ROME – Pope Francis today suffered two incidents of “acute” respiratory difficulty that required him to be put back on a ventilator.

In a statement, the Vatican said that “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, the tubes that connect the windpipe to the lungs, constrict and narrow, limiting the amount of oxygen the body receives.