Long-duration spaceflight alters estimated intracranial pressure and cerebral blood velocity
Name
JP280318.pdf
Description
Published version
Size
753.52 KB
Format
Adobe PDF
Checksum (MD5)
cd323d1e9f3cd193d97955c7e12d33e9
Author(s)
Imaduddin, Syed M
Heldt, Thomas
Date Issued
October 2020
Journal
Journal of Physiology
Publisher
Wiley
Citation
Iwasaki, Ken-ichi et al. “Long-duration spaceflight alters estimated intracranial pressure and cerebral blood velocity.” Journal of Physiology (October 2020): 1-15 © 2020 The Author(s)
Version
Final published version
Abstract
Persistently elevated intracranial pressure (ICP) above upright values is a suspected cause of optic disc oedema in astronauts. However, no systematic studies have evaluated changes in ICP from preflight. Therefore, ICP was estimated non-invasively before and after spaceflight to test whether ICP would increase after long-duration spaceflight. Cerebral blood velocity in the middle cerebral artery (MCAv) was obtained by transcranial Doppler sonography and arterial pressure in the radial artery was obtained by tonometry, in the supine and sitting positions before and after 4−12 months of spaceflight in 11 astronauts (10 males and 1 female, 46 ± 7 years old at launch). Non-invasive ICP (nICP) was computed using a validated model-based estimation method. Mean MCAv increased significantly after spaceflight (ANOVA, P = 0.007). Haemoglobin decreased significantly after spaceflight (14.6 ± 0.8 to 13.3 ± 0.7 g/dL, P < 0.001). A repeated measures correlation analysis indicated a negative correlation between haemoglobin and mean MCAv (r = −0.589, regression coefficient = −4.68). The nICP did not change significantly after spaceflight in the 11 astronauts. However, nICP decreased significantly by 15% in nine astronauts without optic disc oedema (P < 0.005). Only one astronaut increased nICP to relatively high levels after spaceflight. Contrary to our hypothesis, nICP did not increase after long-duration spaceflight in the vast majority (>90%) of astronauts, suggesting that the cephalad fluid shift during spaceflight does not systematically or consistently elevate postflight ICP in astronauts. Independently of nICP and ocular alterations, the present results of mean MCAv suggest that long-duration spaceflight may increase cerebral blood flow, possibly due to reduced haemoglobin concentration.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Institute for Medical Engineering & Science
Terms of Use
Creative Commons Attribution NonCommercial License 4.0
Persistent DSpace Link
DOI of Published Version
10.1113/JP280318
