Former President George H.W. Bush, the 41st president of the United States, has been hospitalized in Houston with a case of pneumonia. Reports suggest that he has been placed on a breathing tube, which would indicate that his case of pneumonia is quite severe.

Bush, who is 92, suffers from vascular parkinsonism, which is a rare syndrome similar to Parkinson’s disease. He has also been using a motorized scooter ever since injuring his vertebra back in 2015.

Pneumonia is a grave risk for the elderly, and a breathing tube indicates he’s not getting enough oxygen in the blood. As a result, doctors have had to put a soft, plastic tube down his windpipe, and then connect it to a ventilator. The tube raises the risk of a secondary infection. Bush would have been sedated for its insertion to avoid discomfort.

Pneumonia is defined as an infection in the lungs. It can affect people of all ages, but it is most risky for the young and the elderly.

The diagnosis prevented him from making the inauguration of Donald Trump on Friday.