Author:
Mastrandrea C. J.,Greaves D. K.,Shoemaker J. K.,Blaber A. P.,Arbeille P.,Hughson R. L.
Abstract
AbstractCardiovascular deconditioning and altered baroreflexes predispose returning astronauts to Orthostatic Intolerance. We assessed 7 astronauts (1 female) before and following long-duration spaceflight (146 ± 43 days) with minimal upright posture prior to testing. We applied lower body negative pressure (LBNP) of up to − 30 mmHg to supine astronauts instrumented for continual synchronous measurements of cardiovascular variables, and intermittent imaging the Portal Vein (PV) and Inferior Vena Cava (IVC). During supine rest without LBNP, postflight elevations to total peripheral resistance (TPR; 15.8 ± 4.6 vs. 20.8 ± 7.1 mmHg min/l, p < 0.05) and reductions in stroke volume (SV; 104.4 ± 16.7 vs. 87.4 ± 11.5 ml, p < 0.05) were unaccompanied by changes to heart rate (HR) or estimated central venous pressure (CVP). Small increases to systolic blood pressure (SBP) and diastolic blood pressure (DBP) were not statistically significant. Autoregressive moving average modelling (ARMA) during LBNP did not identify differences to either arterial (DBP → TPR and SBP → HR) or cardiopulmonary (CVP → TPR) baroreflexes consistent with intact cardiovascular control. On the other hand, IVC and PV diameter-CVP relationships during LBNP revealed smaller diameter for a given CVP postflight consistent with altered postflight venous wall dynamics.
Funder
Natural Sciences and Engineering Research Council of Canada
Canadian Space Agency
Centre National d’Etudes Spatiales
Publisher
Springer Science and Business Media LLC
Reference48 articles.
1. Stenger, M. B. et al. Risk of Orthostatic Intolerance During Re-exposure to Gravity. (NASA Evidence Report, 2015).
2. Meck, J. V., Reyes, C. J., Perez, S. A., Goldberger, A. L. & Ziegler, M. G. Marked exacerbation of orthostatic intolerance after long- vs. short-duration spaceflight in veteran astronauts. Psychosom. Med. 63, 865–873 (2001).
3. Lee, S. M. C., Feiveson, A. H., Stein, S., Stenger, M. B. & Platts, S. H. Orthostatic intolerance after ISS and space shuttle missions. Aerosp. Med. Hum. Perform. 86, A54–A67 (2015).
4. Wood, K. N., Murray, K. R., Greaves, D. K. & Hughson, R. L. Inflight leg cuff test does not identify the risk for orthostatic hypotension after long-duration spaceflight. NPJ Microgravity https://doi.org/10.1038/s41526-019-0082-3 (2019).
5. NASA. HRR-Risk-Risk of Orthostatic Intolerance During Re-Exposure to Gravity. https://humanresearchroadmap.nasa.gov/Risks/risk.aspx?i=86 (2020).