Rome. Pope Francis suffered two acute respiratory crises Monday and was placed back on noninvasive mechanical ventilation, marking another setback in his battle with pneumonia, the Vatican said.

Doctors performed two bronchoscopies to extract "copious" amounts of mucus from his lungs. The Vatican said the mucus was a reaction to the original pneumonia infection rather than a new one, as lab tests showed no additional bacterial presence.

Francis, 88, remained alert and cooperative with medical staff. While the Vatican did not explicitly say he was stable, it referred to the crises in the past tense, suggesting they had passed.

The pontiff, who has chronic lung disease and previously had part of one lung removed, has been battling a complex respiratory infection for more than two weeks.

Dr. John Coleman, a pulmonary critical care specialist at Northwestern Medicine in Chicago, said the latest episodes were more concerning than Friday’s, when Francis suffered a coughing fit, inhaled vomit, and briefly required ventilation.

"The fact that they had to manually remove mucus suggests he’s struggling to clear his airways on his own," said Coleman, who is not involved in Francis' care. "He's taking steps forward, then back."

The Vatican later said the episodes were caused by a "significant accumulation" of mucus and bronchial spasms. The pope was again placed on noninvasive ventilation, which pumps oxygen into the lungs via a mask.

Francis, who is wheelchair-bound and overweight, had been undergoing respiratory physiotherapy to improve lung function. However, the buildup of secretions indicates he may lack the muscle strength to cough forcefully enough to clear his lungs.

The Vatican has not released any images or videos of Francis since before he was hospitalized on Feb. 14, marking the longest absence of his 12-year papacy. The Holy See has defended his decision to recover in private.

On Monday, one of Francis’ close advisers, Archbishop Vincenzo Paglia, encouraged him to make his voice heard, saying, "The world needs leaders like him—universal, not one-sided."

Francis sent a message to a Vatican bioethics conference, lamenting the growing ineffectiveness of international organizations and their focus on national interests. The note, dated Feb. 26, was signed "from Gemelli Polyclinic."

Noninvasive ventilation is often used to avoid intubation, and Francis has not been intubated during this hospitalization. It is unclear if he has given advance directives regarding his care should his condition worsen.

Catholic teaching mandates the defense of life from conception until natural death. While patients must receive basic care, the church allows discontinuation of "extraordinary" treatments if they are no longer beneficial.

Francis has previously endorsed this stance, stating in 2017 that withdrawing "overzealous treatment" can be a moral decision.

Paglia, whose office oversees the church's bioethics policies, said Francis would follow these principles like any other Catholic.

"Today, the pope is giving us an extraordinary lesson on fragility," he said. "Not with words, but with his body."

Francis’ 17-night hospitalization remains far from the longest papal stay. St. John Paul II spent 55 days at Gemelli in 1981 after surgery and complications from an infection.