How it affects the rest of their playoff series against the St. Louis Blues remains to be seen.
Seabrook was suspended for three games by the NHL on his 29th birthday for his elbow to Backes' head late in the third period of St. Louis' 4-3 overtime win in Game 2.
Now Chicago has to dig out of a 2-0 hole without one of its best defensemen in a rocky start to its Stanley Cup title defense.
''You need his size, you need his presence and experience and his leadership,'' Blackhawks coach Joel Quenneville said before Seabrook's suspension was announced. ''He's got the big shot on the point and he's on our power play as well. He kills penalties, so he plays all important minutes.''
Seabrook received a five-minute major and game misconduct penalty after he wiped out Backes at 15:09 of the third, and the Blues used the resulting power play to score the tying goal with 6.4 seconds left in regulation on Vladimir Tarasenko's long wrist shot.
Backes had to be helped off the ice and did not return. The captain has been ruled out for Game 3.
Backes and Seabrook were not made available to the media on the day off, but much of the talk centered on the hit anyway. The TV broadcast picked up someone taunting Backes in the aftermath of the big blow, but it was unclear if it was coming from the ice or the crowd in the corner where the play occurred.
''I saw them talking to him. It makes it a little more gutless,'' Blues forward Ryan Reaves said. ''I don't think there's any need for that. He doesn't even know where he really is. I think if they want to start getting into that battle, we can play the same way. We'll see where it takes us.''
Quenneville said he did not see or hear any players taunting Backes after he went down.
In addition to the hit by Seabrook, Hitchcock also was upset by Bryan Bickell's knee-on-knee collision with Blues center Vladimir Sobotka in the third. He said the Blackhawks forward was involved in a similar play with defenseman Alex Pietrangelo in the first.
''That part bothers me more than the hit on David, a hit that went array,'' Hitchcock said. ''The hit on Sobotka was a continuation of what happened to Petro in the first period.''
Here are five things to watch in Game 3 of this increasingly testy series:
HOME SWEET HOME: The Blackhawks went 11-2 at home in the playoffs last year, outscoring the Wild, Red Wings, Kings and Bruins by a combined score of 41-23. They went 27-7-7 at the United Center this season, including a 2-0-1 mark against the Blues.
''You just feed off of it,'' Quenneville said. ''It'll be exciting to get back here, get some of the positive vibes off it and look to turn this thing around.''
VLADIMIR THE GREAT: Tarasenko missed the last 15 games of the regular season with a broken right thumb. But the 22-year-old Russian forward caused all sorts of headaches for the Blackhawks in the first two games of the series.
The speedy Tarasenko had a first-period goal in the playoff opener, and then had the tying power-play score in Saturday's victory. With Seabrook out for the next three games and Backes' status in question, Tarasenko could take on a more prominent role for the rest of the series.
SO MANY PENALTIES: The Blues and Blackhawks combined for 17 penalties and 61 penalty minutes in Game 2. The defending Stanley Cup champions were responsible for 11 of those penalties and 41 penalty minutes, both season highs.
It looked as if the Blackhawks wanted to match the physicality of the Blues, and it took them out of their puck possession game at times.
''I think a little bit we might have played into their hands, but we've got to get back to our hockey, because when we're playing that way we do a good job and that's how we win,'' Chicago forward Brandon Saad said.
BEEN HERE BEFORE: St. Louis began last year's playoffs with a pair of 2-1 victories over Los Angeles at home, including an overtime win in the opener. The Blues then lost the next four games against the Kings.
''We played the best game all year Game 3 in Los Angeles and lost,'' Hitchcock said.
''This is going to be a very long series and we're going to have to be better than we've been if we expect to win a game in Chicago.''
ABOUT THOSE GOALTENDERS: Blues goalie Ryan Miller has been solid since Chicago's three-goal first period in Game 1. He had 25 saves in Saturday's win, and all three of the Blackhawks' goals came with traffic in front of the net.
Corey Crawford made 48 saves for Chicago in the triple-overtime opener, but he was disappointed with his 27-save performance in Game 2.
''He said he needs to be better, and he needs to be better,'' Quenneville said.
AP Sports Writer R.B. Fallstrom in St. Louis contributed to this report.
Jay Cohen can be reached at http://www.twitter.com/jcohenap