There are services throughout the United States that help emergency medical services translate. We can use the services through 911 or at the scene via a cell phone. Each agency has to contract separately with the translation service, but they're nearly universal.
Plus, it doesn't really matter. If you can't communicate with 911 -- because you don't speak the language or because your life is in danger from a bad guy or a medical condition -- the dispatchers are still going to send someone to your location.
The problem of course is that they only know where you are located by the technology in the phone you are using. Calls to 911 from cell phones can't always pinpoint your location. If it's a landline (landline phones have a wire that goes from the phone to the wall), the 911 center will know your address, but not necessarily where you are in the building.
They also won't know what's wrong with you, but someone is coming who can figure that out.
If you have a medical emergency -- or a fire, or a bad guy -- don't ever be afraid to call 911 even if you don't speak the language.