I have two first aid kits. The large one weights about 430g (~1lb.) The small one which reflects my ultralight backpacking weight reduction thoughts is 100g (~0.22 lb)
The major diferences to get the weight reduction:
the elimination of the triangular bandage and Sepnco ace bandage.
switch from a large (2"x4"x6" zippered case) to a ziplock
and reduced quantities.
In both cases, I do not include tools like tweezers, needles, water purification, as they are in my ditty bag. Also, I keep the Ibuprofen in the ditty to keep from entering the FAK frequently.
Some conditional additions:
For 3rd world countries, I add a drug kit that weighs up to 1/2 to 1 pound...it includes precription meds like Cipro and non prescription meds like enough drugs to deal with a one week cold, sore throat, or the flu. (My regular kit only includes small supplies of Benedril, ammonium, and potasium.) For altitude, I add diamox. For longer trips (over 1 week) I add extra blister stuff, bandaids, tape... Usually not needed
For me, these kits reflect a comfortable level of preparedness based on the assumption of improvising as per the training. Having evac'ed 2 broken arms and two broken legs, as well dealing as the routine cuts bruises etc...I'm okay going into most routine emergencies with what I have.
What does scare the crap out of me is serious trama (requiring spinal precautions) such as a 30+foot fall, or sudden illness such as stroke or cardiac problems. I'm not sure how to improve my FAK to better deal with these emergencies with the addition of up to 1/2 pound. Mostly because it's way over my head and what I really need is a hospital....Haven't figured out how to carry that one yet. I think higher chances of success in these situations are more likely to occur with the addition of another FA qualified member in the group rather than more gear. One person can only do so much - airway, monitor vitals, manage the scene, do the FA, plan the evac,
communicate with the authorities....I'm getting tired already.