Does the FAA have some specific air ambulance safety guidelines to adhere to?
Check out this document published by the FAA which seems to be recent and some notes here on the same topics. The full rules can be found in the FAR at Part 135 Subpart L—Helicopter Air Ambulance Equipment, Operations, and Training Requirements
They are required to do a preflight risk analysis as per §135.617 but this is not really any different than what anyone should be doing before any flight however for them it is very specifically outlined.
(a) Each certificate holder conducting helicopter air ambulance operations must establish, and document in its operations manual, an FAA-approved preflight risk analysis that includes at least the following—
(1) Flight considerations, to include obstacles and terrain along the planned route of flight, landing zone conditions, and fuel requirements;
(2) Human factors, such as crew fatigue, life events, and other stressors;
(3) Weather, including departure, en route, destination, and forecasted;
(4) A procedure for determining whether another helicopter air ambulance operator has refused or rejected a flight request; and
(5) Strategies and procedures for mitigating identified risks, including procedures for obtaining and documenting approval of the certificate holder's management personnel to release a flight when a risk exceeds a level predetermined by the certificate holder.
(b) Each certificate holder must develop a preflight risk analysis worksheet to include, at a minimum, the items in paragraph (a) of this section.
(c) Prior to the first leg of each helicopter air ambulance operation, the pilot in command must conduct a preflight risk analysis and complete the preflight risk analysis worksheet in accordance with the certificate holder's FAA-approved procedures. The pilot in command must sign the preflight risk analysis worksheet and specify the date and time it was completed.
(d) The certificate holder must retain the original or a copy of each completed preflight risk analysis worksheet at a location specified in its operations manual for at least 90 days from the date of the operation.