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Changes in sublingual microcirculatory flow index and vessel density on ascent to altitude

Changes in sublingual microcirculatory flow index and vessel density on ascent to altitude
Changes in sublingual microcirculatory flow index and vessel density on ascent to altitude
We hypothesized that ascent to altitude would result in reduced sublingual microcirculatory flow index (MFI) and increased vessel density. Twenty-four subjects were studied using sidestream dark-field imaging, as they ascended to 5300 m; one cohort remained at this altitude (n = 10), while another ascended higher (maximum 8848 m; n = 14). The MFI, vessel density and grid crossings (GX; an alternative density measure) were calculated. Total study length was 71 days; images were recorded at sea level (SL), Namche Bazaar (3500 m), Everest base camp (5300 m), the Western Cwm (6400 m), South Col (7950 m) and departure from Everest base camp (5300 m; 5300 m-b). Peripheral oxygen saturation (SpO2), heart rate and blood pressure were also recorded. Compared with SL, altitude resulted in reduced sublingual MFI in small (<25 µm; P < 0.0001) and medium vessels (26-50 µm; P = 0.006). The greatest reduction in MFI from SL was seen at 5300 m-b; from 2.8 to 2.5 in small vessels and from 2.9 to 2.4 in medium-sized vessels. The density of vessels <25 µm did not change during ascent, but those >25 µm rose from 1.68 (± 0.43) mm mm-2 at SL to 2.27 (± 0.57) mm mm-2 at 5300 m-b (P = 0.005); GX increased at all altitudes (P < 0.001). The reduction in MFI was greater in climbers than in those who remained at 5300 m in small and medium-sized vessels (P = 0.017 and P = 0.002, respectively). At 7950 m, administration of supplemental oxygen resulted in a further reduction of MFI and increase in vessel density. Thus, MFI was reduced whilst GX increased in the sublingual mucosa with prolonged exposure to hypoxia and was exaggerated in those exposed to extreme altitude.
0958-0670
880-891
Martin, Daniel S.
3e441b48-9221-4308-8ae6-49cbde20753f
Goedhart, Peter
4e176e15-9890-4885-a19e-21336e4e4135
Vercueil, Andre
2c8603fa-d72f-47ab-9cda-3a15f8e49867
Ince, Can
e90ab828-f27d-408a-9392-d6f795f8752b
Levett, Denny Z.H.
4b33b751-32be-4fa3-aaf7-b62e62f08de8
Grocott, Mike P.W.
1e87b741-513e-4a22-be13-0f7bb344e8c2
Caudwell Xtreme Everest Research Group
Martin, Daniel S.
3e441b48-9221-4308-8ae6-49cbde20753f
Goedhart, Peter
4e176e15-9890-4885-a19e-21336e4e4135
Vercueil, Andre
2c8603fa-d72f-47ab-9cda-3a15f8e49867
Ince, Can
e90ab828-f27d-408a-9392-d6f795f8752b
Levett, Denny Z.H.
4b33b751-32be-4fa3-aaf7-b62e62f08de8
Grocott, Mike P.W.
1e87b741-513e-4a22-be13-0f7bb344e8c2

Martin, Daniel S., Goedhart, Peter, Vercueil, Andre, Ince, Can, Levett, Denny Z.H. and Grocott, Mike P.W. , Caudwell Xtreme Everest Research Group (2010) Changes in sublingual microcirculatory flow index and vessel density on ascent to altitude. Experimental Physiology, 95 (8), 880-891. (doi:10.1113/expphysiol.2009.051656). (PMID:20418348)

Record type: Article

Abstract

We hypothesized that ascent to altitude would result in reduced sublingual microcirculatory flow index (MFI) and increased vessel density. Twenty-four subjects were studied using sidestream dark-field imaging, as they ascended to 5300 m; one cohort remained at this altitude (n = 10), while another ascended higher (maximum 8848 m; n = 14). The MFI, vessel density and grid crossings (GX; an alternative density measure) were calculated. Total study length was 71 days; images were recorded at sea level (SL), Namche Bazaar (3500 m), Everest base camp (5300 m), the Western Cwm (6400 m), South Col (7950 m) and departure from Everest base camp (5300 m; 5300 m-b). Peripheral oxygen saturation (SpO2), heart rate and blood pressure were also recorded. Compared with SL, altitude resulted in reduced sublingual MFI in small (<25 µm; P < 0.0001) and medium vessels (26-50 µm; P = 0.006). The greatest reduction in MFI from SL was seen at 5300 m-b; from 2.8 to 2.5 in small vessels and from 2.9 to 2.4 in medium-sized vessels. The density of vessels <25 µm did not change during ascent, but those >25 µm rose from 1.68 (± 0.43) mm mm-2 at SL to 2.27 (± 0.57) mm mm-2 at 5300 m-b (P = 0.005); GX increased at all altitudes (P < 0.001). The reduction in MFI was greater in climbers than in those who remained at 5300 m in small and medium-sized vessels (P = 0.017 and P = 0.002, respectively). At 7950 m, administration of supplemental oxygen resulted in a further reduction of MFI and increase in vessel density. Thus, MFI was reduced whilst GX increased in the sublingual mucosa with prolonged exposure to hypoxia and was exaggerated in those exposed to extreme altitude.

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Published date: August 2010
Organisations: Human Development & Health

Identifiers

Local EPrints ID: 348908
URI: http://eprints.soton.ac.uk/id/eprint/348908
ISSN: 0958-0670
PURE UUID: a8cd2b84-f273-48b0-945a-a39264d3292d
ORCID for Mike P.W. Grocott: ORCID iD orcid.org/0000-0002-9484-7581

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Date deposited: 22 Feb 2013 08:48
Last modified: 15 Mar 2024 03:33

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Contributors

Author: Daniel S. Martin
Author: Peter Goedhart
Author: Andre Vercueil
Author: Can Ince
Author: Denny Z.H. Levett
Corporate Author: Caudwell Xtreme Everest Research Group

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