Characteristics and Determinants of the Sublingual Microcirculation in Populations of Different Ethnicity

Abstract

No previous population study assessed sublingual capillary density (CD) or perfused boundary region (PBR). Lower PBR indicates greater glycocalyx width. In 252 Han and 220 She Chinese and 254 Flemish people (mean age, 51.1 years; 54.7% women), representing random population samples, we measured total and perfused CD and PBR in the sublingual capillary bed, using oblique profiled epi-illumination, and cardiovascular risk factors. In multivariable analyses, we modeled ethnicity as random effect. Significance level was α≤0.05. Compared with Chinese, Flemish had lower total (577 versus 546 n°/mm 2 ) and perfused (338 versus 320 n°/mm 2 ) CD, but similar perfused-to-total CD ratio (mean, 0.59). Perfused-to-total CD ratio increased with age (effect size per 1–SD increase, +0.015 per year), body mass index (+0.008 per kg/m 2 ), total cholesterol (+0.012 per mmol/L), and Framingham risk score (+0.018 per point) with no ethnic differences in these associations. For age and Framingham risk score, associations with perfused-to-total CD ratio were driven by positive relationships with perfused CD, whereas associations with total CD were nonsignificant. Chinese when compared with Flemish had higher hematocrit (43.0 versus 41.1%), PBR (2010 versus 1876 nm), and pulse rate (72.6 versus 63.3 bpm). PBR standardized for hematocrit, perfused CD, and pulse rate decreased with body mass index (–26.7 nm/kg/m2), mean arterial pressure (–30.6 nm/mm Hg), and diastolic pressure (–28.5 nm/mm Hg) with no ethnic differences in these associations. In conclusion, a higher cardiovascular risk profile is associated with functional recruitment of capillaries with preserved glycocalyx that protects the endothelial lining.

Second consensus on the assessment of sublingual microcirculation in critically ill patients: results from a task force of the European Society of Intensive Care Medicine

“…Even though its presence can be noted, its quantification can be problematic because of limitations of the ability of the image acquisition to capture the images sufficiently rapidly to allow quantification of the velocity of hyperdynamic flow (Recommendation #7, Table 3). Caution is required when comparing normal values of total vessel density, because these can be influenced not only by disease states [26] and ethnicity [33] but, more importantly, by the device used. This is because the third-generation IDF devices have improved optics with which 30% more vessels can be visualized in comparison to the previous-generation devices (Recommendation #9, Table 3) [50,51].…”

“…In 2009, an international multicenter observational prevalence study in intensive care patients involving 36 ICUs worldwide enrolling 501 patients identified microcirculatory alterations (microvascular flow index, MFI < 2.6) in combination with tachycardia (heart rate > 90) as an independent risk factor for increased hospital mortality [28]. Various studies have been undertaken to define normal values in adults, newborns, and neonates [29][30][31][32][33], as well as in healthy individuals under extreme environmental conditions [34,35]. In studies where systemic hemodynamic monitoring was being applied, it became increasingly clear that microcirculatory alterations can occur independently from systemic hemodynamic alterations and that these microcirculatory alterations were independently associated with adverse clinical outcome [6][7][8].…”

Sublingual functional capillary rarefaction in chronic heart failure

“…22 The elevated perfused/total capillary ratio in CHF patients possibly reflects the body's partial compensation and corresponds to previous observations of perfused capillary recruitment in persons with a higher cardiovascular risk profile. 23…”

Reproducibility of sublingual microcirculation parameters obtained from sidestream darkfield imaging

“…The parameters used include two markers of microvascular perfusion, the Vascular Density (VD) [3–5] and the Red Blood Cell Filling percentage (RBCF) [5], and an indicator of the endothelial surface layer usually referred to as the glycocalyx, the Perfused Boundary Region (PBR) [6]. Since they can be obtained from a non-invasive, fast, and semi-automated procedure, these parameters have been considered markers of vascular damage with potential diagnostic, prognostic, and therapeutic values[4, 7, 8]. However, subsequent studies did not yield consistent results.…”