Senate Appropriations Chairman Daniel K. Inouye has been hospitalized as doctors work to manage his oxygen intake.

“For the most part, I am OK. However, I am currently working with my doctors to regulate my oxygen intake. Much to my frustration, while undergoing this process, I have to remain in the hospital for my own safety and to allow the necessary observation,” the Hawaii Democrat said in a statement released by his office. “I will be back on the Hill as soon as my doctors allow it.”

Inouye is currently at the Walter Reed National Military Medical Center in Bethesda, Md.

The 88-year old Inouye missed floor votes on Dec. 6 for what was described at the time as a physical examination. He also missed a meeting with New Jersey Gov. Chris Christie, who visited the Capitol that day seeking support for a supplemental spending bill to help deal with the recovery from superstorm Sandy.

Inouye was at the George Washington Unviersity hospital that day and was said to remain at the GWU facility until Sunday, when he was taken to the complex in Bethesda.

An Inouye aide previously explained that the senator had a “sizeable portion of his left lung removed” during the 1960’s following an improper diagnosis of lung cancer.

Inouye is not only the most senior senator, he also serves as the president pro tem — a constitutional position that puts him third in line for the presidency.

Despite his age, Inouye said in an interview over the summer that if he maintains his health, he plans to seek another term in 2016.

“Other than my knees, I’m in terrific shape,” Inouye said at the time.

Kerry Young contributed to this report.