how to open up a medical trust account

I would like to know how to open up a medical trust fund for both of my parents that were injured in a vehicle accident. Both of my parents are retired and on social security benefits including medical/medicare. My parents do not want their benefits jeopardized by receipt of this money as it is for the purpose of medical treatment if required in the future to help with their medical expenses as a direct result of their injuries. Would setting up a medical trust fund help avoid this situation? Any suggestions or recommendations would be appreciated.