The US Consulate lists hospitals that assert they are capable of giving assistance in English at the site here: http://amb-usa.fr/consul/acs/guide/DOC.PDF

A bit farther on they list doctors in private practice who claim to speak English. There are hospitals and doctors listed in Lyon - but I wouldn't count on finding a hospital or practice outside of Paris where English is the main language. This list simply means that the doctors in question speak English and will take English speaking patients and that the hospitals are prepared to treat anglophones.
Cheers,
Bev