BOSTON — Carlton Haynes hugged his left knee, pulling it toward his shoulder as hard as he could. He was desperate to blunt the pain shooting from an open, oozing wound on his right shin. Anahita Dua, a vascular surgeon leading an unusual clinic created by Massachusetts General Hospital that Saturday, told him he was going to the ER and then the OR, where she would remove damaged skin and treat the wound.

Without this stopgap measure, she warned him, he’d almost certainly need amputation. OK, he said, but first he wanted a smoke.

So vascular surgery resident Sujin Lee rolled Haynes, 56, in a wheelchair into the elevator down four flights to the street, wondering how far they would need to go in the spitting rain to leave the hospital’s no-smoking zone. In anticipation, Haynes pulled a cigarette from his pack of Winstons.

“Do you have a lighter?” he asked.

No, she didn’t. Passersby and drivers in parked cars were no help either, as Lee dashed down the street. Then she told Haynes they should head back inside the hospital.