Pope Francis suffered two respiratory attacks on Monday, more than two weeks into a hospital stay for pneumonia.

Doctors had to intervene to extract a large build-up of mucus from the lungs of the 88 year-old, who is battling double pneumonia in the Gemelli Hospital in Rome.

“Today, the Holy Father experienced two episodes of acute respiratory failure, caused by a significant accumulation of endobronchial mucus and consequent bronchospasm,” the Vatican said in a statement released on Monday evening.

The medical team looking after him intervened to aspirate. The Pope, who has been in hospital since Feb 14, was put back on non-invasive mechanical ventilation, the Vatican said.

Despite the acute breathing difficulties, the Pope remained alert and co-operated fully with doctors, the Holy See said. His prognosis remains guarded.

The latest respiratory crisis appeared to be another significant setback in the Pope’s attempts to recover from bronchitis and pneumonia in both lungs.