in microcirculatory networks by hemodilution. Circ Res. 1992;70:1113–21.
41.
PriesARSecombTW. Origins of heterogeneity in tissue perfusion and metabolism. Cardiovasc Res. 2009;81:328–35.
42.
MaibierMReglinBNitzscheBXiangWRongWWHoffmannBDjonovVSecombTWPriesAR. Structure and hemodynamics of vascular networks in the chorioallantoic membrane of the chicken. Am J Physiol Heart Circ Physiol. 2016;311:H913–26.
43.
SmithAFNitzscheBMaibierMPriesARSecombTW. Microvascular hemodynamics in the chick chorioallantoic membrane. Microcirculation. 2016;23:512–22.
44.
PriesARNeuhausDGaehtgensP. Blood viscosity in tube flow: Dependence on diameter and hematocrit. Am J Physiol. 1992;263:H1770–8.
45.
CarrRTWickhamLL. Plasma skimming in serial microvascular bifurcations. Microvasc Res. 1990;40:179–90.
46.
PalmerAA. Axial drift of cells and partial plasma skimming in blood flowing through glass slits. Am J Physiol. 1965;209:1115–22.
