Chirurgeons in the SCA
A chirurgeon is a first-aid officer within the SCA. If there are any first-aid issues that need to be tended to, then these are the people you see. Chirurgeons must hold at least a level 2 first-aid certificate, and report any incidents that occur during an event. In the United States, a basic First Aid card issued by the American Red Cross, American Heart Association or AHSI and and certification in adult CPR are the minimum requirements. Although many Chirurgeons hold mundane medical certifications and licenses.
Chirurgeons are all volunteers who provide first-aid. If serious medical attention is required, a chirurgeon can/will call for Emergency Medical Services or recommend that the patient seek medical care on their own. By limiting their services to First Aid, Chirurgeons, in the US at least, are generally protected by "Good Samaritan" laws.
Also, a chirurgeon may only enter a field of combat at the request of a marshal. Likewise, the laws are written in such a way that a chirurgeon is urged to get injured people off the battlefield as fast as possible. Of course, that is not always possible. In some locales, Chirurgeons are encouraged to become warranted as Amroured Combat Marshalls to allow them to better co-ordinate the care provided on the field of battle.
Society Chirurgeon (USA): http://www.sca.org/officers/chirurgeon/
The Chirurgeon's Point: http://www.chirurgeon.org/