Dorian told reporters that Karlsson will not accompany the Senators (1-0-2) on their current three-game road trip, a trek that includes visits to the Calgary Flames on Friday and Edmonton Oilers the following day.
"We are hopeful that he will play at some point in time next week," Dorion said of the two-time Norris Trophy winner.
Karlsson is recovering from offseason surgery to repair torn tendons in his left foot.
"It's all about conditioning and he has to get used to a different sensation in his foot, but there is no setback at all," Dorion said. "We talked before we left (for the road trip) that the best thing to get him ready is to have him skate with (player development coach) Shean Donovan on a daily basis.
"With Erik, I know he's putting in a lot of hard work on the ice and in the gym to come and help this team sooner than later. It's just conditioning. We all know when Erik steps into the lineup he is not going to play seven minutes. He will play his usual 25 minutes to 30 minutes. I think when you have to play that many minutes, you have to be in shape. Even though Erik is special and in great shape, the more we can get him in that great shape the best it will be for everyone."
Karlsson recorded 18 points while playing in all 19 postseason games last spring for Ottawa in its run to the Eastern Conference final. The Senators fell to eventual Stanley Cup champion Pittsburgh.
The 27-year-old Swede, who led all NHL defensemen in scoring in three of the last four seasons, has collected 117 goals, 339 assists and 280 penalty minutes in 556 career contests.