By the morning of March 4, Rome time (afternoon of March 4, Vietnam time), Pope Francis had switched from non-invasive ventilation to receiving high-dose oxygen through a nasal cannula.

The Holy See Press Office added that the Holy Father continues his respiratory treatment and physiotherapy.

In an earlier press release, the Vatican said Pope Francis "experienced two episodes of acute respiratory failure, caused by a buildup of phlegm in the bronchi, leading to bronchospasm."

Acute respiratory failure is a condition in which the lungs cannot deliver enough oxygen to the blood, or carbon _dioxide builds up in the body.

In a statement on March 4, the Vatican did not say whether the pope was anesthetized during the bronchoscopy.

An unnamed Vatican official said the Pope's blood test results on March 3 were stable.

The medical team treating the patient believes that acute respiratory failure is part of the body's normal response to fighting an infection.

The Holy See Press Office said that while it was not yet possible to give a prognosis for the Pope's health, he remained alert and cooperative during his latest episode of acute respiratory failure and required two bronchoscopy procedures.

The Pope continues to rest and has no plans to visit on March 4.

The Pope has been hospitalized since February 14 and has not appeared in public yet.