Pope Francis' condition appeared to stabilize on Tuesday morning after medical intervention amid two episodes of "acute respiratory failure" on Monday, Vatican sources told ABC News. The pope, 88, was taken off noninvasive mechanical ventilation and resumed receiving supplemental oxygen through a nasal tube,

The 88-year-old, who had part of one lung removed as a young man, experienced two acute respiratory crises on Monday.

Pope Francis suffered two episodes of acute respiratory insufficiency and went back on a ventilator as he remains hospitalized for double pneumonia, the Vatican said Monday night.