ROME – Amid what is now his third week in the hospital, Pope Francis Monday suffered what doctors described as two incidents of “acute” respiratory difficulty that required him to be put back on a ventilator.

In a March 3 statement, the Vatican said that “today the Holy Father experienced two episodes of acute respiratory insufficiency” caused by a “significant accumulation” of mucus in his bronchi, or tubes that connect the lungs to the windpipe.

As a result, the pope experienced a bronchospasm, when the muscles lining the bronchi constrict and narrow, limiting the amount of oxygen the body receives.

Doctors then performed what the Vatican said was a bronchoscopy, meaning a procedure in which doctors look into the airways in the lungs using a small lighted tube, and suctioned out “significant secretions” of mucus from his airways.

Francis in light of these episodes was placed back on a non-invasive mechanical ventilator, a step between the regular oxygen mask and a full mechanical ventilator in which the patient is intubated, on Monday afternoon.

Referred to as NIV, this form of ventilation consists of tightly sealing the oxygen mask to the nose and mouth so there is no passage of air, inducing pressure that is helpful for inhalation, when the patient is too weak to inhale properly on their own.

Doctors said the pope “always remained vigilant, oriented and collaborative” throughout the ordeal.

Given the complexity of his infection and double pneumonia, coupled with his age and underlying respiratory difficulties, his prognosis remains “guarded,” with doctors still unwilling to commit to an overall outcome.

Pope Francis, who was admitted to Rome’s Gemelli Hospital Feb. 14 for treatment of a complex respiratory infection and bronchitis, experienced a bronchospasm Friday in which he ingested his own vomit, requiring doctors to suction his respiratory tract and place him on NIV.

Doctors at the time described the incident as “isolated” and the pope was taken off of ventilation Sunday, while continuing to receive high-flow oxygen therapy administered through the nose.

His two episodes and additional bronchospasm on Monday mark another downturn for the 88-year-old pontiff, and his need for additional use of a ventilator raises questions about the toll his illness has taken on his already fragile respiratory system.

Francis has suffered respiratory illnesses, which are especially dangerous for the pope, who is missing part of one lung and who has chronic respiratory difficulties, with increased frequency in the past two years.

He has also experienced two falls in recent months at his Vatican residence, once in December resulting in a bruise to his chin, and once in January that caused an injury to his arm requiring it to be immobilized for several days.

Prayers are being offered for the pope daily throughout the world, including a daily hour of adoration and two daily Masses at Gemelli Hospital.

A nightly rosary is also being offered in St. Peter’s Square, which on Monday is scheduled to be led by American Cardinal Robert Prevost, head of the Vatican’s Dicastery for Bishops.

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