Fig1: Typical still image captured from video footage of sublingual microcirculatory blood flow at baseline (75 m)

Mentions: A complete data set of microcirculatory images was obtained from all 12 subjects at baseline and 4,900 m. Images were also obtained in subgroups ascending higher, with nine sets of images at 5,600 m and four at 6,400 m. The SDF camera recorded images faultlessly at the maximum altitude (6,400 m). Typical images captured from the same subject at baseline (75 m) and high altitude (4,900 m) can be seen in Figs. 1 and 2, respectively. An example of video footage of sublingual microcirculatory blood flow from the same subject at baseline (75 m) and 6,400 m on Cho Oyu can be found on http://www.sdfimaging.net/dsmsealevelmicrocirc.wmv and http://www.sdfimaging.net/dsm6400metermicrocirc.wmv.Fig. 1

Martin DS, Ince C, Goedhart P, Levett DZ, Grocott MP, Caudwell Xtreme Everest Research Gro - Eur. J. Appl. Physiol. (2009)

Bottom Line: Our data demonstrate that there was a significant reduction in MFI from baseline to 4,900 m in small (less than 25 microm) and medium (26-50 microm) 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.

Affiliation: 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. dan.s.martin@gmail.com

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 microm) and medium (26-50 microm) 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.