Former US president George H.W. Bush on Wednesday was admitted to an intensive care unit in Houston, suffering from pneumonia, Bush's office said, adding that his wife Barbara Bush has also been hospitalized.
The 92-year-old ex-president, who was initially hospitalized on Saturday, was moved to intensive care "to address an acute respiratory problem stemming from pneumonia," Bush's office said in a statement.
"Doctors performed a procedure to protect and clear his airway that required sedation."
He was originally admitted to Houston Methodist Hospital for shortness of breath, Bush spokesman Jim McGrath posted on Twitter.
"President Bush is stable and resting comfortably in the ICU, where he will remain for observation," the office said.
Early Wednesday, the former first lady, 91, was also admitted to the same hospital "as a precaution after experiencing fatigue and coughing," it said.
Bush, who served as president from 1989 to 1993, is the oldest of the four living former US presidents and uses a wheelchair. He has seemed frail in recent public appearances, AFP reported.