Autonomic cardiovascular and respiratory control during prolonged spaceflights aboard the International Space Station

Item Type:	Article
Title:	Autonomic cardiovascular and respiratory control during prolonged spaceflights aboard the International Space Station
Creators Name:	Baevsky, R.M. and Baranov, V.M. and Funtova, I.I. and Diedrich, A. and Pashenko, A.V. and Chernikova, A.G. and Drescher, J. and Jordan, J. and Tank, J.
Abstract:	Impaired autonomic control represents a cardiovascular risk factor during long-term spaceflight. Little has been reported on blood pressure (BP), heart rate (HR), and heart rate variability (HRV) during and after prolonged spaceflight. We tested the hypothesis that cardiovascular control remains stable during prolonged spaceflight. Electrocardiography, photoplethysmography, and respiratory frequency (RF) were assessed in eight male cosmonauts (age 41-50 yr, body-mass index of 22-28 kg/m2) during long-term missions (flight lengths of 162-196 days). Recordings were made 60 and 30 days before the flight, every 4 wk during flight, and on days 3 and 6 postflight during spontaneous and controlled respiration. Orthostatic testing was performed pre- and postflight. RF and BP decreased during spaceflight (P < 0.05). Mean HR and HRV in the low- and high-frequency bands did not change during spaceflight. However, the individual responses were different and correlated with preflight values. Pulse-wave transit time decreased during spaceflight (P < 0.05). HRV reached during controlled respiration (6 breaths/min) decreased in six and increased in one cosmonaut during flight. The most pronounced changes in HR, BP, and HRV occurred after landing. The decreases in BP and RF combined with stable HR and HRV during flight suggest functional adaptation rather than pathological changes. Pulse-wave transit time shortening in our study is surprising and may reflect cardiac output redistribution in space. The decrease in HRV during controlled respiration (6 breaths/min) indicates reduced parasympathetic reserve, which may contribute to postflight disturbances.
Keywords:	Autonomic nervous system, Microgravity, Spaceflight, Heart rate variability, Cardiovascular physiology
Source:	Journal of Applied Physiology
ISSN:	8750-7587
Publisher:	American Physiological Society
Volume:	103
Number:	1
Page Range:	156-161
Date:	1 July 2007
Official Publication:	https://doi.org/10.1152/japplphysiol.00137.2007
PubMed:	View item in PubMed

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