Capillary Blood Flow during Severe Hemodilution Observed by a Noninvasive Transcutaneous Technique Using Flash Epi-illumination

Sakai, Hiromi; Sato, Toshiyuki; Maekawa, Yasunori; Tsuchida, Eishun

doi:10.1006/mvre.2002.2415

Cited by 5 publications

(4 citation statements)

References 26 publications

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“…In the hemodilution group the changes in RBC velocity and functional vascular density were strongly correlated with Hb levels. Our findings differ from those found in other vascular beds such as skin, striated muscle, heart, and brain (2,5,7,27,28,31,33). These differences could result from a different microvascular control in each territory but also from the method used in the assessment.…”

Section: Discussioncontrasting

confidence: 99%

“…These alterations were even more severe when hemodilution reached extreme values, comparable with ours (Hb ϭ 1.1 g/dl) (38). A similar pattern was described in the skin of the rat (33). In contrast to the U-shaped behavior of RBC velocity in muscle and skin, the relationship in the central nervous system (27,28) and in the heart (2) was found to be linear.…”

Section: Discussionsupporting

confidence: 86%

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Intestinal and sublingual microcirculation are more severely compromised in hemodilution than in hemorrhage

Ferrara

Edul

Martins

et al. 2016

Journal of Applied Physiology

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The alterations in O2 extraction in hemodilution have been linked to fast red blood cell (RBC) velocity, which might affect the complete release of O2 from Hb. Fast RBC velocity might also explain the normal mucosal-arterial Pco2 (ΔPco2). Yet sublingual and intestinal microcirculation have not been completely characterized in extreme hemodilution. Our hypothesis was that the unchanged ΔPco2 in hemodilution depends on the preservation of villi microcirculation. For this purpose, pentobarbital-anesthetized and mechanically ventilated sheep were submitted to stepwise hemodilution (n = 8), hemorrhage (n = 8), or no intervention (sham, n = 8). In both hypoxic groups, equivalent reductions in O2 consumption (V̇o2) were targeted. Microcirculation was assessed by videomicroscopy, intestinal ΔPco2 by air tonometry, and V̇o2 by expired gases analysis. Although cardiac output and superior mesenteric flow increased in hemodilution, from the very first step (Hb = 5.0 g/dl), villi functional vascular density and RBC velocity decreased (21.7 ± 0.9 vs. 15.9 ± 1.0 mm/mm(2) and 1,033 ± 75 vs. 850 ± 79 μm/s, P < 0.01). In the last stage (Hb = 1.2 g/dl), these variables were lower in hemodiution than in hemorrhage (11.1 ± 0.5 vs. 15.4 ± 0.9 mm/mm(2) and 544 ± 26 vs. 686 ± 70 μm/s, P < 0.01), and were associated with lower intestinal fractional O2 extraction (0.61 ± 0.04 vs. 0.79 ± 0.02, P < 0.01) but preserved ΔPco2 (5 ± 2 vs. 25 ± 4 mmHg, P < 0.01). Therefore, alterations in O2 extraction in hemodilution seemed related to microvascular shunting, not to fast RBC velocity. The severe microvascular abnormalities suggest that normal ΔPco2 was not dependent on CO2 washout by the villi microcirculation. Increased perfusion in deeper intestinal layers might be an alternative explanation.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 86%

Intestinal and sublingual microcirculation are more severely compromised in hemodilution than in hemorrhage

Ferrara

Edul

Martins

et al. 2016

Journal of Applied Physiology

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“…For extraction of the capillary shape, we used the level-set method (13) (14) . As Sakai,et.al., (15) reported that the RBCs contrasted well against the background tissue; however, the endothelial cells were not observed in images. Capillary shapes were recognized only when they were filled with RBCs.…”

Section: Image Analysis By the Level-set Methodsmentioning

confidence: 97%

High Speed Digital Video Capillaroscopy: Nailfold Capillary Shape Analysis and Red Blood Cell Velocity Measurement

Watanabe

Matsubara

Sanada

et al. 2007

JBSE

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Nailfold capillaroscopy has been shown to reflect microvascular disturbances mainly in connective tissue diseases, and the development of video capillaroscopy made it possible to determine capillary red blood cell velocity by measuring the displacement of plasma gaps between red cells. We improved both temporal and spatial resolutions of video capillaroscopy by developing the high speed digital video capillaroscopy, integrating high speed digital video camera, deep-focus zoom lens, appropriate light source and light collecting adaptor. The first objective of this study is to present the novel method for quantitative capillary shape analysis by using the level-set method. The capillary radius distribution along the capillary center line is obtained and described by the level-set function. Based on this mathematical description of capillary shape, more rigorous definition of the capillary red blood cell velocity than the conventional method is discussed. The second objective of this study is to propose the innovative measurement method of red blood cell velocity in nailfold capillary, and then the possibility of tracking the individual red blood cell movement, not only in the axial direction but also lateral direction, in human nailfold capillary is discussed

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“…Changes in shear stress caused by reducing or increasing viscosity (produced by altering hematocrit or changing macromolecular concentration) have the same vasoconstrictor or vasodilator effects as changes in flow (81). In normal rats and hamsters, isovolemic hemodilution with colloidal solutions (albumin or dextran 70 kDa), mimicking resuscitation after major hemorrhage, caused a reduction in functional capillary density (>50%), an effect that was almost completely prevented by using a high viscosity solution to replace the blood (82)(83)(84)(85). Taken together, these findings demonstrate that physiological shear stress has an important role in maintaining normal perfusion of the microcirculation, and suggest that hemodilution, with a subsequent reduction in shear stress, can disrupt this homeostatic function.…”

Section: The Adverse Effects Of Reduced Endothelial Shear Stressmentioning

confidence: 99%

Capillary leak and edema following resuscitation: the potential contribution of reduced endothelial shear stress caused by haemodilution

Walsh,

Cunning,

Lee

et al. 2023

Shock

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Normal shear stress is essential for the normal structure and functions of the microcirculation. Hemorrhagic shock leads to reduced shear stress due to reduced tissue perfusion. Although essential for the urgent restoration of cardiac output and systemic blood pressure, large volume resuscitation with currently available solutions causes hemodilution, further reducing endothelial shear stress. In this narrative review, we consider how the use of currently available resuscitation solutions results in persistent reduction in endothelial shear stress, despite successfully increasing cardiac output and systemic blood pressure. We consider how this reduced shear stress causes (1) a failure to restore normal vasomotor function and normal tissue perfusion thus leading to persistent tissue hypoxia and (2) increased microvascular endothelial permeability resulting in edema formation and impaired organ function. We discuss the need for clinical research into resuscitation strategies and solutions that aim to quickly restore endothelial shear stress in the microcirculation to normal.

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Capillary Blood Flow during Severe Hemodilution Observed by a Noninvasive Transcutaneous Technique Using Flash Epi-illumination

Cited by 5 publications

References 26 publications

Intestinal and sublingual microcirculation are more severely compromised in hemodilution than in hemorrhage

Intestinal and sublingual microcirculation are more severely compromised in hemodilution than in hemorrhage

High Speed Digital Video Capillaroscopy: Nailfold Capillary Shape Analysis and Red Blood Cell Velocity Measurement

Capillary leak and edema following resuscitation: the potential contribution of reduced endothelial shear stress caused by haemodilution

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