The Pope's condition has deteriorated after suffering a "prolonged asthma-like respiratory crisis" earlier today February 22.
The Vatican said Pope Francis is "not out of danger" and remains critical after experiencing the respiratory crisis, which required high-flow oxygen.
The 88-year old Argentine also required blood transfusions, due to blood tests revealing thrombocytopenia, which is associated with anemia.
The Vatican confirmed in a statement: "The condition of the Holy Father continues to be critical. Therefore, as explained yesterday, the Pope is not out of danger."
It added: "The Holy Father remains alert and spent the day in an armchair, although he is more uncomfortable than yesterday. At the moment, the prognosis remains guarded."
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On Friday his doctors said there was no imminent risk to his life but he was "not out of danger".
The Pope was admitted to Rome's Gemelli hospital on 14 February to treat bronchitis after days spent with difficulty breathing.
The Vatican confirmed on 17 February he had a "polymicrobial infection" of his respiratory tract, which required a change in treatment.
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Having had part of one lung removed after a pulmonary infection aged 21, Pope Francis has previously experienced respiratory problems and was diagnosed with pneumonia in 2023 when he stayed in hospital for three days.
He has had to cancel his regular weekly prayer on Sunday in St Peter's Square for two weeks' running as well as a speech at Rome's Cinecitta film studios, as part of the Catholic Church's Holy Year celebrations.