With 6:24 left in the first period, Keith hit Sedin in open ice and got his elbow up in the Swedish forward's face. Keith was given a two-minute minor penalty for elbowing on the play.
Sedin initially came right back out to participate in the power play with Keith in the penalty box, left for the dressing room shortly after. The Canucks announced he would not return for the remainder of the game.
"Everybody saw the head shot there, so (Sedin will be) re-evaluated tomorrow and I'll know more from there," Canucks coach Alain Vigneault said.
Vigneault called the hit a "deliberate, principal point of contact, everything you're trying to take out of the game."
Keith, the Blackhawks top defenceman at the 2010 Norris Trophy winner, received only a minor penalty on the play.
"I expected a major, and I got a minor, so we'll let the league deal with it," he added. "You saw the hit, you didn't see a puck near the hit, you guys make the judgment call on that and the league will do what they have to do."
"I'm not trying to hurt anybody," Keith said "I hope he's OK. He's one of their best players. He needs to be on the ice."
The game between the two rivals became ugly after the hit, including a brawl in front of the Chicago goal at 9:09 of the second period, ending when Vancouver forward Alex Burrows wrestled Keith to the ground and punched him in the face. Keith was given a 10-minute misconduct and two roughing penalties during the melee, while Burrows was handed a roughing minor and a 10-minute misconduct.
Zack Kassian also received a 10-minute misconduct.
— With files from The Associated Press.