[swatsurgeon]

field anesthesia dpends on, what you would expect, what is available to you.
I carried both local anesthetics as well as IV analgesics and sedatives.
For local anethesia, I like 0.5% lidocaine with epinephrine, 1:200,000.
Remember with lidocaine, there is a toxic level/dosing that you don't want to exceed.
1% has 10 mg of lido per mL
0.5% has 5 mg/mL
we try to stay below 5-6mg/kg, with 7 mg/kg being truly toxic, therefore just do the math....the average 70 kg person can "safely" receive ~350-420mg...translation 35-42 mL of 1% lidocaine.
In the field I try to balance local with IV. The body is already hyped up and pain is a funny thing when you're that hyped, it doesn't always hurt as much as we expect it to under normal circumstances and I take advantage of that.....meaning use what I have to in the field not what I preconceive as needing in the operating room.
Technique: IV morphine or fentanyl, titrate to get them in space, give IV versed 2-5 mg, or Ketamine ~100mg, be ready to support respirations, inject lido 0.5% with epi around skin edges, wait 2 minutes for lido effect, re-inject only when pain found/caused by what I am doing, titrate the IV drugs, give until in farther in space, keep cutting...faster is better. When down to bone, inject the periosteum (covering of bone) then saw through. Make sure you know anatomy so you can clamp major vessels before cutting them (if possible),....all done under tourniquet!!
this is a brief review but brings out some important points.
Sometimes you have nothing but a knife and tourniquet...it sucks but life over limb and a limb under tight tourniquet will dull sensation.
I hope you never have to do this to someone but if you do, do it right.