According to this audio of the emergency call, the pop star was, indeed, unconscious upon the arrival of EMTs -- and she was revived with Narcan, an emergency medication to reverse the effects of a narcotic overdose
Who Administered the Narcan?
Per Us Weekly: "One of her friends had Narcan on hand in case something like this happened. Her friends knew this was coming because she’s been using so much again. They were up all night partying the night before at her house. Luckily, the Narcan worked and she will recover."
Who Called the Paramedics?
We turn to Us Weekly again for this part of the story: "She had two friends with her at her house that called 911. They were hysterical when paramedics arrived and Demi was unconscious. But the friends acted very quickly and saved her life." (We cannot verify this report at this time.)
So... Those Close to Lovato Knew She Was in Trouble?
Yes, some of those close to her. TMZ reports that Lovato got into a major argument with her sober coach about a month ago and that a handful of friends were well aware she was using drugs again, weeks before she confessed to a relapse in the track "Sober."
More Insight Into Lovato of Late:
An Entertainment Tonight source says that, recently, Lovato has been "depressed, has anxiety and is always late, adding: "Slowly people she cared about started to drift away from her, because it was an unhealthy situation to be around. People stopped wanting to work with her, and she pushed away people who actually had her best interest in mind ... She's just not in a good place."
A History of Addiction
In 2010, Lovato entered rehab after getting into a fight with a backup dancer. In 2013, she checked into a sober living facility. Ever since, Demi has been very open about her struggles with substance abuse and with an eating disorder.