In my setting, kinetic firearms are the handheld weaponry of choice for most people, despite centuries of technological advancement (and stagnation, somewhat). These range from chemical-propelled guns to electromagnetic guns, each with their own advantages. In practice, except for specialized weapons, the receiving end of these firearms suffer similar amounts of damage to what one might expect from real-life guns.
In addition, a significant fraction of the human population across all inhabited star systems live in small space space stations or in spacecraft, where they often deal with low and zero gravity. There are many physiological issues that arise from these environments, but most of them have solutions or workarounds. Said solutions reflect a near-future level of technological sophistication, and include such things as lab-grown synthetic foods and nutritional/hormonal supplements, all of which I have figured out plausible explanations for. However...
Injuries do not heal well in microgravity, much less debilitating injuries, and as of now there don't seem to be any definitive real-life solution for this. But the more daring of these space-dwelling "spacers" often find themselves with such injuries, which include gunshot wounds from the previously mentioned firearms. Anything from a stray shotgun pellet to the back to a sniper round through the rib would not heal properly in microgravity without assistance, and left untreated could kill the victim, but artificial gravity sources such as centrifuges can sometimes be unavailable. After all, your ship's propulsion systems may have been damaged in the same fight that earned you a gunshot wound, leaving you stranded far form any centrifuge station. Built-in centrifuges and spin tethers can also be expensive to install on a ship, and most opt out of such features.
How, then, would spacers go about treating serious wounds during extended stays in microgravity? What sort of realistic technological solutions for this might one find in, say, a zero-g first aid kit?