Long duration weightlessness in space induces a blood shift

International Space Station
International Space Station. Credits: ESA

In a study published today in The Journal of Physiology, researchers found that in space, the shift of blood and fluid from the lower to the upper body caused by weightlessness is much higher and the blood pressure much lower than previously thought.

Researchers measured the volume of blood ejected by the heart into the and monitored the in eight astronauts aged between 45-53 years during a 24 h period with portable equipment. Recordings were taken before, during and after 3-6 months of spaceflight. A was also collected to analyse the nervous regulation of the cardiovascular system.

The team of researchers found that the shift of blood and fluid from the lower to the upper body caused by weightlessness was much higher than previously thought. The burden to the heart was also more than expected despite the heart rate remaining the same. At the same time, blood pressure was considerably reduced by 10 mmHg, which corresponds to the effect of normal against .

Dr Peter Norsk, lead author of the study says: "The discovery is important because during long duration missions, the blood volume burden to the heart could constitute a health problem during future long duration missions. We know that some astronauts experience vision problems some months into spaceflight and this may in fact be caused by the augmented fluid and blood volume shift to the upper body.

Although the blood volume burden to the heart is higher than expected, blood pressure is lower because the blood vessels are more relaxed (dilated). This is actually good for the body and the blood vessels.Thus, there are one or more spaceflight factors leading to these changes, which haven't been identified yet. In the future, the spaceflight factors that induce the fluid shifts and relaxation (dilatation) of the blood vessels should be identified."

Explore further

Blood pressure drugs help keep heart trouble at bay, FDA says

More information: Norsk P, Asmar A, Damgaard M & Christensen NJ (2015) Fluid Shifts, Vasodilatation and Ambulatory Blood Pressure Reduction during Long Duration Spaceflight. J Physiol DOI: 10.1113/jphysiol.2014.284869
Journal information: Journal of Physiology

Provided by Wiley
Citation: Long duration weightlessness in space induces a blood shift (2015, January 14) retrieved 17 September 2019 from https://medicalxpress.com/news/2015-01-duration-weightlessness-space-blood-shift.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more