Pope Francis was in stable condition Tuesday and breathing with just the help of supplemental oxygen after respiratory crises a day earlier, but will resume using a ventilation mask at night, the Vatican said.

Pope Francis was described by doctors as being in stable condition Tuesday following additional respiratory difficulties a day prior, however, he continues to use periodic ventilation and his prognosis remains unclear.

Francis suffered the two crises Monday. Doctors extracted “copious” amounts of mucus that had accumulated in his lungs, the Vatican said in a late update.