My first aid kit is a self named trauma kit. This way if I say 'go get the trauma kit', we know what bag will show up. I don't need a first aid kit that fits in a glove box unless I need a bandage for a splinter.
The IV solution in my trauma kit expired in November. It's a standard saline solution so I'm not worried about what the bag says (as long as the fluid looks clear and everything is sealed), but since the entire kit often rides around in one of the vehicles I replaced both of them. Extreme vehicle temperatures can degrade packaging and I can't guarantee the kits would continue to be sterile.
Bandages like smaller bandaids that aren't packaged well will often separate and the bandage is no longer sterile. Packing your bandages in zip locks is a good idea, a vacuum sealer is a better solution. We have bandages ranging from 8x8 to small butterfly closures. I checked each bandage pack or baggie to make sure everything looked good and nothing appeared dried out.
Makeshift splints should be in your bag should you need to immobilize an arm, finger, elbow or knee. The free paint stirring sticks at Home Depot or Lowes work great for this. If you need a larger splint just find a large tree branch. Broken bones do not normally cause infection, but foreign material (bacteria) entering an external break wound site can easily cause an infection. Infections will cause recovery (and proper treatment) to be prolonged. If there is an open fracture, antibiotics should be started right away, general antibiotics since in a SHTF scenario you wont be able to know what kind of bacteria is causing the infection. Open fractures in a long term shtf situation will have a very high mortality rate as they need surgery to be aligned properly. An internal break can often be pressed back into position (as close as possible anyhow) so it can heal (it will never be the same but hopefully better than useless).
Need to clean a wound out? Make a small hole in the cap of a plastic water bottle and you have a pressure wash. Before you make a hole you should use sterilize the knife, bottle top and your hands as best as you are able to.
Suture kits are often packaged similar to single bandaids so we check to make sure they are intact. Don't now how to suture? Easy, practice on some chicken breast, pig leg, vinyl scrap, etc. The average suture is 1/2 in apart to allow the wound to drain. The suture doesn't need to be one long strip like you would use sewing, each 1/2 inch stitch can be an individual stitch, just make sure you have a good knot (doesn't even need to be pretty as long as it holds). Dissolvable stitches are a great way to stitch and forget, but if the wound is deep it will often take longer to heal and normal sutures are the best bet.
If you are going to suture, you should have some sort of topical like lidocaine. You can use ice from the freezer to numb an area (snow or cold stream water will also work), be sure to sterilize and dry the wound again. You might have to buy it from an online Canadian pharmacy, but I get mine from the states without a license as they say is required, most places just ship. Once again, antibiotics are a good idea if you need to stitch someone up.
Rubbing alcohol, peroxide, sterile wipes, hand cleaner, bar/liquid soap, wraps, pads, tweezers, scalpel, iodine, bandaids, quick clot, tourniquet, eye wash, rubber gloves, antibiotics, etc. There are a lot of things you could/should have. I bet I get into my trauma bag 8 times a year, mainly for tweezers or nail clippers while we are out in the woods doing whatever.
I've been unlucky and broke my leg and foot. The positive side to this is we have aluminum crutches and a walking boot at home.
Check dates, conditions, quantities and make sure you know how to use it. As with all things, now is the time to check/stock, it sucks to need something as small as a finger bandaid and you don't have anything.
Cheerful subject, I know.