Laughton was down on the ice for several minutes and immobilized before he was taken off.
"You never like to see that," Carlson told the Washington Times. "I was thinking about him. I hope he's fine. I haven't heard anything. It's just one of those plays where we're kind of even and he tries to stick-handle through me and take it to the net. I'm just trying to defend him."
Laughton was transported to Thomas Jefferson University Hospital. The Flyers said he would stay overnight for precautionary reasons, and that all tests were negative.
"Your first thought is always concern for the player, for your teammate," Flyers coach Dave Hakstol told ESPN. "It's never a sight you want to see. Thoughts right now are just, we don't know a whole lot more than you guys know, but hopefully Scotty will be fine."
In two Stanley Cup Playoff games entering Wednesday, Laughton, 21, had a minus-1 rating and seven shots on goal.
The Flyers avoided being swept with a 2-1 win. Game 5 is at Verizon Center in Washington on Friday (7 p.m. ET; NBCSN, CBC, TVA Sports, CSN-PH, CSN-DC). The Capitals lead the best-of-7 series 3-1.
"I mean, when that happens, hockey is in the rearview," Flyers defenseman Shayne Gostisbehere told the newspaper. "We just wanted to make sure he was OK. We're praying for him and hope he's doing well. We just told him that we're here for him. This [win] is for him, and we're going to keep going."