Did several months in S.America a few years back, with a group of 15 Europeans. Altiplano to Amazon
The injuries we had to deal with were
A broken wrist
A broken collarbone
A Diabetic coma
HACE
Hypothermia
Sandfly bites (Industrial)
Mozzie bites (Industrial)
cuts, scrapes, grazes,
Sunburn
Thrush
Colds
and lots of diorear (spelling) and its side effects of dehydration, so lots of Immodium and Dyralite
We went to hospital in Equador, Peru, Bolivia and Chile.
As long as you have the money, the hospitals were as good as the NHS
Only real issue is the hospitals are a long way apart.
The Collarbone was 9hrs in a dug out canoe, followed by 12 hrs in a 4X4 along jungle tracks before being treated by the ex presidents personal doctor, US trained, who had been exiled to a remote, but very good, hospital.
The broken wrist we splinted with chrome trim off the side of a truck which was OK until we arrived at a town with a hospital 3 days later
The Diabetic coma, HACE and Hypothermia we dealt with ourselves
The system in the hospitals is 'pay as you go'
Walk in, see the nurse, she says broken wrist. pay the nurse.
go to xray, pay for xray
take xray to doctor, he says broken wrist, pay doctor
get local anisthetic, pay anithitist
go to bone setter to set bone, pay bone setter
go to plaster of paris dept. pay plasterer
go to sling fitter, pay for sling and fitting
pay porter who has been wheeling around patient like a taxi with whatever is on his "meter"
It's a system. it works pretty well. As long as you have money (cash, Yankee dollars prefered).
Forget the insurance, that is what the receipts are for later. They don't take credit cards unless it's several nights stay or you need to pay surgeons
So bottom line is a good, travel 1st aid kit, with bandages, padding, micropore, take normal pain killers, gloves, lemsip, savlon, plasters lots of serious relief for bites and dealing with upset tummy and it's side effects and no harm in doing a 1st aid course and get the manual
With the possible exception of syringes (which are easy and cheap to get here) I would not bother with any 1st aid kit that you can't use yourself.
I'd strongly suggest best place to get the kit is Nomad Travel
http://www.nomadtravel.co.uk/pages/nomad-travel-clinics
You pay slightly over the odds, but it's good stuff
PS - Don't take any medicines that look like white powder, can cause serious problems with the customs officers