Demi Lovato's Assistant Screamed 'She's Dead!' As Bodyguard May Have Saved Her Life

Demi Lovato was in such dire condition when she OD'd her assistant thought she was dead, and one of her bodyguards may have saved her life ... TMZ has learned.

Sources with direct knowledge tell TMZ, the bodyguard somehow knew there was an emergency at Demi's home a week ago Tuesday morning, and when he entered the home Demi's assistant was screaming, "She's dead, she's dead!"

We're told the bodyguard rushed to Demi's side and it appeared she was not breathing. Our sources say there was blood on her pillow ... an ominous sign, because it's evidence of hemorrhaging. It appears there was also vomit and her airways may have been clogged.

Our sources say the bodyguard administered some sort of first aid to keep Demi alive before paramedics arrived. Based on what we're told it appears the bodyguard propped Demi up and tried clearing her airway which allowed her to breathe.

As we reported ... when paramedics arrived they administered Narcan, which reverses the effects of an opioid OD.

Our sources say the bodyguard, the assistant and others on Demi's team were aware she had fallen off the wagon months before. As early as Coachella in April, we're told Demi was "way out of it" at French Montana's house party.