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      Abnormal blood flow in the sublingual microcirculation at high altitude

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      Author(s): 1 , , 2 , 2 , 1 , 1 , for the Caudwell Xtreme Everest Research Group
      Publication date (Electronic):
      Journal: European Journal of Applied Physiology
      Publisher: Springer-Verlag
      Keywords: Hypoxia, Microcirculation, Altitude, Oxygen

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          Abstract

          We report the first direct observations of deranged microcirculatory blood flow at high altitude, using sidestream dark-field imaging. Images of the sublingual microcirculation were obtained from a group of 12 volunteers during a climbing expedition to Cho Oyu (8,201 m) in the Himalayas. Microcirculatory flow index (MFI) was calculated from the moving images of microcirculatory red blood cell flow, and comparison was made between the baseline and high altitude measurements. Peripheral oxygen saturation (SpO 2) and Lake Louise scores (LLS) were recorded along with MFI. Our data demonstrate that there was a significant reduction in MFI from baseline to 4,900 m in small (less than 25 μm) and medium (26–50 μm) sized blood vessels ( P = 0.025 and P = 0.046, respectively). There was no significant correlation between MFI and SpO 2 or MFI and LLS. Disruption of blood flow within microcirculatory may explain persistent abnormal oxygen flux to tissues following the normalisation of systemic oxygen delivery that accompanies acclimatisation to high altitude.

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          Quantifying bedside-derived imaging of microcirculatory abnormalities in septic patients: a prospective validation study

          E. Boerma, Keshen Mathura, Peter HJ van der Voort … (2005)
          Introduction The introduction of orthogonal polarization spectral (OPS) imaging in clinical research has elucidated new perspectives on the role of microcirculatory flow abnormalities in the pathogenesis of sepsis. Essential to the process of understanding and reproducing these abnormalities is the method of quantification of flow scores. Methods In a consensus meeting with collaboraters from six research centres in different fields of experience with microcirculatory OPS imaging, premeditated qualifications for a simple, translucent and reproducible way of flow scoring were defined. Consecutively, a single-centre prospective observational validation study was performed in a group of 12 patients with an abdominal sepsis and a new stoma. Flow images of the microcirculation in vascular beds of the sublingual and stoma region were obtained, processed and analysed in a standardised way. We validated intra-observer and inter-observer reproducibility with kappa cross-tables for both types of microvascular beds. Results Agreement and kappa coefficients were >85% and >0.75, respectively, for interrater and intrarater variability in quantification of flow abnormalities during sepsis, in different subsets of microvascular architecture. Conclusion Semi-quantitative analysis of microcirculatory flow, as described, provides a reproducible and transparent tool in clinical research to monitor and evaluate the microcirculation during sepsis.
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            Microvascular alterations in patients with acute severe heart failure and cardiogenic shock.

            Yasser Sakr, Jean-Louis Vincent, Jacques Creteur … (2003)
            Microvascular blood flow alterations may impair tissue oxygenation and may participate in the development of multiple organ failure in patients with severe heart failure. We hypothesized that microvascular blood flow alterations are present in patients with severe heart failure and cardiogenic shock. We used an orthogonal polarization spectral imaging technique to investigate the sublingual microcirculation in 40 patients with acute severe heart failure, including 31 patients with cardiogenic shock, and in a control group of 15 patients who were examined the day before cardiac surgery. The effects of topical application of acetylcholine (10-2M) were also tested in 5 patients with cardiogenic shock. Five sublingual areas were recorded, allocated a random number, and later analyzed semiquantitatively. Data were analyzed with non-parametric tests and presented as medians (percentiles 25-75). The density of all the vessels was similar in the 3 groups. The proportion of perfused small (<20 microm) vessels was lower in patients with cardiac failure and cardiogenic shock than in control patients (63% [46%-65%] and 49% [38%-64%] vs 92% [90%-93%], P <.001). The perfusion of large vessels was preserved in all groups. The proportion of perfused vessels was higher in patients who survived than in patients who did not survive in all vessels (90% [84%-93%] vs 81% [74%-87%], P <.05) and in small vessels (64% [49%-68%] vs 43% [37%-62%], P <.05). The topical application of acetylcholine totally reversed these alterations Microvascular blood flow alterations are frequently observed in patients with severe heart failure and are more severe in patients who do not survive.
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              Maximal exercise at extreme altitudes on Mount Everest.

              J Milledge, F Sarnquist, David S. Boyer … (1983)
              Maximal exercise at extreme altitudes was studied during the course of the American Medical Research Expedition to Everest. Measurements were carried out at sea level [inspired O2 partial pressure (PO2) 147 Torr], 6,300 m during air breathing (inspired PO2 64 Torr), 6,300 m during 16% O2 breathing (inspired PO2 49 Torr), and 6,300 m during 14% O2 breathing (inspired PO2 43 Torr). The last PO2 is equivalent to that on the summit of Mt. Everest. All the 6,300 m studies were carried out in a warm well-equipped laboratory on well-acclimatized subjects. Maximal O2 uptake fell dramatically as the inspired PO2 was reduced to very low levels. However, two subjects were able to reach an O2 uptake of 1 l/min at the lowest inspired PO2. Arterial O2 saturations fell markedly and alveolar-arterial PO2 differences increased as the work rate was raised at high altitude, indicating diffusion limitation of O2 transfer. Maximal exercise ventilations exceeded 200 l/min at 6,300 m during air breathing but fell considerably at the lowest values of inspired PO2. Alveolar CO2 partial pressure was reduced to 7-8 Torr in one subject at the lowest inspired PO2, and the same value was obtained from alveolar gas samples taken by him at rest on the summit. The results help to explain how man can reach the highest point on earth while breathing ambient air.
              Article 0 comments Cited 27 times – based on 0 reviews     Review now
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                Author and article information

                Contributors
                : +44-780-1444428 , dan.s.martin@gmail.com
                Journal
                Journal ID (nlm-ta): Eur J Appl Physiol
                Title: European Journal of Applied Physiology
                Publisher: Springer-Verlag (Berlin/Heidelberg )
                ISSN (Print): 1439-6319
                ISSN (Electronic): 1439-6327
                Publication date (Electronic): 31 March 2009
                Publication date (Print): June 2009
                Volume: 106
                Issue: 3
                Pages: 473-478
                Affiliations
                [1 ]Centre for Altitude, Space and Extreme Environment Medicine (CASE Medicine), UCL Institute of Human Health and Performance, First Floor, Charterhouse Building, Archway Campus, Highgate Hill, London, N19 5LW UK
                [2 ]Department of Physiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
                Article
                Publisher ID: 1023
                DOI: 10.1007/s00421-009-1023-8
                PMC ID: 2688617
                PubMed ID: 19333616
                SO-VID: a2a863ee-6918-4c62-87f5-ec9798f10463
                Copyright © © The Author(s) 2009
                History
                Date accepted : 16 February 2009
                Categories
                Subject: Short Communication
                Custom metadata
                issue-copyright-statement © Springer-Verlag 2009

                ScienceOpen disciplines: Anatomy & Physiology
                Keywords: microcirculation,oxygen,hypoxia,altitude
                Data availability:
                ScienceOpen disciplines: Anatomy & Physiology
                Keywords: microcirculation, oxygen, hypoxia, altitude

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