Pope Francis, in critical condition with a complicated lung infection, rested well during a peaceful night following a respiratory crisis and blood transfusions, the Vatican said Sunday.

Vatican spokesperson Matteo Bruni's one-line statement didn't mention if Francis was up or eating breakfast. "The night passed quietly, the pope rested."

The brief update came after doctors said the 88-year-old pope, who had part of one lung removed as a young man, was in critical condition. On Saturday morning, he suffered a prolonged asthmatic respiratory crisis while being treated for pneumonia and a complex lung infection.

The pope received "high flows" of oxygen to help him breathe. He also received blood transfusions after tests showed low counts of platelets, which are needed for clotting, the Vatican said in a late update.

The Saturday statement also said that the pontiff "continues to be alert and spent the day in an armchair although in more pain than yesterday." Doctors said the prognosis was "reserved."

Doctors have said Francis’ condition is touch-and-go, given his age, fragility and pre-existing lung disease.

Main threat facing pope is sepsis

They have warned that the main threat facing Francis would be the onset of sepsis, a serious infection of the blood that can occur as a complication of pneumonia. As of Friday, there was no evidence of any sepsis, and Francis was responding to the various drugs he is taking, the pope’s medical team said in their first in-depth update on the pope’s condition.

Saturday’s blood tests showed that he had developed a low platelet count, a condition called platelopenia or thrombocytopenia. Platelets are cell-like fragments that circulate in the blood that help form blood clots to stop bleeding or help wounds heal. Low platelet counts can be caused by a number of things, including side effects from medicines or infections, according to the U.S. National Institutes of Health.

Francis, who has chronic lung disease and is prone to bronchitis in winter, was admitted to Gemelli hospital on Feb. 14 after a weeklong bout of bronchitis worsened.

Doctors first diagnosed the complex viral, bacterial and fungal respiratory tract infection and then the onset of pneumonia in both lungs. They prescribed "absolute rest" and a combination of cortisone and antibiotics, along with supplemental oxygen when he needs it.

Speculation that Francis might resign

Meanwhile, the Vatican hierarchy went on the defensive to tamp down rumors and speculation that Francis might decide to resign. There is no provision in canon law for what to do if a pope becomes incapacitated. Francis has said that he has written a letter of resignation that would be invoked if he were medically incapable of making such a decision. The pope remains fully conscious, alert, eating and working.

The Vatican secretary of state, Cardinal Pietro Parolin, gave a rare interview to Corriere della Sera to respond to speculation and rumors about a possible resignation. It came after the Vatican issued an unusual and official denial of an Italian media report that said Parolin and the pope’s chief canonist had visited Francis in the hospital in secret. Given the canonical requirements to make a resignation legitimate, the implications of such a meeting were significant, but the Vatican flat-out denied that any such meeting occurred.

Parolin said such speculation seemed "useless" when what really mattered was the health of Francis, his recovery and return to the Vatican.

"On the other hand, I think it is quite normal that in these situations uncontrolled rumors can spread or some misplaced comment is uttered. It is certainly not the first time it has happened," Parolin was quoted as saying. "However, I don’t think there is any particular movement, and so far I haven’t heard anything like that."

Holy Year celebrations continue

Deacons, meanwhile, were gathering at the Vatican for their special Holy Year weekend. Francis got sick at the start of the Vatican’s Holy Year, the once-every-quarter-century celebration of Catholicism. This weekend, Francis was supposed to have celebrated deacons, a ministry in the church that precedes ordination to the priesthood.

In his place, the Holy Year organizer was to celebrate Sunday’s Mass, the Vatican said. And for the second consecutive weekend, Francis is skipping his traditional Sunday noon blessing, which he could have delivered from Gemelli if he were up to it.

"Look, even though he’s not [physically] here, we know he’s here," said Luis Arnaldo Lopez Quirindongo, a deacon from Ponce, Puerto Rico, who was at the Vatican on Saturday for the Jubilee celebration. "He’s recovering, but he’s in our hearts and is accompanying us, because our prayers and his go together."