Many who know him said that Francis, driven by a sense of mission and a discipline born of his early training, essentially worked himself into the hospital.

The Vatican said Pope Francis is "not out of danger" on Feb. 22. They explained that the Holy Father required "high flows" of oxygen after he suffered from a prolonged asthmatic respiratory crisis. Blood transfusions were also required for the Pope after prior tests revealed he had a low platelet count.

The health of Pope Francis, who has been hospitalized for over a week with pneumonia, worsened on Saturday, raising fears that the pontiff might not survive his struggle with respiratory infections.

The Vatican said on Saturday that Pope Francis' health had deteriorated over the past 24 hours and for the first time described his condition as "critical", reporting he had needed supplemental oxygen and blood transfusions.