Pope Francis is in critical condition after experiencing respiratory problems on Saturday. 

"This morning, Pope Francis experienced an asthma-like respiratory crisis of prolonged intensity, which required the administration of high-flow oxygen," the Vatican announced in a statement. 

"Today's blood tests also revealed thrombocytopenia, associated with anemia, which required the administration of blood transfusions." 

Francis, 88, was admitted to Gemelli Hospital on Feb. 14 after a weeklong bout of bronchitis. He is now said to have double pneumonia, which is complicated by chronic bronchiectasis and asthmatic bronchitis. 

The Vatican said Francis is alert and "spent the day in an armchair, although he is more uncomfortable than yesterday." His prognosis is "guarded." 

"The condition of the Holy Father continues to be critical," according to the statement. "Therefore, as explained yesterday, the Pope is not out of danger."

On Friday, Dr. Sergio Alfieri, the head of medicine and surgery at Rome's Gemelli Hospital, said at a press conference that the biggest concern is sepsis. 

"Sepsis, with his respiratory problems and his age, would be really difficult to get out of," he said. "But this is the real risk in these cases: that these germs pass to the bloodstream."

"He knows he's in danger," Alfieri added. "And he told us to relay that."

“To the question ‘is the pope out of danger?’ No, the pope is not out of danger,” he added. “If you then ask if in this moment the pope is in a life-threatening situation, the answer is also no.”

Francis has led the Catholic church since 2013. 

Last week, he was spotted wearing a sling on his arm after a fall at his residence. It was his second fall in several weeks.