ROME (AP) — The recovery of Pope Francis from double pneumonia continued Wednesday as he inched toward notching some important milestones in his papacy: The 12th anniversary Thursday of his election as pope and a near-record in length of hospital stays for a pontiff.

The Vatican reported Friday that he experienced sudden breathing problems that required “non-invasive mechanical ventilation” but that he remained “alert.”

Pope Francis, battling double pneumonia in hospital for almost a month, remains stable and a recent X-ray confirmed improvements in his condition that had been seen in previous days, the Vatican said on Wednesday.