I heard an unsourced claim about wounds, bruises and internal bleeding healing much worse in 0g conditions than in normal gravity. Is it true? And if so - could you provide a quantitative comparison, how much worse it is?
$\begingroup$ The reason why internal bleeding (not so much just bruises) is worse is because the blood doesn’t have a constant g-field forcing it to “drain” into other parts of the body where it will be cleaned up. The blood just collects at the rupture site, causing more problems. I don’t have a source for this, but I think it would make injuries that normally only require bed rest and physical therapy require invasive surgery. $\endgroup$– CourageousPotatoMay 26, 2019 at 22:57
It's a lot worse in space than on land. Quantitative studies on wound healing in zero g haven't really been done as of about 2013 (the latest paper I could find). However, there are some sources that explain some of the issues. The first one, here, talks about how astronauts say that minor wounds don't heal until they are back on Earth (sorry, the exact definition of "minor" is missing from that article, but this article describes it as a "small nick"). Another source, here, uses the number 100mL/min, which is sourced in that article as being something of a point of no return where the crew member probably would not survive, presumably due to blood loss as clotting won't happen. That article also talks about some practical issues of how blood would spray in the spacecraft or potentially pool around the wound, obscuring vision and making surgery much more difficult. The original article for the 100mL/min claim is here, and it has a bunch more information with specific numbers about mortality.
The latest paper I've been able to find here is behind a paywall, but the abstract states that little is known about zero-g wound healing.
7$\begingroup$ Incidentally, this was a big plot point in season 3 of The Expanse. $\endgroup$ May 27, 2019 at 1:04
$\begingroup$ Somehow I think I don't want to go into space unless/until they build a nice big ring with artificial gravity... $\endgroup$– AnoEDec 15, 2021 at 9:40