The former Wigan Athletic and Birmingham City boss believes that the second season is always the most difficult for teams promoted from the Championship to the top flight.
"In my experience the second season is always the most difficult because the expectation has risen a bit," Bruce told ITV Sport.
"We've brought in four, five, six players to strengthen the squad, but everybody's expectation is that we're going to stay in the division comfortably.
"I'm certainly aware that it's going to be difficult, this league. Everybody else has improved their squads. You look at squad by squad, they've all got bigger and better, and we hope that we've done enough, certainly by the end of the window, to stay there."
Hull travel to Loftus Road to take on Queens Park Rangers this afternoon.
Click here for our live commentary of the match.