Pope Francis, who has been batting double pneumonia in hospital for almost three weeks, remained stable throughout the day and has not had any new breathing crises, the Vatican said.
The 88-year-old was admitted to Rome's Gemelli hospital on 14 February with a severe respiratory infection that has triggered other complications, which doctors have not yet been able to overcome.
The Vatican said the pope spent the day sat in an armchair and resumed some work activity.
He will again receive non-invasive ventilation overnight.
Francis suffered what the Vatican described as two episodes of "acute respiratory insufficiency" on Monday.
Yesterday's health bulletin was more upbeat, saying the pope was stable throughout the day and did not have any new breathing crises.
However, his doctors reiterated again that his prognosis was "guarded," meaning he was not yet out of danger.
'Worried about him'
"I think it's serious, very serious. Of course, we are all very worried about him," Liana Cardozo, a tourist from Brazil, said at St Peter's Square.
The pope has not been seen in public since entering hospital, his longest such absence since his papacy started 12 years ago. His doctors have not said how long the treatment might last.
Francis' prolonged absence has stoked speculation, even from senior cardinals, that he could follow in the footsteps of his predecessor Benedict XVI and resign.
But biographers and friends of the pontiff described him as a "fighter," with no plans to resign.
His illness has meant that the pope has already missed a number of Church events, including a 5 March service known as Ash Wednesday, which marks the start of a 40-day period leading to Easter Sunday and which he normally presides over.
Francis has experienced several bouts of ill health over the last two years and is prone to lung infections because he had pleurisy as a young adult and had part of one lung removed.
Double pneumonia is a serious infection in both lungs that can inflame and scar them, making it difficult to breathe.
