The defeat leaves QPR 10 points adrift of safety with only four matches remaining - a position Redknapp does not expect his side to recover from.
"It looks like that's it," the Rangers boss said. "It is almost impossible now.
"It is a big disappointment but even today I felt in the first half we were bang in the game.
"I was disappointed to come in at half-time 1-0 down as I thought we did okay in the first half."