The 23-year-old lay motionless behind the Calgary Flames' net before medical staff moved him onto the stretcher. He gave the crowd a thumbs-up as he was being taken off the ice.
Mueller had full feeling and movement in his extremities and was alert, oriented, and conscious, the team announced. He was taken to the hospital for further evaluation.
The Swiss blue-liner entered the evening with 10 points in 46 games.