In a personification of the old cliche “The show must go on,” Mandy Patinkin gamely mined his repertoire Saturday night at the Maine Center for the Arts in Orono.

The Broadway veteran was suffering from an unspecified respiratory ailment, something to which he readily admitted: “I’m dying here. I’ve got enough drugs in me to take care of all your families through 2097.”

Which made for a decidedly offbeat, but very entertaining, evening. Because of his condition, the singer and his accompanist, Paul Ford, constantly were editing his regular program, subbing songs in and out, searching for what he could best perform.

This led to a significant amount of audience participation. Patinkin took requests, which he strived to fulfill, even at one point signaling offstage for a songbook so he could refresh his memory with the lyrics for “Brother, Can You Spare a Dime?”

He also brought members of the near-capacity crowd on stage to help out. A 3 1/2-year-old boy, Simeon, although clearly uncomfortable, sang “Twinkle, Twinkle, Little Star.” As his mother led Simeon back to his seat, Patinkin asked, “Who wants to come up next, because it will save my voice?”

Patinkin also told stories, and oh, the stories he’d tell. He reminisced about how his father had taken him to New York City as a bar-mitzvah present, to see Angela Lansbury, his father’s favorite performer, in “Mame,” and how, 13 years later, he sat chatting with Lansbury at a party, shortly after his father died at the age of 52. She introduced him to the composer with whom he would become most intricately linked, Stephen Sondheim, who played “Anyone Can Whistle” for Patinkin on piano.

Patinkin’s most recent album is a tribute to Sondheim, and he sang as much Sondheim as he could Saturday night. But his ailment forced him to reach deep into his repertoire, including the Irving Berlin song “Cohen Owes Me Ninety Seven Dollars.” Several times he lost his way lyrically, but the audience didn’t mind, as they were so enjoying an old pro doing his level best to entertain them, awarding him with a standing ovation at the end of the longer-than-scheduled show.