From an email from a Sefardi halakha mailing list:
Please stop, pray, and recite Tehillim for Maran HaGaon HaRav Ovadia Yosef Shlita who is now in a state of medically induced coma and is on a respirator. The Hacham's condition had deteriorated last night. The Rav's children are at his bedside at this time.
"Haim" has just been added to the Rav's name, which is now Ovadia Haim Yosef ben Gorjieh. [There are various spellings and pronounciations used for Rabbi Yosef's mother's name, which is almost certainly "Georgia."]
It is being stressed that The Rav’s major organs are not failing and the decision to place him into a medically induced coma and on a mechanical respirator was made to permit the elderly Rav’s body to rest, and NOT due to system failure B”H.
A spokesperson for the Hadassah Ein Kerem Hospital reportedly confirmed Yosef's condition.
"Due to Rabbi Ovadia Yosef's deteriorating respiratory condition, it was decided to provide him with preventative respiratory support. His condition is otherwise the same," the spokesperson told Ha'aretz.