Pope Francis, battling double pneumonia in hospital for two weeks, had an "isolated breathing crisis" on Friday and received "non-invasive mechanical ventilation" to help him breathe, the Vatican said in a statement.

Amid ongoing health issues facing Pope Francis, here is the process by the Vatican when a pontiff passes away.

The Vatican, though, made alternative plans for Ash Wednesday next week, making clear Francis still had a long road ahead. Cardinal Angelo De Donatis, a Vatican official and former vicar of Rome, will preside over the March 5 ceremony and procession that inaugurates the church’s solemn Lenten season leading up to Easter in April.