I worked as a nurse for the Indian Health Service for 6 years in the past. Where I worked-the Navajo Reservation- there are several clinics and health centers and 4 hospitals - Tuba City, Chinle, Fort Defiance and Gallup.
Care at these facilities is free to any registered member of a tribe that is recognized by the US Federal government.
Access issues that I am aware of - one of the biggest access issues on the reservation is transportation to the health facilities. Many people live in EXTREMELY isolated areas and have no reliable transportation. This is a barrier to people who needed care for chronic conditions (diabetes, HTN, etc) and for routine prenatal care visits.
There is an EMS system, but many people do not have telephones, requiring people in need of emergency care to travel to the nearest store, trading post, etc. to activate the EMS system. When EMT's are dispatched they often have to travel long distances over muddy, holey dirt roads to get to the patient, which may greatly reduce the likelihood that a trauma or heart attack patient will survive.
Another access issue- many of the Navajo elders do not speak English well, if at all. Navajo was not traditionally a written language, though there is a written version, but I do not believe that many Navajo elders read Navajo.
There is little to no written teaching materials in Navajo, or other Native American languages.
Most healthcare professionals working on the Navajo Res (doctors, RN's, pharmacists)are Anglo (non-Indian) and do not speak Navajo- it is a very difficult language to learn. So these healthcare professionals have to communicate with non-English speaking patients through available interpretors - unit secretaries, nursing assistants, LPN's, family members, or anyone handy who speaks Navajo. As there are no medical terms in Navajo using someone with little medical knowledge to interpret can get rather dicey.
When I was last on the Rez (3 years ago) there was no certification program for Navajo interpreters, similar to certification for those who interpret in sign language for hearing impaired people.
So here are 2 access issues - transportation and language. Hope this helps. If I can be of any help feel free to PM me.
Best of luck with your project!