The Penguins game Wednesday was costly for the Islanders beyond the loss of goaltender Rick DiPietro; Blake Comeau is out with a concussion as well.
There is no immediate timetable for him, the Islanders said. He will be monitored daily.
Comeau suffered the head injury after taking a hard, blind-side hit from Max Talbot during the first period; no penalty was assessed to Talbot on the play.
Comeau did not miss a shift during the game, but felt unwell during practice yesterday, forcing him to leave early.
"He showed signs that we was fine [Wednesday night] and that nothing was wrong and then yesterday he said he wasn't feeling well," Capuano said.
With Comeau out of the lineup, enforcer Trevor Gillies will play tonight.