Astronaut working on the outsdie of the International Space Station

Microgravity made some astronauts on the Worldwide Space Station expertise reversed blood flow.


Being in microgravity can have unusual results on the physique now it has emerged that it may well make peoples blood flow backwards.

The adjustments to circulation triggered two astronauts to develop small blood clots, which might have been deadly. Happily, although, the person and lady affected got here to no hurt.

The blood adjustments occurred in a vessel known as the left inside jugular vein, one in all two that usually transfer blood out of the top after we are mendacity down. After we are upright, they principally collapse to cease an excessive amount of blood from draining out of the top, with our circulation taking a distinct route by veins with extra resistance as an alternative.


On Earth, folks have often been noticed with backwards blood flow in the left inside jugular vein if there’s a blockage decrease down, comparable to from a tumour rising in their chest.

Microgravity is thought to vary peoples blood flow, so Karina Marshall-Goebel of KBR, an engineering, procurement and development firm based mostly in Texas, and her colleagues puzzled if it could additionally have an effect on this vein.

They carried out measurements and ultrasound scans of the blood vessel in 9 males and two ladies on the bottom earlier than and after their missions on the Worldwide Space Station. The astronauts took measurements 50 and 150 days into their flights.

In two of the astronauts, the blood flow was backwards maybe as a result of the dearth of gravity triggered organs in the chest to shift round, urgent on the vein decrease down, says Marshall-Goebel. She provides that this vein is predisposed to be blocked based mostly on the place it lies in the physique.

In one other 5 members of the crew, blood in this vein was kind of stagnant, and in one in all these, the scan revealed a clot blocking the vessel. That was positively alarming, says Marshall-Goebel. Blood clots will be deadly in the event that they get carried to the lungs, so the particular person started taking blood-thinning medicines to interrupt it down.

Due to this shock discovering, the staff requested a panel of specialists to evaluation all of the earlier scans and one other small clot was noticed in one astronaut who had already returned to Earth.

The staff additionally had the contributors check a tool on the space station that encases their decrease physique in a chamber with decrease air strain for an hour to suck extra blood into their legs. They discovered that this improved blood flow in 10 of 17 assessments, however worsened it in two.

Marshall-Goebel says the findings could trigger feminine astronauts to rethink taking the contraceptive tablet to suppress their durations whereas on the space station, as this raises the chance of blood clots.

The 2 astronauts in this research who had a clot included one man and one lady, though the staff arent giving any additional particulars to guard their privateness.

Journal reference: JAMA Community Open, DOI: 10.1001/jamanetworkopen.2019.15011

Article amended on
18 November 2019

This story was amended as astronauts on the Worldwide Space Station expertise microgravity

Extra on these matters:


Please enter your comment!
Please enter your name here