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A guide to human in vivo microcirculatory flow image analysis

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Critical Care

BioMed Central

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      Abstract

      Various noninvasive microscopic camera technologies have been used to visualize the sublingual microcirculation in patients. We describe a comprehensive approach to bedside in vivo sublingual microcirculation video image capture and analysis techniques in the human clinical setting. We present a user perspective and guide suitable for clinical researchers and developers interested in the capture and analysis of sublingual microcirculatory flow videos. We review basic differences in the cameras, optics, light sources, operation, and digital image capture. We describe common techniques for image acquisition and discuss aspects of video data management, including data transfer, metadata, and database design and utilization to facilitate the image analysis pipeline. We outline image analysis techniques and reporting including video preprocessing and image quality evaluation. Finally, we propose a framework for future directions in the field of microcirculatory flow videomicroscopy acquisition and analysis. Although automated scoring systems have not been sufficiently robust for widespread clinical or research use to date, we discuss promising innovations that are driving new development.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1213-9) contains supplementary material, which is available to authorized users.

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      Most cited references 48

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      Microvascular blood flow is altered in patients with sepsis.

      Microvascular blood flow alterations are frequent in animal models of sepsis and may impair tissue oxygenation. We hypothesized that alterations of the microcirculation are present in patients with sepsis. We used an orthogonal polarization spectral imaging technique to investigate the sublingual microcirculation in 10 healthy volunteers, 16 patients before cardiac surgery, 10 acutely ill patients without sepsis (intensive care unit control subjects), and 50 patients with severe sepsis. The effects of topical application of acetylcholine (10(-2) M) were tested in 11 patients with sepsis. In each subject, five to seven sublingual areas were recorded and analyzed semiquantitatively. Data were analyzed with nonparametric tests and are presented as medians (25th-75th percentiles). No significant difference in microvascular blood flow was observed between healthy volunteers and patients before cardiac surgery or intensive care unit control subjects. The density of all vessels was significantly reduced in patients with severe sepsis (4.5 [4.2-5.2] versus 5.4 [5.4-6.3]/mm in volunteers, p < 0.01). The proportion of perfused small (< 20 microm) vessels was reduced in patients with sepsis (48 [33-61] versus 90 [89-92]% in volunteers, p < 0.001). These alterations were more severe in nonsurvivors. The topical application of acetylcholine totally reversed these alterations. In conclusion, microvascular blood flow alterations are frequent in patients with sepsis and are more severe in patients with a worse outcome.
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        Persistent microcirculatory alterations are associated with organ failure and death in patients with septic shock.

        To characterize the time course of microcirculatory alterations and their relation to outcome in patients with septic shock. Prospective, observational study. Thirty-one-bed, medico-surgical intensive care unit in a university hospital. Forty-nine patients with septic shock. The sublingual microcirculation was investigated with an orthogonal polarization spectral imaging device on the day of onset of septic shock (baseline) and each day until resolution of shock. Five sequences of 20 secs each were recorded and analyzed off-line by a semiquantitative method. Data were analyzed with nonparametric tests and presented as median (25th-75th percentiles). Three patients died after the resolution of shock from unrelated causes and were excluded. Of the other 46 patients, 26 survived and 20 died: 13 due to unresolving shock and seven due to persistent multiple organ failure after resolution of shock. At the onset of shock, survivors and nonsurvivors had similar vascular density (5.6 [4.7-7.0] vs. 6.2 [5.4-7.0]/mL; p = nonsignificant) and percentage of perfused small vessels (65.0 [53.1-68.9] vs. 58.4 [47.5-69.1]%; p = nonsignificant). Small vessel perfusion improved over time in survivors (analysis of variance, p <.05 between survivors and nonsurvivors) but not in nonsurvivors. Despite similar hemodynamic and oxygenation profiles and use of vasopressors at the end of shock, patients dying after the resolution of shock in multiple organ failure had a lower percentage of perfused small vessels than survivors (57.4 [46.6-64.9] vs. 79.3 [67.2-83.2]%; p =.02). Microcirculatory alterations improve rapidly in septic shock survivors but not in patients dying with multiple organ failure, regardless of whether shock has resolved.
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          How to evaluate the microcirculation: report of a round table conference

          Introduction Microvascular alterations may play an important role in the development of organ failure in critically ill patients and especially in sepsis. Recent advances in technology have allowed visualization of the microcirculation, but several scoring systems have been used so it is sometimes difficult to compare studies. This paper reports the results of a round table conference that was organized in Amsterdam in November 2006 in order to achieve consensus on image acquisition and analysis. Methods The participants convened to discuss the various aspects of image acquisition and the different scores, and a consensus statement was drafted using the Delphi methodology. Results The participants identified the following five key points for optimal image acquisition: five sites per organ, avoidance of pressure artifacts, elimination of secretions, adequate focus and contrast adjustment, and recording quality. The scores that can be used to describe numerically the microcirculatory images consist of the following: a measure of vessel density (total and perfused vessel density; two indices of perfusion of the vessels (proportion of perfused vessels and microcirculatory flow index); and a heterogeneity index. In addition, this information should be provided for all vessels and for small vessels (mostly capillaries) identified as smaller than 20 μm. Venular perfusion should be reported as a quality control index, because venules should always be perfused in the absence of pressure artifact. It is anticipated that although this information is currently obtained manually, it is likely that image analysis software will ease analysis in the future. Conclusion We proposed that scoring of the microcirculation should include an index of vascular density, assessment of capillary perfusion and a heterogeneity index.
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            Author and article information

            Affiliations
            [ ]Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215 USA
            [ ]The Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, 99 Brookline Ave., Boston, MA 02215 USA
            Contributors
            ORCID: http://orcid.org/0000-0001-9102-1963, mmassey@bidmc.harvard.edu
            nshapiro@bidmc.harvard.edu
            Journal
            Crit Care
            Critical Care
            BioMed Central (London )
            1364-8535
            1466-609X
            10 February 2016
            10 February 2016
            2015
            : 20
            26861691
            4748457
            1213
            10.1186/s13054-016-1213-9
            © Massey and Shapiro. 2016

            Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

            Funding
            Funded by: FundRef http://dx.doi.org/10.13039/100000050, National Heart, Lung, and Blood Institute;
            Award ID: R01-HL091757
            Award Recipient :
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            Review
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            © The Author(s) 2016

            Emergency medicine & Trauma

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