Ehlers had to be helped off the ice after the hit, which came late in the third period of Washington's 4-3 overtime win.
No penalty was called on the play.
"I'm disappointed," Lowry said. "When you lose a player, you're disappointed. We have the luxury of replay. It's a fast game. The four of them didn't see it the same way we saw it."
Lowry said Ehlers will be re-evaluated on Wednesday.
Ehlers is third in team scoring with 25 points (13 goals, 12 assists) this season.