Raffl was injured when he was checked into the boards by Gabriel Landeskog with about three minutes left in the first period. After the game, Raffl did not speak with reporters, but he appeared glassy-eyed.
Landeskog was not penalized on the play, and Flyers coach Craig Berube said he thought it was a clean hit.
The Flyers were already without Read.
"You're missing two good forwards . . . but guys have to step up," Berube said. "Injuries happen, so there's no sense worrying about it."
If Read returns, this is how the lines may look Saturday:
Giroux centering Voracek and Scott Hartnell.
Brayden Schenn centering Wayne Simmonds and Vinny Lecavalier.
Couturier centering Read and Steve Downie.
Adam Hall centering Chris VandeVelde and Zac Rinaldo.
VandeVelde may play to eat up some of the penalty-killing time that Raffl provided.
Thursday's loss snapped the Flyers' four-game winning streak; they are 3-1 on the six-game road trip.
"We're not playing our best," said Couturier, whose neutral-zone turnover led to Colorado's first goal. He said the Flyers played a strong road game Thursday, "but didn't get the results. We have six points out of eight on the trip and haven't played our best. It's nice to get the points, but we have to build off this and get better."
Berube was happy with his team's effort against the Avs.
"The team played good. I thought everybody did. We didn't have any passengers," he said. "The team showed up and played a good, solid, hard game. It's tough. You come to Colorado and with the altitude, it's not easy. I've played in it, and it's not an easy thing. . . . The guys played smart; they kept their shifts short."
But they ran into a hot goaltender, Semyon Varlamov, who sent them to just their second regulation loss in the last 10 games (7-2-1). Varlamov made nine of his 29 saves on the Flyers' three power plays.
Breakaways. Phoenix captain Shane Doan (12 goals) has been cleared to play. The 37-year-old center was found to have Rocky Mountain Spotted Fever in December and hasn't played since Dec. 4. Phoenix went 4-3-5 in the 12 games Doan missed. . . . Steve Mason, who made 29 saves and was outstanding Thursday, suffered his first regulation loss in the last nine games. . . . Simmonds' goal gave him seven tallies in the last five games. . . . With Raffl out, Schenn played a career-high 21:40. . . . Giroux played 23:08 but was held without a point. It marked the first time in nearly two months that he had consecutive games without a point.